DETECTION AND RANGING APPARTUS AND DETECTION AND RANGING METHOD

• US 20090079617A1
• Filed: 08/28/2008
• Published: 03/26/2009
• Est. Priority Date: 09/26/2007
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation), Fujitsu Limited
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation), Fujitsu Limited
• Inventors: KONDO, Yasuyuki, OHGUCHI, Katsuyuki, SHIRAKAWA, Kazuo
• Granted Patent: US 7,859,450 B2
• Time in Patent Office: Days
• US Class Current: 342/146
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 13/34 using transmission of continuous, frequency-modulated waves while heterodyning the received signal, or a signal derived therefrom, with a locally-generated signal related to the contemporaneously transmitted signal
• CPC Class Codes: G01S 13/87 Combinations of radar systems, e.g. primary radar and secondary radar
• CPC Class Codes: G01S 13/931 of land vehicles
• CPC Class Codes: G01S 2013/0254 Active array antenna
• CPC Class Codes: G01S 7/032 Constructional details for solid-state radar subsystems

Abstract

In a detection and ranging apparatus that performs direction-of-arrival estimation using a sensor array and that enlarges an effective aperture using a plurality of transmitting sensors, adverse effects associated with time division switching are eliminated, achieving high-accuracy measurement. A transmitter wave is spread in modulators by using mutually orthogonal codes, and the resulting transmitter waves are radiated from two transmitting sensors. Signals received by receiving sensors are each split by a splitter into two parts, which are then respectively despread in a demodulator by using the same codes as those used in the transmitter.

Claims

1. A detection and ranging apparatus comprising:

M spreaders for generating M spread transmitter waves by spreading a transmitter wave using mutually orthogonal M orthogonal codes, where M is an integer not smaller than 2;

M transmitting sensor elements for transmitting out said M spread transmitter waves;

N receiving sensor elements, where N is an integer not smaller than 2;

a receiving control part for splitting each of N received signals obtained at said N receiving sensor elements into M parts, and for generating M×

N despread outputs by despreading the M parts using said M orthogonal codes; and

a direction-of-arrival estimating part for estimating, based on said M×

N despread outputs, directions of arrival of reflected signals arriving from a plurality of targets.

2. A detection and ranging apparatus according to claim 1, wherein said M spreaders each include a BPSK modulator for spreading said transmitter wave by binary phase-shift keying (BPSK) said transmitter wave with a corresponding one of said orthogonal codes.

3. A detection and ranging apparatus according to claim 1, further comprising a transmitter wave generator for selectively generating one of a carrier wave frequency-modulated by a triangular wave and an unmodulated carrier wave, as said transmitter wave.

4. A detection and ranging apparatus according to claim 1, wherein

said M orthogonal codes includes a first orthogonal code and a second orthogonal code having a higher chip rate than said first orthogonal code, and

at least the transmitter wave spread by said first orthogonal code is a carrier wave frequency-modulated by a triangular wave,

said apparatus further comprising

a first distance calculating part for taking as an input the despread output produced by despreading with said first orthogonal code, and for calculating a distance to a target from the frequency of said despread output in an upsweep section of said triangular wave and the frequency of said despread output in a downsweep section of said triangular wave, and

a second distance calculating part for taking as an input the despread output produced by despreading with said second orthogonal code, and for calculating the distance to said target from the phase of said second orthogonal code used for said despreading.

5. A detection and ranging apparatus according to claim 4, further comprising a correcting part for correcting the distance calculated by said first distance calculating means, based on a difference between the distances calculated by said first and second distance calculating means for the same target.

6. A detection and ranging apparatus according to claim 1, wherein said N receiving sensor elements are arranged at equally spaced intervals, and

said M transmitting sensor elements are two transmitting sensor elements arranged so as to flank said N receiving sensor elements.

7. A detection and ranging apparatus according to claim 6, further comprising a phase shifter for adjusting the phase of a radio wave to be radiated from at least one of said two transmitting sensor elements.

8. A detection and ranging apparatus according to claim 1, wherein said N receiving sensor elements are arranged at equally spaced intervals, and

said M transmitting sensor elements are arranged one spaced apart from another by a distance that is N times as great as the distance by which said N receiving sensor elements are spaced apart.

9. A detection and ranging method of detecting a direction of arrival of a signal, comprising

spreading signals to be input to M transmitting sensor elements by mutually orthogonal M orthogonal codes, respectively, to transmit out simultaneously from said M transmitting sensor elements, where M is an integer not smaller than 2, and

splitting each of signals output from N receiving sensor elements, where N is an integer not smaller than 2, into M parts, and despreading the M parts using said M orthogonal codes.