Radar ambiguity resolving detector

• US 9,835,723 B2
• Filed: 10/30/2014
• Issued: 12/05/2017
• Est. Priority Date: 10/30/2014
• Status: Active Grant

• Current Assignee: NXP B.V. (NXP Semiconductors NV)
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Jansen, Feike Guus, Zivkovic, Zoran
• Primary Examiner(s): Gregory, Bernarr E
• Application Number:
  US14/527,840
• Publication Number:
  US 20160124086A1
• Time in Patent Office: 1,132 Days
• CPC Class Codes: G01S 13/227 with repetitive trains of uniform pulse sequences, each sequence having a different pulse repetition frequency
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/5246 post processors for coherent MTI discriminators, e.g. residue cancellers, CFAR after Doppler filters
• CPC Class Codes: G01S 13/582 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 7/2922 by using a controlled threshold
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing

Abstract

Various exemplary embodiments relate to a method for determining the velocity of an object using radar system having a processor, including: receiving, by a processor, a first digital signal corresponding to a first transmit signal; receiving, by the processor, a second digital signal corresponding to a second transmit signal; processing the first digital signal to produce a first range/relative velocity matrix; detecting objects in the first range/relative velocity matrix to produce a first detection vector; unfolding the first detection vector; processing the second digital signal to produce a second range/relative velocity matrix; interpolating the second range/relative velocity matrix in the relative velocity direction wherein the interpolated second range/relative velocity matrix has a frequency spacing corresponding to the frequency spacing of the first range/relative range velocity matrix in the relative velocity direction; detecting objects in the second range/relative velocity matrix to produce a second detection vector; unfolding the second detection vector; and determining a true velocity of the detected objects based upon the unfolded first and second detection vectors.

Claims

1. A radar system comprising:

a waveform generator configured to produce a first transmit signal including a first sequence of waveforms and a second transmit signal including a second sequence of waveforms, wherein the first and second transmit signals have different waveform repetition rates and the length of the sequences of the first and second signals is nearly equal;

a transmitter configured to transmit the first and second transmit signals;

a first receiver comprising;

a first downconverter configured to downconvert the first received signal to produce a first downconverted signal and downconvert the second received signal to produce a second downconverted signal, wherein the first received signal corresponds to the first transmitted signal and the second received signal corresponds to the second transmitted signal; and

a first analog to digital converter configured to convert the first downconverted signal to a first digital signal and the second downconverted signal to a second digital signal;

a digital signal processor configured to;

process the first digital signal to produce a first range/relative velocity matrix;

detect objects in the first range/relative velocity matrix to produce a first detection vector;

unfold the first detection vector;

process the second digital signal to produce a second range/relative velocity matrix;

interpolate the second range/relative velocity matrix in the relative velocity direction wherein the interpolated second range/relative velocity matrix has a frequency spacing corresponding to the frequency spacing of the first range/relative velocity matrix in the relative velocity direction;

detect objects in the second range/relative velocity matrix to produce a second detection vector;

unfold the second detection vector; and

determine a true velocity of the detected objects based upon the unfolded first and second detection vectors.

2. The radar system of claim 1, wherein:

the first transmit signal is a frequency modulated continuous wave (FMCW) signal including a first sequence of frequency chirped waveforms and the second transmit signal is a FMCW signal including a second sequence of frequency chirped waveforms;

downconverting the first transmit signal includes mixing the first transmit signal with a first received signal and mixing the second transmit signal with a second received signal

producing the first range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the first digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity; and

producing the second range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the second digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity.

3. The radar system of claim 1, wherein:

the first transmit signal is a pulsed radar signal including a first sequence waveforms having a first pulse repetition frequency (PRF) and the second transmit signal is a pulsed radar signal including a second sequence of waveforms having a second PRF;

producing the first range/relative velocity matrix includes performing range gating on the first digital signal and a fast Fourier transform (FFT) on the first digital signal; and

producing the second range/relative velocity matrix includes performing range gating on the second digital signal and a FFT on the second digital signal.

4. The radar system of claim 1, further comprising:

a first antenna associated with the first receiver;

a second receiver comprising;

a second mixer configured to downconvert the third received signal to produce a third downconverted signal and downconvert the fourth received signal to produce a fourth downconverted signal, wherein the third received signal corresponds to the first transmitted signal and the fourth received signal corresponds to the second transmitted signal; and

a second analog to digital converter configured to convert the third downconverted signal to a third digital signal and the fourth downconverted signal to a fourth digital signal;

a second antenna associated with the second receiver;

wherein the digital signal processor is further configured to;

combine the third digital signal with the first digital signal and combine the fourth digital signal with the second digital signal before processing the first and second digital signals to produce first and second range/relative velocity matrices;

determine a angle of arrival (AOA) match for the detected objects based upon the unfolded first and second detection vectors.

5. The radar system of claim 4, wherein the digital signal processor is further configured to calculate the AOA of detected objects.

6. The radar system of claim 1, wherein detecting an object includes using a constant false alarm rate detector.

7. The radar system of claim 1, wherein determining a true velocity of the detected objects includes performing a logical AND operation on the first and second unfolded detection vectors.

8. A method for determining the velocity of an object using radar system having a processor, comprising:

receiving, by a processor, a first digital signal corresponding to a first transmit signal;

receiving, by the processor, a second digital signal corresponding to a second transmit signal;

processing the first digital signal to produce a first range/relative velocity matrix;

detecting objects in the first range/relative velocity matrix to produce a first detection vector;

unfolding the first detection vector;

processing the second digital signal to produce a second range/relative velocity matrix;

interpolating the second range/relative velocity matrix in the relative velocity direction wherein the interpolated second range/relative velocity matrix has a frequency spacing corresponding to the frequency spacing of the first range/relative range velocity matrix in the relative velocity direction;

detecting objects in the second range/relative velocity matrix to produce a second detection vector;

unfolding the second detection vector; and

determining a true velocity of the detected objects based upon the unfolded first and second detection vectors.

9. The method of claim 8, further comprising:

downconverting the first received signal to produce a first downconverted signal;

downconverting the second received signal to produce a second downconverted signal; and

converting the first downconverted signal to a first digital signal and the second downconverted signal to a second digital signal,

wherein the first received signal corresponds to the first transmitted signal and the second received signal corresponds to the second transmitted signal.

10. The method of claim 9, wherein:

the first transmit signal is a frequency modulated continuous wave (FMCW) signal including a first sequence of frequency chirped waveforms and the second transmit signal is a FMCW signal including a second sequence of frequency chirped waveforms;

downconverting the first transmit signal includes mixing the first transmit signal with a first received signal and mixing the second transmit signal with a second received signal

producing the first range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the first digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity; and

producing the second range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the second digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity.

11. The method of claim 9, wherein:

the first transmit signal is a pulsed radar signal including a first sequence waveforms having a first pulse repetition frequency (PRF) and the second transmit signal is a pulsed radar signal including a second sequence of waveforms having a second PRF;

producing the first range/relative velocity matrix includes performing range gating on the first digital signal and a fast Fourier transform (FFT) on the first digital signal; and

producing the second range/relative velocity matrix includes performing range gating on the second digital signal and a FFT on the second digital signal.

12. The method of claim 9, further comprising:

downconverting the first received signal to produce a third downconverted signal;

downconverting the second received signal to produce a fourth downconverted signal;

wherein the third received signal corresponds to the first transmitted signal and the fourth received signal corresponds to the second transmitted signal; and

converting the third downconverted signal to a third digital signal and the fourth downconverted signal to a fourth digital signal;

combining the third digital signal with the first digital signal and combining the fourth digital signal with the second digital signal before processing the first and second digital signals;

determining a angle of arrival (AOA) match for the detected objects based upon the unfolded first and second detection vectors,

wherein a first antenna receives the first and second received signals, and

wherein a second antenna receives the third and fourth received signals.

13. The method of claim 12, further comprising calculating the AOA of detected objects.

14. The method of claim 9, wherein detecting an object includes using a constant false alarm rate detector.

15. The method of claim 9, wherein determining a true velocity of the detected objects includes performing a logical AND operation on the first and second unfolded detection vectors.

16. A radar system comprising:

a transmitter configured to transmit a first transmit signal and a second transmit signal;

a receiver producing a first digital signal and a second digital signal;

a digital signal processor configured to;

receive, by a processor, the first digital signal corresponding to the first transmit signal;

processing the first digital signal to produce a first range/relative velocity matrix;

detect objects in the first range/relative velocity matrix to produce a first detection vector;

unfold the first detection vector;

when objects are detected in the first signal data;

receive the second digital signal corresponding to the second transmit signal;

process the second digital signal to produce a first range/relative velocity matrix;

interpolate the second range/relative velocity matrix in the relative velocity direction wherein the interpolated second range/relative velocity matrix has a frequency spacing corresponding to the frequency spacing of the first range/relative range velocity matrix in the relative velocity direction;

detect objects in the second range/relative velocity matrix to produce a second detection vector;

unfold the second detection vector; and

determine a true velocity of the detected objects based upon the unfolded first and second detection vectors.

17. The radar system of claim 16, wherein the first and second digital signal data each include received data from two different receive antennas and further comprising determining a angle of arrival (AOA) match for the detected objects based upon the unfolded first and second detection vectors.

18. The radar system of claim 16, further the receiver is further configured to:

downconvert the first received signal to produce a first downconverted signal;

downconvert the second received signal to produce a second downconverted signal; and

convert the first downconverted signal to the first digital signal and the second downconverted signal to the second digital signal,

wherein the first received signal corresponds to the first transmitted signal and the second received signal corresponds to the second transmitted signal.

19. The radar system of claim 18, wherein:

the first transmit signal is a frequency modulated continuous wave (FMCW) signal including a first sequence of frequency chirped waveforms and the second transmit signal is a FMCW signal including a second sequence of frequency chirped waveforms;

downconverting the first transmit signal includes mixing the first transmit signal with a first received signal and mixing the second transmit signal with a second received signal

producing the first range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the first digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity; and

producing the second range/relative velocity matrix includes performing a two dimensional fast Fourier transform (FFT) on the second digital signal wherein the FFT in a first direction corresponds to range and the FFT in a second direction corresponds to relative velocity.

20. The radar system of claim 18, wherein:

the first transmit signal is a pulsed radar signal including a first sequence waveforms having a first pulse repetition frequency (PRF) and the second transmit signal is a pulsed radar signal including a second sequence of waveforms having a second PRF;

producing the first range/relative velocity matrix includes performing range gating on the first digital signal and a fast Fourier transform (FFT) on the first digital signal; and

producing the second range/relative velocity matrix includes performing range gating on the second digital signal and a FFT on the second digital signal.