Life detecting radars

• US 10,201,278 B2
• Filed: 04/18/2014
• Issued: 02/12/2019
• Est. Priority Date: 04/18/2013
• Status: Active Grant

• Current Assignee: California Institute of Technology
• Original Assignee: California Institute of Technology
• Inventors: Lux, James Paul, Cable, Vaughn P., Haque, Salman-ul Mohammed, McKee, Michael Ray, Ghaemi, Hirad, Kalantar Ohanian, Richard
• Primary Examiner(s): Akar, Serkan
• Assistant Examiner(s): Negarestan, Farshad
• Application Number:
  US14/256,748
• Publication Number:
  US 20140316261A1
• Time in Patent Office: 1,761 Days
• CPC Class Codes: A61B 5/0022 Monitoring a patient using a global network, e.g. telephone networks, internet
• CPC Class Codes: A61B 5/024 Detecting, measuring or recording pulse rate or heart rate A61B5/0205, A61B5/021 take precedence
• CPC Class Codes: A61B 5/0507 using microwaves or terahertz waves
• CPC Class Codes: A61B 5/0816 Measuring devices for examining respiratory frequency measuring frequency of electric signals G01R23/00
• CPC Class Codes: A61B 5/1126 using a particular sensing technique
• CPC Class Codes: A61B 5/117 Identification of persons methods or arrangements for recognising patterns, e.g. fingerprints, G06F18/00, G06V40/00; identification of persons by analysing their voice or speech G10L17/00
• CPC Class Codes: A61B 5/7257 using Fourier transforms
• CPC Class Codes: A62B 33/00 Devices for allowing seemingly-dead persons to escape or draw attention; Breathing apparatus for accidentally buried persons
• CPC Class Codes: G01S 13/347 using more than one modulation frequency
• 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 13/88 Radar or analogous systems specially adapted for specific applications electromagnetic prospecting or detecting of objects, e.g. near-field detection, G01V3/00
• CPC Class Codes: G01S 7/003 Transmission of data between radar, sonar or lidar systems and remote stations
• CPC Class Codes: G16H 40/67 for remote operation
• CPC Class Codes: G16Z 99/00 Subject matter not provided for in other main groups of this subclass

Abstract

Systems and methods for detecting biometrics using a life detecting radar are disclosed. Life detecting radars can include transmit antennas configured to transmit continuous microwave (“CW”) radio signals that reflect back upon making contact with various objects. The signal can be systematically varied in frequency to provide a signal that is essentially continuous with short gaps between transmissions at different frequencies. The reflected return signals are received by one or more receive antennas and processed to detect one or more targets. The received signal can include a static (i.e. constant phase) signal corresponding to reflections from objects that do not move. The received signal can also include a phase varying signal that corresponds to reflections from a living target having measurable biometrics including (but not limited to) breathing patterns and heartbeats. Clutter can be removed and the remaining portions of the received signal are analyzed for target detection.

Claims

1. A life detecting radar comprising:

an antenna switching matrix configured to make multiple measurements at a same time comprising a plurality of transmit antennas configured to propagate a plurality of beams using continuous microwave signals stepping among a limited set of frequencies for obtaining range measurements, wherein switching and frequency patterns of the plurality of beams are selected to prevent the same frequency from being used on two separate beams at the same period in time;

at least one transmit antenna in the plurality of transmit antennas configured to propagate at least one beam using a continuous wave transmit signal set at a plurality of frequencies, where the at least one beam illuminates at least one sensing area;

at least one receive antenna configured to receive a return signal associated with reflections from objects of the at least one transmit signal within the at least one sensing area, where the return signal comprises at least one signal component having static phase associated with reflections from nonmoving objects and at least one signal component having time varying phase associated with at least one target;

a processor;

a memory containing a radar application, wherein execution of the radar application by the processor configures the processor to;

receive the return signal from the at least one receive antenna;

determine a static phase component of the return signal;

generate a cancellation signal at RF frequency by sampling at least one transmit signal and modulating the sampled transmit signal such that the phase and amplitude of the cancellation signal is adjusted to match an estimated phase and amplitude of the static phase component of the return signal;

process the return signal by subtracting the cancellation signal from the return signal to attenuate the at least one signal component having static phase; and

detect the at least one target by analyzing the at least one signal component having time varying phase for a biometric identifier by;

transforming the processed return signal from a frequency to a time domain data set;

generating range bins, where each range bin has a sequence of samples taken from the time domain data set;

analyzing each range bin for unique targets by examining a band limited version of the processed return signal for repetitive characteristics; and

matching the repetitive characteristics to a biometric identifier of a human, wherein the biometric identifier includes at least one microwave cardiogram (MCG) and at least one breathing pattern that can be utilized to discriminate among a plurality of unique targets located within the at least one sensing area, and wherein uniqueness of MCG allows for the separation of combined MCGs from multiple targets to discriminate among the targets.

2. The life detecting radar of claim 1, wherein the radar application further configures the processor to generate a user interface that allows the processor to receive inputs for controlling the life detecting radar.

3. The life detecting radar of claim 2, wherein the user interface is generated on a separate device configured to communicate with the life detecting radar via a wireless communication channel.

4. The life detecting radar of claim 1, wherein the plurality of transmit antennas are configured to rapidly switch the plurality of beams and frequencies to allow for multiple measurements to be made during a short enough time period wherein the at least one target'"'"'s heartbeat signal is assumed constant during the time period.

5. The life detecting radar of claim 1, wherein the plurality of transmit antennas are configured to rapidly switch the plurality of beams and frequencies to allow for multiple measurements to be made during a short enough time period wherein the at least one target'"'"'s respiration signal is relatively constant.

6. The life detecting radar of claim 1, wherein the radar application further configures the processor to receive the return signal from the at least one receive antenna and collect samples for each sensing area at a sampling rate between 300-500 Hz.

7. The life detecting radar of claim 1, wherein the life detecting radar utilizes a plurality of radio frequency modules that transmit and receive signals.

8. The life detecting radar of claim 1, wherein the life detecting radar further comprises a camera for collecting digital image data.

9. The life detecting radar of claim 1, wherein the life detecting radar further comprises a Global Positioning System for providing location information.

10. The life detecting radar of claim 1, wherein transforming the processed return signal from a frequency to a time domain data set includes utilizing an Inverse Fast Fourier Transform.

11. The life detecting radar of claim 1, wherein the radar application further configures the processor to produce a prototype waveform from the at least one signal component having time varying phase and compare the prototype waveform against a data collection of human and animal waveforms to detect the at least one target.

12. The life detecting radar of claim 1, wherein detecting a target by analyzing the at least one signal component further includes first identifying which targets are likely to be in a search area in front of the transmit antenna.

13. The life detecting radar of claim 1, wherein the at least one transmit antenna is further configured to propagate eight beams arranged in cardinal and intermediate directions.

14. The life detecting radar of claim 13, wherein the at least one transmit antenna is further configured to utilize 10 frequencies.

15. The life detecting radar of claim 1, wherein the sequence of samples taken from the time domain data set includes phase and quadrature data samples.

16. The life detecting radar of claim 1, wherein at least one antenna is configured to be used as both a transmit antenna and a receive antenna.

17. The life detecting radar of claim 1, wherein the at least one transmit signal used to generate the cancellation signal is received by one of the at least one receive antennas.

18. A method of detecting a target using a processor of a life detecting radar, the method comprising:

propagating, using an antenna switching matrix comprising a plurality of antennas to make multiple measurements at a same time, a plurality of beams using continuous microwave signals stepping among a limited set of frequencies for obtaining range measurements, wherein at least one beam is propogated using a continuous wave transmit signal set at a plurality of frequencies, where the plurality of beams illuminate at least one sensing area using a plurality of transmit antennas and wherein switching and frequency patterns are selected to prevent the same frequency from being used on two separate beams at the same period in time;

receiving a return signal associated with reflections of the at least one transmit signal from objects within the at least one sensing area using at least one receive antenna, where the return signal comprises at least one signal component having static phase associated with reflections from nonmoving objects and at least one signal component having time varying phase associated with at least one target;

receiving the return signal from the at least one receive antenna using a life detecting radar system;

determining a static phase component of the return using the life detecting radar system;

generating a cancellation signal at RF frequency by sampling the at least one transmit signal and modulating the sampled transmit signal such that the phase and amplitude of the cancellation signal is adjusted to match an estimated phase and amplitude of the static phase component of the return signal using the life detecting radar system;

processing the return signal by subtracting the cancellation signal from the return signal to attenuate the at least one signal component having static phase using the life detecting radar system; and

detecting the at least one target by analyzing the at least one signal component having time varying phase for a biometric identifier by using the life detecting radar system by;

transforming the processed return signal from a frequency to a time domain data set;

generating range bins, where each range bin has a sequence of samples taken from the time domain data set;

analyzing each range bin for unique targets by examining a band limited version of the processed return signal for repetitive characteristics; and

matching the repetitive characteristics to a biometric identifier of a human, wherein the biometric identifier includes at least one microwave cardiogram and at least one breathing pattern that can be utilized to discriminate among a plurality of unique targets located within the at least one sensing area, and wherein uniqueness of MCG allows for the separation of combined MCGs from multiple targets to discriminate among the targets.

19. A life detecting radar comprising:

an antenna switching matrix configured to make multiple measurements at the same time comprising a plurality of transmit antennas configured to propagate a plurality of beams using continuous microwave signals stepping among a limited set of frequencies for obtaining range measurements wherein switching and frequency patterns are selected to prevent the same frequency from being used on two separate beams at the same period in time;

at least one transmit antenna in the plurality of transmit antennas configured to propagate eight beams using continuous wave transmit signals set using ten frequencies, where;

the eight beams are arranged in cardinal and intermediate directions and illuminate a plurality of sensing areas to resolve a twenty meter search range; and

wherein the at least one transmit antenna is configured to rapidly switch among the eight beams and ten frequencies to allow for multiple measurements to be made during a short enough time period wherein a target'"'"'s biometric identifiers are relatively constant;

at least one receive antenna configured to receive a return signal associated with reflections from objects within the at least one sensing area of the at least one transmit signal, where the return signal comprises at least one signal component having static phase associated with reflections from nonmoving objects and at least one signal component having time varying phase associated with at least one target;

a processor;

a memory containing a radar application, wherein execution of the radar application by the processor configures the processor to;

receive the return signal from the at least one receive antenna and collect samples for each sensing area at a sampling rate between 300-500 Hz;

determine a static phase component of the return signal;

generate a cancellation signal at RF frequency by sampling the at least one transmit signal and modulating the sampled signal such that the phase and amplitude of the cancellation signal is adjusted to match an estimated phase and amplitude of the static phase component of the return signal, where the at least one transmit signal used to generate the cancellation signal is received by one of the at least on receive antennas;

process the return signal by subtracting the cancellation signal from the return signal to attenuate the at least one signal component having static phase; and

detect the at least one target by analyzing the at least one signal component having time varying phase for a biometric identifier by;

transforming the processed return signal from a frequency to a time domain data set;

generating range bins, where each range bin has a sequence of samples taken from the time domain data set;

analyzing each range bin for unique targets by examining a band limited version of the processed return signal for repetitive characteristics; and

matching the repetitive characteristics to a biometric identifier of a human, wherein the biometric identifier includes at least one microwave cardiogram and at least one breathing pattern that can be utilized to discriminate among a plurality of unique targets located within the at least one sensing area, and wherein uniqueness of MCG allows for the separation of combined MCGs from multiple targets to discriminate among the targets.