Method for the phase calibration of high-frequency components of a radar sensor

Patent metadata

Field	Value
Publication number	US-11500061-B2
Application number	US-201916772147-A
Country	US
Kind code	B2
Filing date	Mar 7, 2019
Priority date	May 17, 2018
Publication date	Nov 15, 2022
Grant date	Nov 15, 2022

Abstract

A method for calibrating two receiving units of a radar sensor that includes an array of receiving antennas formed by two sub-arrays and an evaluation unit, which is designed to carry out an angle estimation for located radar targets based on phase differences between the signals received by the receiving antennas, each receiving unit including parallel reception paths for the signals of the receiving antennas of one of the sub-arrays. The method includes: analyzing the received signals and deciding whether a multi-target scenario or a single-target scenario is present, in the case of a single-target scenario, measuring phases of the signals received in the sub-arrays and calculating a phase offset between the two sub-arrays, and calibrating the phases in the two receiving units based on the calculated offset.

First claim

What is claimed is:

1. A method for a radar sensor, the radar sensor including two receiving units, an array of receiving antennas formed of a first sub-array and a second sub-array, and an evaluation unit, the radar sensor being configured to carry out an angle estimation for located radar targets based on phase differences between signals received by the receiving antennas, each of the two receiving units including parallel reception paths for the signals of the receiving antennas of a respective one of the first and second sub-arrays, the method comprising the following steps:
analyzing the received signals;
determining, based on the analysis, whether a multi-target scenario or a single-target scenario is present; and
in response to the determination being that the single-target scenario is present, performing a calibration by:
measuring phases of the signals received via the sub-arrays;
determining expected phases of the signals of the second sub-array based on a slope of the phases of the signals of the first sub-array;
based on a difference between (a) the determined expected phases of the signals of the second sub-array and (b) the measured phases of the signals of the second sub-array, calculating a phase offset between the first sub-array as a whole and the second sub-array as a whole; and
calibrating the phases in the two receiving units based on the calculated phase offset.

2. The method as recited in claim 1 , wherein a quality of an angle estimation function is assessed for deciding whether the multi-target scenario or the single-target scenario is present.

3. The method as recited in claim 2 , wherein separate angle estimation functions are formed for the two sub-arrays and a quality of each of the angle estimation functions is assessed for deciding whether the multi-target scenario or the single-target scenario is present.

4. The method as recited in claim 1 , wherein the radar sensor is an FMCW radar sensor, and wherein a transmit signal is modulated in each measuring cycle according to a sequence of consecutive frequency ramps, in which multiple phase offsets are determined in each measuring cycle, in each case for one of the frequency ramps, and measured phase offsets are statistically evaluated to form a correction value for the calibration.

5. The method as recited in claim 1 , wherein the calibration is carried out in each measuring cycle.

6. The method as recited in claim 5 , wherein the angle estimation is carried out in each measuring cycle based on phase correction values that have been obtained in the same measuring cycle via the calibration.

7. A method for a radar sensor, the radar sensor including a real array of a number of receiving antennas, an evaluation unit designed to carry out an angle estimation for located radar targets based on phase differences between signals received by the receiving antennas, a first transmitting unit connected to and feeding a first transmitting antenna, and a second transmitting unit connected to and feeding a second transmitting antenna, the first and second transmitting antennas being physically offset from each other in a direction in which the receiving antennas of the real array are offset from one another, a combination of the two transmitting antennas and the real array forming a virtual array of twice the number of receiving antennas, a first half of the virtual array formed by the receiving antennas of the real array when the radar sensor transmits using the first transmitting antenna and a second half of the virtual array formed by the receiving antennas of the real array when the radar sensor transmits using the second transmitting antenna, the method comprising the following steps:
analyzing the received signals;
determining, based on the analysis, whether a multi-target scenario or a single-target scenario is present; and
in response to the determination being that the single-target scenario is present, performing a calibration by:
measuring phases of the received signals via the first and second halves of the virtual array;
based on the measured phases, calculating a phase offset between the first half of the virtual array as a whole and the second half of the virtual array as a whole; and
calibrating phases in the two transmitting units based on the calculated phase offset.

8. The method as recited in claim 7 , wherein a quality of an angle estimation function is assessed for deciding whether the multi-target scenario or the single-target scenario is present.

9. The method as recited in claim 8 , wherein separate angle estimation functions are calculated for the real array and for the virtual array and a quality of both of the angle estimation functions is assessed for deciding whether the multi-target scenario or the single-target scenario is present.

10. The method as recited in claim 7 , wherein the radar sensor is an FMCW radar sensor, and wherein a transmit signal is modulated in each measuring cycle according to a sequence of consecutive frequency ramps, in which multiple phase offsets are determined in each measuring cycle, in each case for one of the frequency ramps, and measured phase offsets are statistically evaluated to form a correction value for the calibration.

11. The method as recited in claim 7 , wherein the calibration is carried out in each measuring cycle.

12. The method as recited in claim 11 , wherein the angle estimation is carried out in each measuring cycle based on phase correction values that have been obtained in the same measuring cycle via the calibration.

13. The method as recited in claim 7 , wherein the physical offset is such that, after modifying the signals according to the calibration, a distance between (a) a nearest signal phase of the second half of the virtual array to the signal phases of the first half of the virtual array and (b) a nearest signal phase of the first half of the virtual array to the signal phases of the second half of the virtual array is approximately equal to a distance an adjacent pair of the signal phases of the first half of the virtual array.

14. The method as recited in claim 7 , further comprising:
determining expected phases of the signals of the second half of the virtual array based on a slope of the phases of the signals of the first half of the virtual array, wherein the phase offset is calculated based on a difference between (a) the determined expected phases of the signals of the second half of the virtual array and (b) the measured phases of the signals of the second half of the virtual array.

15. The method as recited in claim 7 , wherein:
the first transmitting unit is arranged on a first physical integrated circuit on which a first receiving unit is arranged;
the second transmitting unit is arranged on a second physical integrated circuit on which a second receiving unit is arranged;
a first subset of the receiving antennas of the real array is physically connected to the first receiving unit and not the second receiving unit; and
a second subset of the receiving antennas of the real array is physically connected to the second receiving unit and not the first receiving unit.

16. A radar sensor comprising:
two receiving units;
an array of receiving antennas formed of a first sub-array and a second sub-array;
an evaluation unit configured to carry out an angle estimation for located radar targets based on phase differences between signals received by the receiving antennas; and
a control unit configured to control functions of the radar sensor;
wherein each of the receiving units includes parallel reception paths for signals

Assignees

• Bosch Gmbh Robert

Inventors

• Loesch Benedikt
• Baur Klaus
• Mayer Marcel
• Schoor Michael

Classifications

• G01S7/40 Primary

  Means for monitoring or calibrating · CPC title

• G01S7/032

  Constructional details for solid-state radar subsystems · CPC title

• G01S7/4008 Primary

  of transmitters · CPC title

• G01S7/42

  Diversity systems specially adapted for radar · CPC title

• G01S13/584

  adapted for simultaneous range and velocity measurements · CPC title