Doppler resolution improvement in low-duty cycle transmission

Patent metadata

Field	Value
Publication number	US-10591596-B2
Application number	US-201715592690-A
Country	US
Kind code	B2
Filing date	May 11, 2017
Priority date	May 11, 2017
Publication date	Mar 17, 2020
Grant date	Mar 17, 2020

Abstract

A system and method for obtaining a Doppler frequency of a target are disclosed. A receiver receives a first plurality of samples of a first echo signal from the target and a second plurality of samples of a second echo signal from the target. The second plurality of samples is separated from the first plurality of samples by a time period. A phase shift is determined for the duration of the time period and the phase shift is applied to the second plurality of samples. The first plurality of samples is combined with the second plurality of samples to obtain combined samples, and the Doppler frequency for the target is obtained from the combined samples.

First claim

What is claimed is:

1. A method of obtaining a Doppler frequency of a target, comprising:
obtaining a first plurality of samples of a first echo signal from the target;
obtaining a second plurality of samples of a second echo signal from the target, wherein the second plurality of samples is separated from the first plurality of samples by a time period having a duration;
shifting the second plurality of samples with respect to the first plurality of samples by the time period to combine the first plurality of samples and the second plurality of samples;
determining a phase shift corresponding to a duration of the time period for a frequency of the first echo signal determined from the first plurality of samples;
applying the phase shift to the second plurality of samples to remove a discontinuity between a phase of the last sample of the first plurality of samples and a phase of the first sample of the second plurality of samples; and
obtaining the Doppler frequency for the target from the combined samples.

2. The method of claim 1 , wherein the first plurality of samples includes k samples and the second plurality of samples includes k samples and the combined samples includes 2k samples.

3. The method of claim 1 , wherein combining the first plurality of samples and the second plurality of samples further includes removing the time period.

4. The method of claim 3 , wherein applying the phase shift to the second plurality of samples corrects for the effect of removing the time period.

5. The method of claim 1 , wherein combining the first plurality of samples and the second plurality of samples further includes concatenating the first plurality of samples and the second plurality of samples.

6. The method of claim 1 , further comprising performing an FFT on the combined plurality of samples to obtain the Doppler frequency.

7. The method of claim 1 , further comprising determining a relative velocity of the target from the Doppler frequency.

8. The method of claim 7 , further comprising maneuvering a vehicle with respect to the target based on the relative velocity.

9. The method of claim 1 , wherein the first plurality of samples is a reflection from the target of a plurality of chirp signals transmitted during a first transmission frame from the target and the second plurality of samples is a reflection from the target of a plurality of chirp signals transmitted during a second transmission frame.

10. A system for obtaining a Doppler frequency of a target, comprising:
a receiver for receiving a first plurality of samples of a first echo signal from the target and a second plurality of samples of a second echo signal from the target, wherein the second plurality of samples is separated from the first plurality of samples by a time period having a duration; and
a processor configured to:
shift the second plurality of samples with respect to the first plurality of samples by the time period to combine the first plurality of samples and the second plurality of samples,
determine a phase shift corresponding to a duration of the time period for a frequency of the first echo signal determined from the first plurality of samples,
apply the phase shift to the second plurality of samples to remove a discontinuity between a phase of the last sample of the first plurality of samples and a phase of the first sample of the second plurality of samples, and
obtain the Doppler frequency for the target from the combined samples.

11. The system of claim 10 , wherein the first plurality of samples includes k samples and the second plurality of samples includes k samples and the combined samples includes 2k samples.

12. The system of claim 10 , wherein the processor is further configured to combine the first plurality of samples and the second plurality of samples to remove the time period.

13. The system of claim 12 , wherein applying the phase shift to the second plurality of samples corrects for the effect of removing the time period.

14. The system of claim 10 , wherein the processor is further configured to combine the first plurality of samples and the second plurality of samples by concatenating the first plurality of samples and the second plurality of samples.

15. The system of claim 10 , wherein the processor is further configured to perform an FFT on the combined plurality of samples to obtain the Doppler frequency.

16. The system of claim 10 , wherein the processor is further configured to determine a relative velocity of the target from the Doppler frequency.

17. The system of claim 16 , wherein the processor is further configured to maneuver a vehicle with respect to the target based on the relative velocity.

18. The system of claim 10 , wherein the first plurality of samples is a reflection from the target of a plurality of chirp signals transmitted by a transmitter during a first transmission frame and the second plurality of samples is a reflection from the target of a plurality of chirp signals transmitted by the transmitter during a second transmission frame.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Pokrass Alexander
• Bilik Igal
• Laifenfeld Moshe

Classifications

• G01S13/343

  using sawtooth modulation · CPC title

• G01S7/411 Primary

  Identification of targets based on measurements of radar reflectivity (G01S7/415 takes precedence) · CPC title

• G01S13/30

  using more than one pulse per radar period · CPC title

• G01S13/931 Primary

  of land vehicles · CPC title

• G01S7/354

  Extracting wanted echo-signals (Doppler systems G01S13/50) · CPC title