Radar apparatus, radar apparatus controlling method

• US 20060012511A1
• Filed: 12/01/2004
• Published: 01/19/2006
• Est. Priority Date: 07/13/2004
• Status: Active Grant

• Current Assignee: Fujitsu Ten Limited (DENSO Corporation), Fujitsu Limited
• Original Assignee: Fujitsu Ten Limited (DENSO Corporation), Fujitsu Limited
• Inventors: Ishii, Satoshi, Shima, Nobukazu, Hitotsuya, Masaki, Yatsuka, Hiroyuki, Dooi, Yoshikazu
• Granted Patent: US 7,148,840 B2
• Time in Patent Office: Days
• US Class Current: 342/70
• CPC Class Codes: G01S 13/08 Systems for measuring distance only indirect measurement G01S13/46
• CPC Class Codes: G01S 13/582 adapted for simultaneous range and velocity measurements
• 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 2013/9321 Velocity regulation, e.g. cruise control
• CPC Class Codes: G01S 2013/93271 in the front of the vehicles
• CPC Class Codes: G01S 2013/93272 in the back of the vehicles
• CPC Class Codes: G01S 7/02 of systems according to group G01S13/00

Abstract

A radar apparatus comprises: a transmitter unit having a high-frequency oscillating unit whose oscillation frequency is variable, and a pulse amplitude modulating unit for amplitude-modulating a pulse of a transmission high-frequency signal output from the high-frequency oscillating unit with a first control pulse signal; a receiver unit having a gating unit for controlling ON/OFF of an input of a received high-frequency signal with a second control pulse signal; and a controlling and signal processing unit for controlling the transmitter unit and the receiver unit, and for switching a first operation mode for making the apparatus function as an FM-CW radar, and a second operation mode for making the apparatus function as a pulse radar.

Claims

1. A radar apparatus, comprising:

a transmitter unit having a high-frequency oscillating unit whose oscillation frequency is variable, and a pulse amplitude modulating unit for amplitude-modulating a pulse of a transmission high-frequency signal output from said high-frequency oscillating unit with a first control pulse signal;

a receiver unit having a gating unit for turning on and off an input of a reception high-frequency signal with a second control pulse signal; and

a controlling unit for controlling said transmitter unit and said receiver unit, and for switching between a first operation mode for making the apparatus function as an FM-CW radar and a second operation mode for making the apparatus function as a pulse radar.

2. The radar apparatus according to claim 1, wherein:

said receiver unit comprises a reception signal processing circuit having a first frequency converter for frequency-converting the reception high-frequency signal via the gating unit with an output of the high-frequency oscillating unit, a first band-pass filter provided on an output side of the first frequency converter, a second frequency converter for frequency-converting an output of the first band-pass filter with the first control pulse signal, and a second band-pass filter provided on an output side of the second frequency converter; and

said controlling unit makes the apparatus function as the FM-CW radar by switching to an FM-CW modulation mode for outputting the transmission high-frequency signal as a continuous wave, which is frequency-modulated by inputting a triangular wave to the high-frequency oscillating unit, and by making the first control pulse signal of said transmitter unit and the second control pulse signal of said receiver unit inversely operate to alternately make a transmission of the transmitter high-frequency signal and a reception of the receiver high-frequency signal, in the first operation mode, and

said controlling unit makes the apparatus function as the pulse radar by generating a short width pulse from the first control pulse signal and driving the pulse amplitude modulating unit, and by sliding the second control pulse signal of the receiver unit at a predetermined delay time interval from the first control pulse signal to gate the reception high-frequency signal, in the second operation mode.

3. The radar apparatus according to claim 2, wherein:

the receiving signal processing circuit comprises a third band-pass filter which is provided in parallel with the second band-pass filter and whose pass frequency band is different, and a switch for selecting the output of the second or the third band-pass filter; and

said controlling unit has a function for selecting the second band-pass filter of the receiving signal processing circuit, and for setting a band of the second band-pass filter to a maximum frequency of a beat frequency, which is a difference between frequencies of the transmission high-frequency signal and the reception high-frequency signal, when the apparatus functions as the FM-CW radar, and

said controlling unit has a function for frequency-modulating the transmission high-frequency signal, and for switching to the third band-pass filter whose central frequency is the beat frequency, and whose pass band is set to a band width of a Doppler frequency according to a relative speed of a target in the reception signal processing circuit, when the apparatus functions as the pulse radar.

4. The radar apparatus according to claim 2, wherein

said controlling unit has a function for changing a modulation frequency and a modulation width of frequency modulation of the transmission high-frequency signal according to a delay time of the gating unit so that a frequency of a beat signal obtained by mixing the transmission high-frequency signal and the reception high-frequency signal becomes constant, when the apparatus functions as the pulse radar.

5. The radar apparatus according to claim 2, wherein

said controlling unit has a function for switching between FFT (Fast Fourier Transform) and computation of a summation of time sections so that the FFT is performed after A/D-converting a beat signal obtained by mixing the transmission high-frequency signal and the reception high-frequency signal, and a distance to a target is calculated with a frequency of a peak value of the FFT, when the apparatus functions as the FM-CW radar, or the distance to the target is calculated by using the delay time of the sliding, at which a summation of absolute values or a summation of square values,

which are obtained by A/D-converted beat signal, shows peak, when the apparatus functions as the pulse radar.

6. The radar apparatus according to claim 2, wherein

said controlling unit has a function for quickly detecting a relative speed of a target with data of one measurement by performing FFT (Fast Fourier Transform) simultaneously with a calculation of a summation of absolute values of a difference from an average of preset time sections, or a summation of square values, and by calculating a Doppler frequency, when the apparatus functions as the pulse radar.

7. The radar apparatus according to claim 1, further comprising

a first antenna having a narrow beam width, and a second antenna having a wide beam width, which are connected in common or individually to said transmitter unit and said receiver unit, wherein

said controlling unit switches to the first antenna at the time of the first operation mode for making the apparatus function as the FM-CW radar, and switches to the second antenna at the time of the second operation mode for making the apparatus function as the pulse radar.

8. The radar apparatus according to claim 1, further comprising:

antennas connected in common or individually to said transmitter unit and said receiver unit; and

a scanning mechanism for making an antenna scan in a horizontal direction, wherein

said controlling unit has a function for detecting a target within a scanning range in the horizontal direction based on a scanning position in the horizontal direction by the scanning mechanism, and the receiver high-frequency signal.

9. The radar apparatus according to claim 1, further comprising:

antennas connected in common or individually to said transmitter unit and said receiver unit; and

a scanning mechanism for making an antenna scan in a horizontal direction, wherein

said controlling unit has a function for executing a detection process having a high resolution in the horizontal direction by making the scanning by the antenna in the first operation mode for making the apparatus function as the FM-CW radar, and a function for detecting a target within a beam of the transmission high-frequency signal emitted from the antenna at a high response speed without making the scanning by the antenna in the second operation mode for making the apparatus function as the pulse radar.

10. A method for controlling a radar apparatus for detecting a target in a receiver unit by detecting a wave, which is reflected from the target, of a transmission high-frequency emitted from a transmitter unit, comprising

detecting the target while switching in cyclic time interval a first operation mode for frequency-modulating and radiating the transmission high-frequency, and a second operation mode for amplitude-modulating and radiating the transmission high-frequency, in the transmitter unit.

11. The method for controlling a radar apparatus according to claim 10, further comprising:

making the apparatus function as an FM-CW radar for detecting a distance and a relative speed of the target based on a FFT (Fast Fourier Transform) of a beat signal which is a difference of two frequencies;

one is continuously emitting transmitter high-frequency signal which is frequency-modulated with a triangular wave as an oscillation frequency control signal in the transmitter unit;

another one is a reflection wave from the target;

the beat signal is obtained by mixing these two signal; and

by detecting the two frequencies of beat signals respectively corresponding to up and down sections of the triangular wave, range and velocity of the target are detected, in the first operation mode; and

making the apparatus function as a pulse radar for detecting the distance to the target according to a delay time with which a signal level of the reflection wave becomes a maximum by intermittently emitting a transmission high-frequency which is amplitude-modulated with a first control pulse signal in the transmitter unit, by performing gating for controlling presence/absence of an input of the reflection wave with a second control pulse signal in the receiver unit, by gating the reflection wave by sliding the second control pulse signal at a preset delay time interval from the first control pulse signal, in the second operation mode.

12. The method for controlling a radar apparatus according to claim 10, further comprising

making the amplitude modulation after frequency-modulating the transmission high frequency by using a triangular wave as an oscillation frequency control signal in the second operation mode;

calculating a distance to a target with a frequency of a peak value of the FFT (Fast Fourier Transform) after A/D converting a beat signal obtained by mixing the reflection wave and the transmitter high-frequency, at the time of the first operation mode where the apparatus functions as the FM-CW radar; and

switching between the FFT and computation of a summation of a time section so that the distance to the target is calculated by using a delay time of sliding, with which a sum or a sum of squares of absolute values, which is obtained based on a value after the beat signal is A/D-converted, of a difference from an average of a preset time section indicates a peak, at the time of the second operation mode where the apparatus functions as the pulse radar.

13. The method for controlling a radar apparatus according to claim 10, further comprising:

amplitude-modulating the transmission high-frequency by using a triangular wave as an oscillation frequency control signal after frequency-modulating the transmission high frequency at the time of the second operation mode where the apparatus functions as the pulse radar; and

quickly detecting a relative speed and the distance of the target with data of one measurement by performing the FFT simultaneously with computation of a sum or a sum of squares of absolute values of a difference from an average of a preset time section, and by measuring a Doppler frequency.

14. The method for controlling a radar apparatus according to claim 10, further comprising

switching to a high gain antenna having a narrow beam width at the time of the first operation mode where the apparatus functions as the FM-CW radar and detects the target in a long range, and switching to a low gain antenna having a wide beam width at the time of the second operation mode where the apparatus functions as the pulse radar and detects the target in a short range.

15. The method controlling a radar apparatus according to claim 10, further comprising

executing a detection process having a high resolution in a horizontal direction by making scanning in the horizontal direction at the time of the first operation mode where the apparatus functions as the FM-CW radar and detects the target in a long range, and quickly detecting a target within a beam of the transmission high-frequency signal emitted from a fixed antenna without making scanning in the horizontal direction at the time of the second operation mode where the apparatus functions as the pulse radar and detects the target in a short range.