Patent US3412252A successfully refreshed from Google Patents.
Patent US4608559A successfully refreshed from Google Patents.
US4608559A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Local modulated carrier data network with a collision avoidance protocol
Assignee: Computer Automation Inc
•
Filing: 1982-08-19
•
Granted: 1986-08-26
•
Expires: 2002-08-19
Abstract
Abstract A modem for a single frequency, modulated RF carrier local data network for a distributed data processing system and a method for line acquisition and contention resolution. The protocol established for line acquisition and contention resolution is implemented by a modem controller. The controller causes the receiver section to listen for foreign carriers to determine when the line is busy. When the client device of the modem desires to send a data packet to another unit, the modem controller causes the receiver to listen for a certain pre-burst period and then causes the transmitter to send a burst of RF carrier out on the line and simultaneously causes the receiver to listen to the line for interference beating, i.e. changes in amplitude on the line which indicates another unit is requesting the line. To insure beat patterns, the frequency of the burst carrier is swept over a range during the burst. If a contention is found, a resolution thereof is made utilizing a random delay and retry protocol. After the burst, the controller causes the receiver to listen to the line for other carriers. If none are found, the controller causes the transmitter to transmit a data packet preceded by a preamble of 100% modulation level RF carrier. During the preamble period, all receivers in the system set their respective automatic gain control levels to a level for comfortable reception. The gain level so established depends upon the strength of the received signal. This amplification level is maintained throughout the entire data packet.
Inventors
- 👤 Michael S. Friedman
- 👤 Kenneth D. Thomas
- 👤 Philip T. Chan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:16
CPC Classifications
H; H04; H04L; H04L12/00; H04L12/28; H04L12/2801
Claims Analysis
Total Claims: 60
Claim 1
Independent Claim
218 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy, said burst being a sinusoidal radio frequency carrier having a fixed amplitude; means for receiving signals on said transmission medium, said receiving means comprising: a variable gain receiver coupled to said transmission medium to receive carrier energy and amplify it in accordance with said variable gain; a demodulator for converting the received signal into a D.C. signal which has an amplitude which varies with the amplitude of the output from said variable gain receiver; a comparator means for comparing the output signal of said demodulator to a reference signal during said burst and for generating a contention signal when said D.C. signal achieves a predetermined relationship to said reference signal; and a means for setting the gain of said variable gain receiver to a predetermined level during bursting such that the comparator means will not generate said contention signal unless interference beating with another carrier is causing the amplitude of the received signal to vary; and means for preventing data transmission in response to detection by said receiving means of energy from any other modem while said burst is being transmitted.
Claim 2
Independent Claim
218 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy, said burst being a sinusoidal radio frequency carrier having a fixed amplitude; means for receiving signals on said transmission medium, said receiving means comprising: a variable gain receiver coupled to said transmission medium to receive carrier energy and amplify it in accordance with said variable gain; a demodulator for converting the received signal into a D.C. signal which has an amplitude which varies with the amplitude of the output from said variable gain receiver; a comparator means for comparing the output signal of said demodulator to a reference signal during said burst and for generating a contention signal when said D.C. signal achieves a predetermined relationship to said reference signal; and a means for setting the gain of said variable gain receiver to a predetermined level during bursting such that the comparator means will not generate said contention signal unless interference beating with another carrier is causing the amplitude of the received signal to vary; and means for preventing data transmission in response to detection by said receiving means of energy from any other modem while said burst is being transmitted.
Claim 3
Independent Claim
73 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy; means for varying the frequency of said burst; means for receiving signals on said transmission medium; and means for preventing data transmission in response to detection by said receiving means of energy from any other modem.
Claim 4
Independent Claim
73 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy; means for varying the frequency of said burst; means for receiving signals on said transmission medium; and means for preventing data transmission in response to detection by said receiving means of energy from any other modem.
Claim 5
Independent Claim
96 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems comprising: means for transmitting a non data bearing burst of waveform with a frequency that varies during the burst; means for receiving signals on said transmission medium and detecting amplitude changes on said transmission media caused by interference beating between the signals from two or more transmitters contending for the transmission media; and means for detecting the presence of any signal on said transmission medium during a predetermined post burst listening period.
Claim 6
Independent Claim
96 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems comprising: means for transmitting a non data bearing burst of waveform with a frequency that varies during the burst; means for receiving signals on said transmission medium and detecting amplitude changes on said transmission media caused by interference beating between the signals from two or more transmitters contending for the transmission media; and means for detecting the presence of any signal on said transmission medium during a predetermined post burst listening period.
Claim 7
Dependent Claim
25 words
An apparatus as defined in claim 2 or 3 wherein said non data bearing burst is a sinusoidal radio frequency carrier having a fixed amplitude.
Claim 8
Dependent Claim
143 words
An apparatus as defined in claim 4 wherein said receiving means includes: a variable gain receiver coupled to said transmission medium to receive carrier energy and amplify it in accordance with said variable gain; a demodulator for converting the received signal into a D.C. signal which has an amplitude which varies with the amplitude of the output from said variable gain receiver; a comparator means for comparing the output signal of said demodulator to a reference signal during said burst and for generating a contention signal when said D.C. signal achieves a predetermined relationship to said reference signal; and a means for setting the gain of said variable gain receiver to a predetermined level during bursting such that said comparator means will not generate said contention signal unless interference beating with another carrier is causing the amplitude of the received signal to vary.
Claim 9
Dependent Claim
58 words
An apparatus as defined in claim 5 further including a controller means coupled to said transmitting means and said detecting means to cause said transmitting means to transmit said burst while simultaneously causing said gain setting means to set the gain of said variable gain receiver at a predetermined level to detect interference beating on said transmission medium.
Claim 10
Dependent Claim
61 words
An apparatus as defined in claim 6 wherein said controller means also is coupled to said comparator means and causes said gain setting means to set the gain of said receiver to a second predetermined level during said post burst listening period and monitors the output of said comparator means to determine if a signal is present on said transmission media.
Claim 11
Dependent Claim
34 words
An apparatus as defined in claim 2 or 3 further comprising means for controlling a delay imposed before a retry to transmit is initiated by generation of a random number which determines the delay.
Claim 12
Dependent Claim
37 words
An apparatus as defined in claim 2 or 3 wherein each transmitter and receiver modem in the data network both transmits data to the other modems and receives data from the other modems on a single frequency.
Claim 13
Dependent Claim
23 words
An apparatus as defined in claim 9 wherein each section of each modem receives data from the transmitter section in its own modem.
Claim 14
Dependent Claim
52 words
An apparatus as defined in claim 10 further comprising means for automatically adjusting the gain of the receiver section of each modem in the data network to a predetermined level during an unmodulated preamble signal preceding each transmitted data packet and holding that level constant during receipt of the entire data packet.
Claim 15
Independent Claim
146 words
An apparatus for detecting contentions for the transmission medium in a broadband local data network comprising: first means for generating a burst of energy containing no data; second means for causing the frequency of said burst to be varied during the burst; third means for receiving energy from said transmission medium and for generating a signal when the amplitude of said received energy is above a threshold level, said third means having variable gain; fourth means for setting the gain of said third means during said burst such that said third means will generate no signal unless interference beating is causing the amplitude of the received energy to vary; and fifth means for determining whether interference beating has occurred and for causing a retry to transmit a predetermined period later as determined by a random number generated by the randomness of the interference beat pattern itself.
Claim 16
Independent Claim
146 words
An apparatus for detecting contentions for the transmission medium in a broadband local data network comprising: first means for generating a burst of energy containing no data; second means for causing the frequency of said burst to be varied during the burst; third means for receiving energy from said transmission medium and for generating a signal when the amplitude of said received energy is above a threshold level, said third means having variable gain; fourth means for setting the gain of said third means during said burst such that said third means will generate no signal unless interference beating is causing the amplitude of the received energy to vary; and fifth means for determining whether interference beating has occurred and for causing a retry to transmit a predetermined period later as determined by a random number generated by the randomness of the interference beat pattern itself.
Claim 17
Dependent Claim
97 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; and means in each transceiver for reserving the transmission medium prior to sending data, said reserving means operating independent of any network control signal and guaranteeing exclusive access to said transmission medium independent of the order of connection of said transceivers to said transmission medium.
Claim 18
Dependent Claim
97 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; and means in each transceiver for reserving the transmission medium prior to sending data, said reserving means operating independent of any network control signal and guaranteeing exclusive access to said transmission medium independent of the order of connection of said transceivers to said transmission medium.
Claim 19
Dependent Claim
57 words
A locata data network as defined in claim 13 wherein said means in each transceiver for reserving said transmission medium comprises: means for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and means for listening for interference with any other signal on said transmission medium.
Claim 20
Dependent Claim
34 words
A local data network as defined in claim 14 further comprising means in each transceiver for detecting contentions for reserving said transmission medium by listening for any signal on said medium after said burst.
Claim 21
Dependent Claim
47 words
A local data network as defined in claim 14 or 15 further comprising means for controlling the time delay before another attempt to transmit is made by generating a random number and using said random number to determine the amount of delay before again attempting to transmit.
Claim 22
Dependent Claim
208 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; means in each transceiver for avoiding contentions for said transmission medium by two or more transceivers attempting to simultaneously transmit, comprising: means for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and means for listening for interference with any other signal on said transmission medium; means in each transceiver for detecting contentions for said transmission medium by listening for any signal on said medium after said burst; means for controlling the time delay before another attempt to transmit is made by generating a random number and using said random number to determine the amount of delay before again attempting to transmit; and means for transmitting a non data bearing preamble preceding each data packet and means for adjusting the gain of each receiver for effective reception during said preamble and holding said gain for each transceiver constant during reception of the corresponding data packet.
Claim 23
Dependent Claim
208 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; means in each transceiver for avoiding contentions for said transmission medium by two or more transceivers attempting to simultaneously transmit, comprising: means for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and means for listening for interference with any other signal on said transmission medium; means in each transceiver for detecting contentions for said transmission medium by listening for any signal on said medium after said burst; means for controlling the time delay before another attempt to transmit is made by generating a random number and using said random number to determine the amount of delay before again attempting to transmit; and means for transmitting a non data bearing preamble preceding each data packet and means for adjusting the gain of each receiver for effective reception during said preamble and holding said gain for each transceiver constant during reception of the corresponding data packet.
Claim 24
Dependent Claim
161 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; means in each transceiver for avoiding contentions for said transmission medium by two or more transceivers attempting to simultaneously transmit, comprising: means for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and means for listening for interference with any other signal on said transmission medium; means in each transceiver for detecting contentions for said transmission medium by listening for any signal on said medium after said burst; and means for altering the frequency of said burst carrier during said burst and means for detecting contentions by detecting amplitude changes on said transmission medium caused by interference beating.
Claim 25
Dependent Claim
161 words
A local data network comprising: a transmission medium; a plurality of transceivers, each for sending data to and receiving data from the other transceivers over said transmission medium, each transceiver utilizing a modulated carrier wave of a single frequency for both transmitting and receiving, said frequency being the same for each transceiver; means in each transceiver for avoiding contentions for said transmission medium by two or more transceivers attempting to simultaneously transmit, comprising: means for transmitting a non data bearing burst of carrier by each transceiver desiring to send data prior to sending said data; and means for listening for interference with any other signal on said transmission medium; means in each transceiver for detecting contentions for said transmission medium by listening for any signal on said medium after said burst; and means for altering the frequency of said burst carrier during said burst and means for detecting contentions by detecting amplitude changes on said transmission medium caused by interference beating.
Claim 26
Dependent Claim
81 words
A data network comprising: a transmission medium; a plurality of transceivers each for sending data to and receiving data from the other transceivers in said data network over said transmission medium; means for causing each transceiver to send a preamble of non data bearing energy prior to transmission of said data; and means for setting the gain of each transceiver in said network during the preamble of a transmission from any transceiver and holding said gain constant during the corresponding data.
Claim 27
Dependent Claim
81 words
A data network comprising: a transmission medium; a plurality of transceivers each for sending data to and receiving data from the other transceivers in said data network over said transmission medium; means for causing each transceiver to send a preamble of non data bearing energy prior to transmission of said data; and means for setting the gain of each transceiver in said network during the preamble of a transmission from any transceiver and holding said gain constant during the corresponding data.
Claim 28
Dependent Claim
75 words
A data network for transferring packets of information between data devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting packets of data on said bus line to prevent collisions of packets of data from more than one transmitter section.
Claim 29
Dependent Claim
75 words
A data network for transferring packets of information between data devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting packets of data on said bus line to prevent collisions of packets of data from more than one transmitter section.
Claim 30
Dependent Claim
87 words
A data network for transferring packets of information between data sections which listen to said access devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting a packet of data on said bus line, wherein said transmitter sections automatically sweep the carrier frequency over a range of frequencies during said access burst.
Claim 31
Dependent Claim
87 words
A data network for transferring packets of information between data sections which listen to said access devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting a packet of data on said bus line, wherein said transmitter sections automatically sweep the carrier frequency over a range of frequencies during said access burst.
Claim 32
Dependent Claim
47 words
The data network of claim 21 wherein said transceiver modem includes a receiver section having burst gain control circuitry that reduces the gain of the receiver section during the transmission of an access burst by the transmitter section of the same transceiver modem to a predetermined level.
Claim 33
Dependent Claim
41 words
The data network of claim 22 wherein said receiver section includes interference detection circuitry that detects the presence of amplitude pulses produces by the interference occurring when two carrier bursts each having changing frequency are present on said transmission medium simultaneously.
Claim 34
Dependent Claim
69 words
The data network of claim 23 wherein said transceiver modem includes a randomizing retry time delay means to delay retry attempts to send by a random delay, said delay means connected to said interference detection circuitry so that when interference between access bursts is detected, the time of occurrence of said amplitude pulses is used to randomize the time delay before said transceiver modem again produces an access burst.
Claim 35
Dependent Claim
74 words
The data network of claim 24 wherein said retry time delay means produces a random binary digit by toggling a beat counting flip-flop using the time of occurence of said amplitude pulses to control said toggling during a predefined sampling time window which occurs during said access burst, so that said random binary digit controls the time delay before said transceiver modem will again start a sequence of steps to produce an access burst.
Claim 36
Dependent Claim
118 words
A data network for transferring packets of information between data devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting a packet of data on said bus line, each said transceiver modem also having a receiver section having automatic gain control circuitry which samples a constant amplitude preamble signal at the start of each data packet in order to establish an appropriate amplification level for good reception, and which holds the amplification level constant for the packet after the preamble signal has occurred.
Claim 37
Dependent Claim
118 words
A data network for transferring packets of information between data devices, said network comprising: a transmission medium; a plurality of taps located on said transmission medium; and a plurality of transceiver modems connected to said taps and having amplitude modulated radio frequency transmitter sections that produce access bursts of radio frequency carrier prior to transmitting a packet of data on said bus line, each said transceiver modem also having a receiver section having automatic gain control circuitry which samples a constant amplitude preamble signal at the start of each data packet in order to establish an appropriate amplification level for good reception, and which holds the amplification level constant for the packet after the preamble signal has occurred.
Claim 38
Dependent Claim
38 words
The data network of claim 20 or 21 or 22 or 23 or 24 or 25 or 26 wherein all said transmitter and receiver sections of all said modems transmit and receive data on the same frequency carrier.
Claim 39
Independent Claim
192 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d) thereby avoiding collisions in the data packets transmitted by more than one transmitter.
Claim 40
Independent Claim
192 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d) thereby avoiding collisions in the data packets transmitted by more than one transmitter.
Claim 41
Dependent Claim
55 words
The method of claim 28 further including the step of: (f) delaying another attempt to transmit a data packet for a random time period after step (d) if (a) conflicting carrier was detected during steps (a), (c) and (d), said transmission access being retried by repeating the method steps by beginning again with step (a).
Claim 42
Independent Claim
214 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period, said transmitting step including changing the frequency of carrier during said access burst so that if two or more carriers are present on the bus line simultaneously, interference beating will be produced between the conflicting carriers; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d).
Claim 43
Independent Claim
214 words
A method of transmitting packets of digital data using a plurality of transmitters each of which outputs an amplitude modulated radio frequency carrier having the same frequency on a single transmission medium coupled to a plurality of receivers which each have passbands encompassing the frequency of carrier said transmitters output, said method comprising the steps of: (a) listening to said transmission medium in order to detect the presence of conflicting carrier thereon for a predetermined period after the termination of the previous packet; (b) transmitting an access burst of carrier on said transmission medium for a predetermined period after said previous listening period, said transmitting step including changing the frequency of carrier during said access burst so that if two or more carriers are present on the bus line simultaneously, interference beating will be produced between the conflicting carriers; (c) listening to said bus line during the transmission of said access burst in order to detect the presence of conflicting carriers on said transmission medium during said access burst; (d) listening to said transmission medium in order to detect the presence of carrier thereon for a predetermined period after said access burst; and (e) transmitting a data packet on said transmission medium if no conflicting carrier was detected during steps (a), (c), and (d).
Claim 44
Dependent Claim
54 words
The method of claim 30 further comprising the step: (g) detecting the presence of amplitude pulses produced due to said interfeence beating during step (b), so that the time of occurrence of said amplitude pulses provides a randomizing function for controlling the minimum time delay before transmission of an access burst may be retried.
Claim 45
Independent Claim
74 words
A method of receiving packets of digital data on an amplitude modulated radio frequency carrier bus line, said method comprising the steps of: (a) listening to the transmission medium for a packet preamble in order to sample the preamble and establish a receive amplification level corresponding to the strength of the preamble signal; and (b) listening to the transmission medium after said preamble and holding the receive amplification level established during said preamble constant.
Claim 46
Independent Claim
74 words
A method of receiving packets of digital data on an amplitude modulated radio frequency carrier bus line, said method comprising the steps of: (a) listening to the transmission medium for a packet preamble in order to sample the preamble and establish a receive amplification level corresponding to the strength of the preamble signal; and (b) listening to the transmission medium after said preamble and holding the receive amplification level established during said preamble constant.
Claim 47
Independent Claim
51 words
A method of avoiding contentions in transmitting packets of digital data on a broadband local data network comprising: transmitting a non data bearing burst of waveform; varying the frequency of the waveform during the burst; and listening for amplitude changes caused by interference beating between the transmitted burst and other signals.
Claim 48
Independent Claim
51 words
A method of avoiding contentions in transmitting packets of digital data on a broadband local data network comprising: transmitting a non data bearing burst of waveform; varying the frequency of the waveform during the burst; and listening for amplitude changes caused by interference beating between the transmitted burst and other signals.
Claim 49
Dependent Claim
25 words
The method of claim 33 further comprising listening during a post burst period for the presence of any other signal present on the transmission media.
Claim 50
Dependent Claim
38 words
A method as defined in claim 34 further comprising generating a random number from the randomness of the interference beat pattern itself and waiting a time determined by the random number so generated before attempting to transmit again.
Claim 51
Dependent Claim
63 words
A method as defined in claim 35 further comprising transmitting a data packet with an unmodulated preamble portion prior to transmitting each data packet and automatically adjusting the gain of each receiver in the system during said preamble according to the strength of its incoming signal and holding the gain levels so established constant during receipt of the data packet following the preamble.
Claim 52
Dependent Claim
44 words
An apparatus as defined in claim 3 further comprising means for imposing a delay before a retry to transmit is initiated by generation of a random number which determines the delay, said random number being generated by the randomness of the interference beat pattern.
Claim 53
Independent Claim
98 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy on said transmission medium; means for receiving signals on said transmission medium, said receiving means receiving said burst while said burst is being transmitted; means for preventing data transmission in response to detection by said receiving means of energy from any other modem; and means for transmitting data over the transmission medium if no energy from any other modem is detected.
Claim 54
Independent Claim
98 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy on said transmission medium; means for receiving signals on said transmission medium, said receiving means receiving said burst while said burst is being transmitted; means for preventing data transmission in response to detection by said receiving means of energy from any other modem; and means for transmitting data over the transmission medium if no energy from any other modem is detected.
Claim 55
Dependent Claim
23 words
An apparatus as defined in claim 38 wherein said non data bearing burst is a sinusoidal radio frequency carrier having a fixed amplitude.
Claim 56
Dependent Claim
32 words
An apparatus as defined in claim 38 further comprising means for controlling a delay imposed before a retry to transmit is initiated by generation of a random number which determines the delay.
Claim 57
Dependent Claim
35 words
An apparatus as defined in claim 38 wherein each transmitter and receiver modem in the data network both transmits data to the other modems and receives data from the other modems on a single frequency.
Claim 58
Dependent Claim
23 words
An apparatus as defined in claim 41 wherein each section of each modem receives data from the transmitter section in its own modem.
Claim 59
Independent Claim
168 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy on said transmission medium; means for receiving signals on said transmission medium, said receiving means receiving said burst while said burst is being transmitted; means for preventing data transmission in response to detection by said receiving means of energy from any other modem; and means for automatically adjusting the gain of the receiver section of each modem in the data network to a predetermined level during an unmodulated preamble signal preceding each transmitted data packet and holding that level constant during receipt of the entire data packet, wherein each section of each modem receives data from the transmitter section in its own modem and each transmitter and receiver modem in the data network both transmits data to the other modems and receives data from the other modems on a single frequency.
Claim 60
Independent Claim
168 words
An apparatus for detecting contentions for the transmission medium in a modulated carrier local data network having a plurality of transmitter and receiver modems, each modem comprising: means for transmitting a non data bearing burst of energy on said transmission medium; means for receiving signals on said transmission medium, said receiving means receiving said burst while said burst is being transmitted; means for preventing data transmission in response to detection by said receiving means of energy from any other modem; and means for automatically adjusting the gain of the receiver section of each modem in the data network to a predetermined level during an unmodulated preamble signal preceding each transmitted data packet and holding that level constant during receipt of the entire data packet, wherein each section of each modem receives data from the transmitter section in its own modem and each transmitter and receiver modem in the data network both transmits data to the other modems and receives data from the other modems on a single frequency.
References Cited (Backward Citations)
US3470324A
Cited
US3445822A
Cited
US3919641A
Cited
US3949168A
Cited
US3988712A
Cited
US4063220A
Cited
US4096355A
Cited
US4086534A
Cited
US4099024A
Cited
US4156106A
Cited
US4251881A
Cited
US4281380A
Cited
US4233589A
Cited
US4284976A
Cited
US4253188A
Cited
US4255742A
Cited
US4259663A
Cited
US4271523A
Cited
US4271507A
Cited
US4234952A
Cited
US4282512A
Cited
US4445214A
Cited
US4380052A
Cited
US4409592A
Cited
US4432088A
Cited
US4332027A
Cited
US4409593A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-08-25 | 1990-02-24 | 1990-08-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-08-25 | 1994-02-24 | 1994-08-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-08-25 | 1998-02-24 | 1998-08-26 | $7700.00 | Window Closed / Lapsed |