RADAR DEVICE

• US 20090021421A1
• Filed: 10/15/2007
• Published: 01/22/2009
• Est. Priority Date: 07/19/2007
• Status: Active Grant

• Current Assignee: Mitsubishi Electric Corporation
• Original Assignee: Mitsubishi Electric Corporation
• Inventors: MITSUMOTO, Masashi, WAKAYAMA, Toshio, UEHARA, Naohisa
• Granted Patent: US 7,548,193 B2
• Time in Patent Office: Days
• US Class Current: 342/175
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 7/354 Extracting wanted echo-signals Doppler systems G01S13/50
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing
• CPC Class Codes: G01S 7/358 using I/Q processing

Abstract

For enabling determination on whether a sign of a Doppler frequency or a target angle is positive or negative even when only a real signal can be obtained as a received signal, the present invention provides a radar device including: an oscillator; a transmitting element; a distributor; receivers using the local wave to detect the received wave to generate a real received signal; a plurality of inter-channel phase correcting units; a spatial frequency information generating unit for converting a received signal string obtained by gathering a plurality of phase-corrected received signals into a signal in a spatial frequency domain; and a sign selecting unit for selecting a signal having a larger amplitude in a spatial frequency spectrum when two signals from a positive direction and a negative direction which are symmetrical with respect to a direction at approximately 0 degree.

Claims

1. A radar device for emitting a wave into space, receiving the wave reflected by an object present in the space, and performing signal processing on the received wave to measure the object, comprising:

an oscillator for generating the wave;

a transmitting element for emitting the wave generated in the oscillator into the space;

a local wave extracting unit for extracting a part of the wave generated in the oscillator to output the part of the wave as a local wave;

a plurality of receiving elements provided at positions different from each other, for receiving an incoming wave and outputting the received wave;

a plurality of receivers each using the local wave output from the local wave extracting unit to detect the received wave received by each of the plurality of receiving elements to generate a real received signal;

a plurality of inter-channel phase correcting units for multiplying the real received signal obtained by each of the plurality of receivers by a phase correction factor different for each of the plurality of receivers, the phase correction factor being represented by a complex number;

a spatial frequency information generating unit for converting a received signal string obtained by gathering phase-corrected received signals output from the plurality of inter-channel phase correcting units into a signal in a spatial frequency domain; and

a sign selecting unit for selecting a signal having a larger amplitude in a spatial frequency spectrum when two signals from a positive direction and a negative direction which are symmetrical with respect to a direction at 0 degree are detected in the spatial frequency information generating unit.

2. The radar device according to claim 1, further comprising a plurality of time-direction Fourier transform units between the plurality of inter-channel phase correcting units and the spatial frequency information generating unit, for performing Fourier transform on the phase-corrected received signal in a time axis direction,

wherein the spatial frequency information generating unit converts the received signal string obtained by gathering a plurality of Fourier-transformed signals from the plurality of time-direction Fourier transform units in an amount corresponding to the plurality of receivers into the signal in the spatial frequency domain, and

wherein the sign selecting unit selects the signal having a larger amplitude when two signals in the positive direction and the negative direction symmetrical with respect to the direction at 0 degree, which have a positive frequency and a negative frequency symmetrical to each other, are detected.

3. The radar device according to claim 1, further comprising a plurality of time-direction Fourier transform units between the plurality of receivers and the plurality of inter-channel phase correcting units, for performing Fourier transform on the real received signal obtained in each of the plurality of receivers in a time axis direction,

wherein each of the plurality of inter-channel phase correcting units multiplies the Fourier-transformed signal from each of the plurality of time-direction Fourier transform units by the phase correction factor represented by the complex number,

wherein the spatial frequency information generating unit converts the received signal string obtained by gathering a plurality of Fourier-transformed signals from the plurality of time-direction Fourier transform units in an amount corresponding to the plurality of receivers into the signal in the spatial frequency domain, and

wherein the sign selecting unit selects the signal having a larger amplitude when two signals in the positive direction and the negative direction symmetrical with respect to the direction at 0 degree, which have a positive frequency and a negative frequency symmetrical to each other, are detected.

4. The radar device according to claim 1, further comprising a plurality of time-direction Fourier transform units between the spatial frequency information generating unit and the sign selecting unit, for performing Fourier transform on the signal in the spatial frequency domain obtained in the spatial frequency information generating unit for each frequency in a time axis direction,

wherein the sign selecting unit selects the signal having a larger amplitude when two signals in the positive direction and the negative direction symmetrical with respect to the direction at 0 degree, which have a positive frequency and a negative frequency symmetrical to each other, are detected.

5. The radar device according to claim 1, wherein at least a half of the plurality of receivers is fed with power so that a phase of a local wave to be input thereto is shifted by 90 degrees as compared with that of a local wave to be input to the other one of the plurality of receivers.

6. The radar device according to claim 5, wherein the at least a half of the plurality of receivers and the local wave extracting unit have a phase shifter for rotating the phase of the signal by 90 degrees provided therebetween.

7. The radar device according to claim 5, wherein the phase of the signal is shifted by 90 degrees by changing an electrical path length of a power feeding line between the at least a half of the plurality of receivers and the local wave extracting unit.

8. The radar device according to claim 1, wherein at least a half of the plurality of receivers is fed with power so that a phase of the received wave to be input thereto is shifted by 90 degrees as compared with that of the received wave to be input to the other one of the plurality of receivers.

9. The radar device according to claim 8, wherein the at least a half of the plurality of receivers and at least a half of the plurality of receiving elements have a phase shifter for rotating the phase of the signal by 90 degrees provided therebetween.

10. The radar device according to claim 8, wherein the phase of the signal is shifted by 90 degrees by changing an electrical path length of a power feeding line between the at least a half of the plurality of receivers and at least a half of the plurality of receiving elements.

11. A radar device for emitting a wave into space, receiving the wave reflected by an object present in the space, and performing signal processing on the received wave to measure the object, comprising:

an oscillator for generating the wave;

a transmitting element for emitting the wave generated in the oscillator into the space;

a local wave extracting unit for extracting a part of the wave generated in the oscillator to output the part of the wave as a local wave;

a plurality of receiving elements provided at positions different from each other, for receiving an incoming wave and outputting the received wave;

a plurality of receivers each using the local wave output from the local wave extracting unit to detect the received wave received by each of the plurality of receiving elements to generate a real received signal;

a plurality of inter-channel phase correcting units for multiplying the real received signal obtained by each of the plurality of receivers by a phase correction factor different for each of the plurality of receivers, the phase correction factor being represented by a complex number;

a spatio-temporal Fourier transform unit for performing two-dimensional Fourier transform on a phase-corrected received signal output from each of the plurality of inter-channel phase correcting units in a time axis direction as well as in a receiving element direction; and

a sign selecting unit for selecting a signal having a larger amplitude when two signals in a positive direction and a negative direction symmetrical with respect to a direction at 0 degree, which have a positive frequency and a negative frequency symmetrical to each other, are detected in the spatio-temporal Fourier transform unit.