SPREAD SPECTRUM RADAR APPARATUS

• US 20090074031A1
• Filed: 09/17/2008
• Published: 03/19/2009
• Est. Priority Date: 09/19/2007
• Status: Active Grant

• Current Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: FUKUDA, Takeshi
• Granted Patent: US 7,564,400 B2
• Time in Patent Office: Days
• US Class Current: 375/130
• CPC Class Codes: G01S 13/325 using transmission of coded signals, e.g. P.S.K. signals
• CPC Class Codes: G01S 7/023 Interference mitigation, e.g. reducing or avoiding non-intentional interference with other HF-transmitters, base station transmitters for mobile communication or other radar systems, e.g. using electro-magnetic interference [EMI] reduction techniques auxiliary means for detecting or identifying radar signals or the like G01S7/021; means for anti-jamming G01S7/36
• CPC Class Codes: G01S 7/0233 Avoidance by phase multiplex
• CPC Class Codes: G01S 7/0234 Avoidance by code multiplex
• CPC Class Codes: G01S 7/352 Receivers
• CPC Class Codes: G01S 7/358 using I/Q processing
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

It is an object of the present invention to prevent the sensitivity of radar apparatus from falling. A spread spectrum radar apparatus which detects an object, includes a carrier wave oscillator which generates a carrier wave, transmission unit which transmits a spread signal which is the carrier wave spread using a first PN code, an intermediate demodulated signal generating unit which receives a reflected wave which is the spread signal reflected from the object, and despreads the reflected wave using a delayed second PN code that has a cyclically reversed logical value of the first PN code, to generate an intermediate demodulated signal, a low-pass filter through which a specific frequency component of the intermediate demodulated signal passes, and a sampling unit which samples an output signal from the low-pass filter, and the sampling unit samples the output signal in synchronization with the cycle of the reversal.

Claims

1. A spread spectrum radar apparatus which detects an object by transmitting and receiving a spread signal obtained by spectrum-spreading, said spread spectrum radar apparatus comprising:

an oscillating unit configured to generate a carrier wave;

a code reversal unit configured to output a second pseudo noise code that has a cyclically reversed logical value of a first pseudo noise code;

a transmission unit configured to transmit a spread signal which is the carrier wave that has been spread using one of the first pseudo noise code and the second pseudo noise code;

an intermediate demodulated signal generating unit configured to receive a reflected wave which is the spread signal reflected from the object after the spread signal is transmitted by said transmission unit, and to despread the reflected wave using a code which is delayed code of the other one of the first pseudo noise code and the second pseudo noise code, to generate an intermediate demodulated signal;

a filter through which a specific frequency component of the intermediate demodulated signal passes; and

a sampling unit configured to sample an output signal from said filter,

wherein said sampling unit is configured to sample the output signal in synchronization with the cycle of the reversal.

2. The spread spectrum radar apparatus according to claim 1, further comprising:

a clock generator which generates a clock signal; and

a frequency divider which generates an iteration code by dividing the frequency of the clock signal into half,

wherein said code reversal unit is configured to reverse the first pseudo noise code according to the logical value of the iteration code to output the second pseudo noise code, and

said sampling unit is configured to sample the output signal in synchronization with the clock signal.

3. The spread spectrum radar apparatus according to claim 2, further comprising

a delaying unit configured to delay the clock signal,

wherein said delaying unit is configured to delay the clock signal for a period in which processing by said filter is performed and output the delayed clock signal to said sampling unit, and

said sampling unit is configured to sample the output signal in synchronization with the delayed clock signal.

4. The spread spectrum radar apparatus according to claim 2,

wherein said filter has a characteristic that an impulse response takes a finite value when time t=0, and that the absolute value of ±

nT−

T/10<

t<

±

nT+T/10 is local minimum, where n is a natural number and where the half of the clock signal is T.

5. The spread spectrum radar apparatus according to claim 4,

wherein said filter is a Nyquist filter whose sampling frequency is a frequency twice as much as the frequency of the clock signal.

6. The spread spectrum radar apparatus according to claim 5,

wherein said filter is a raised cosine filter.

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

an analog-digital converter which converts the intermediate demodulated signal which is an analog signal into a digital signal, at a predetermined sampling frequency,

wherein said filter is an finite impulse response digital filter.

8. The spread spectrum radar apparatus according to claim 7, further comprising

a low-pass filter whose cutoff frequency is a half of the sampling frequency,

wherein said analog-digital converter converts the intermediate demodulated signal which passed through said low-pass filter into the digital signal.

9. A vehicle comprising

a spread spectrum radar apparatus which detects an object by transmitting and receiving a spread signal obtained by spectrum-spreading, the spread spectrum radar apparatus including:

an oscillating unit configured to generate a carrier wave;

a code reversal unit configured to output a second pseudo noise code that has a cyclically reversed logical value of a first pseudo noise code;

a transmission unit configured to transmit a spread signal which is the carrier wave that has been spread using one of the first pseudo noise code and the second pseudo noise code;

an intermediate demodulated signal generating unit configured to receive a reflected wave which is the spread signal reflected from the object after the spread signal is transmitted by the transmission unit, and to despread the reflected wave using a code which is delayed code of the other one of the first pseudo noise code and the second pseudo noise code, to generate an intermediate demodulated signal;

a filter through which a specific frequency component of the intermediate demodulated signal passes; and

a sampling unit configured to sample an output signal from the filter,

wherein the sampling unit is configured to sample the output signal in synchronization with the cycle of the reversal.

10. A control method for a spread spectrum radar apparatus which detects an object by transmitting and receiving a spread signal obtained by spectrum-spreading, said control method comprising:

generating a carrier wave;

outputting a second pseudo noise code that has a cyclically reversed logical value of a first pseudo noise code;

transmitting a spread signal which is the carrier wave that has been spread using one of the first pseudo noise code and the second pseudo noise code;

receiving a reflected wave which is the spread signal reflected from the object after the spread signal is transmitted in said transmitting;

generating an intermediate demodulated signal by despreading the reflected wave using a code which is delayed code of the other one of the first pseudo noise code and the second pseudo noise code; and

sampling an output signal including a specific frequency component of the intermediate demodulated signal passed through,

wherein in said sampling, the output signal is sampled in synchronization with the cycle of the reversal.