Hybrid FMCW-interferometry radar for positioning and monitoring and methods of using same

• US 10,436,888 B2
• Filed: 05/29/2015
• Issued: 10/08/2019
• Est. Priority Date: 05/30/2014
• Status: Active Grant

• Current Assignee: Texas Tech University System
• Original Assignee: Texas Tech University System
• Inventors: Li, Changzhi, Wang, Guochao
• Primary Examiner(s): Bythrow, Peter M
• Application Number:
  US15/315,299
• Publication Number:
  US 20170102457A1
• Time in Patent Office: 1,593 Days
• CPC Class Codes: G01S 13/341 wherein the rate of change of the transmitted frequency is adjusted to give a beat of predetermined constant frequency, e.g. by adjusting the amplitude or frequency of the frequency-modulating signal
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/536 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
• CPC Class Codes: G01S 13/56 for presence detection presence detection using near field arrangements G01V3/00, e.g. G01V3/08, G01V3/12; burglar, theft or intruder alarms with electrical actuation G08B13/22 - G08B13/26
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/886 for alarm systems alarms with electrical actuation G08B13/22
• CPC Class Codes: G01S 7/10 Providing two-dimensional and co-ordinated display of distance and direction
• CPC Class Codes: G01S 7/35 Details of non-pulse systems
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

Disclosed is a system and method for a hybrid radar system that integrates frequency-modulated continuous wave (FMCW) mode and interferometry mode. The radar works as a time division system that continuously switches between the FMCW mode and interferometry mode. The FMCW mode is responsible for absolute range detection and the interferometry mode takes cares of the weak physiological movement monitoring. The respective accuracies in range detection and displacement measurement complements the advantages of the two radar modes, providing versatile performance. By steering the antenna beam, the proposed radar system becomes an ideal solution for indoor health care, human localization, and human-computer interaction. Objects or human targets with or without stationary clutters can be precisely located. At the same time, the targets'"'"' vital signs and gestures can be monitored.

Claims

1. A method for object localization and monitoring, comprising the steps of:

transmitting, via a transmitting antenna coupled to a computing device, a first signal comprising frequency modulated continuous wave (FMCW) signal;

transmitting, via the transmitting antenna and concurrent with the transmission of said first signal, a second signal, said second signal comprising a single-tone interferometry signal;

receiving, via a receiving antenna coupled to the computing device, a third signal comprising an FMCW signal, wherein the third signal comprises a reflection of the first signal;

receiving, via the receiving antenna, a fourth signal comprising a single-tone interferometry signal, wherein the fourth signal comprises a reflection of the second signal;

determining, via the computing device, signal information associated with the third and fourth signals;

calculating, via the computing device, range and displacement information respective to the computing device based on said signal information; and

visibly displaying, on a display associated with said computing device, range, displacement and gesture recognition based on the calculated range and displacement information.

2. The method of claim 1, wherein said first and second signals comprise a sequence of signals transmitted via a time division multiplexed transmitter.

3. The method of claim 1, wherein said first and said third signals comprise a chirped beat signal comprising an up-ramp linear frequency-modulated signal.

4. The method of claim 1, wherein said second and fourth signals comprise an interferometry signal having a fixed operating frequency.

5. The method of claim 1, wherein the receiving of said third signal and said fourth signal alternate.

6. The method of claim 1, wherein determining signal information further comprises extracting an integral beat signal and reconstructing the interferometry signal, which are used to provide range information and displacement information respectively.

7. The method of claim 6, wherein extracting the integral beat signal further comprises mixing a replica of the transmitted first signal with the received third signal.

8. The method of claim 7, wherein said mixing results in said integral beat signal represented by variable S_b(t) in equation:

9. The method of claim 1, wherein a waveform of said first signal is designed to be phase coherent.

10. The method of claim 7, wherein said extracting further comprises predicting following beat signals based on a FMCW burst interval.

11. The method of claim 6, wherein said determining signal information further comprises calculating the interferometry signal of a point-scatterer in baseband I/Q using arctangent demodulation.

12. The method of claim 11, wherein said calculating the interferometry signal further comprises utilizing said interferometry signal information to solve for variables B_Q (τ

) and B_l(τ

) for said interferometry signal in equations;

13. The method of claim 12, further comprising eliminating the integral beat signal by determining said integral beat signal and replacing said integral beat signal with linear interpolation without introducing significant distortion to the interferometry signal.

14. The method of claim 1, further comprising:

determining angular information of a room by steering an antennae beam defined by the transmitting antenna,

combining said angular information and said range and displacement information,

calculating a two-dimensional polar coordinate; and

displaying said two-dimensional polar coordinate as a top view of the objects in a room on the display associated with said computing device.

15. The method of claim 1, further comprising monitoring micro-Doppler effects of an object using said interferometry signal.

16. The method of claim 15, wherein said micro-Doppler effects comprise physiological motion monitoring, gestures and other minor discrete movements.

17. The method of claim 1, further comprising localization and monitoring of multiple objects in a room.

18. The method of claim 17, wherein said multiple objects comprise living organisms.

19. The method of claim 18, wherein said multiple objects comprise humans.

20. The method of claim 17, wherein said localization of multiple objects differentiates between living organisms and stationary objects (clutters) in a room.

21. A non-transitory computer-readable storage medium tangibly encoded with computer-executable instructions, that when executed by a processor associated with a computing device, performs a method of object localization and monitoring, comprising:

transmitting, by way of a transmitting antenna coupled to the computing device, a first signal comprising frequency modulated continuous wave (FMCW) signal;

transmitting, by way of the transmitting antenna and concurrent with the transmission of said first signal, a second signal, said second signal comprising a single-tone interferometry signal;

receiving, by way of a receiving antenna coupled to the computing device, a third signal comprising an FMCW signal, wherein the third signal comprises a reflection of the first signal;

receiving, by way of the receiving antenna, a fourth signal comprising a single-tone interferometry signal, wherein the fourth signal comprises a reflection of the second signal;

determining signal information associated with the third and fourth signals;

calculating range and displacement information respective to the computing device based on said signal information; and

visibly displaying, on a display associated with said computing device, range, displacement and gesture recognition based on the calculated range and displacement information.

22. The non-transitory computer-readable storage medium of claim 21, wherein:

said first and third signals comprise a chirped beat signal comprising an up-ramp linear frequency-modulated signal, and

said second and fourth signals comprise an interferometry signal having a fixed operating frequency.

23. The non-transitory computer-readable storage medium of claim 21, further comprising monitoring micro-Doppler effects of an object using said interferometry signal, said micro-Doppler effects comprising physiological motion monitoring, gestures and other minor discrete movements.

24. A system comprising:

a transceiver defining a transmitting antenna and a receiving antenna; and

a computing device coupled to the transceiver, the computing device comprising;

a processor; and

a coupled to the processor, memory storing computer-executable instructions that are executable by the processor to cause the computing device to execute operations comprising;

a processor;

transmitting, via the transceiver, a first signal comprising frequency modulated continuous wave (FMCW) signal;

transmitting, via the transceiver and concurrent with the transmission of said first signal, a second signal, said transmission comprising a single-tone interferometry signal;

receiving, via the transceiver, a third signal comprising an FMCW signal, wherein the third signal comprises a reflection of the first signal;

receiving, via the transceiver, a fourth signal comprising a single-tone interferometry signal, wherein the fourth signal comprises a reflection of the second signal;

determining signal information associated with said received third signal and said received fourth signal;

calculating range and displacement information respective to the computing device based on said signal information; and

visibly displaying, on a display associated with said computing device, range, displacement, clutter, and gesture recognition based on the calculated range and displacement information for object localization, physiological and movement monitoring.