Automotive radar with range migration mitigation capability
A linear chirp radar system, apparatus and method use a radar control processing unit to control an LFM radar front end which generates analog-to-digital (ADC) sample signals from one or more target return signals received in response to transmitted linear chirp radar signals, where the radar control processing unit is connected and configured to mitigate range migration by directly filtering the ADC samples using a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies to generate a focused ADC Doppler cube, and by applying a Fourier Transform on each Doppler cell in the focused ADC Doppler cube to generate a focused range-Doppler cube.
1. A radar system, comprising:
a radio-frequency (RF) transmitter unit and first plurality of transmit antennas which are connected to transmit linear chirp radar signals in a sequence of transmit frames;
a RF receiver unit and a first plurality of receive antennas which are connected to generate analog-to-digital (ADC) sample signals from one or more target return signals received in response to the linear chirp radar signals; and
a radar control processing unit connected and configured to control the RF transmitter unit and the RF receiver unit to mitigate range migration by directly filtering the ADC samples using a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies to generate a focused ADC Doppler cube, and by applying a Fourier Transform on each Doppler cell in the focused ADC Doppler cube to generate a focused range-Doppler cube.
2. The radar system of claim 1 , wherein the radar control processing unit is configured to generate, from the ADC sample signals, an ADC sample-chirp antenna cube for each transmit frame.
3. The radar system of claim 2 , wherein the radar control processing unit is configured to directly filter the ADC samples by computing range migration mitigated Doppler spectrums for each ADC sample in the ADC sample-chirp antenna cube, recursively chirp-by-chirp until a last chirp is processed.
4. The radar system of claim 1 , wherein the radar control processing unit is configured to apply the Fourier Transform by performing Doppler fast Fourier transform (FFT) on ADC samples in the focused ADC Doppler cube to generate a range spectrum from each Doppler bin sample in the focused ADC Doppler cube.
5. The radar system of claim 1 , wherein the radar control processing unit is configured to directly filter the ADC samples by applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a time-domain convolution from the ADC samples.
6. The radar system of claim 5 , wherein the radar control processing unit is configured to compute the time-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
7. The radar system of claim 1 , wherein the radar control processing unit is configured to directly filter the ADC samples by applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a frequency-domain convolution from the ADC samples.
8. The radar system of claim 7 , wherein the radar control processing unit is configured to compute the frequency-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
9. A method for operating a radar system, comprising:
transmitting linear chirp radar signals in a sequence of transmit frames from a first plurality of transmit antennas;
generating analog-to-digital (ADC) sample signals from one or more target return signals received at a first plurality of receive antennas in response to the linear chirp radar signals; and
processing the ADC sample signals at a radar control processing unit connected and configured to mitigate range migration in the ADC sample signals by directly filtering the ADC samples using a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies to generate a focused ADC Doppler cube, and by applying a Fourier Transform on each Doppler cell in the focused ADC Doppler cube to generate a focused range-Doppler cube.
10. The method of claim 9 , wherein processing the ADC sample signals comprises generating, from the ADC sample signals, an ADC sample-chirp antenna cube for each transmit frame.
11. The method of claim 10 , wherein directly filtering the ADC samples comprises computing range migration mitigated Doppler spectrums for each ADC sample in the ADC sample-chirp antenna cube, recursively chirp-by-chirp until a last chirp is processed.
12. The method of claim 9 , wherein directly filtering the ADC samples comprises applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a time-domain convolution from the ADC samples.
13. The method of claim 12 , wherein applying the frequency-scaled discrete DFT Doppler filter comprises computing the time-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
14. The method of claim 9 , wherein directly filtering the ADC samples comprises applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a frequency-domain convolution from the ADC samples.
15. The method of claim 14 , applying the frequency-scaled discrete DFT Doppler filter comprises computing the frequency-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
16. A radar apparatus comprising:
a plurality of transmitter modules configured to transmit a plurality of linear chirp waveforms in a sequence of transmit frames;
at least a first receiver module connected and configured to receive one or more target return signals reflected from the plurality of linear chirp waveforms by at least one target and to generate analog-to-digital (ADC) sample signals from one or more target return signals; and
a radar control processing unit connected and configured to control the plurality of transmitter modules and at least the first receiver module to mitigate range migration by directly filtering the ADC samples using a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies to generate a focused ADC Doppler cube, and by applying a Fourier Transform on each Doppler cell in the focused ADC Doppler cube to generate a focused range-Doppler cube.
17. The radar apparatus of claim 16 , wherein the radar control processing unit is configured to apply the Fourier Transform by performing Doppler fast Fourier transform (FFT) on ADC samples in the focused ADC Doppler cube to generate a range spectrum from each Doppler bin sample in the focused ADC Doppler cube.
18. The radar apparatus of claim 16 , wherein the radar control processing unit is configured to directly filter the ADC samples by applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a time-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
19. The radar apparatus of claim 16 , wherein the radar control processing unit is configured to directly filter the ADC samples by applying a frequency-scaled discrete Fourier Transform (DFT) Doppler filter which computes a frequency-domain convolution from the ADC samples using a Fast Fourier Transform hardware accelerator and an Inverse Fast Fourier Transform hardware accelerator.
20. The radar apparatus of claim 16 , wherein the radar control processing unit is configured to directly filter the ADC samples by computing range migration mitigated Doppler spectrums for each ADC sample in the ADC sample-chirp antenna cube, recursively chirp-by-chirp until a last chirp is processed.