360° MIMO RADAR SYSTEM HAVING MULTIPLE RADAR SENSORS AND PHASE CALIBRATION VIA OVER-LAPPING VIRTUAL TX AND RX ANTENNAS OF ADJACENT RADAR SENSORS

Abstract

The invention describes a radar system consisting of a plurality of subcomponents each individually having all components of a radar device which comprise at least transmitters, receivers, a mixer and a phase locked loop, wherein an individual phase code is generated for each transmitter; and transmitters and receivers of all subcomponents of the radar system together provide a virtual overall arrangement according to the Multiple Input Multiple Output method, wherein at least one virtual sub-arrangement of the overall arrangement, provided by a combination of transmitters of a subcomponent and receivers of a subcomponent, has at least one overlapping column or one overlapping row with another virtual sub-arrangement of the overall arrangement, wherein the at least other virtual sub-arrangement is provided by another combination of transmitters of a subcomponent and receivers of a subcomponent.

Claims

1. Radar system consisting of a plurality of subcomponents, each individually having all components of a radar device, which comprises at least transmitters, receivers, a mixer and a phase locked loop, wherein an individual phase code is generated for each transmitter; and transmitters and receivers of all subcomponents of the radar system together provide a virtual overall arrangement according to the Multiple Input Multiple Output method, wherein at least one virtual sub-arrangement of the overall arrangement, provided by a combination of transmitters of a subcomponent and receivers of a subcomponent, has at least one overlapping column or one overlapping row with another virtual sub-arrangement of the overall arrangement, wherein the at least other virtual sub-arrangement is provided by another combination of transmitters of a subcomponent and receivers of a subcomponent.

2. Radar system according to claim 1, characterized in that a common crystal oscillator is used by all subcomponents as a reference phase for the phase locked loops.

3. Radar system according to claim 1, characterized in that all transmitters of the radar system are operated with a phase code according to the phase modulated continuous wave modulation method.

4. Radar system according to claim 1, characterized in that the overlapping columns or the overlapping rows are used at least for a phase calibration of the received signals.

5. Radar system according to claim 1, characterized in that a part of the post-processing of the received signals, which includes at least a correlation and a Fourier transformation for a speed analysis, takes place within the subcomponents.

6. Radar system according to claim 1, characterized in that the individual subcomponents are synchronized.

7. Radar system according to claim 6, characterized in that the synchronization takes place via a trigger signal that connects the individual subcomponents and/or via transmitted, preferably coded, signals.

8. Radar system according to claim 1, characterized in that the overlapping columns or the overlapping rows are used for a phase and amplitude calibration of the received signals.

9. Radar system according to claim 1, characterized in that the carrier signals of all transmitted waves have a right circular polarization or that the carrier signals of all transmitted waves have a left circular polarization.

10. Radar system according to claim 9, characterized in that half of all subcomponents have receivers which are configured for a left circular polarization, and the other half of the subcomponents have receivers which are configured for a right circular polarization.

11. Radar system according to claim 10, characterized in that a comparison of separate signal processings of the subcomponents that have receivers configured for a left circular polarization and the subcomponents that have receivers configured for a right circular polarization are used for the analysis of polarimetric properties of detected objects, preferably for an object classification and road condition detection.

12. Radar system according to claim 10, characterized in that a common signal processing of the subcomponents that have receivers configured for a left circular polarization and the subcomponents that have receivers configured for a right circular polarization is used for the analysis of precise angular positions of detected objects by calibrating the received signals in terms of phase and amplitude by means of overlapping columns or rows, taking polarimetric properties into account.

13. Radar system according to claim 1, characterized in that all transmitters and all receivers of all subcomponents of the radar system jointly provide a virtual overall arrangement according to the multiple input multiple output method.

14. Radar system according to claim 1, characterized in that an individual phase code can be generated for each group of transmitters.

15. Use of the radar system according to claim 1 for installation in a moving base, which is preferably an automobile and preferably operates in a frequency range between 76 GHz and 81 GHz.

16. Method for a 360° vehicle environment detection, preferably using the radar system according to claim 1, wherein the vehicle has a plurality of radar systems and their post-processed received data is transmitted to a central unit on the vehicle with this received data preferably containing the following object information: Distance Azimuth and elevation angles Speeds Micro-Doppler Polarimetric properties Object classes.

Description

[0019] Further advantages, features and possible applications of the present invention are addressed in the following description of the preferred exemplary embodiments in conjunction with the drawing, in which:

[0020] FIG. 1 is a schematic depiction of the PMCW-MIMO radar system according to the application consisting, for example, of two subcomponents.

[0021] FIG. 2 is a schematic depiction of an exemplary embodiment of the transmitter and receiver arrangement of the radar system according to the application consisting of two subcomponents.

[0022] FIG. 3 is a schematic depiction of the virtual overall arrangement for the transmitter and receiver arrangement according to FIG. 2.

[0023] FIG. 4 is a schematic depiction of an embodiment of the radar system according to the application consisting of 4 subcomponents.

[0024] FIG. 5 is a schematic depiction of an exemplary embodiment of the transmitter and receiver arrangement of the radar system according to the application when using circular polarimetry.

[0025] FIG. 6 is a schematic depiction of the virtual overall arrangement for the transmitter and receiver arrangement according to FIG. 5.

[0026] FIG. 7 is a schematic depiction of an exemplary arrangement of the radar system according to the application with a varying number of subcomponents in a vehicle for an 360° environment detection.

[0027] FIG. 1 is a schematic depiction of the PMCW MIMO radar system according to the application, for example, for a radar system consisting of two subcomponents. The subcomponents of the radar system comprise a plurality of transmitters (subcomponent 1: TX.sub.IS1 to TX.sub.NS1, subcomponent 2: TX.sub.IS2 to TX.sub.NS2), which are operated as much at the same time as possible. An individual phase code is generated for each transmitter and the digital signals are converted to analog using a DAC. An up-conversion to the frequency range between approx. 76 and 81 GHz follows. Each transmitter transmits its individual code, and the returning signals are sent to all receivers (subcomponent 1: RX.sub.IS1 to RX.sub.NS1, subcomponent 2: RX.sub.IS2 to RX.sub.NS2) of the radar system. The received signals are down-converted to the baseband. The same VCO is used for the up- and down-conversion within a subcomponent. The analog received signals in the baseband are converted to digital signals by means of an ADC. Then, the correlation takes place. The transmission signals from each transmitter in the overall system can now be extracted for each receiver. A virtual overall arrangement according to the MIMO principle can be generated from the positions of the transmitters and receivers. A signal processing, which includes a Doppler FFT for a target velocity analysis and some of the calculations for the beam formations, is carried out for each subcomponent. Furthermore, the radar system according to the application comprises elements that either connect the subcomponents or are used jointly by all subcomponents. Each subcomponent comprises a VCO that is located within a PLL. A common crystal is used as the reference phase for all PLLs of the subcomponents. This creates a kind of pseudo-coherence between the subcomponents. To ensure that the subcomponents can jointly be used as an overall radar system, a precise synchronization of all subcomponents is required. According to the invention, this is done by means of overlapping columns or rows. In this regard, the respective columns or rows of different transmitter-receiver combinations of different subcomponents are found in the same positions in the virtual overall arrangement.

[0028] FIG. 2. shows an exemplary embodiment of the transmitter and receiver arrangement of the overall radar system according to the application which consists of two subcomponents with each having 12 transmitting antennas and 8 receiving antennas.

[0029] FIG. 3 is a schematic depiction of the virtual overall arrangement, the antenna element positions of which result from the transmitter and receiver arrangement according to FIG. 2. When using two subcomponents, four antenna sub-arrangements that have to be synchronized with one another result. The sub-arrangements are created by all existing transmitter-receiver combinations: [0030] First sub-arrangement: Transmitter of subcomponent 1 and receiver of subcomponent 1 [0031] Second sub-arrangement: Transmitter of subcomponent 2 and receiver of subcomponent 1 [0032] Third sub-arrangement: Transmitter of subcomponent 1 and receiver of subcomponent 2 [0033] Fourth sub-arrangement: Transmitter of subcomponent 2 and receiver of subcomponent 2

[0034] The sub-arrangements are synchronized with the phase and amplitude calibration values from the overlapping columns. There is one overlapping column each between the sub-arrangements. In this context, there are virtual columns of two adjacent sub-arrangements in exactly the same position. The overall arrangement is then synchronized, for example, in the following manner: The second sub-arrangement is calibrated to the phase and amplitude values of the first sub-arrangement. The third sub-arrangement is then calibrated to the second sub-arrangement, and subsequently the fourth sub-arrangement is calibrated to the third sub-arrangement.

[0035] FIG. 4 shows an embodiment of the radar system according to the application consisting of four subcomponents. This results in a total of 16 antenna sub-arrangements that are created from the existing transmitter-receiver combinations. Between two sub-arrangements there is an overlapping column for calibrating the phase and amplitude values. There are a total of 15 overlapping columns.

[0036] FIG. 5 shows how circular polarimetry can be used. The same antenna element positions were used as in FIG. 2 but with the difference that the antennas were configured for the following polarizations: [0037] The transmitters of subcomponent 1 were configured for a left circular polarization. This means that the high-frequency carrier signal has a left circular polarization. [0038] The receivers of subcomponent 1 were configured for a right circular polarization. Right circular components of the returning signals are received. [0039] The transmitters of subcomponent 2 were configured for a left circular polarization. This means that the high-frequency carrier signal has a left circular polarization. [0040] The receivers of subcomponent 2 were configured for a left circular polarization. Left circular components of the returning signals are received.

[0041] In this case, the right and left circular polarization can also be interchanged when applied to all antenna elements.

[0042] FIG. 6 is a schematic depiction of the virtual overall antenna arrangement that results from the transmitter and receiver arrangement according to FIG. 5. This results in four sub-arrangements. In the case of sub-arrangements 1 and 2, the transmitters are each configured for a left circular polarization and the receivers for a right circular polarization. In sub-arrangements 3 and 4, the transmitters are each configured for a left circular polarization and the receivers for a left circular polarization. An overlapping column for synchronizing the phases and amplitude values is located between all sub-arrangements. However, since sub-arrangement 2 and sub-arrangement 3 have different polarizations in their transmitter-receiver combinations, the polarimetry must be taken into account during the synchronization. Due to the dependence of the phase and amplitude values on the polarization, the phase and amplitude values must be calibrated for each returning signal or target object so that a synchronized overall arrangement is created. This overall arrangement can be used, for example, to analyze precise angular positions in azimuth.

[0043] To evaluate the polarimetric properties in addition to evaluating the overall arrangement, sub-arrangements 1 and 2 can be processed together for cross-polar properties and, separately therefrom, sub-arrangements 3 and 4 can be processed together for copolar properties. A comparison of these two evaluations allows for the analysis of polarimetric properties which can then be used, for example, for object classifications.

[0044] FIG. 7 shows, by way of example, the arrangement of radar systems with polarimetry, according to the application, in a vehicle for a 360° environment detection. In this context, radar systems are used that have subcomponents whose receivers are configured for either a left or right circular polarization. The number of subcomponents that use a right circular polarization is equal to the number of subcomponents that use a left circular polarization. The two subcomponent types are each arranged mirror-symmetrically to one another. The radar systems are positioned around the vehicle.