Interferometer-type radar

• US 7,436,348 B2
• Filed: 03/31/2006
• Issued: 10/14/2008
• Est. Priority Date: 03/31/2005
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Nohmi, Hitoshi
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): Bythrow; Peter M
• Application Number:
  US11/393,837
• Publication Number:
  US 20060220949A1
• Time in Patent Office: 928 Days
• Field of Search: 342/25, 342/90, 342 95- 97, 342107-116, 342/118, 342/128, 342/130, 342/133, 342/139, 342/146, 342/147, 342/156, 342159-162, 342/175, 342/189, 342/192, 342/196, 342/417, 342/424
• US Class Current: 342/25.00R
• CPC Class Codes: G01S 13/343 using sawtooth modulation
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 13/904 SAR modes
• CPC Class Codes: G01S 13/9064 Inverse SAR [ISAR]
• CPC Class Codes: G01S 7/35 Details of non-pulse systems
• CPC Class Codes: G01S 7/356 involving particularities of FFT processing

Abstract

A transmitter for transmitting signals to targets and a receiver having a large-diameter array antenna for receiving signals reflected from targets are included. The transmitter has a function of outputting an FMCW signal for detecting direction and velocity of the target from a transmitting antenna. The receiver includes: a plurality of correlation processors for performing correlation processing to receiving signals received by respective interference blocks configured such that the large-diameter array antenna is divided into a plurality of equal blocks; and a synthesizer for vector-synthesizing same signal components of signals outputted from the plurality of correlation processors.

Claims

1. An interferometer-type radar comprising:

a transmitter for transmitting a signal to a target; and

a receiver having a large-diameter array antenna for receiving a reflection signal reflected from the target, wherein

the transmitter has a function of outputting an FMCW signal for detecting direction and velocity of the target from a transmitting antenna, and

the receiver includes;

a plurality of correlation processors for performing correlation processing to receiving signals received by respective interference blocks configured such that the large-diameter array antenna is divided into a plurality of equal blocks;

a synthesizer for vector-synthesizing same signal components by modulating both a phase and an amplitude of signals outputted from the plurality of correlation processors;

a data processor having a function of obtaining the direction of the target with a low spatial resolution based on a reflection signal from the target received by a largest aperture of the large-diameter array antenna; and

a target selection unit for obtaining the direction of the target with a spatial resolution according to a largest distance between antennas by performing digital beam forming of the receiving signal before the correlation processing.

2. The interferometer-type radar, as claimed in claim 1, wherein the large-diameter array antenna is so configured that a plurality of antenna elements are aligned in a matrix on an antenna face.

3. The interferometer-type radar, as claimed in claim 1, wherein the interference blocks are arranged such that an antenna face of the large-diameter antenna is equally divided vertically and horizontally.

4. The interferometer-type radar, as claimed in claim 1, wherein the correlation processor is provided independently for each interference block.

5. The interferometer-type radar, as claimed in claim 1, wherein arrangement of the interference blocks on the large-diameter array antenna satisfies a condition of C>

2B·

D sinθ

, where a transmission frequency band of the transmitter is B, a largest distance between antennas between most distant interference blocks among a plurality of interference blocks to be vector-synthesized is D, a directional angle of the target from a normal direction of an antenna face is θ

, and light velocity is C.

6. The interferometer-type radar, as claimed in claim 1, wherein a plurality of antenna elements in the interference block are in a matrix such that a plurality of antenna elements provided on the large-diameter array antenna are equally divided.

7. An interferometer-type radar comprising:

a transmitter for transmitting a signal to a target; and

a receiver having a large-diameter array antenna for receiving a reflection signal reflected from the target, wherein

the transmitter has a function of outputting an FMCW signal for detecting direction and velocity of the target from a transmitting antenna, and

the receiver includes;

a plurality of correlation processors for performing correlation processing to receiving signals received by respective interference blocks configured such that the large-diameter array antenna is divided into a plurality of equal blocks;

a synthesizer for vector-synthesizing same signal components by modulating both a phase and an amplitude of signals outputted from the plurality of correlation processors;

an individual MTI unit for measuring velocity of the target with high accuracy by using the velocity and distance data of the target obtained in coarse MTI and coarse ranging; and

an individual ranging processor for performing correction of Doppler frequency by the velocity of the target by using velocity data of the individual MTI unit and frequency correction of an FMCW baseband signal according to a distance change to thereby range a position of the target with high accuracy.

8. A method of processing signals transmitted and received by an interferometer-type radar, comprising:

transmitting a signal to a target; and

receiving, by a large-diameter array antenna of the interferometer-type radar, a reflection signal reflected from the target, wherein

the transmitting step comprises outputting an FMCW signal for detecting direction and velocity of the target from a transmitting antenna of the interferometer-type radar, and

wherein the receiving step comprises;

performing, by a plurality of correlation processors, correlation processing to receiving signals received by respective interference blocks configured such that the large-diameter array antenna is divided into a plurality of equal blocks;

vector-synthesizing same signal components by modulating both a phase and an amplitude of signals outputted from the plurality of correlation processors;

obtaining the direction of the target with a low spatial resolution based on a reflection signal from the target received by a largest aperture of the large-diameter array antenna; and

obtaining the direction of the target with a spatial resolution according to a largest distance between antennas by performing digital beam forming of the receiving signal before the correlation processing.