Range and direction of arrival migration with doppler ambiguity estimation

1. A method of determining a radial velocity of an object via a radar system, comprising:

transmitting a chirp signal at the object, the object having a radial velocity with respect to the radar system;

receiving a reflection of the chirp signal from the object;

obtaining an ambiguous Doppler measurement related to the radial velocity of the object;

obtaining a range walk rate indicative of a range migration of the object during the chirp signal by determining a slope of a line of peak energies in a Range-chirp map for the reflection of the chirp signal;

determining an unambiguous Doppler measurement using the range walk rate and the ambiguous Doppler measurement; and

determining the radial velocity from the unambiguous Doppler measurement,

wherein obtaining the range walk rate further comprises locating maximal energy peaks in range cells in a range-Doppler-Beam-Range Rate-direction-of-arrival (DOA) Rate energy map and determining a curve connecting the range cells.

2. The method of claim 1 , further comprising performing a Radon transform on a radar signal to obtain a Radon parameter space.

3. The method of claim 2 , further comprising performing at least one of: (i) determining the range walk rate from a peak in the Radon parameter space; (ii) determining a direction of arrival rate from a peak in the Radon parameter space; and (iii) reducing a power loss due to at least one of a range migration and a DOA migration.

4. The method of claim 2 , further comprising performing the Radon transform as a Fast Fourier Transform on range and direction of arrival transform terms to reduce a computational expense in determining the Radon transform.

5. The method of claim 1 , further comprising navigating a vehicle with respect to the object using the radial velocity determined from resolving the Doppler ambiguity.

6. A radar system for a vehicle, comprising:

a transmitter for transmitting a chirp signal towards an object;

a receiver for receiving a reflection of the chirp signal from the object; and

a processor configured to:

obtain an ambiguous Doppler measurement related to a radial velocity of the object from the reflection;

obtain a range walk rate indicative of a range migration of the object during the chirp signal by determining a slope of a line of peak energies in a Range-chirp map for the reflection of the chirp signal, including locating maximal energy peaks in range cells in a range-Doppler-Beam-Range Rate-direction-of-arrival (DOA) Rate energy map and determining a curve connecting the range cell;

resolve the Doppler ambiguity of the Doppler measurement using the range walk rate to reduce an ambiguity of the radial velocity of the object, determine an unambiguous Doppler measurement using the range walk rate and the ambiguous Doppler measurement; and

determine the radial velocity from the unambiguous Doppler measurement.

7. The radar system of claim 6 , the processor is further configured to perform a Radon transform on a radar signal to obtain a Radon parameter space.

8. The radar system of claim 7 , the processor is further configured to perform at least one of: (i) determining a range walk rate from a peak in the Radon parameter space; (ii) determining a direction of arrival rate from a peak in the Radon parameter space; and (iii) reducing a power loss due to at least one of a range migration and a DOA migration.

9. The radar system of claim 7 , wherein the processor is further configured to perform the Radon transform as a Fast Fourier Transform on range and direction of arrival transform terms to reduce a computational expense in determining the Radon transform.

10. The radar system of claim 6 , wherein the processor is further configured to navigate the vehicle with respect to the object using the radial velocity determined from resolving the Doppler ambiguity.

11. A vehicle, comprising:

a transmitter for transmitting a chirp signal towards an object;

a receiver for receiving a reflection of the chirp signal from the object; and

a processor configured to:

obtain an ambiguous Doppler measurement related to a radial velocity of the object from the reflection;

obtain a range walk rate indicative of a range migration of the object during the chirp signal by determining a slope of a line of peak energies in a Range-chirp map for the reflection of the chirp signal, including locating maximal energy peaks in range cells in a range-Doppler-Beam-Range Rate-direction-of-arrival (DOA) Rate energy map and determining a curve connecting the range cell;

resolve the Doppler ambiguity of the Doppler measurement using the range walk rate to reduce an ambiguity of the radial velocity of the object, determine an unambiguous Doppler measurement using the range walk rate and the ambiguous Doppler measurement; and

determine the radial velocity from the unambiguous Doppler measurement.

12. The vehicle of claim 11 , wherein the processor is further configured to perform a Radon transform on a radar signal to obtain a Radon parameter space.

13. The vehicle of claim 12 , wherein the processor is further configured to perform at least one of: (i) determining a range walk rate from a peak in the Radon parameter space; (ii) determining a direction of arrival rate from a peak in the Radon parameter space; and (iii) reducing a power loss due to at least one of a range migration and a DOA migration.

14. The vehicle of claim 11 , wherein the processor is further configured to perform a Radon transform as a Fast Fourier Transform on range and direction of arrival transform terms to reduce a computational expense in determining the Radon transform.