US5650769A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radio receiver for use in a radio tracking system and a method of operation thereof
Assignee: NTP Inc
•
Filing: 1995-02-24
•
Granted: 1997-07-22
•
Expires: 2015-02-24
Abstract
Abstract A radio tracking and ranging system is disclosed which has at least one mobile radio frequency transmitter and a radio frequency receiver. The radio frequency receiver has a range control which sets a maximum range that each mobile radio frequency transmitter may be moved from the radio frequency receiver without generating an alert to the user of the radio frequency receiver. Each radio frequency transmitter has a "panic" switch which permits a user of the radio frequency transmitter to transmit an alert or alarm to the user of the radio frequency receiver. After receipt of an alert, the user of the radio frequency receiver switches the radio frequency receiver into a tracking mode for locating a direction from which a maximum signal strength is received which is indicative of the relative bearing of the radio frequency transmitter which is being tracked from the radio frequency receiver. Signal processing techniques are used to eliminate the effects of fading and interference in detecting an identification code periodically broadcast by each radio frequency transmitter and further, to eliminate the effects of fading and interference on RSSI signals which are used for determining the range of each radio frequency transmitter relative to the radio frequency receiver and tracking of each radio frequency transmitter.
Inventors
- 👤 Thomas J. Campana, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 06:04
CPC Classifications
G; G08; G08B; G08B21/00; G08B21/02; G08B21/0202; G08B21/0222; G08B21/0227; G08B21/023; G08B21/0263
Claims Analysis
Total Claims: 199
Claim 1
Independent Claim
232 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, calculating an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the calculated integrals which is updated to include newly calculated integrals only when each newly calculated integral differs from the computed average of the calculated integrals by less than a function of the average of the calculated integrals so as to exclude from the computation of the average of the calculated integrals newly calculated integrals which differ from the average of the calculated integrals by more than the function, comparing the average of the calculated integrals to a numerical value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 2
Independent Claim
232 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, calculating an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the calculated integrals which is updated to include newly calculated integrals only when each newly calculated integral differs from the computed average of the calculated integrals by less than a function of the average of the calculated integrals so as to exclude from the computation of the average of the calculated integrals newly calculated integrals which differ from the average of the calculated integrals by more than the function, comparing the average of the calculated integrals to a numerical value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 3
Dependent Claim
234 words
A method in accordance with claim 1 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by each radio frequency transmitter which is used to compute the average of the calculated integrals; and after generation of the alert using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 4
Dependent Claim
251 words
A method in accordance with claim 1 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and in response to reception of the alert from one of the at least one radio frequency transmitter using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 5
Dependent Claim
107 words
A method in accordance with claim 3 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 6
Dependent Claim
198 words
A method in accordance with claim 1 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 7
Dependent Claim
111 words
A method in accordance with claim 5 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 8
Dependent Claim
45 words
A method in accordance with claim 6 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compare sample value.
Claim 9
Dependent Claim
198 words
A method in accordance with claim 2 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 10
Dependent Claim
111 words
A method in accordance with claim 8 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 11
Dependent Claim
45 words
A method in accordance with claim 9 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 12
Dependent Claim
198 words
A method in accordance with claim 3 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 13
Dependent Claim
111 words
A method in accordance with claim 11 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 14
Dependent Claim
45 words
A method in accordance with claim 12 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 15
Dependent Claim
198 words
A method in accordance with claim 4 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 16
Dependent Claim
111 words
A method in accordance with claim 14 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 17
Dependent Claim
45 words
A method in accordance with claim 15 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 18
Dependent Claim
38 words
A method in accordance with claim 1 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 19
Dependent Claim
15 words
A method in accordance with claim 17 wherein: the amplifier is an intermediate frequency amplifier.
Claim 20
Dependent Claim
38 words
A method in accordance with claim 2 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 21
Dependent Claim
15 words
A method in accordance with claim 19 wherein: the amplifier is an intermediate frequency amplifier.
Claim 22
Dependent Claim
38 words
A method in accordance with claim 3 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 23
Dependent Claim
15 words
A method in accordance with claim 21 wherein: the amplifier is an intermediate frequency amplifier.
Claim 24
Dependent Claim
38 words
A method in accordance with claim 4 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 25
Dependent Claim
15 words
A method in accordance with claim 23 wherein: the amplifier is an intermediate frequency amplifier.
Claim 26
Dependent Claim
38 words
A method in accordance with claim 5 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 27
Dependent Claim
15 words
A method in accordance with claim 25 wherein: the amplifier is an intermediate frequency amplifier.
Claim 28
Dependent Claim
38 words
A method in accordance with claim 6 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 29
Dependent Claim
15 words
A method in accordance with claim 27 wherein: the amplifier is an intermediate frequency amplifier.
Claim 30
Dependent Claim
38 words
A method in accordance with claim 7 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 31
Dependent Claim
15 words
A method in accordance with claim 29 wherein: the amplifier is an intermediate frequency amplifier.
Claim 32
Independent Claim
174 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, calculating an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the calculated integrals which is updated to include newly calculated integrals, comparing the average of the calculated integrals to a numerical value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 33
Independent Claim
174 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, calculating an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the calculated integrals which is updated to include newly calculated integrals, comparing the average of the calculated integrals to a numerical value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 34
Dependent Claim
234 words
A method in accordance with claim 31 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by each radio frequency transmitter which is used to compute the average of the calculated integrals; and after generation of the alert using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 35
Dependent Claim
251 words
A method in accordance with claim 31 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and in response to reception of the alert from one of the at least one radio frequency transmitter using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 36
Dependent Claim
107 words
A method in accordance with claim 33 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 37
Dependent Claim
198 words
A method in accordance with claim 31 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 38
Dependent Claim
111 words
A method in accordance with claim 35 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 39
Dependent Claim
45 words
A method in accordance with claim 36 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 40
Dependent Claim
198 words
A method in accordance with claim 32 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 41
Dependent Claim
111 words
A method in accordance with claim 38 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 42
Dependent Claim
45 words
A method in accordance with claim 39 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 43
Dependent Claim
198 words
A method in accordance with claim 33 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 44
Dependent Claim
111 words
A method in accordance with claim 41 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 45
Dependent Claim
45 words
A method in accordance with claim 42 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 46
Dependent Claim
198 words
A method in accordance with claim 34 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 47
Dependent Claim
111 words
A method in accordance with claim 44 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 48
Dependent Claim
45 words
A method in accordance with claim 45 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 49
Dependent Claim
38 words
A method in accordance with claim 31 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 50
Dependent Claim
15 words
A method in accordance with claim 47 wherein: the amplifier is an intermediate frequency amplifier.
Claim 51
Dependent Claim
38 words
A method in accordance with claim 32 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 52
Dependent Claim
15 words
A method in accordance with claim 49 wherein: the amplifier is an intermediate frequency amplifier.
Claim 53
Dependent Claim
38 words
A method in accordance with claim 33 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 54
Dependent Claim
15 words
A method in accordance with claim 51 wherein: the amplifier is an intermediate frequency amplifier.
Claim 55
Dependent Claim
38 words
A method in accordance with claim 34 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 56
Dependent Claim
15 words
A method in accordance with claim 53 wherein: the amplifier is an intermediate frequency amplifier.
Claim 57
Dependent Claim
38 words
A method in accordance with claim 35 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 58
Dependent Claim
15 words
A method in accordance with claim 55 wherein: the amplifier is an intermediate frequency amplifier.
Claim 59
Dependent Claim
38 words
A method in accordance with claim 36 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 60
Dependent Claim
15 words
A method in accordance with claim 57 wherein: the amplifier is an intermediate frequency amplifier.
Claim 61
Dependent Claim
38 words
A method in accordance with claim 37 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 62
Dependent Claim
15 words
A method in accordance with claim 59 wherein: the amplifier is an intermediate frequency amplifier.
Claim 63
Independent Claim
166 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, producing a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the received signal strength indicators, comparing the average of the received signal strength indicators to a value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 64
Independent Claim
166 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, producing a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing an average of a plurality of the received signal strength indicators, comparing the average of the received signal strength indicators to a value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 65
Dependent Claim
230 words
A method in accordance with claim 61 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by each radio frequency transmitter which is used to calculate the average of the calculated integrals; and after generation of the alert using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 66
Dependent Claim
243 words
A method in accordance with claim 61 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user contains an alert; and in response to reception of the alert from one of the at least one radio frequency transmitter using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user displaying a magnitude of an integral of each successively received signal strength indicator generated in response to reception of the radio frequency carrier from the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of radio frequency receiver relative to the radio frequency receiver.
Claim 67
Dependent Claim
107 words
A method in accordance with claim 63 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 68
Dependent Claim
198 words
A method in accordance with claim 61 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 69
Dependent Claim
111 words
A method in accordance with claim 65 wherein: the processing of the detected individual cycles of the subcarrier includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 70
Dependent Claim
45 words
A method in accordance with claim 66 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 71
Dependent Claim
38 words
A method in accordance with claim 61 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 72
Dependent Claim
15 words
A method in accordance with claim 68 wherein: the amplifier is an intermediate frequency amplifier.
Claim 73
Dependent Claim
38 words
A method in accordance with claim 62 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 74
Dependent Claim
15 words
A method in accordance with claim 70 wherein: the amplifier is an intermediate frequency amplifier.
Claim 75
Dependent Claim
38 words
A method in accordance with claim 63 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 76
Dependent Claim
15 words
A method in accordance with claim 72 wherein: the amplifier is an intermediate frequency amplifier.
Claim 77
Dependent Claim
38 words
A method in accordance with claim 64 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 78
Dependent Claim
15 words
A method in accordance with claim 74 wherein: the amplifier is an intermediate frequency amplifier.
Claim 79
Dependent Claim
38 words
A method in accordance with claim 65 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 80
Dependent Claim
15 words
A method in accordance with claim 76 wherein: the amplifier is an intermediate frequency amplifier.
Claim 81
Dependent Claim
38 words
A method in accordance with claim 66 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 82
Dependent Claim
15 words
A method in accordance with claim 78 wherein: the amplifier is an intermediate frequency amplifier.
Claim 83
Dependent Claim
38 words
A method in accordance with claim 67 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 84
Dependent Claim
15 words
A method in accordance with claim 80 wherein: the amplifier is an intermediate frequency amplifier.
Claim 85
Dependent Claim
244 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, calculates an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of a plurality of the calculated integrals which is updated to include newly calculated integrals only when each newly calculated integral differs from the computed average of the calculated integrals by less than a function of the average of the calculated integrals so as to exclude from the computation of the average of the calculated integrals newly calculated integrals which differ from the average of the calculated integrals by more than the function, compares the average of the calculated integrals to a value representing the set range and generates an alert when the comparison reveals that at least one radio frequency transmitter is outside the set range.
Claim 86
Dependent Claim
244 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, calculates an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of a plurality of the calculated integrals which is updated to include newly calculated integrals only when each newly calculated integral differs from the computed average of the calculated integrals by less than a function of the average of the calculated integrals so as to exclude from the computation of the average of the calculated integrals newly calculated integrals which differ from the average of the calculated integrals by more than the function, compares the average of the calculated integrals to a value representing the set range and generates an alert when the comparison reveals that at least one radio frequency transmitter is outside the set range.
Claim 87
Dependent Claim
236 words
A radio frequency in accordance with claim 82 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by each radio frequency transmitter which is used to calculate the average of the calculated integrals; and a directional antenna, the directional antenna after generation of the alert receiving transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 88
Dependent Claim
245 words
A radio frequency receiver in accordance with claim 82 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and the directional antenna in response to reception of the alert from one of the at least one radio frequency transmitter receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of the radio frequency carrier from the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of radio frequency receiver relative to the radio frequency receiver.
Claim 89
Dependent Claim
109 words
A radio frequency receiver in accordance with claim 84 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 90
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 82 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 91
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 86 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 92
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 86 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 93
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 83 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 94
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 89 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 95
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 90 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 96
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 84 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 97
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 92 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 98
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 93 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 99
Dependent Claim
200 words
A radio frequency receiver in accordance with claim 85 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the at least one identification frame group with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the at least one identification frame group of the radio frequency transmitter and decodes the plurality of numerical values to produce at least the identification code of the radio frequency transmitter.
Claim 100
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 95 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 101
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 96 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 102
Dependent Claim
41 words
A radio receiver in accordance with claim 82 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 103
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 98 wherein: the amplifier is an intermediate frequency amplifier.
Claim 104
Dependent Claim
41 words
A radio receiver in accordance with claim 83 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 105
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 100 wherein: the amplifier is an intermediate frequency amplifier.
Claim 106
Dependent Claim
41 words
A radio receiver in accordance with claim 84 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 107
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 102 wherein: the amplifier is an intermediate frequency amplifier.
Claim 108
Dependent Claim
41 words
A radio receiver in accordance with claim 85 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 109
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 104 wherein: the amplifier is an intermediate frequency amplifier.
Claim 110
Dependent Claim
41 words
A radio receiver in accordance with claim 86 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 111
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 106 wherein: the amplifier is an intermediate frequency amplifier.
Claim 112
Dependent Claim
41 words
A radio receiver in accordance with claim 87 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 113
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 108 wherein: the amplifier is an intermediate frequency amplifier.
Claim 114
Dependent Claim
41 words
A radio receiver in accordance with claim 88 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 115
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 110 wherein: the amplifier is an intermediate frequency amplifier.
Claim 116
Dependent Claim
184 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, calculates an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of the calculated integrals which is updated to include newly calculated integrals, compares the average of the calculated integrals to a numerical value representing the set range and generates an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 117
Dependent Claim
184 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, calculates an integral of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of the calculated integrals which is updated to include newly calculated integrals, compares the average of the calculated integrals to a numerical value representing the set range and generates an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 118
Dependent Claim
237 words
A radio frequency receiver in accordance with claim 112 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by each radio frequency transmitter which is used to calculate the average of the calculated integrals; and a directional antenna, the directional antenna after generation of the alert receiving transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 119
Dependent Claim
248 words
A radio frequency receiver in accordance with claim 112 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and a directional antenna, the directional antenna in response to reception of the alert from one of the at least one radio frequency transmitter receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of the radio frequency carrier from the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of radio frequency receiver relative to the radio frequency receiver.
Claim 120
Dependent Claim
109 words
A radio frequency receiver in accordance with claim 114 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 121
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 112 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 122
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 116 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 123
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 117 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 124
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 113 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 125
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 119 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 126
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 120 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 127
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 114 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 128
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 122 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 129
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 123 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 130
Dependent Claim
198 words
A radio frequency receiver in accordance with claim 115 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the at least one identification frame group with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the at least one identification frame group of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 131
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 125 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 132
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 126 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 133
Dependent Claim
41 words
A radio receiver in accordance with claim 112 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 134
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 128 wherein: the amplifier is an intermediate frequency amplifier.
Claim 135
Dependent Claim
41 words
A radio receiver in accordance with claim 113 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 136
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 130 wherein: the amplifier is an intermediate frequency amplifier.
Claim 137
Dependent Claim
41 words
A radio receiver in accordance with claim 114 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 138
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 132 wherein: the amplifier is an intermediate frequency amplifier.
Claim 139
Dependent Claim
41 words
A radio receiver in accordance with claim 115 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 140
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 134 wherein: the amplifier is an intermediate frequency amplifier.
Claim 141
Dependent Claim
41 words
A radio receiver in accordance with claim 116 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 142
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 136 wherein: the amplifier is an intermediate frequency amplifier.
Claim 143
Dependent Claim
41 words
A radio receiver in accordance with claim 117 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 144
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 138 wherein: the amplifier is an intermediate frequency amplifier.
Claim 145
Dependent Claim
41 words
A radio receiver in accordance with claim 118 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 146
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 140 wherein: the amplifier is an intermediate frequency amplifier.
Claim 147
Dependent Claim
185 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, produces a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of a plurality of the received signal strength indicators, compares the average of the received signal strength indicators to a numerical value representing the set range and generates an alert when a comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 148
Dependent Claim
185 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, produces a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes an average of a plurality of the received signal strength indicators, compares the average of the received signal strength indicators to a numerical value representing the set range and generates an alert when a comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 149
Dependent Claim
241 words
A radio frequency receiver in accordance with claim 142 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by each radio frequency transmitter which is used to calculate the average of the calculated integrals; and a directional antenna, the directional antenna after generation of the alert receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the radio frequency receiver to generate the alert to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 150
Dependent Claim
248 words
A radio frequency receiver in accordance with claim 142 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and a directional antenna, the directional antenna in response to reception of the alert from one of the at least one radio frequency transmitter receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the processor controls display of a magnitude of an integral of each successively received signal strength indicator generated in response to reception of the radio frequency carrier from the radio frequency transmitter from which the alert was received to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude of the integral of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of radio frequency receiver relative to the radio frequency receiver.
Claim 151
Dependent Claim
109 words
A radio frequency receiver in accordance with claim 144 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 152
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 142 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 153
Dependent Claim
116 words
A radio frequency receiver in accordance with claim 146 wherein: the processing of the detected individual cycles of the subcarrier by the processor includes calculating the integral by taking a plurality of samples of each selected modulated part of each of the individual cycles with each sample having a numerical value and each sample is compared with a range of numerical values representing a valid sample which should be included within the calculation of the integral and when the comparison reveals that the sample value is outside the range of numerical values, the compared sample value is replaced with a value which is a function of the sample values adjacent the sample value which is replaced.
Claim 154
Dependent Claim
47 words
A radio frequency receiver in accordance with claim 147 wherein: the compared sample value is replaced with a value which is an average of at least one sample value which precedes the compared sample value and at least one sample value which succeeds the compared sample value.
Claim 155
Dependent Claim
41 words
A radio receiver in accordance with claim 142 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 156
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 149 wherein: the amplifier is an intermediate frequency amplifier.
Claim 157
Dependent Claim
41 words
A radio receiver in accordance with claim 143 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 158
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 151 wherein: the amplifier is an intermediate frequency amplifier.
Claim 159
Dependent Claim
41 words
A radio receiver in accordance with claim 144 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 160
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 153 wherein: the amplifier is an intermediate frequency amplifier.
Claim 161
Dependent Claim
41 words
A radio receiver in accordance with claim 145 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 162
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 155 wherein: the amplifier is an intermediate frequency amplifier.
Claim 163
Dependent Claim
41 words
A radio receiver in accordance with claim 146 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 164
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 157 wherein: the amplifier is an intermediate frequency amplifier.
Claim 165
Dependent Claim
41 words
A radio receiver in accordance with claim 147 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 166
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 159 wherein: the amplifier is an intermediate frequency amplifier.
Claim 167
Dependent Claim
41 words
A radio receiver in accordance with claim 148 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 168
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 161 wherein: the amplifier is an intermediate frequency amplifier.
Claim 169
Independent Claim
171 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, producing a first function of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing a second function in response to at least one first function of the received signal strength indicator, comparing the second function to a value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 170
Independent Claim
171 words
A method for determining where at least one radio frequency transmitter is located with respect to a set range measured from a radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: in response to receiving each radio frequency carrier determining if an identification code of one of the at least one radio frequency transmitter is contained therein, producing a first function of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computing a second function in response to at least one first function of the received signal strength indicator, comparing the second function to a value representing the set range and generating an alert when the comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 171
Dependent Claim
229 words
A method in accordance with claim 163 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by each radio frequency transmitter; and after generation of the alert using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying in response to a function of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the generation of the alert a magnitude display to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, producing a maximum magnitude display in response to the function of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 172
Dependent Claim
257 words
A method in accordance with claim 163 further comprising: using an omnidirectional antenna to receive the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and in response to reception of the alert from one of the at least one radio frequency transmitter using a directional antenna to receive transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the radio frequency receiver displaying, in response to a function of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the alert was received, a magnitude display to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude display in response to the function of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 173
Dependent Claim
107 words
A method in accordance with claim 165 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 174
Dependent Claim
198 words
A method in accordance with claim 163 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter processing detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically comparing each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substituting for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decoding the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 175
Dependent Claim
25 words
A method in accordance with claim 163 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 176
Dependent Claim
25 words
A method in accordance with claim 164 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 177
Dependent Claim
25 words
A method in accordance with claim 165 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 178
Dependent Claim
25 words
A method in accordance with claim 166 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 179
Dependent Claim
25 words
A method in accordance with claim 167 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 180
Dependent Claim
38 words
A method in accordance with claim 163 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 181
Dependent Claim
15 words
A method in accordance with claim 173 wherein: the amplifier is an intermediate frequency amplifier.
Claim 182
Dependent Claim
38 words
A method in accordance with claim 168 wherein: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least one radio frequency transmitter, produces each received signal strength indicator.
Claim 183
Dependent Claim
15 words
A method in accordance with claim 175 wherein: the amplifier is an intermediate frequency amplifier.
Claim 184
Dependent Claim
190 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, produces a first function of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes a second function in response to at least one first function of the received signal strength indicator, compares the second function to a numerical value representing the set range and generates an alert when a comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 185
Dependent Claim
190 words
A radio frequency receiver for determining where at least one radio frequency transmitter is located with respect to a set range measured from the radio frequency receiver with each radio frequency transmitter periodically transmitting an identification code from each radio frequency transmitter which identifies each radio frequency transmitter with a radio frequency carrier modulated with a subcarrier with the subcarrier being modulated with the identification code comprising: a processor contained in the radio frequency receiver, the processor in response to reception of each radio frequency carrier determines if an identification code of one of the at least one radio frequency transmitter is contained therein, produces a first function of a received signal strength indicator of each radio frequency carrier determined to contain an identification code of one of the at least one radio frequency transmitter, computes a second function in response to at least one first function of the received signal strength indicator, compares the second function to a numerical value representing the set range and generates an alert when a comparison reveals that at least one of the at least one radio frequency transmitter is outside the set range.
Claim 186
Dependent Claim
252 words
A radio frequency receiver in accordance with claim 177 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by each radio frequency transmitter which is used to calculate the function of each received signal strength indicator; and a directional antenna, the directional antenna after generation of the alert receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the identification codes were transmitted which caused the radio frequency receiver to generate the alert and in response to the radio frequency receiver being moved by a user the processor in response to a function of each successively received signal strength indicator generated in response to reception of transmissions of the radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted which caused the radio frequency receiver to generate the alert controls display of a magnitude display to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier containing the identification code of the radio frequency transmitter from which the identification codes were transmitted to generate the alert is received, produces a maximum magnitude display in response to the function of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which is outside of the set range is determined by the user of the radio frequency receiver relative to the radio frequency receiver.
Claim 187
Dependent Claim
253 words
A radio frequency receiver in accordance with claim 178 further comprising: an omnidirectional antenna, the omnidirectional antenna receiving the radio frequency carrier transmitted by one of the at least one radio frequency transmitter which contains the identification code of the one radio frequency transmitter and an alert which signals to a user of the radio frequency receiver that the user of the one radio frequency transmitter is transmitting a change in status of the user; and a directional antenna, the directional antenna in response to reception of the alert from one of the at least one radio frequency transmitter receives transmissions of the radio frequency carrier containing the identification code identifying the radio frequency transmitter from which the alert was transmitted and in response to the radio frequency receiver being moved by a user the processor, in response to a function of each successively received signal strength indicator generated in response to reception of the radio frequency carrier from the radio frequency transmitter from which the alert was received, controls displaying a magnitude display to permit a user of the radio frequency receiver to locate a direction, from which a radio frequency carrier is received from the radio frequency transmitter transmitting the alert, producing a maximum magnitude display in response to a function of each successively received signal strength indicator relative to the radio frequency receiver whereby a direction of the radio frequency transmitter which transmitted the alert is determined by the user of radio frequency receiver relative to the radio frequency receiver.
Claim 188
Dependent Claim
109 words
A radio frequency receiver in accordance with claim 179 further comprising: the subcarrier of each received radio frequency carrier is modulated with at least one identification frame group, each identification frame group comprising a plurality of frames with at least one of the plurality of frames of the identification frame group containing bits encoding the identification code of each radio frequency transmitter, a plurality of bits of error correction code in each frame, synchronization information for synchronizing a clock of the radio frequency receiver, and a command field for encoding the alert transmitted to the radio frequency receiver from the user of the radio frequency transmitter transmitting the alert.
Claim 189
Dependent Claim
202 words
A radio frequency receiver in accordance with claim 178 wherein: the subcarrier of each received radio frequency carrier has cycles which are modulated with bits encoding the identification code of the radio frequency transmitter which transmitted the received radio frequency carrier with each cycle of the subcarrier being modulated with bits at a plurality of separated angular positions; and for each radio frequency carrier received from each radio frequency transmitter the processor processes detected individual cycles of the subcarrier to calculate an integral of at least one selected modulated part of each of the individual cycles, numerically compares each of the calculated integrals with a plurality of stored numerical ranges which ranges each represent one of a plurality of possible numerical values that the selected part may encode to identify a stored range numerically including the calculated integral, substitutes for the at least one selected part of each of the cycles the one of the plurality of numerical values representative of the identified stored range including the calculated integral with each numerical value encoding one bit of the identification code of the radio frequency transmitter and decodes the plurality of numerical values to produce the identification code of the radio frequency transmitter.
Claim 190
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 177 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 191
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 178 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 192
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 179 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 193
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 180 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 194
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 181 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 195
Dependent Claim
27 words
A radio frequency receiver in accordance with claim 182 wherein: the second function is responsive to a plurality of first functions of the received signal strength indicator.
Claim 196
Dependent Claim
41 words
A radio receiver in accordance with claim 177 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 197
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 188 wherein: the amplifier is an intermediate frequency amplifier.
Claim 198
Dependent Claim
41 words
A radio receiver in accordance with claim 182 further comprising: an amplifier, responsive to each radio carrier modulated with the subcarrier containing the identification of one of the at least on radio frequency transmitter, for producing each received signal strength indicator.
Claim 199
Dependent Claim
17 words
A radio frequency receiver in accordance with claim 190 wherein: the amplifier is an intermediate frequency amplifier.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2000-07-21 | 2001-01-20 | 2001-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-07-21 | 2005-01-20 | 2005-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-07-21 | 2009-01-20 | 2009-07-22 | $7700.00 | Window Closed / Lapsed |