RADIO FREQUENCY SIGNAL ACQUISITION AND SOURCE LOCATION SYSTEM

• US 20100225480A1
• Filed: 03/31/2008
• Published: 09/09/2010
• Est. Priority Date: 09/11/2007
• Status: Active Grant

• Current Assignee: RF Controls LLC
• Original Assignee: RF Controls LLC
• Inventors: Pierce, Matthew E., Bloy, Graham P., Hofer, Russell
• Granted Patent: US 8,421,631 B2
• Time in Patent Office: Days
• US Class Current: 340/572.100
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted
• CPC Class Codes: G01S 13/878 Combination of several spaced transmitters or receivers of known location for determining the position of a transponder or a reflector G01S13/874 takes precedence
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/04 Position of source determined by a plurality of spaced direction-finders
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: G06K 7/01 Details
• CPC Class Codes: G06K 7/10079 the collision being resolved in the spatial domain, e.g. temporary shields for blindfolding the interrogator in specific directions
• CPC Class Codes: G08B 13/2462 Asset location systems combined with EAS inventory, tracking, logistic G06Q10/00; entrance control systems G07C9/00
• CPC Class Codes: H01Q 1/2216 used in interrogator/reader equipment
• CPC Class Codes: H01Q 3/36 with variable phase-shifters

Abstract

A radio frequency signal acquisition and source location system, including a first signal acquisition and source location module comprising an RF transceiver coupled to an antenna, the antenna provided with a electronic steering circuit. The antenna operative to launch an interrogation signal, the interrogation signal steerable by an electronic steering circuit. A processor operatively coupled to the RF transceiver and the electronic steering circuit, the processor provided with a data storage for storing a signal data record for each of at least one response signal(s) received by the RF transceiver(s). The signal data record including a signal identification, a received signal strength indicator and an RF signal direction along which respective signal(s) are received by the antenna, the RF signal direction derived from the electronic steering circuit. A position logic operative upon the data record(s) deriving a three dimensional signal origin location of each response signal.

Claims

1. A radio frequency signal acquisition and source location system, comprising:

a first signal acquisition and source location module comprising an RF transceiver coupled to an antenna, the antenna provided with a electronic steering circuit;

the antenna operative to launch an interrogation signal, the interrogation signal steerable by an electronic steering circuit; and

a processor operatively coupled to the RF transceiver and the electronic steering circuit;

the processor provided with a data storage for storing a signal data record for each of at least one response signal(s) received by the RF transceiver(s);

the signal data record including a signal identification, a received signal strength indicator and an RF signal direction along which respective signal(s) are received by the antenna, the RF signal direction derived from the electronic steering circuit; and

a position logic operative upon the data record(s) to derive a three dimensional signal origin location of each response signal.

2. The system of claim 1, wherein the electronic steering circuit directs each antenna through a sweep pattern of a zone to obtain the signal data record(s).

3. The system of claim 2, wherein the sweep pattern is a raster scan.

4. The system of claim 2, wherein the sweep pattern excludes selected areas within the zone.

5. The system of claim 1, wherein the position logic identifies a primary signal data record;

the primary signal data record being the signal data record in which the received signal strength indicator is the highest among signal data record(s) having a common signal identification;

the three dimensional signal origin location of each response signal derived from the RF signal direction of each of the primary signal data record(s) and the respective received signal strength indicator(s);

the received signal strength indicator proportional to a distance along the RF signal direction from the antenna.

6. The system of claim 1, further including a second signal acquisition and source location module and an edge server;

the edge server provided with a data connection with the first signal acquisition and source location module and the second signal acquisition and source location module;

the edge server receiving the primary signal data records from each of the first and second signal acquisition and source location modules and performing a triangulation operation upon the primary signal data records having a common signal identification to generate a higher order three dimensional signal origin location for each.

7. The system of claim 6, wherein the edge server compares successive three dimensional signal origin locations for each response signal to calculate a velocity of a corresponding response signal source.

8. The system of claim 6, wherein the edge server is integral with the first signal acquisition and source location module.

9. The system of claim 1, wherein at least one of the plurality of antennas is a phased array steerable antenna.

10. The system of claim 9, wherein the phased array steerable antenna is a panel or array provided with a plurality of radiating elements, each of the radiating elements individually drivable by the electronic steering circuit provided as a phase shifter controlled by a beam steering unit.

11. The system of claim 1, wherein the antenna has a transmit antenna element separate from a receive antenna element.

12. The system of claim 11, wherein the transmit and the receive elements are respective arrays of transmit and receive elements.

13. The system of claim 1, wherein the electronic steering circuit is a beam steering unit operatively coupled with a phase shifter of each of the antenna.

14. The system of claim 13, wherein the phase shifter is a plurality of phase shifters, one for each of a plurality of antenna elements of the antenna.

15. The system of claim 13, wherein the phase shifter includes an electronic phase shift element.

16. The system of claim 1, wherein the RF transceiver is an RFID reader.

17. The system of claim 1, wherein the interrogation signal is operative to initiate backscatter modulation in an RFID tag, and the response signal includes data representing at least a tag identification or item identity of each RFID tag initiated into back scatter modulation by the interrogation signal.

18. The system of claim 1, wherein the antenna and the electronic steering circuit are coupled to the processor by a digital data link.

19. The system of claim 1, wherein the plurality of antenna is positioned spaced apart and facing a zone.

20. The system of claim 19, wherein the antenna is positioned above the zone.

21. The system of claim 1, further including a discrimination logic of the processor operative upon the signal data record(s) to filter the signal data record(s) between an actual signal(s) and a ghost signal(s).

22. The system of claim 21, wherein the discrimination logic is a multi-path ambiguity resolution logic.

23. The system of claim 21, wherein the discrimination logic compares the received signal strength indicator of each of the data record(s) having a common signal identifying data, discarding these data records other than the one data record having the highest received signal strength indicator.

24. The system of claim 1, further including an operator feedback including the three dimensional signal origin location within the zone and the signal identifying data of each of the actual signals.

25. A radio frequency signal acquisition and source location system, comprising:

a first signal acquisition and source location module comprising an RF transceiver coupled to an antenna, the antenna provided with a phase shifter controlled by a beam steering unit;

the antenna operative to launch an interrogation signal operative to energize backscatter modulation in an RFID tag within a zone, the interrogation signal steerable by the beam steering unit through a sweep pattern of the zone; and

a processor operatively coupled to the RF transceiver and the beam steering unit;

the processor provided with a data storage for storing a signal data record for each of at least one response signal(s) received from the RFID tag(s) by the RF transceiver(s);

the signal data record including at least a tag identification or item identity, a received signal strength indicator and an RF signal direction along which respective signal(s) are received by the at least one antenna, the RF signal direction derived from the electronic steering circuit; and

a position logic operative upon the data record(s) to derive a three dimensional signal origin location of each RFID tag.

26. A radio frequency signal acquisition and source location system, comprising:

a first signal acquisition and source location module and a second signal acquisition and source location module;

the first and the second signal acquisition and source location modules each comprising an RF transceiver coupled to an antenna, the antenna provided with a phase shifter controlled by a beam steering unit;

the antenna operative to launch an interrogation signal operative to energize backscatter modulation in an RFID tag(s), the interrogation signal steerable by the beam steering unit through a sweep pattern of a zone; and

a processor operatively coupled to the RF transceiver and the beam steering unit;

the processor provided with a data storage for storing a signal data record for each of at least one response signal(s) received from the RFID tag(s) by the RF transceiver(s) as the interrogation beam passes through the sweep pattern;

the signal data record including, for each of a plurality of recording positions within the sweep pattern, at least a tag identification or item identity, a received signal strength indicator and an RF signal direction along which respective signal(s) are received by the antenna, the RF signal direction derived from the beam steering unit; and

a position logic operative upon the data record(s) to derive a primary RF signal direction of each RFID tag;

the first signal acquisition and source location module and the second signal acquisition and source location modules coupled to an edge server by a data connection;

the edge server receiving the primary RF signal direction from each of the first and second signal acquisition and source location modules as an input to a triangulation logic to generate a higher order three dimensional signal origin location for each of the RFID tag(s) in the zone.

27. A method for radio frequency signal acquisition and source location, comprising the steps of:

steering, via a electronic steering circuit, an interrogation signal through a sweep pattern of a zone;

recording a data record of each of a signal identification, a received signal strength indicator and an RF signal direction along which respective response signal(s) are received, the RF signal direction derived from the electronic steering circuit;

performing a position logic operation with the RF signal direction and the received signal strength indicator as inputs to derive a first three dimensional signal origin location within the zone of each of the response signal(s).

28. The method of claim 27, wherein the interrogation signal is operative to enable or energize a RFID tag for backscatter modulation transmission of the response signal, the response signal including at least a tag identification or item identity of the RFID tag.

29. The method of claim 27, wherein the position logic operation identifies the data record(s) wherein the signal identification is the same;

maps the respective response signal(s) within the zone; and

applies a curve fitting analysis to generate a predicted response signal location where the signal strength indicator is maximized, designating the predicted response signal location as the first three dimensional signal origin location for the response signal.

30. The method of claim 27, wherein the position logic operation identifies the data record(s) wherein the signal identification is the same;

maps the respective response signal(s) within the zone; and

designates a middle location between the respective signals as the first three dimensional signal origin location for the response signal.

31. The method of claim 27, wherein the position logic operation identifies the data record(s) wherein the signal identification is the same;

maps the respective response signal(s) within the zone; and

designates a middle location between the respective signals, weighted by the location of the data record with the highest signal strength indicator, as the first three dimensional signal origin location for the response signal.

32. The method of claim 27, wherein the first three dimensional signal origin location is a defined area.

33. The method of claim 32, further including the step of identifying a center of the defined area as the first three dimensional signal origin location.

34. The method of claim 27, further including the step of calibrating the interrogation signal sweep pattern to pass over only the zone, before performing the sweep pattern.

35. The method of claim 34, further including the step of calibrating the interrogation signal sweep pattern to exclude portions of the zone that are subject to RF interference.

36. The method of claim 27, further including the step of performing a discrimination logic operation upon the data record(s) to filter the data record(s) between an actual signal(s) and a ghost signal(s).

37. The method of claim 36, wherein the discrimination logic is a multi-path ambiguity resolution logic.

38. The method of claim 36, further including the application of a probability weighting factor to the actual signal(s) and the ghost signal(s) during the discrimination logic operation, then filtering for the actual signal(s) according to the value of the probability weighting factor.

39. The method of claim 27, further including applying a variable sweep rate during the steering of the signal beam through the sweep pattern;

the sweep rate reduced upon detection of a response signal and increased after passage of a period without detecting another signal.

40. The method of claim 27, further including validation of the three dimensional signal origin location via timing of a delay between the interrogation signal initiation and a corresponding reception of a signal.

41. The method of claim 27, further including modulation of the interrogation signal strength to identify a cut-off signal strength below which the signal is not responsive to the interrogation signal, the cut-off signal strength proportional to a distance between the antenna and the first three dimensional signal origin location.

42. The method of claim 27, wherein the first three dimensional signal origin location is output to an edge server also being fed by a second electronic steering circuit steering a second interrogation signal through a corresponding sweep pattern of the zone and generating a second signal data record;

the edge server triangulating between the first three dimensional signal origin location and the second three dimensional signal origin location to generate a corresponding higher order three dimensional signal origin location.

43. The method of claim 27, wherein the sweep pattern excludes selected areas within the zone.

44. A method for radio frequency signal acquisition and source location, comprising the steps of:

in a first module, steering, via a first electronic steering circuit, a first interrogation signal through a first sweep pattern of a zone;

recording a first data record of each of a signal identification, a received signal strength indicator and an RF signal direction along which respective response signal(s) are received, the RF signal direction derived from the electronic steering circuit, using signal processing or computation;

performing a position logic operation with the RF signal direction and the received signal strength indicator as inputs to derive a first beam direction of the response signal(s);

outputting the signal identification and the first beam direction to an edge server;

the edge server receiving additional data records and additional beam direction data for the respective response signal(s) from at least a second module with a second electronic steering circuit steering a second interrogation signal through a second sweep pattern of the zone;

performing a triangulation logic operation at the edge server to determine an intersection point of the first beam direction and at least the second beam direction(s) and designating the intersection point as a three dimensional signal origin location of the respective response signal(s).

45. The method of claim 44, wherein the position logic operation identifies the data record(s) wherein the signal identification is the same;

maps the respective response signal(s) within the zone; and

applies a curve fitting analysis to generate a predicted RF signal direction where the signal strength indicator is maximized, and designating the predicted RF signal direction as the RF signal direction of the respective response signal(s).

46. The method of claim 44, wherein the first and second interrogation signal(s) are operative to energize an RFID tag for backscatter modulation transmission of the response signal, the response signal including at least a tag identification or item identity of the RFID tag.

47. The method of claim 44, further including the step of calculating the dimensions of the three dimensional signal origin location, from a cross section dimension, of the first and second interrogation beams and designating a center of the three dimensional signal origin location as the three dimensional signal origin location.