Frequency modulated continuous wave radar system with interference mitigation

1. A non-transitory computer-readable storage device storing machine instructions which, when executed by one or more processors, cause the one or more processors to:

determine a chirp period Tc for radar chirps in a radar frame;

determine a maximum chirp dither Δc(max);

determine a chirp slope S for the radar chirps in the radar frame;

determine a maximum slope dither Ψ(max);

determine, for a radar frame N, at least one of:

a random chirp dither Δc(N) between negative Δc(max) and positive Δc(max), and

a random slope dither Ψ(N) between negative Ψ(max) and positive Ψ(max); and

cause a radar sensor circuit to generate the radar chirps in the radar frame N based on the chirp period Tc, the chirp slope S, and the at least one of the random chirp dither Δc(N) and the random slope dither Ψ(N).

2. The storage device of claim 1 , wherein the machine instructions to cause the radar sensor circuit to generate the radar chirps in the radar frame N cause the one or more processors to cause the radar sensor circuit to transmit a plurality of radar chirps having the chirp slope S plus the random slope dither Ψ(N).

3. The storage device of claim 1 , wherein the machine instructions to cause the radar sensor circuit to generate the radar chirps in the radar frame N cause the one or more processors to cause the radar sensor circuit to transmit a plurality of radar chirps at intervals equal to the chirp period Tc plus the random chirp dither Δc(N).

4. The storage device of claim 1 , further comprising machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine a period TF for a radar frame;

determine a maximum frame dither ΔF(max);

determine, for the radar frame N, a random frame dither ΔF(N) between negative ΔF(max) and positive ΔF(max); and

cause the radar sensor circuit to generate the radar frame N further based on the period TF and the random frame dither ΔF(N).

5. The storage device of claim 4 , wherein the period TF for the radar frame is based on an update rate and the maximum frame dither ΔF(max) is based on a threshold deviation from the update rate.

6. The storage device of claim 4 , wherein the machine instructions to cause the radar sensor circuit to generate the radar chirps in the radar frame N cause the one or more processors to cause the radar sensor circuit to transmit a plurality of radar chirps during the period TF plus the random frame dither ΔF(N).

7. The storage device of claim 4 , further comprising machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine, for a subsequent radar frame N+1, a subsequent random frame dither ΔF(N+1) between negative ΔF(max) and positive ΔF(max); and

cause the radar sensor circuit to generate radar chirps in the subsequent radar frame N+1 further based on the period TF and the subsequent random frame dither ΔF(N+1).

8. The storage device of claim 7 , wherein the subsequent random frame dither ΔF(N+1) is not equal to the random frame dither ΔF(N).

9. The storage device of claim 1 , further comprising machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine, for a subsequent radar frame N+1, at least one of:

a subsequent random chirp dither Δc(N+1) between negative Δc(max) and positive Δc(max), and

a subsequent random slope dither Ψ(N+1) between negative Ψ(max) and positive Ψ(max); and

cause the radar sensor circuit to generate radar chirps in the subsequent radar frame N+1 based on the chirp period Tc, the chirp slope S, and the at least one of the subsequent random chirp dither Δc(N+1) and the subsequent random slope dither Ψ(N+1).

10. The storage device of claim 9 , wherein the subsequent random chirp dither Δc(N+1) is not equal to the random chirp dither Δc(N).

11. The storage device of claim 9 , wherein the subsequent random slope dither Ψ(N+1) is not equal to the random slope dither Ψ(N).

12. The storage device of claim 1 , wherein the chirp period Tc for the radar chirp is based on a threshold unambiguous velocity and the maximum chirp dither Δc(max) is based on a threshold deviation from the threshold unambiguous velocity.

13. The storage device of claim 1 , wherein the chirp slope S is based on a frequency range of radar chirps in the radar frame, a threshold range resolution, and the chirp period Tc, and wherein the maximum slope dither Ψ(max) is based on a threshold deviation from the threshold range resolution.

14. An apparatus, comprising:

one or more processors; and

one or more non-transitory computer-readable media storing machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine at least one of a chirp period Tc for radar chirps in a radar frame and a chirp slope S for radar chirps in the radar frame;

in response to determining the chirp period Tc:

determine a maximum chirp dither Δc(max);

determine, for a radar frame N, a random chirp dither Δc(N) between negative Δc(max) and positive Δc(max);

in response to determining the chirp slope S:

determine a maximum slope dither Ψ(max); and

determine, for the radar frame N, a random slope dither Ψ(N) between negative Ψ(max) and positive Ψ(max); and

cause a radar sensor circuit to generate radar chirps in the radar frame N based on the at least one of (1) the chirp period Tc and the random chirp dither Δc(N), and (2) the chirp slope S and the random slope dither Ψ(N).

15. The apparatus of claim 14 , wherein the one or more non-transitory computer-readable media further comprise machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine a period TF for the radar frame;

determine a maximum frame dither ΔF(max); and

determine, for the radar frame N, a random frame dither ΔF(N) between negative ΔF(max) and positive ΔF(max), wherein the machine instructions to cause the radar sensor circuit to generate the radar chirps in the radar frame N cause the one or more processors to cause the radar sensor circuit to generate the radar chirps in the radar frame N based on the period TF and the random frame dither ΔF(N).

16. The apparatus of claim 15 , wherein the one or more non-transitory computer-readable media further comprise machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine, for a subsequent radar frame N+1, a subsequent random frame dither ΔF(N+1) between negative ΔF(max) and positive ΔF(max); and

cause the radar sensor circuit to generate radar chirps in the subsequent radar frame N+1 based on the period TF and the subsequent random frame dither ΔF(N+1).

17. The apparatus of claim 16 , wherein the subsequent random frame dither ΔF(N+1) is not equal to the random frame dither ΔF(N).

18. The apparatus of claim 14 , wherein the one or more non-transitory computer-readable media further comprise machine instructions which, when executed by the one or more processors, cause the one or more processors to:

determine, for a subsequent radar frame N+1, at least one of a subsequent random chirp dither Δc(N+1) between negative Δc(max) and positive Δc(max) and a subsequent random slope dither Ψ(N) between negative Ψ(max) and positive Ψ(max); and

cause the radar sensor circuit to generate radar chirps in the subsequent radar frame N+1 based on the at least one of the chirp period Tc and the subsequent random chirp dither Δc(N+1) and the chirp slope S and the subsequent random slope dither Ψ(N+1).

19. The apparatus of claim 18 , wherein:

the subsequent random chirp dither Δc(N+1) is not equal to the random chirp dither Δc(N); and

the subsequent random slope dither Ψ(N+1) is not equal to the random slope dither Ψ(N).

20. The apparatus of claim 14 , further comprising the radar sensor circuit.

21. A method for dithering radar frames, comprising:

determining at least one of a chirp period Tc for radar chirps in a radar frame and a chirp slope S for radar chirps in the radar frame;

in response to determining the chirp period Tc:

determining a maximum chirp dither Δc(max);

determining, for a radar frame N, a random chirp dither Δc(N) between negative Δc(max) and positive Δc(max);

in response to determining the chirp slope S:

determining a maximum slope dither Ψ(max); and

determining, for the radar frame N, a random slope dither Ψ(N) between negative Ψ(max) and positive Ψ(max); and

causing a radar sensor circuit to generate radar chirps in the radar frame N based on the at least one of (1) the chirp period Tc and the random chirp dither Δc(N) and (2) the chirp slope S and the random slope dither Ψ(N).

22. The method of claim 21 , wherein the chirp period Tc for the radar chirps is based on a threshold unambiguous velocity associated with the radar sensor circuit, and wherein the maximum chirp dither Δc(max) is based on a threshold deviation from the threshold unambiguous velocity.

23. The method of claim 21 , further comprising:

determining a period TF for the radar frame;

determining a maximum frame dither ΔF(max); and

determining, for the radar frame N, a random frame dither ΔF(N) between negative ΔF(max) and positive ΔF(max), wherein causing the radar sensor circuit to generate the radar chirps in the radar frame N comprises causing the radar sensor circuit to generate the radar chirps in the radar frame N based on the period TF and the random frame dither ΔF(N).

24. The method of claim 23 , wherein the period TF for the radar frame is based on an update rate associated with the radar sensor circuit, and wherein the maximum frame dither ΔF(max) is based on a threshold deviation from the update rate.

25. The method of claim 21 , wherein the chirp slope S is based on a frequency range of radar chirps in the radar frame, a threshold range resolution, and the chirp period Tc, and wherein the maximum slope dither Ψ(max) is based on a threshold deviation from the threshold range resolution.