# US 11,994,575 B2 · Frequency modulated continuous wave radar system with interference mitigation

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,994,575 B2
- Document ID: US11994575B2
- Status: Granted
- Kind: B2
- Application number: 17/478,312
- Filed: 2021-09-17
- Published: 2022-04-21
- Granted: 2024-05-28
- Earliest claimed: 2020-10-16
- Assignees: Texas Instruments Incorporated
- Applicants: Texas Instruments Incorporated
- Inventors: Sandeep Rao; Anand Dabak
- Web page: https://patentgrep.com/patent/US11994575B2

## CPC

- G01S 7/0235: {Avoidance by time multiplex}
- G01S 13/34: using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
- G01S 7/021: {Auxiliary means for detecting or identifying radar signals or the like, e.g. radar jamming signals}
- G01S 7/35: Details of non-pulse systems
- G01S 13/343: {using sawtooth modulation}
- G01S: RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES

## Abstract

A method for dithering radar frames includes 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, a maximum chirp dither Δc(max) is determined, and for the radar frame N, a random chirp dither Δc(N) between negative Δc(max) and positive Δc(max) is determined. In response to determining the chirp slope S, a maximum slope dither Ψ(max) is determined, and for the radar frame N, a random slope dither Ψ(N) between negative Ψ(max) and positive Ψ(max) is determined. A radar sensor circuit generates 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).

## Claims

### Claim 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).

### Claim 2 (depends on 1)

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).

### Claim 3 (depends on 1)

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).

### Claim 4 (depends on 1)

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).

### Claim 5 (depends on 4)

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.

### Claim 6 (depends on 4)

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).

### Claim 7 (depends on 4)

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).

### Claim 8 (depends on 7)

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).

### Claim 9 (depends on 1)

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).

### Claim 10 (depends on 9)

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).

### Claim 11 (depends on 9)

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).

### Claim 12 (depends on 1)

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.

### Claim 13 (depends on 1)

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.

### Claim 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).

### Claim 15 (depends on 14)

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).

### Claim 16 (depends on 15)

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).

### Claim 17 (depends on 16)

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

### Claim 18 (depends on 14)

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).

### Claim 19 (depends on 18)

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).

### Claim 20 (depends on 14)

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

### Claim 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).

### Claim 22 (depends on 21)

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.

### Claim 23 (depends on 21)

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).

### Claim 24 (depends on 23)

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.

### Claim 25 (depends on 21)

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.