HIGH-PRECISION TIME OF FLIGHT MEASUREMENT SYSTEMS

• US 20160363659A1
• Filed: 06/14/2016
• Published: 12/15/2016
• Est. Priority Date: 06/15/2015
• Status: Active Grant

• Current Assignee: Humatics Corporation
• Original Assignee: Humatics Corporation
• Inventors: Cohen, Gary A., Yoerger, Dana R., Mindell, David A., Charvat, Gregory L.
• Granted Patent: US 10,591,592 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/66 Radar-tracking systems; Analogous systems
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 13/76 wherein pulse-type signals are transmitted
• CPC Class Codes: G01S 13/82 wherein continuous-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 13/885 for ground probing prospecting or detecting using electromagnetic waves G01V3/12
• CPC Class Codes: G01S 2205/01 specially adapted for specific applications
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0247 Determining attitude
• CPC Class Codes: G01S 5/0294 Trajectory determination or predictive filtering, e.g. target tracking or Kalman filtering
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing
• CPC Class Codes: G01S 7/358 using I/Q processing
• CPC Class Codes: H04W 4/029 Location-based management or tracking services

Abstract

A system and method is disclosed for measuring time of flight to an object. A transmitter transmits an electromagnetic signal and provides a reference signal corresponding to the electromagnetic signal. A receiver receives the electromagnetic signal and provides a response signal corresponding to the received electromagnetic signal. A detection circuit is configured to determine a time of flight between the transmitter and the receiver based upon the reference signal and the response signal.

Claims

1. A system for measuring time of flight to an object, comprising:

at least one transmitter configured to transmit an electromagnetic signal and provide a reference signal corresponding to the electromagnetic signal;

at least one receiver configured to receive the electromagnetic signal and in response provide a response signal corresponding to the received electromagnetic signal; and

a detection circuit configured to determine a time of flight between the transmitter and the receiver based upon the reference signal and the response signal.

2. The system of claim 1 wherein the detection circuit is further configured to determine a distance between the transmitter and the receiver based at least in part upon the time of flight.

3. The system of claim 1 wherein the electromagnetic signal is one of a frequency modulated continuous wave (FMCW) signal, a direct sequence spread spectrum signal (DSSS), a pulse compressed signal, and a frequency hopping spread spectrum (FHSS) signal.

4. The system of claim 1 wherein the detection circuit includes a mixer that receives the reference signal and the response signal, and provides a beat signal corresponding to the time of flight between the transmitter and the receiver.

5. The system of claim 4 wherein the detection circuit further comprises:

an analog to digital converter that receives the beat signal and provides a sampled beat signal; and

a processor coupled to an output of the analog to digital converter that receives the sampled beat signal and performs a fast Fourier transform on the sampled beat signal.

6. The system of claim 1 further comprising a cable coupled between the detection circuit and at least one of the transmitter and the receiver, the cable configured to convey to the detection circuit at least one of the reference signal and the response signal.

7. The system of claim 1 wherein the detection circuit is configured to wirelessly receive at least one of the reference signal and the response signal.

8. The system of claim 1 wherein the transmitter includes a pseudo noise generator.

9. The system of claim 1 wherein the transmitter is configured to transmit and the receiver is configured to receive the electromagnetic signal having one of a command protocol and an embedded unique code in the electromagnetic signal to address and enable each receiver.

10. The system of claim 1 wherein the receiver further comprises an auxiliary wireless receiver configured to receive an auxiliary wireless signal configured with a unique code to target the receiver, and wherein the receiver is further configured to power up the receiver to provide the response signal when the receiver has received the auxiliary wireless signal and not to provide the response signal when the receiver has not received the auxiliary wireless signal.

11. The system of claim 10, wherein the auxiliary wireless receiver is configured to receive the auxiliary wireless signal that is any of a Bluetooth signal, a Zigbee signal, a Wi-Fi signal, and a cellular signal.

12. The system of claim 10, wherein the receiver further comprises:

at least one antenna configured to receive the electromagnetic signal at a first frequency; and

a multiplier coupled to the at least one antenna to receive the electromagnetic signal at the first frequency and that provides a multiplied signal having a harmonic component at a second frequency that is a harmonic multiple of the first frequency.

13. The system of claim 12, wherein the receiver further comprises a power source that is configured to normally bias the multiplier to a biased off state and that is configured to bias on the multiplier to an on state in response to receipt of the auxiliary wireless signal configured with the unique code to target the receiver.

14. The system of claim 13, wherein the power source is further configured to forward bias the multiplier to increase a sensitivity and range of the receiver.

15. The system of claim 13, wherein the receiver has no active components other than the multiplier, which is configured to normally be off so as to require substantially no power.

16. The system of claim 15, wherein the power source is one of a low power battery source or power is derived by one or more energy harvesting techniques.

17. The system of claim 15, wherein the at least one antenna comprises a single antenna for both receiving the electromagnetic signal at the first frequency and transmitting the multiplied signal at the second frequency.

18. The system of claim 12, wherein the receiver further comprises the multiplier integrated with the at least one antenna element.

19. The system of claim 12, wherein the transmitter further comprises a plurality of receive channels configured to receive the electromagnetic signal at the second frequency in a spatially diverse array.

20. The system of claim 19, wherein the plurality of receive channels can either be multiplexed to receive the electromagnetic signal at the second frequency at different times or can be configured to operate simultaneously.

21. The system of claim 12, wherein the transmitter is configured to provide a modulated electromagnetic signal and the receiver is configured to receive the modulated electromagnetic signal to uniquely address the receiver.

22. The system of claim 12, wherein the transmitter and the receiver are configured to operate simultaneously.

23. The system of claim 1, wherein the transmitter comprises in phase and 90°

out of phase (quadrature) channels with multipliers that are modulated in quadrature to send coded electromagnetic signals to a plurality of receivers simultaneously.

24. The system of claim 1, wherein the at least one receiver includes a plurality of receivers and the at least one transmitter and the plurality of receivers are configured to time share and uniquely address each receiver of the plurality of receivers.

25. The system of claim 1, wherein the at least one receiver includes a plurality of receivers and the at least one transmitter and the plurality of receivers are configured to dynamically assess and address the plurality of receivers that are moving faster than others more frequently.

26. The system of claim 1, wherein the at least one receiver includes a plurality of receivers and the at least one transmitter and the plurality of receivers are configured with their own proprietary micro-location frequency allocation protocol so that the receiver and at least one transmitter can operate at unused frequency bands that exist amongst existing allocated frequency bands.

27. The system of claim 26, wherein the at least one transmitter and the plurality of receivers are configured to license-free bands.

28. The system of claim 27, wherein the at least one transmitter and the plurality of receivers are configured to communicate with existing systems at existing licensed frequencies to use existing frequency allocations in situations that warrant using existing frequency band allocations.

29. The system of claim 27, wherein the at least one transmitter and the plurality of receivers are configured to detect loading issues within any used frequency band and to allocate signals to be used based on system usage.

30. The system of claim 1, further comprising a plurality of transmitters configured to transmit a plurality of electromagnetic signals, the detection circuit configured to determine one or more distances between the receiver and one or more of the transmitters.

31. The system of claim 12, wherein the detection circuit is further configured to determine a position of the receiver at least in part from one or more of the one or more distances.

32. The system of claim 1, further comprising a plurality of transmitters configured to transmit a plurality of electromagnetic signals, the detection circuit configured to determine one or more time differences of arrival between two or more of the plurality of electromagnetic signals.

33. The system of claim 32, wherein the detection circuit is further configured to determine a position of the receiver at least in part from one or more of the one or more time differences of arrival.

34. A method of measuring time of flight to an object, comprising:

receiving a reference signal from an interrogator, the reference signal corresponding to an electromagnetic signal transmitted by the interrogator;

receiving a response signal from a transponder, the response signal provided by the transponder in response to receiving the electromagnetic signal, and the response signal corresponding to the received electromagnetic signal; and

determine a time of flight of the electromagnetic signal between the interrogator and the transponder based upon the reference signal and the response signal.

35. The method of claim 34, further comprising determining the distance between the interrogator and the transponder based at least in part upon the time of flight.

36. The method of claim 34, wherein the electromagnetic signal is one of a frequency modulated continuous wave (FMCW) signal, a direct sequence spread spectrum (DSSS) signal, a pulse compressed signal, and a frequency hopping spread spectrum (FHSS) signal.

37. The method of claim 34, wherein determining the time of flight includes mixing the response signal and the reference signal to provide a beat signal corresponding to the time of flight.

38. The method of claim 37, further comprising:

converting the beat signal into a digital form to provide a sampled beat signal; and

performing a fast Fourier transform on the sampled beat signal.

39. The method of claim 34, wherein at least one of the reference signal and the response signal are received via a cable.

40. The method of claim 34, wherein at least one of the reference signal and the response signal are received wirelessly.

41. The method of claim 34, wherein the electromagnetic signal is generated, at least in part, from a pseudo noise generator.

42. The method of claim 34, wherein the response signal is received from the transponder only when the transponder has received an auxiliary signal, and the response signal is not received from the transponder when the transponder has not received the auxiliary signal.

43. The method of claim 42, wherein the auxiliary signal is one of a Bluetooth signal, a Zigbee signal, a Wi-Fi signal, a cellular signal, and a unique code.

44. The method of claim 34, further comprising:

receiving a plurality of response signals from the transponder, each of the plurality of response signals provided in response to receiving one of a plurality of electromagnetic signals from a plurality of interrogators; and

determining one or more distances between the transponder and one or more of the plurality of interrogators.

45. The method of claim 44, further comprising determining a position of the transponder at least in part from one or more of the one or more distances.

46. The method of claim 34, further comprising:

receiving a plurality of response signals from the transponder, each of the plurality of response signals provided in response to receiving one of a plurality of electromagnetic signals from a plurality of interrogators; and

determining one or more time differences of arrival between two or more of the plurality of electromagnetic signals.

47. The method of claim 46, further comprising determining a position of the transponder at least in part from one or more of the one or more time differences of arrival.