# US 10,502,824 B2 · Frequency modulation scheme for FMCW radar

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- Number: US 10,502,824 B2
- Document ID: US10502824B2
- Status: Granted
- Kind: B2
- Application number: 15/342,186
- Filed: 2016-11-03
- Published: 2017-05-11
- Granted: 2019-12-10
- Earliest claimed: 2015-11-09
- Assignees: Infineon Technologies AG
- Applicants: Infineon Technologies AG
- Inventors: Andre Roger; Ygnace Romain; Farhan Bin Khalid
- Web page: https://patentgrep.com/patent/US10502824B2

## CPC

- G01S 13/343: {using sawtooth modulation}
- G01S 7/023: {Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques (auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36)}
- G01S 7/0235: {Avoidance by time multiplex}
- G01S 7/35: Details of non-pulse systems
- G01S 13/931: of land vehicles
- 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 a radar transmitter is described herein. In accordance with one exemplary embodiment, the method includes generating an RF transmit signal composed of at least one sequence of sub-sequent chirp pulses, wherein pseudo-randomly selected chirp pulses are blanked, and radiating the RF transmit signal via at least one antenna as radar signal.

## Claims

### Claim 1

A transmitter circuit for a FMCW radar sensor, the transmitter circuit comprising:
an RF oscillator that operably generates a frequency-modulated RF transmit signal;
wherein the RF transmit signal is composed of at least one chirp sequence,
wherein each chirp sequence includes a defined number of consecutive chirp pulses having a defined pulse length,
wherein, in each chirp sequence, randomly selected chirp pulses are omitted.

### Claim 2 (depends on 1)

The transmitter circuit of claim 1,
wherein the randomly selected chirp pulses are selected based on a pseudo-random sequence.

### Claim 3 (depends on 1)

The transmitter circuit of claim 1,
wherein the pseudo-random sequence is stored in a memory or is generated by a random number generator.

### Claim 4 (depends on 1)

The transmitter of claim 1 further comprising:
a controller circuit coupled to the RF oscillator and configured to omit the randomly selected chirp pulses by blanking.

### Claim 5 (depends on 1)

The transmitter circuit of claim 1 further comprising:
a controller circuit coupled to the RF oscillator and configured to enable and disable the RF oscillator in order to omit the randomly selected chirp pulses,
wherein the randomly selected chirp pulses are selected based on a pseudo-random sequence.

### Claim 6 (depends on 5)

The transmitter circuit of claim 5,
wherein the pseudo-random sequence is fixed or
wherein the pseudo-random sequence is regularly varied.

### Claim 7 (depends on 1)

The transmitter circuit of claim 1 further comprising:
an antenna coupled to the RF oscillator to radiate the RF transmit signal as radar signal.

### Claim 8 (depends on 1)

The transmitter circuit of claim 1 further comprising:
an RF amplifier coupled to the RF oscillator to amplify the RF transmit signal; and
an antenna coupled to the RF amplifier to radiate the amplified RF transmit signal as radar signal.

### Claim 9 (depends on 8)

The transmitter circuit of claim 8, further comprising
a controller circuit configured to enable and disable the RF oscillator or the RF amplifier to blank the randomly selected chirps pulses.

### Claim 10 (depends on 1)

The transmitter circuit of claim 1,
wherein the RF oscillator comprises a frequency control input for receiving a modulation signal; a frequency of the RF transmit signal being modulated in response to the modulation signal.

### Claim 11

A method for an FMCW radar device, the method comprising:
generating an RF transmit signal composed of at least one chirp sequence each chirp sequence including a defined number of consecutive chirp pulses having a defined pulse length,
wherein, in each chirp sequence, randomly selected chirp pulses are omitted;
radiating the RF transmit signal via at least one antenna as radar signal.

### Claim 12 (depends on 11)

The method of claim 11, wherein the RF transmit signal is amplified before being radiated by the at least one antenna.

### Claim 13 (depends on 11)

The method of claim 11,
wherein the at least one chirp sequence is composed of M consecutive chirp pulses, wherein M−K chirp pulses are omitted so that K chirp pulses are radiated as radar signal.

### Claim 14 (depends on 13)

The method of claim 13,
wherein the ratio (M−K)/M is at least 1/3.

### Claim 15 (depends on 11)

The method of claim 11,
wherein the chirp pulses to be omitted are randomly selected in accordance with a sequence of random numbers.

### Claim 16 (depends on 15)

The method of claim 15,
wherein the sequence of random numbers is fixed or
wherein the sequence of random numbers is varied regularly.

### Claim 17 (depends on 15)

The method of claim 15,
wherein the sequence of random numbers is stored in a memory or
wherein the sequence of random numbers is generated by a pseudo-random generator.

### Claim 18 (depends on 11)

The method of claim 11, wherein
receiving, as radar echo signal, a portion of the radar signal, which is back-scattered at a radar target, the radar echo signal including an echo of the chirp pulses of the radiated radar signal; and
down-converting the radar echo signal from an RF band into a base-band or IF-band.

### Claim 19 (depends on 18)

The method of claim 18 further comprising
digitizing the down-converted radar echo signal to obtain a digital signal for each chirp pulse echo included in the radar echo signal.

### Claim 20 (depends on 19)

The method of claim 19,
wherein each digital signal is composed of N samples.

### Claim 21 (depends on 19)

The method of claim 19, further comprising
transforming the digital signals into the frequency domain.

### Claim 22 (depends on 19)

The method of claim 19,
wherein the at least one chirp sequence is composed of M consecutive chirp pulses, wherein M−K chirp pulses are omitted so that K chirp pulses are radiated as radar signal; and
wherein K digital signals are obtained representing the radar echo of the K chirp pulses in the base-band or IF-band.

### Claim 23 (depends on 22)

The method of claim 22 further comprising:
determining an underdetermined equation system based on the K digital signals and a matrix, which includes information about which of the M consecutive chirp pulses have been omitted.

### Claim 24 (depends on 23)

The method of claim 23 further comprising:
solving the underdetermined equation system using an optimization algorithm.

### Claim 25 (depends on 23)

The method of claim 23,
wherein the optimization algorithm is configured to minimize a norm of residual errors.

### Claim 26

A method for an FMCW radar device, the method comprising:
generating an RF transmit signal composed of at least one chirp sequence, each chirp sequence including a defined number of consecutive chirp pulses having a defined pulse length,
wherein, in each chirp sequence, randomly selected chirp pulses are omitted;
radiating the RF transmit signal via at least one antenna as radar signal;
receiving, as radar echo signal, a portion of the radar signal, which is back-scattered at a radar target, the radar echo signal including an echo of the chirp pulses of the radiated radar signal; and
down-converting the radar echo signal from an RF band into a base-band or IF-band and digitizing the down-converted radar echo signal to obtain a digital signal for each chirp pulse included in the radar echo signal; and
calculating a Range-Doppler map based on the digital signals.

### Claim 27 (depends on 26)

The method of claim 26,
wherein the sequence of chirp pulses is composed of M consecutive chirp pulses, wherein only K out of the M consecutive chirp pulses are not omitted and thus included in the radiated radar signal; and
wherein the digitizing of the down-converted radar echo signal yields K digital signals corresponding to K chirp pulses included in the radar echo signal, each of the K digital signals being composed of N samples.

### Claim 28 (depends on 27)

The method of claim 27, further comprising
calculating a Range-Doppler map composed of N times M samples based on the K digital signals.