Radar sensor and method for determining a relative speed of a radar target

Patent metadata

Field	Value
Publication number	US-11733368-B2
Application number	US-201716477104-A
Country	US
Kind code	B2
Filing date	Nov 16, 2017
Priority date	Jan 11, 2017
Publication date	Aug 22, 2023
Grant date	Aug 22, 2023

Abstract

An estimation is described of the speed of objects with the aid of a radar sensor that includes multiple transmitting antennas. Multiple nested sequences of frequency ramps are emitted with the aid of multiple transmitting antennas. An individual phase encoding takes place for each transmitting antenna with the aid of a harmonic code. For estimating the speed of the object, the ambiguities due to the code multiplex are resolved.

First claim

What is claimed is:

1. A method for determining a relative speed of a radar target, the method comprising:
emitting phase-modulated transmission signals with the aid of multiple transmitting antenna elements, a ramp-shaped frequency-modulated transmission signal that has multiple temporally nested sequences of ramps being generated, wherein ramps within a particular sequence follow one another at a predetermined time interval in a time-delayed manner, and wherein a phase of the generated ramp-shaped frequency-modulated transmission signal is phase-modulated for each transmitting antenna element using a harmonic code;
receiving signals in response to the emitted phase-modulated transmission signals;
computing a two-dimensional spectrum for each sequence of the transmission signal via a two-dimensional Fourier transform of baseband signals of the received response signals, wherein a transformation in a first dimension takes place ramp by ramp, and wherein a transformation in a second dimension takes place via a ramp index that counts the ramps within the sequence;
ascertaining values of relative speeds of a radar target which, starting from a peak in one of the computed two-dimensional spectra, are periodic with a predetermined speed period;
identifying matches in a phase relationship between values of the two-dimensional spectra, at the same positions, with phase relationships to be expected for several of the ascertained values of relative speeds; and
selecting, based on the identified match of the phase relationships, an estimated value by selecting-of one of the relative speeds of the radar target by evaluating a relative speed spectrum S(v) at locations that correspond to periodic values of a relative speed v obtained from evaluations according to a position of the peak, wherein based on a linear relationship, the selected estimated value for relative speed v is determined for distance d, and wherein based on measurement vector a_m and control vector a(v), a normalized likelihood function in the form of the relative speed spectrum S(v), is as follows:

S
⁡

(
v
)

=

1



a
-

⁢

m
H



2

⁢



a
-

⁢

m
H

·

a
⁡

(
v
)



2

,

where superscript H of measurement vector a_m is the Hermitian adjoint vector with respect to measurement vector a_m, which is a row vector in which the individual components are the complex conjugate to the components of vector a_m.

2. The method as recited in claim 1 , further comprising:
associating one of the received response signals with one of the multiple transmitting antennas.

3. The method as recited in claim 1 , wherein within at least one of the sequences of ramps, the ramps have the same ramp slope and the same difference of a ramp center frequencies, wherein ramps with the same ramp index in each case have the same ramp slope and the same ramp center frequency in the nested ramps.

4. The method as recited in claim 1 , wherein the harmonic code for the phase modulation of the transmission signals for the individual transmitting antennas is adapted as a function of a number of the transmitting antennas.

5. The method as recited in claim 1 , wherein the predetermined speed period is formed using the following speed offset Δv:

Δ
⁢

⁢
v

=

1

f
⁢

⁢
0

⁢

c

2
⁢

(

1
-

s_slow
s_fast

)

⁢

Δ
⁢

⁢
l

Tr
⁢

⁢
2
⁢

r
·
NTX

,

where f0 is the average transmission frequency, c is the speed of light, Tr2r is a time interval between two successive ramps of a sequence, NTX is the number of the transmitting antennas, s_fast is the ramp slope of a ramp, and s_slow is the slope of the ramp center frequency of a ramp sequence.

6. A radar sensor for determining a relative speed of a radar target, comprising:
a plurality of transmitting antennas configured to emit phase-modulated and ramp-shaped frequency-modulated transmission signals, wherein the transmission signals include multiple temporally nested sequences, wherein the ramps within a particular sequence follow one another at a predetermined time interval in a time-delayed manner, wherein a phase of the transmission signal is phase-modulated for each of the plurality of transmitting antennas using a harmonic code, and wherein the phase-modulated and ramp-shaped frequency-modulated transmission signals are emitted with the plurality of transmitting antennas; and
a receiving antenna for receiving

Assignees

• Bosch Gmbh Robert

Inventors

• Schoor Michael
• Loesch Benedikt

Classifications

• G01S13/583 Primary

  using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves and based upon the Doppler effect resulting from movement of targets · CPC title

• G01S7/023

  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) · CPC title

• G01S7/0232

  Avoidance by frequency multiplex · CPC title

• G01S7/0234

  Avoidance by code multiplex · CPC title

• G01S7/354

  Extracting wanted echo-signals (Doppler systems G01S13/50) · CPC title