US6046683A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Modulated backscatter location system
Assignee: CACI LGS Innovations LLC
•
Filing: 1996-12-31
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Granted: 2000-04-04
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Expires: 2016-12-31
Abstract
Abstract A radio communications system is that can determine the location of an RFID Tag. The radio communication system includes at least one Interrogator for generating and transmitting a modulated radio signal to one or more Tags. The Interrogator is at a known location, and is in motion with respect to the Tag at a known velocity. One or more Tags of the system receive and demodulate the modulated radio signal, which contains a first information signal which specifies which Tag or Tags should respond using Modulated Backscattering. The Tag generates a subcarrier signal, and backscatter modulates the reflection of the radio signal using the subcarrier signal, thereby forming a reflected signal. The Interrogator receives and demodulates the reflected signal. The Interrogator then determines the Tag's relative direction from the location and velocity of the Interrogator, and from the Doppler shift of the subcarrier signal. More than one of such measurements allow the location of the Tag to be determined.
Inventors
- 👤 Alex Pidwerbetsky
- 👤 R. Anthony Shober
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 03:38
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/38; H04B1/40; G; G01; G01S; G01S13/00; G01S13/87; G01S13/878; G01S5/00; G01S5/02; G01S5/04; G06; G06K; G06K7/00; G06K7/0008; G01S13/02; G01S13/50; G01S13/52; G01S13/536; G01S13/88; G01S13/89; G01S13/90; G01S13/904; G01S3/00; G01S3/02; G01S3/14; G01S3/46; G01S3/48
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
89 words
A modulated backscatter location system, comprising: at least one transponder that receives a first transmitted signal and modulates a reflected first transmitted signal using a subcarrier signal; and at least one interrogator having a transmitter that transmits said first transmitted signal and a receiver that receives said reflected first transmitted signal, said interrogator having a demodulator that obtains a received subcarrier signal from said reflected first transmitted signal, and a processor that analyzes said received subcarrier signal to determine an angle of arrival of said reflected first transmitted signal.
Claim 2
Dependent Claim
89 words
A modulated backscatter location system, comprising: at least one transponder that receives a first transmitted signal and modulates a reflected first transmitted signal using a subcarrier signal; and at least one interrogator having a transmitter that transmits said first transmitted signal and a receiver that receives said reflected first transmitted signal, said interrogator having a demodulator that obtains a received subcarrier signal from said reflected first transmitted signal, and a processor that analyzes said received subcarrier signal to determine an angle of arrival of said reflected first transmitted signal.
Claim 3
Dependent Claim
33 words
The modulated backscatter location system of claim 1, comprising a plurality of interrogators that each determine an angle of arrival of a reflected signal and transmit said angle of arrival to another location.
Claim 4
Dependent Claim
15 words
The modulated backscatter location system of claim 2, wherein said another location is an interrogator.
Claim 5
Dependent Claim
15 words
The modulated backscatter location system of claim 2, wherein said another location is a server.
Claim 6
Dependent Claim
30 words
The modulated backscatter location system of claim 1, wherein said demodulator comprises a mixer that mixes said reflected first transmitted signal with another signal to obtain said received subcarrier signal.
Claim 7
Dependent Claim
15 words
The modulated backscatter location system of claim 1, wherein said demodulator is a homodyne demodulator.
Claim 8
Dependent Claim
24 words
The modulated backscatter location system of claim 1, wherein said processor determines a frequency difference between said received subcarrier signal and said subcarrier signal.
Claim 9
Dependent Claim
36 words
The modulated backscatter location system of claim 1, comprising a plurality of fixed transponders having a known location, each of said transponders responding to a received signal by modulating a reflected received signal using said subcarrier.
Claim 10
Dependent Claim
39 words
The modulated backscatter location system of claim 8, wherein said processor determines an angle of arrival of a reflected transmitted signal from each of said fixed transponders and determines a location of said interrogator using said angles of arrival.
Claim 11
Dependent Claim
23 words
The modulated backscatter location system of claim 1, wherein said angle of arrival is relative to a direction of travel of said interrogator.
Claim 12
Dependent Claim
58 words
A modulated backscatter location interrogator, comprising: a transmitter that transmits a first transmitted signal; a receiver that receives a reflected first transmitted signal; a demodulator that obtains a received subcarrier signal from said reflected first transmitted signal; and a processor that analyzes said received subcarrier signal to determine an angle of arrival of said reflected first transmitted signal.
Claim 13
Dependent Claim
58 words
A modulated backscatter location interrogator, comprising: a transmitter that transmits a first transmitted signal; a receiver that receives a reflected first transmitted signal; a demodulator that obtains a received subcarrier signal from said reflected first transmitted signal; and a processor that analyzes said received subcarrier signal to determine an angle of arrival of said reflected first transmitted signal.
Claim 14
Dependent Claim
19 words
The modulated backscatter location interrogator of claim 11, wherein said processor communicates said angle of arrival to another location.
Claim 15
Dependent Claim
30 words
The modulated backscatter location interrogator of claim 11, wherein said demodulator comprises a mixer that mixes said reflected first transmitted signal with another signal to obtain said received subcarrier signal.
Claim 16
Dependent Claim
15 words
The modulated backscatter location interrogator of claim 11, wherein said demodulator is a homodyne demodulator.
Claim 17
Dependent Claim
24 words
The modulated backscatter location interrogator of claim 11, wherein said processor determines a frequency difference between said received subcarrier signal and a subcarrier signal.
Claim 18
Dependent Claim
38 words
The modulated backscatter location interrogator of claim 11, wherein said processor determines an angle of arrival for each of a plurality of reflected first transmitted signals and determines a location of said interrogator using said angles of arrival.
Claim 19
Dependent Claim
23 words
The modulated backscatter location interrogator of claim 11, wherein said angle of arrival is relative to a direction of travel of said interrogator.
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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) | 2003-04-04 | 2003-10-04 | 2004-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2007-04-04 | 2007-10-04 | 2008-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2011-04-04 | 2011-10-04 | 2012-04-04 | $7700.00 | Window Closed / Lapsed |