Patent US3715832A successfully refreshed from Google Patents.
Patent US5986570A successfully refreshed from Google Patents.
US5986570A
Expired / Lapsed
US
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Method for resolving signal collisions between multiple RFID transponders in a field
Assignee: Round Rock Research LLC
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Filing: 1997-09-03
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Granted: 1999-11-16
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Expires: 2017-09-03
Abstract
Abstract Communications between an RFID interrogator and an RFID transponder require that no more than one transponder be present in the reading range of the interrogator and transmitting into motion at any given time. If multiple transponders are in the field, then a collision between the return signals of the transponders occurs, rendering the signals unreadable. A method to resolve the collisions and allow for accurate transmission of each transponder's data is given. This method is especially effective over other methods when the transponder is a read-only type of device, whereby there is no communications interrogator on board the read-only transponder.
Inventors
- 👤 Donald L. Black
- 👤 Dale Yones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 20:55
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10009; G06K7/10019; G06K7/10029; G06K7/10039; G06K7/0008
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
80 words
A method for an interrogator reading one or more RFID transponders in a field comprising the steps of: a. providing a carrier signal; b. detecting the presence of at least one transponder; c. receiving data from all active transponders in the field; d. determining whether the interrogator has received a valid data transmission; and e. upon determining an invalid data transmission, informing all active transponders in the field that there was an incomplete read, the informing including suppressing the carrier.
Claim 2
Independent Claim
80 words
A method for an interrogator reading one or more RFID transponders in a field comprising the steps of: a. providing a carrier signal; b. detecting the presence of at least one transponder; c. receiving data from all active transponders in the field; d. determining whether the interrogator has received a valid data transmission; and e. upon determining an invalid data transmission, informing all active transponders in the field that there was an incomplete read, the informing including suppressing the carrier.
Claim 3
Dependent Claim
31 words
The method recited in claim 1, wherein steps (c) and (d) are iteratively repeated until the interrogator determines that it has read the complete data for each transponder in the field.
Claim 4
Dependent Claim
27 words
The method recited in claim 2, further comprising the step of transmitting the complete data for each transponder from the interrogator to a computer system for processing.
Claim 5
Dependent Claim
39 words
The method recited in claim 2, wherein the interrogator includes a demodulator and the step of detecting the presence of one or more transponders comprises receiving data from the demodulator and modifying the carrier signal in a predetermined manner.
Claim 6
Dependent Claim
25 words
The method recited in claim 4, wherein the step of modifying the carrier signal in a predetermined manner comprises sending out the carrier signal continuously.
Claim 7
Dependent Claim
40 words
The method as recited in claim 2, wherein the step of determining whether the interrogator has received an invalid data transmission comprises detecting the interrogator's inability to compute a proper synchronization word, a proper CRC, or a proper word length.
Claim 8
Dependent Claim
35 words
The method as recited in claim 2, wherein the step of informing active transponders in the field that there was an incomplete read comprises suppressing the carrier signal for a predetermined number of clock cycles.
Claim 9
Dependent Claim
34 words
The method as recited in claim 2, wherein the step of informing active transponders in the field that there was an incomplete read is performed prior to the transponder sending its complete data transmission.
Claim 10
Dependent Claim
37 words
The method as recited in claim 8 wherein the step of informing active transponders in the field that there was an incomplete read is performed substantially simultaneously upon the determination that invalid data transmission has been received.
Claim 11
Dependent Claim
35 words
The method as recited in claim 2, wherein the receiving step comprises receiving the data in groups of one or more bits and checking the validity of each group of data as it is received.
Claim 12
Dependent Claim
31 words
The method as recited in claim 2, wherein the step of determining complete data transmission comprises determining that the CRC is valid and modifying the carrier signal in a predetermined manner.
Claim 13
Dependent Claim
30 words
The method as recited in claim 9, wherein step of modifying the carrier signal in a predetermined manner comprises suppressing the carrier signal for a predetermined number of clock cycles.
Claim 14
Independent Claim
165 words
A method for an interrogator reading one or more RFID transponders in a field, the interrogator including a demodulator, the method comprising: providing a carrier signal; detecting the presence of at least one transponder, the detecting including receiving data from the demodulator and modifying the carrier signal by suppressing the carrier signal for a predetermined number of clock cycles; receiving data from all active transponders in the field, the receiving including receiving the data in groups of one or more bits and checking the validity of each group of data as the group is received; determining whether the interrogator has received a valid data transmission by detecting the interrogator's inability to compute a proper synchronization word, a proper CRC, or a proper word length; upon determining an invalid data transmission, modifying the carrier signal to inform all active transponders in the field that there was an incomplete read; and transmitting the complete data for each transponder from the interrogator to a computer system for processing.
Claim 15
Independent Claim
165 words
A method for an interrogator reading one or more RFID transponders in a field, the interrogator including a demodulator, the method comprising: providing a carrier signal; detecting the presence of at least one transponder, the detecting including receiving data from the demodulator and modifying the carrier signal by suppressing the carrier signal for a predetermined number of clock cycles; receiving data from all active transponders in the field, the receiving including receiving the data in groups of one or more bits and checking the validity of each group of data as the group is received; determining whether the interrogator has received a valid data transmission by detecting the interrogator's inability to compute a proper synchronization word, a proper CRC, or a proper word length; upon determining an invalid data transmission, modifying the carrier signal to inform all active transponders in the field that there was an incomplete read; and transmitting the complete data for each transponder from the interrogator to a computer system for processing.
Claim 16
Dependent Claim
26 words
The method as recited in claim 13, wherein the step of modifying the carrier signal is performed prior to the transponder sending its complete data transmission.
Claim 17
Dependent Claim
29 words
The method as recited in claim 13 wherein the step of modifying the carrier signal is performed substantially simultaneously upon the determination that invalid data transmission has been received.
Claim 18
Dependent Claim
43 words
The method as recited in claim 13 wherein the receiving and the determining whether the interrogator has received a valid data transmission are iteratively repeated until the interrogator determines that the interrogator has read the complete data for each transponder in the field.
Claim 19
Dependent Claim
41 words
The method as recited in claim 16, wherein determining that the interrogator has read the complete data for one of the transponders in the field comprises determining that a CRC is valid and modifying the carrier signal in a predetermined manner.
Claim 20
Independent Claim
187 words
A method for an interrogator reading one or more RFID transponders in a field, the interrogator including a demodulator, the method comprising: providing a carrier signal; detecting the presence of at least one transponder, the detecting including receiving data from the demodulator and modifying the carrier signal in a predetermined manner; receiving data from all active transponders in the field, the receiving including receiving the data in groups of one or more bits and checking the validity of each group of data as it is received; determining whether the interrogator has received a valid data transmission; the receiving and the determining being iteratively repeated until the interrogator determines that the interrogator has read complete data for each transponder in the field, the determining that the interrogator has read complete data for one of the transponders including determining that the CRC is valid and suppressing the carrier; upon determining an invalid data transmission, modifying the carrier signal to inform all active transponders in the field that there was an incomplete read; and transmitting the complete data for each transponder from the interrogator to a computer system for processing.
Claim 21
Independent Claim
187 words
A method for an interrogator reading one or more RFID transponders in a field, the interrogator including a demodulator, the method comprising: providing a carrier signal; detecting the presence of at least one transponder, the detecting including receiving data from the demodulator and modifying the carrier signal in a predetermined manner; receiving data from all active transponders in the field, the receiving including receiving the data in groups of one or more bits and checking the validity of each group of data as it is received; determining whether the interrogator has received a valid data transmission; the receiving and the determining being iteratively repeated until the interrogator determines that the interrogator has read complete data for each transponder in the field, the determining that the interrogator has read complete data for one of the transponders including determining that the CRC is valid and suppressing the carrier; upon determining an invalid data transmission, modifying the carrier signal to inform all active transponders in the field that there was an incomplete read; and transmitting the complete data for each transponder from the interrogator to a computer system for processing.
Claim 22
Dependent Claim
25 words
The method recited in claim 18, wherein the step of modifying the carrier signal in a predetermined manner comprises sending out the carrier signal continuously.
Claim 23
Dependent Claim
31 words
The method as recited in claim 18, wherein the step of modifying the carrier signal in a predetermined manner comprises suppressing the carrier signal for a predetermined number of clock cycles.
Claim 24
Dependent Claim
26 words
The method as recited in claim 20, wherein the step of modifying the carrier signal is performed prior to the transponder sending its complete data transmission.
Claim 25
Dependent Claim
29 words
The method as recited in claim 20 wherein the step of modifying the carrier signal is performed substantially simultaneously upon the determination that invalid data transmission has been received.
Claim 26
Dependent Claim
40 words
The method as recited in claim 18, wherein the step of determining whether the interrogator has received an invalid data transmission comprises detecting the interrogator's inability to compute a proper synchronization word, a proper CRC, or a proper word length.
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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) | 2002-11-15 | 2003-05-17 | 2003-11-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-11-15 | 2007-05-17 | 2007-11-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-11-15 | 2011-05-17 | 2011-11-16 | $7700.00 | Window Closed / Lapsed |