ELECTRONICALLY SCANNED RADAR SYSTEM

• US 20100019950A1
• Filed: 12/26/2007
• Published: 01/28/2010
• Est. Priority Date: 12/27/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Watanabe, Yuu, Natsume, Kazuma, Sakamoto, Mai, Yamano, Chiharu
• Granted Patent: US 8,169,361 B2
• Time in Patent Office: Days
• US Class Current: 342/104
• CPC Class Codes: G01S 13/345 using triangular modulation
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: 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
• CPC Class Codes: G01S 7/2813 Means providing a modification of the radiation pattern for cancelling noise, clutter or interfering signals, e.g. side lobe suppression, side lobe blanking, null-steering arrays specially adapted to secondary radar systems G01S13/762; aerials or aerials systems H01Q21/29, H01Q25/00
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing

Abstract

A sampled beat signal RD is split into a plurality of short-time data SD in the time direction, for each of antenna elements. Interference component frequency of an interference wave is detected from a frequency spectrum of the short-time data SD. A digital beam forming process is performed for the interference component frequency of the interference wave to extract a peak of the electrical power of an azimuth direction and estimate an absolute value of an incoming direction of interference components. Based on the absolute value of the incoming direction of the estimated interference components, a filter for suppressing the interference components is operated to suppress the interference components.

Claims

1. An electronically scanned radar system comprising:

a transmitting antenna for freely emitting a transmission signal consisting of a continuous wave;

a receiving antenna consisting of antenna elements corresponding to respective channels;

a mixer for obtaining a beat signal by mixing a reception signal received by each of the antenna elements with the transmission signal;

an AD converter for obtaining a reception data consisting of an N number of sampled data by sampling the beat signal obtained by the mixer at a predetermined sampling frequency; and

a target detection section for detecting a distance from a target or/and a relative speed of the a target, on the basis of the reception data sampled by the AD converter, characterized by;

a data cutting out part for cutting out an (N−

M+1) number of data each consisting of an M(<

N) number of sampled data continuous in the time direction, from the reception data consisting of the N number of sampled data;

a frequency spectrum calculation part for calculating a frequency spectrum of each of the (N−

M+1) number of data;

an interference frequency detection part for detecting an interference component frequency of an interference wave from the frequency spectrum;

an interference component removal part for removing the interference component frequency from the beat signal, the interference component frequency being detected by the interference frequency detection part;

a buffer part for merging the data cut out by the data cutting out part and removed with the frequency components to restore a data having a length before being cut out; and

detection of a distance from the target or/and a relative speed of the target on the basis of the data restored by the buffer part.

2. The radar system according to claim 1, characterized in that the data cutting out part sets the number M so that the frequency is substantially unchanged in the continuous M number of sampled data in the case where the M number of sampled data is sampled by the sampling frequency.

3. The radar system according to claim 1, characterized in that, in removing the interference component frequency detected by the interference frequency detection part from the beat signal, the interference component removal part removes the beat signal from a portion where the beat signal corresponding to the reception wave intersects with the beat signal corresponding to the interference wave.

4. The radar system according to claim 1, characterized in that the interference component removal part is a projection matrix working on the data cut out by the data cutting out part.

5. The radar system according to claim 1, characterized in that:

the channel is provided in plural number, and a plurality of reception antennas are provided, each reception antenna consisting of antenna elements corresponding to the plurality of channels;

the mixer is provided in plural number in order to obtain a beat signal for each of the antenna elements by mixing a reception signal received by each of the antenna elements with the transmission signal; and

the AD converter is provided in plural number in order to sample the beat signal of each of the channels at a predetermined sampling frequency, which beat signal has been obtained from each of the plurality of mixers, to obtain the reception data consisting of the N number of sampled data for each of the channels corresponding to the respective antenna elements.

6. The radar system according to claim 5, characterized in that the system comprises a peak direction extraction part for performing a digital beam forming process for the interference component frequency to extract a peak of the electrical power of an azimuth direction from the interference component frequency, and the interference component removal part calculates an absolute value of an incoming direction of the interference component frequency extracted at the peak direction extraction part and uses a filter for removing the interference component frequency on the basis of the absolute value.

7. The radar system according to claim 5, characterized in that the system comprises a peak direction extraction part for performing a digital beam forming process for the interference component frequency to extract a peak of the electrical power of an azimuth direction from the interference component frequency, and the interference component removal part uses a filter for removing only a portion where the beat signal corresponding to the interference wave coming from the same direction as that of the reception wave intersects with the beat signal corresponding to the reception signal, from the beat signal in a portion where the beat signal corresponding to the reception signal intersects with the beat signal corresponding to the interference wave.

8. The radar system according to claim 6, characterized in that the filter is a projection matrix that works on the data cut out by the data cutting out part.

9. The radar system according to claim 1, characterized in that the interference frequency detection part detects the interference component frequency on the basis of time transient information of the frequency spectrum.

10. The radar system according to claim 1, characterized in that the interference frequency detection part detects a component as the interference component frequency, which component maximizes an electrical power value of the frequency spectrum.

11. The radar system according to claim 2, characterized in that, in removing the interference component frequency detected by the interference frequency detection part from the beat signal, the interference component removal part removes the beat signal from a portion where the beat signal corresponding to the reception wave intersects with the beat signal corresponding to the interference wave.

12. The radar system according to claim 11, characterized in that the interference component removal part is a projection matrix working on the data cut out by the data cutting out part.

13. The radar system according to claim 12, characterized in that:

the channel is provided in plural number, and a plurality of reception antennas are provided, each reception antenna consisting of antenna elements corresponding to the plurality of channels;

the mixer is provided in plural number in order to obtain a beat signal for each of the antenna elements by mixing a reception signal received by each of the antenna elements with the transmission signal; and

the AD converter is provided in plural number in order to sample the beat signal of each of the channels at a predetermined sampling frequency, which beat signal has been obtained from each of the plurality of mixers, to obtain the reception data consisting of the N number of sampled data for each of the channels corresponding to the respective antenna elements.

14. The radar system according to claim 13, characterized in that the system comprises a peak direction extraction part for performing a digital beam forming process for the interference component frequency to extract a peak of the electrical power of an azimuth direction from the interference component frequency, and the interference component removal part calculates an absolute value of an incoming direction of the interference component frequency extracted at the peak direction extraction part and uses a filter for removing the interference component frequency on the basis of the absolute value.

15. The radar system according to claim 13, characterized in that the system comprises a peak direction extraction part for performing a digital beam forming process for the interference component frequency to extract a peak of the electrical power of an azimuth direction from the interference component frequency, and the interference component removal part uses a filter for removing only a portion where the beat signal corresponding to the interference wave coming from the same direction as that of the reception wave intersects with the beat signal corresponding to the reception signal, from the beat signal in a portion where the beat signal corresponding to the reception signal intersects with the beat signal corresponding to the interference wave.

16. The radar system according to claim 14, characterized in that the filter is a projection matrix that works on the data cut out by the data cutting out part.

17. The radar system according to claim 16, characterized in that the interference frequency detection part detects the interference component frequency on the basis of time transient information of the frequency spectrum.

18. The radar system according to claim 17, characterized in that the interference frequency detection part detects a component as the interference component frequency, which component maximizes an electrical power value of the frequency spectrum.