FMCW RADAR REDUCED POWER MODE

• US 20200132811A1
• Filed: 10/29/2018
• Published: 04/30/2020
• Est. Priority Date: 10/29/2018
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: GOSWAMI, Piyali, RAO, Sandeep, BHARADWAJ, Sachin
• Granted Patent: US 10,996,313 B2
• Time in Patent Office: Days
• 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 7/352 Receivers
• CPC Class Codes: G01S 7/40 Means for monitoring or calibrating
• CPC Class Codes: G01S 7/4008 of transmitters
• CPC Class Codes: G01S 7/415 Identification of targets based on measurements of movement associated with the target

Abstract

A method of operating a frequency modulated continuous wave (FMCW) radar system includes receiving, by at least one processor, digital intermediate frequency (IF) signals from a mixer coupled to a receive antenna. The method also includes computing, by the at least one processor, a motion metric based on the digital IF signals; operating, by the at least one processor, the FMCW radar system in a classification mode, in response to determining that the motion metric is above a threshold; and operating, by the at least one processor, the FMCW radar system in a detection mode, in response to determining that the motion metric is below the threshold for at least a first amount of time. An amount of power consumed by the FMCW radar system in the detection mode is less than an amount of power consumed by the FMCW radar system in the classification mode.

Claims

1. A method of operating a frequency modulated continuous wave (FMCW) radar system, the method comprising:

receiving, by at least one processor, digital intermediate frequency (IF) signals from a mixer coupled to a receive antenna;

computing, by the at least one processor, a motion metric based on the digital IF signals;

operating, by the at least one processor, the FMCW radar system in a classification mode, in response to determining that the motion metric is above a threshold; and

operating, by the at least one processor, the FMCW radar system in a detection mode, in response to determining that the motion metric is below the threshold for at least a first amount of time;

wherein an amount of power consumed by the FMCW radar system in the detection mode is less than an amount of power consumed by the FMCW radar system in the classification mode.

2. The method of claim 1, wherein computing the motion metric further comprises:

performing a two-dimensional (2D) fast Fourier transform (FFT) on the digital IF signals to generate a range-Doppler array; and

computing a total energy in a subset of the range-Doppler array;

wherein the motion metric is based on the computed total energy.

3. The method of claim 2, wherein the subset comprises bins of the range-Doppler array having a velocity greater than a minimum velocity threshold.

4. The method of claim 2, wherein the subset comprises bins of the range-Doppler array having a range less than a maximum distance threshold.

5. The method of claim 2, wherein the subset comprises bins of the range-Doppler array having a velocity greater than a minimum velocity threshold and a range less than a maximum distance threshold.

6. The method of claim 1, wherein operating the FMCW radar system in the classification mode further comprises:

transmitting a frame of chirps from a plurality of transmit antennas in an interleaved manner;

wherein a time between consecutive chirps in the classification mode is less than a time between consecutive chirps in the detection mode.

7. The method of claim 1, wherein operating the FMCW radar system in the classification mode further comprises:

processing the digital IF signals to determine whether a gesture was performed; and

in response to determining that a gesture was performed, classifying the gesture.

8. The method of claim 1, wherein operating the FMCW radar system in the detection mode further comprises:

transmitting a frame of chirps from a single transmit antenna;

wherein a time between consecutive chirps in the detection mode is greater than a time between consecutive chirps in the classification mode.

9. The method of claim 1, further comprising:

operating the FMCW radar system in a standby mode, in response to determining that the motion metric is below the threshold for at least a second amount of time, the second amount of time being greater than the first amount of time;

wherein an amount of power consumed by the FMCW radar system in the standby mode is less than an amount of power consumed by the FMCW radar system in the detection mode.

10. The method of claim 9, wherein operating the FMCW radar system in the standby mode further comprises:

transmitting a plurality of frames of chirps from a single transmit antenna;

wherein an inter-frame idle time in the standby mode is greater than an inter-frame idle time in the detection mode.

11. A frequency modulated continuous wave (FMCW) radar system, comprising:

a receive antenna;

a receive channel coupled to the receive antenna, the receive channel configured to generate a digital intermediate frequency (IF) signal from a radio frequency signal received by the receive antenna; and

a processor coupled to the receive channel, the processor configured to;

compute a motion metric based on the digital IF signals;

operate the FMCW radar system in a classification mode, in response to determining that the motion metric is above a threshold; and

operate the FMCW radar system in a detection mode, in response to determining that the motion metric is below the threshold for at least a first amount of time;

wherein an amount of power consumed by the FMCW radar system in the detection mode is less than an amount of power consumed by the FMCW radar system in the classification mode.

12. The FMCW radar system of claim 11, wherein the processor is further configured to:

perform a two-dimensional (2D) fast Fourier transform (FFT) on the digital IF signals to generate a range-Doppler array; and

compute a total energy in a subset of the range-Doppler array;

wherein the motion metric is based on the computed total energy.

13. The FMCW radar system of claim 12, wherein the subset comprises bins of the range-Doppler array having a velocity greater than a minimum velocity threshold.

14. The FMCW radar system of claim 12, wherein the subset comprises bins of the range-Doppler array having a range less than a maximum distance threshold.

15. The FMCW radar system of claim 12, wherein the subset comprises bins of the range-Doppler array having a velocity greater than a minimum velocity threshold and a range less than a maximum distance threshold.

16. The FMCW radar system of claim 11, further comprising:

a plurality of transmit antennas;

wherein in the classification mode, the processor is configured to cause the transmit antennas to transmit a frame of chirps in an interleaved manner;

wherein a time between consecutive chirps in the classification mode is less than a time between consecutive chirps in the detection mode.

17. The FMCW radar system of claim 16, wherein in the detection mode, the processor is further configured to cause a single transmit antenna to transmit a frame of chirps, wherein a time between consecutive chirps in the detection mode is greater than a time between consecutive chirps in the classification mode.

18. The FMCW radar system of claim 11, wherein in the classification mode, the processor is further configured to:

process the digital IF signals to determine whether a gesture was performed; and

in response to a determination that a gesture was performed, classify the gesture.

19. The FMCW radar system of claim 11, wherein the processor is further configured to:

operate the FMCW radar system in a standby mode, in response to determining that the motion metric is below the threshold for at least a second amount of time, the second amount of time being greater than the first amount of time;

wherein an amount of power consumed by the FMCW radar system in the standby mode is less than an amount of power consumed by the FMCW radar system in the detection mode.

20. The FMCW radar system of claim 19, wherein in standby mode, the processor is further configured to cause a single antenna to transmit a plurality of frames of chirps, wherein an inter-frame idle time in the standby mode is greater than an inter-frame idle time in the detection mode.