RADAR APPARATUS

• US 20110122013A1
• Filed: 03/19/2010
• Published: 05/26/2011
• Est. Priority Date: 05/20/2009
• Status: Abandoned Application

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Oosuga, Kazuki, Takeya, Shinichi, Yoshida, Takuji, Goto, Hideto, Yoshida, Tomohiro, Kawabata, Kazuaki, Niwa, Masato
• Application Number:
  US12/996,058
• Publication Number:
  US 20110122013A1
• Time in Patent Office: Days
• US Class Current: 342/109
• CPC Class Codes: G01S 13/44 Monopulse radar, i.e. simultaneous lobing
• CPC Class Codes: G01S 13/584 adapted for simultaneous range and velocity measurements
• CPC Class Codes: G01S 2013/0263 Passive array antenna
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14

Abstract

The present invention includes: a transmitter/receiver 20 that transmits an FMCW modulated sweep signal at least twice; an FFT unit 32 that performs Fast Fourier Transform on the at least two sweep signals received in response to the transmission from the transmitter/receiver; and an MRAV processor 35a that calculates ranges and velocities of multiple targets by calculating beat frequencies corresponding to at least two sweeps by the transmitter/receiver based on the at least two sweep signals obtained by the Fourier Transform performed by the FFT unit, calculating velocities based on a frequency difference and a time difference of the calculated beat frequencies, and calculating ranges based on the calculated velocities and beat frequencies.

Claims

1. A radar apparatus comprising:

a transmitter/receiver that transmits an FMCW modulated sweep signal M times;

an FFT unit that performs Fast Fourier Transform on the M sweep signals received in response to transmission from the transmitter/receiver; and

an MRAV processor configured so that, when a maximum value of each sweep signal is calculated from the M sweep signals obtained by the Fourier Transform performed by the FFT unit, the MRAV processor performs;

amplitude integration on beat frequency-sweep axis in a sweep direction for each of beat frequencies by using F (sweep number, target number) resulting from calculation of the beat frequencies by phase monopulse, amplitude monopulse, or MUSIC of M sweeps;

calculates a least square line with respect to a relative range and a sweep time of a sweep number exceeding a predetermined threshold sweep for each frequency bank exceeding the predetermined threshold;

calculates a target velocity from a slope of the least square line; and

calculates a target range.

2. The radar apparatus according to claim 1, wherein, when the sweep signals undergo Fast Fourier Transform, the MRAV processor calculates the beat frequencies with high precision within banks based on:

a monopulse error signal calculated for a bank at which Σ

signal has a local maximum value by using a result of performing Fast Fourier Transform on two sequences of the Σ

signal and a Δ

signal;

a monopulse error signal calculated based on Σ and

Σ

u, Σ

u being a greater signal of banks adjacent to the bank at which the Σ

signal has a local maximum value;

or a monopulse error signal calculated by performing FFT and MUSIC system on bank signals extracted in a range of ±

M banks of the bank at which the Σ

signal has a local maximum value.

3. A radar apparatus comprising:

a transmitter/receiver that transmits an FMCW modulated sweep signal at least twice;

an FFT unit that performs Fast Fourier Transform on the at least two sweep signals received in response to transmission from the transmitter/receiver; and

an MRAV processor that calculates ranges and velocities of multiple targets by calculating beat frequencies corresponding to at least two sweeps by the transmitter/receiver based on the at least two sweep signals obtained by the Fourier Transform performed by the FFT unit, calculating velocities based on a frequency difference and a time difference of the calculated beat frequencies, and calculating ranges based on the calculated velocities and beat frequencies.

4. The radar apparatus according to claim 3, wherein, when the sweep signals undergo Fast Fourier Transform, the MRAV processor calculates the beat frequencies with high precision within banks based on:

a monopulse error signal calculated for a bank at which Σ

signal has a local maximum value by using a result of performing Fast Fourier Transform on two sequences of the Σ

signal and a Δ

signal;

a monopulse error signal calculated based on Σ and

Σ

u, Σ

u being a greater signal of banks adjacent to the bank at which the Σ

signal has a local maximum value;

or a monopulse error signal calculated by performing FFT and MUSIC system on bank signals extracted in a range of ±

M banks of the bank at which the Σ

signal has a local maximum value.

5. The radar apparatus according to claim 3, further comprising a second FFT unit that performs Fast Fourier Transform on an output of the FFT unit, wherein

the transmitter/receiver transmits the FMCW modulated sweep signal N times (#1 to #N), and

the MRAV processor extracts a local maximal value based on a result of Fast Fourier Transform on each sweep, and calculates a beat frequency of the bank signal having a local maximum value from results of Fast Fourier Transform by the second FFT unit for each of two sets of M sweeps, the Fast Fourier Transform being performed to extract banks having local maximum values from FFT signals of sweep of #1 to #N1 (M sweeps) and #N2 to #N (M sweeps).

6. The radar apparatus according to claim 3, wherein, when calculating each local maximum value from two M sweep signals, the MRAV processor calculates Σ

and Δ

of M sweeps, and calculates the beat frequency with high precision from a monopulse error voltage.

7. The radar apparatus according to claim 3, wherein, when calculating each local maximum value from two M sweep signals, the MRAV processor calculates Σ

and Σ

u of M sweeps, and calculates the beat frequency with high precision from a monopulse error voltage.

8. The radar apparatus according to claim 3, wherein, when calculating each local maximum value from two M sweep signals, the MRAV processor calculates the beat frequency by performing FFT and MUSIC processing on M sweeps.

9. The radar apparatus according to claim 3, further comprising a sign reversing unit that reverses signs of range, velocity, and angle according to a sign of calculated range if the radar apparatus employs a system in which when the sweep signal has a real number, Complex Fourier Transform is performed on a sampled signal to extract a positive or negative signal from the beat frequencies, thereby obtaining a complex number signal.

10. The radar apparatus according to claim 3, further comprising a sweep controller that controls a sweep so that a sweep signal having an increased slope is transmitted for a short range and a sweep signal having a decreased slope is transmitted for a long range.

11. The radar apparatus according to claim 10, wherein the sweep controller selects two sweeps having different time intervals by using a critical factor calculated based on velocity and range.

12. The radar apparatus according to claim 10, wherein the sweep controller selects two sweeps having different time intervals by periodically changing to a different sweep for every cycle.

13. A radar apparatus comprising:

a transmitter/receiver that transmits an FMCW modulated sweep signal M times;

an FFT unit that perform Fast Fourier Transform on the M sweep signals received in response to the transmission from the transmitter/receiver; and

an MRAV processor that performs smoothing over sweeps using F (sweep number, target number) resulting from calculation of beat frequencies by phase monopulse, amplitude monopulse, or MUSIC of the M sweeps when calculating a maximum value of each sweep signal from the M sweep signals obtained by Fourier Transform performed by the FFT unit, and calculates a range after calculating a velocity based on results of the smoothing.

14. A radar apparatus comprising:

a transmitter/receiver that transmits an FMCW modulated sweep signal M times;

an FFT unit that performs Fast Fourier Transform on the M sweep signals received in response to transmission from the transmitter/receiver; and

an MRAV processor that calculates a local maximum value on beat frequency-sweep axis by Hough transformation using F (sweep number, target number) resulting from calculation of beat frequencies by phase monopulse, amplitude monopulse, or MUSIC of the M sweeps when calculating a maximum value of each sweep signal from the M sweep signals obtained by Fourier Transform performed by the FFT unit, and calculates a range after calculating a velocity corresponding to the calculated local maximum value from a beat frequency difference and a sweep time.