Method for analyzing the resolution and/or the accuracy of a transmission unit and radar sensor

Abstract

A method for analyzing the resolution and/or the accuracy of a transmission unit of a radar sensor is described wherein a transmitter signal is received via a receiving unit. At least one echo signal based on said received signal is simulated. The frequency difference of said transmitter signal and said echo signal is determined. Said frequency difference is filtered and transformed in order to obtain a transform. At least one maximum of said frequency difference in said transform is detected. Spectral properties of said frequency difference in said transform are determined. At least one quality parameter of said spectral properties is outputted. Further, a radar sensor is described.

Claims

1. A method for analyzing the resolution and/or the accuracy of a transmission unit of a radar sensor comprising: transmitting a transmitter signal via the transmission unit of the radar sensor, receiving the transmitter signal reflected from a target via a receiving unit; simulating at least one echo signal based on said received transmitter signal, the at least one simulated echo signal being produced by delaying and/or frequency shifting said received transmitter signal, determining a frequency difference of said received transmitter signal and said simulated echo signal, said frequency difference being a beat frequency, filtering and transforming said frequency difference in order to obtain a transform; detecting at least one maximum of said frequency difference in said transform; determining spectral properties of said frequency difference in said transform; and outputting at least one quality parameter of said spectral properties as an output value, said quality parameter indicating the quality of the transmission unit.

2. The method according to claim 1, wherein said simulated echo signal is processed with at least one simulation of a processing unit of said receiving unit.

3. The method according to claim 1, wherein several different echo signals are simulated and wherein different several frequency differences are determined for said several different echo signals simulated.

4. The method according to claim 1, wherein said transmission unit and said receiving unit are housed in said radar sensor.

5. The method according to claim 1, wherein a resolution and/or an accuracy of the transmission unit are or is analyzed depending on said transmitter signal.

6. The method according to claim 1, wherein the time, the frequency offset, the amplitude and/or the addition of noise are considered during the simulation.

7. The method according to claim 1, wherein said simulated echo signal is mixed down by said transmitter signal in order to obtain said frequency difference.

8. The method according to claim 1, wherein said spectral properties comprise the full width at half maximum, the amplitude, the distance between at least two maxima, the steepness, the standard deviation, the mean value and/or the deviation from a preset.

9. The method according to claim 1, wherein said simulated echo signal is preset as a position setting for the frequency difference.

10. The method according to claim 1, wherein a processing unit decodes said frequency difference.

11. The method according to claim 1, wherein said output value is a length specification.

12. The method according to claim 1, wherein an accuracy and/or a resolution of said simulated echo signal is compared with an ideal frequency modulated continuous wave chirp.

13. A radar sensor comprising a receiving unit, a transmission unit and a processing unit, said transmission unit being configured to transmit a transmitter signal, said receiving unit being configured to receive said transmitter signal transmitted by said transmitter unit and reflected from a target and said processing unit being configured to simulate at least one echo signal based on said received signal by delaying and/or frequency shifting said received transmitter signal, said processing unit being configured to determine a frequency difference of said received transmitter signal and said simulated echo signal, said frequency difference being a beat frequency difference in order to obtain a transform, said processing unit being configured to detect at least one maximum of said frequency difference in said transform, said processing unit being configured to determine spectral properties of said frequency difference in said transform, and wherein said processing unit is configured to output at least one quality parameter of said spectral properties as an output valve, said quality parameter indicating the quality of said transmission unit.

14. The radar sensor according to claim 13, wherein said radar sensor is at least part of a continuous wave radar system.

15. A method for analyzing the resolution and/or the accuracy of a transmission unit of a radar sensor comprising the following steps: transmitting a transmitter signal via the transmission unit of the radar sensor, receiving the transmitter signal reflected from a target via a receiving unit, simulating at least one echo signal based on said received transmitter signal, the at least one simulated echo signal being produced by delaying and/or frequency shifting said received transmitter signal, determining a frequency difference of said received transmitter signal and said simulated echo signal, said frequency difference being a beat frequency, filtering and transforming said frequency difference in order to obtain a transform, detecting at least one maximum of said frequency difference in said transform, determining spectral properties of said frequency difference in said transform, and outputting at least one quality parameter of said spectral properties as an output value, the output value corresponding to resolution and/or accuracy of the transmission unit.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) The invention will now be described with reference to an exemplary embodiment which is shown in the enclosed drawings. In the drawings,

(2) FIG. 1 schematically shows a radar sensor according to the invention,

(3) FIG. 2 shows a flow-chart of a method for analyzing the resolution and/or the accuracy of a transmission unit of a radar sensor according to the invention, and

(4) FIG. 3 shows a sketch illustrating several steps of the method according to the invention.

DETAILED DESCRIPTION

(5) In FIG. 1, a radar sensor 10 is schematically shown which comprises a transmission unit 12, a receiving unit 14 and a processing unit 16.

(6) Alternatively, the radar sensor 10 comprises the processing unit 16 and a transceiver replacing the transmission unit 12 and the receiving unit 14. In other words, the transmission unit 12 and the receiving unit 14 may be formed in one piece having both transmission and receiving functions.

(7) In the shown embodiment, the transmission unit 12, the receiving unit 14 and the processing unit 16 are mutually housed within a housing of the radar sensor 10.

(8) Further, the radar sensor 10 may be a continuous wave radar sensor, in particular a frequency modulated continuous wave radar sensor. Accordingly, the radar sensor 10 is part of a radar system, in particular a continuous wave radar system; preferably a frequency modulated continuous wave radar system.

(9) Generally, the radar sensor 10 is configured to execute a method which is illustrated in the flow-chart shown in FIG. 2 which is described hereinafter.

(10) In FIG. 2, a method for analyzing the resolution and/or the accuracy of the transmission unit 12 of the radar sensor 10 is shown in a flow-chart.

(11) According to this Figure, a transmission unit 12 emits a transmitter signal which is typically used for measuring an object 18 by radar measurement, for instance an automotive object.

(12) The transmitter signal may be reflected by the object 18 such that the receiving unit 14 receives a received signal being a reflected transmitter signal.

(13) Alternatively, the receiving unit 14 is directly coupled to the transmission unit 12 such that the receiving unit 14 receives the transmitter signal directly, without any reflectance. This direct coupling is illustrated by the dashed connection line 20. In case a transceiver is used instead of a receiving unit 14 being separately formed with respect to the transmission unit 16, the connection line 20 is not necessary since both functions are provided in one unit.

(14) Based on the received signal, the radar sensor 10, in particular the processing unit 16, simulates at least one (further) echo signal in order to measure and analyze the resolution and/or accuracy of the transmission unit 12 of the radar sensor 10 which are quality parameters of the spectral properties.

(15) For simulating purposes, a time shift and/or a frequency shift are/is applied to the received signal. Thus, the measured transmitter signal is delayed, particularly runtime shifted, and/or frequency shifted, in particular Doppler shifted, in order to obtain the at least one echo signal.

(16) Furthermore, the time, the frequency offset, the amplitude and/or the addition of noise are considered during the simulation of the at least one echo signal in order to obtain a realistic echo signal as it would appear when the transmitter signal is reflected by the object 18 to be detected.

(17) In order to obtain a simulation being as realistic as possible, the simulated echo signal is virtually processed by at least one simulation of the processing unit which usually processes the reflected transmitter signals (received signals) which are received by the receiving unit 14.

(18) In general, several different echo signals are simulated wherein different time shifts and/or frequency shifts are applied to the transmitter signal received by the receiving unit 14.

(19) Afterwards, the frequency difference of the transmitter signal generated by the transmission unit 12 and the (simulated) echo signal is determined. Thus, the so called beat frequency is obtained being the frequency difference. The beat frequency is produced by down converting or down mixing the echo signal with the transmitter signal providing the instantaneous frequency.

(20) A spectrogram (frequency over time diagram) of such a frequency difference is shown in a sketch in FIG. 3 to which reference is made. In this sketch, the beat frequency is labeled by f.sub.B.

(21) As several different echo signals are simulated, several different frequency differences can be determined which are used for analyzing purposes of the transmission unit 12.

(22) Afterwards, the obtained frequency difference (beat frequency) is filtered and transformed by applying a window function as well as a Fourier transformation, for instance. Thus, a transform of the beat frequency is generated which is used for further processing, particularly for determining the spectral properties of the frequency difference.

(23) In general, the (Fourier) transform of the frequency difference (beat frequency) shows its (frequency) spectrum which is also shown in the sketch of FIG. 3.

(24) Depending on the frequency difference, its spectrum has at least one maximum which can be detected automatically by the processing unit 16, for instance. Thus, the at least one maximum is provided in the (Fourier) transform of the frequency difference (beat frequency).

(25) Further, the processing unit 16 automatically determines spectral properties of the frequency difference by analyzing the spectrum of the frequency difference, in particular its (Fourier) transform. The processing unit 16 analyzes the shape of the transform, for instance in order to obtain spectral properties such as full width at half maximum, also called half width, the amplitude, the distance between at least two maxima, the steepness, the standard deviation, the mean value and/or the deviation from a preset.

(26) These parameters being the most important spectral properties can be determined automatically by analyzing the spectrum (Fourier transform) of the frequency deviation (beat frequency).

(27) For instance, the simulated echo signal may have a certain frequency shift and/or a certain time shift in order to locate this shift at a certain position being of interest. Thus, the accuracy of the transmitter signal can be analyzed precisely at this certain point being of interest.

(28) After the processing unit 16 has analyzed the frequency difference of the transmitter signal and the (simulated) echo signal(s) in order to obtain the spectral properties, at least one quality parameter of the transmission unit 12 is outputted as an output value. The quality parameter might be the resolution and/or the accuracy. Thus, the user of the radar sensor 10 easily recognizes if the transmission unit 12 has a good resolution and/or if the transmission unit 12 is accurate.

(29) The quality parameter can be outputted in the unit of length, in particular as a length specification. Thus, the resolution and/or accuracy are/is provided in meter (m), centimeter (cm) or millimeter (mm).

(30) In addition, the resolution and/or the accuracy obtained may be compared with the ones of an ideal frequency modulated continuous wave chirp (FMCW chirp) wherein the frequency differences (beat frequencies) are used for comparing purposes, in particular their transforms.

(31) The processing unit 16 may be configured to decode the frequency difference in order to obtain information about the transmitter signal and/or the received signal which has been reflected by the object 18 before it has been received by the receiving unit 14.

(32) As the method is applied to the transmitter signal based on which the at least one echo signal is simulated, it is ensured that the resolution and/or accuracy of the transmission unit 12 is determined in dependency of the transmitter signal.

(33) Thus, the radar sensor 10, in particular the processing unit 16, is configured to output at least one quality parameter of spectral properties obtained by performing the method described above such as the accuracy and/or the resolution.

(34) Furthermore, the receiving unit 14 may be provided outside the housing of the radar sensor 10 wherein a connecting line is provided for establishing a connection between the receiving unit 14 and the radar sensor 10, in particular the processing unit 16 of the radar sensor 10. Alternatively, the receiving unit 14 may be connected to a separate processing unit used for simulating the echo signals.

(35) Accordingly, a radar sensor 10 and a method are provided for determining and outputting a quality parameter.