JP2000009829A - Radar apparatus using spread spectrum system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a radar apparatus in which a leakage signal affecting the detection of a target object is suppressed, in which a target object at a short distance or a target object with a small receiving electric power can be detected, and by which a transmitting antenna and a receiving antenna are integrated so as to be miniaturized without affecting the detection of a target object. SOLUTION: The radar apparatus is provided with a pseudo noise(PN) signal generator 2 for transmission, which generates a PN signal for transmission, a modulator 3, which modulates carrier waves by the PN signal for transmission, a transmitting antenna 9, by which the PN signal for transmission, modulated by the modulator 3 is transmitted to an object, a receiving antenna 10, which receives a received signal as a signal transmitted by the transmitting antenna 9 and reflected by the object so as to be returned, a demodulator 17, which demodulates the receives signal received by the receiving antenna 10, and signal cutoff means 7, 6, which cut off or attenuate a signal to the direction of the demodulator 17 from the modulator 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radar apparatus using a spread spectrum method.

[0002]

2. Description of the Related Art FIG.
FIG. 1 is a configuration diagram showing a radar apparatus using a conventional spread spectrum method disclosed in Japanese Patent Application Laid-Open Publication No. H10-115,004. In the figure, 101 is a transmitting antenna, 102 is a receiving antenna, 103 is a transmitting PN.
A signal generator, 104, 105, 106, and 107 are mixers, 108 is a reception PN signal generator, 109 is a correlation operation unit, 110 is a reception PN delay circuit, 111 is an intermediate frequency oscillator, 112 is a transmission oscillator, and 113 is a transmission oscillator. A sign setting circuit, 114 is a Doppler counter, 115 is a phase modulation circuit, and 116 is a phase shift circuit.

Next, the operation will be described. The fundamental oscillation signal output from the transmission oscillator 112 is modulated by the transmission PN signal generated by the transmission PN signal generator 103, and the transmission antenna 101 transmits a radio wave composed of a predetermined unit. Reference numeral 102 receives the reflected wave of the transmitted radio wave. Then, in the correlation operation unit 109,
A correlation operation is performed between the reception signals from the mixers 104 and 105 and the reception PN signal from the reception PN signal generator 108,
The distance from the target object to be reflected is measured from the delay time of the received radio wave.

When performing a correlation operation between the reception signals from the mixers 104 and 105 and the reception PN signal from the reception PN signal generator 108, the correlation operation unit 109 first receives the reception PN signal.
A reception PN signal is generated by shifting the transmission PN signal from the delay circuit 110 by the first shift amount in the coarse unit by the first shift amount, and the reception PN signal and the mixers 104 and 105 are generated.
A correlation operation is performed on the received signal from the target object a number of times corresponding to the required detection distance of the target object.

Next, with respect to three shifts including one shift before and after the number of shifts in which the correlation is obtained, a reception PN shifted by a second shift amount reset to a fine unit corresponding to the required accuracy is set. A signal is generated, and a correlation operation is performed between the received PN signal and the received signals from the mixers 104 and 105 by the number of times corresponding to the required detection distance of the target object. Thus, the phase of the transmission PN signal and the mixers 104, 10
The distance to the target object is calculated by calculating the phase difference (delay time) from the phase of the received signal from the target signal No. 5.

[0006]

Since the conventional radar apparatus using the spread spectrum system is configured as described above, the signal modulated by the phase modulation circuit 115 leaks in the circuit, so that the transmission oscillator When the signal is transmitted to the mixers 104 and 105 via the path for transmitting the signal of 112,
The signal is combined with a signal received by the receiving antenna 102 and input to the correlation calculator 109. Therefore, there is a problem that the received signal is overlapped with a received signal due to reflection from a target object existing in a short distance, and the target object cannot be detected.

[0007] In the case of using the longest code sequence (M-sequence) to PN signal, a code length of the PN signal N, When the _{f P} of the PN signal frequency (chip rate), the correlation characteristics of the PN signal 2 Therefore, the correlation value (1 / N) when the phase is separated by 1 / f _P or more affects the correlation value of the received signal due to the reflection from the target object, and the detection becomes difficult. is there.

In order to reduce the size of the device, the transmitting and receiving antennas 101 and 102 are used as a common transmitting and receiving antenna 117 as shown in FIG. The transmission signal directly leaks into the reception signal due to the reverse loss (isolation) of the above, and is combined with the reception signal due to the reflection of the target object, thus causing the same problem as described above.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and detects a short-distance target object or a target object with small received power by suppressing a leak signal which affects target object detection. It is another object of the present invention to provide a radar apparatus using a spread spectrum system which can integrate a transmitting antenna and a receiving antenna for miniaturization without affecting target object detection.

[0010]

According to a first aspect of the present invention, there is provided a radar apparatus using a spread spectrum system, wherein a transmitting PN signal generating means for generating a transmitting PN signal and a carrier wave are modulated by the transmitting PN signal. Modulating means, transmitting means for transmitting the transmission signal modulated by the modulating means to the object, and receiving means for receiving a signal transmitted by the transmitting means is reflected by the object and returns a received signal, The demodulator includes demodulating means for demodulating a received signal received by the receiving means, and signal blocking means for blocking or attenuating a leak signal leaking from the modulating means toward the demodulating means.

In the radar apparatus using the spread spectrum system according to the second aspect of the present invention, the carrier waves input to the transmission P modulation means and the demodulation means are generated by the same generation means,
Distributing means for distributing and inputting the carrier wave to the modulating means and demodulating means is provided, and the signal blocking means passes a signal from the distributing means toward the modulating means and blocks a leak signal leaking from the modulating means toward the distributing means. Alternatively, it is an irreversible means for attenuating.

According to a third aspect of the present invention, there is provided a radar apparatus using a spread spectrum system, wherein at least one of a distribution means and a modulation means or a distribution means and a demodulation means is provided with an attenuation means for attenuating a signal. ing.

According to a fourth aspect of the present invention, there is provided a radar apparatus using a spread spectrum system, a transmitting PN signal generating means for generating a transmitting PN signal, a modulating means for modulating a carrier with the transmitting PN signal, and a modulating means. Transmitting and receiving means for transmitting a transmission signal modulated in the object to the target, receiving a reception signal reflected back from the object, a demodulation means for demodulating the reception signal received by the transmission and reception means, Signal transmission means for transmitting the transmission signal to the transmission / reception means and transmitting the reception signal from the transmission / reception means to the demodulation means.

According to a fifth aspect of the present invention, there is provided a radar apparatus using a spread spectrum system, wherein the demodulating means includes signal removing means for removing or attenuating signals other than the received signal received by the receiving means.

According to a sixth aspect of the present invention, there is provided a radar apparatus using a spread spectrum system, wherein the demodulation means frequency-converts a reception signal received by the reception means or the transmission / reception means into an intermediate frequency band; Signal removing PN signal generating means for generating a signal removing PN signal in accordance with a signal other than the received signal received by the control unit, a signal whose frequency has been converted by the frequency converting means, and a signal removing PN signal.
An unnecessary signal multiplying means for multiplying the signal by a signal and a frequency removing means for removing or attenuating the intermediate frequency from the signal multiplied by the unnecessary signal multiplying means are provided.

According to a seventh aspect of the present invention, in the radar apparatus using the spread spectrum system, the signal removing means includes a recovery PN corresponding to a signal other than the received signal received by the receiving means.
There is provided a received signal restoring means for multiplying the signal by the signal from the frequency removing means.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 FIG. 1 is a block diagram showing a radar apparatus using a spread spectrum system according to Embodiment 1 of the present invention. In the figure, 1 is a clock generator for determining a chip rate of a PN signal, 2 is a PN signal generator for generating a PN signal (M sequence) according to the clock, 3 is an intermediate frequency (IF) modulator, 4 is An up-converter for frequency-converting the signal modulated by the intermediate frequency (IF) modulator 3 into a carrier frequency band, 5 is a carrier oscillator, 6 is a distributor, 7 is an attenuator, 8 is an isolator, 9 is a transmitting antenna, 10 Is a receiving antenna, 11 is a downconverter for converting a received signal into an intermediate frequency band, 1
Reference numerals 2 and 15 denote mixers, 13 denotes a delay circuit for removing a PN signal according to a signal other than a received signal, 14 denotes a band rejection filter that attenuates an intermediate frequency, 16 denotes an IF oscillator that generates an intermediate frequency, and 17 denotes an IF. Reference numeral 18 denotes a receiving delay circuit for delaying a PN signal to measure a delay time of a received signal, 19 denotes a correlation calculator, and 20 denotes a distance calculator.

Next, the operation of the radar apparatus shown in FIG. 1 will be described. PN signal generator 2 operates based on a clock generator 1 for generating a clock of frequency f _P clock, and outputs the PN signal of the chip rate f _P. Assuming that the PN signal generated by the PN signal generator 2 is an M-sequence and the code length is N chips (here, chip means the minimum unit of the PN signal), the correlation characteristic is shown in FIG. Become like

The PN signal generated by the PN signal generator 2 is phase-modulated by the modulator 3 to a center frequency f _IF based on the intermediate frequency f _IF generated by the IF oscillator 16. This phase-modulated signal is expressed by equation (1), and the spectrum waveform is as shown in FIG.

PN (t) cos (2πf _IF t) (1) where t is time, and PN (t) is a PN signal generated by the PN signal generator 2 and its value is +1 or It is -1.

In the carrier oscillator 5, the carrier frequency f _RF
And an intermediate frequency f _IF , a frequency (f _RF −f _IF ) is generated, and the generated (f _RF −f _IF ) signal is distributed by the distributor 6, and the attenuator 7 and the isolator 8
Is input to the up-converter 4 via.

In the up-converter 4, the signal of the formula (1) phase-modulated by the modulator 3 is frequency-converted by the signal of the frequency (f _RF -f _IF ) inputted from the isolator 8, and the signal of the formula (2) is transmitted. A credit signal is generated.

PN (t) cos (2πf _RF t + φ) (2) where φ is the phase difference between the signal from the IF oscillator 16 and the signal input from the isolator 8.

The transmission signal of formula (2) frequency-converted by the up-converter 4 is transmitted by the transmission antenna 9 toward the target object, and the signal reflected by the target object and returned is received by the reception antenna 10. And input to the down converter 11.

In the down converter 11, the receiving antenna 1
The signal received at 0 is frequency-converted by the signal of the frequency (f _RF -f _IF ) input from the distributor 6, and is frequency-converted to an intermediate frequency band.

When the up-converter 4 converts the frequency of the signal of the expression (1), a transmission signal is actually output in the direction of the isolator 8 due to leakage in the circuit. The signals sequentially pass and are input to the down converter 11.

However, in the radar device according to the present embodiment, the signal due to the leakage is transmitted to the isolator 8
And the power input to the down-converter 11 is suppressed by being attenuated by the reverse loss (isolation), the loss caused by the attenuator 7, and the isolation between the output terminals of the distributor 6.

For the above reason, the down converter 11
As shown in FIG. 5, the frequency-converted signal is
A signal obtained by frequency-converting the received signal from the target object and a signal based on the leak signal are combined. However, in FIG. 5, the magnitude relation of the power of each signal changes depending on the reception power of the reception signal and the degree of suppression of the leakage signal. For the sake of simplicity of description, the spectrum waveform is represented by an envelope, and only the bandwidth of ± f _P centered on f _IF is described.
Here, the leak signal is expressed by equation (3), and the frequency-converted signal of the received signal is expressed by equation (4).

[0029] _{PN (t-T L) cos} (2πf IF (t-T L)) ··· (3) PN (t-T d) cos (2πf IF (t-T d) + φ) ··· ( 4)

Here, _TL is a delay time until a leakage signal is output from the modulator 3 by the down converter 11, and T _d is a delay time.
Is the amount of delay that occurs before the transmission signal is transmitted by the transmission antenna 9, the signal returned by reflection from the target object is received by the reception antenna 10, and the frequency is converted by the down converter 11. In the delay circuit 13 for elimination, P
The delay amount is set so that the PN signal having the same phase as the N signal is output, and the PN signal delayed by a predetermined amount is input to the mixers 12 and 15. This removal PN signal is (5)
It is expressed by an equation.

PN (t−T _L ) (5)

In the mixer 12, the removing delay circuit 13
Is multiplied by the combined signal of FIG. 5 output from the down converter 11. Therefore, the multiplied signal output from the mixer 12 is given by equation (6).

[0033] PN _{(t-T L) [PN (t-T L) cos} (2πf IF (t-T L)) + PN (t-T d) cos (2πf IF (t-T d) + φ) ] = _{cos (2πf IF (t-T} L)) + PN (t-T L) PN (t-T d) cos (2πf IF (t-T d) + φ) ··· (6)

In the equation (6), PN (t− _TL ) ² =
1 is used. The first term of the equation (6) is a component due to a leak signal, and the second term is obtained by multiplying a received signal by a PN signal for removal. FIG. 6 shows the spectrum waveform of the multiplied signal (that is, equation (6)) by the mixer 12.

From the signal multiplied by the mixer 12, only a signal having a frequency of f _IF is removed by the band rejection filter 14. Therefore, the signal output from the band rejection filter 14 is expressed by equation (7), and the spectrum waveform is as shown in FIG.

PN (t−T _L ) PN (t−T _d ) cos (2πf _IF (t−T _d ) + φ) (7)

The band rejection filter 1 is controlled by the mixer 15.
4 is multiplied by the removal PN signal represented by the expression (5) by the mixer 15 by the mixer 15;
The signal of equation (8) is output from the mixer 15.

PN (t−T _L ) × PN (t−T _L ) PN (t−T _d ) cos (2πf _IF (t−T _d ) + φ) = PN (t−T _d ) cos (2πf _IF (T−T _d ) + φ) (8)

FIG. 8 shows the spectrum waveform of equation (8).
Equation (8) indicates that the transmission signal phase-modulated to the intermediate frequency band by the modulator 3 has a time T _d required for a round trip to the target object.
Is a signal reconstructed as a signal to which is added.

The signal restored by the mixer 15 is a demodulator 1
The signal is demodulated by the IF oscillator 16 using the signal of the frequency f _IF generated by the IF oscillator 16, and is input to the correlation calculator 19 as PN (t−T _d ).

In the reception delay circuit 18, the PN signal generated by the PN signal generator 2 is changed while the amount of delay is sequentially changed.
The signal is delayed and input to the correlation calculator 19. The PN signal delayed by the reception delay circuit 18 and the demodulator 1
The correlation operation with the received signal demodulated in step 7 is performed by a correlation calculator 19.
And the calculation result is input to the distance calculator 20.

When the correlation value exceeds a predetermined value, the delay amount (ie, Td) set by the reception delay circuit 18 is input to the distance calculator 20.

The correlation values calculated by the correlation calculator 19 and input to the distance calculator 20 are as shown in FIG. When the correlation value is equal to or more than a predetermined amount, the delay amount set by the reception delay circuit 18 is Tdi (where i is the number of the target object). Further, if the distance to the target object i is Ri, the delay time Tdi is expressed by equation (9). Here, c is the speed of light.

Tdi = 2Ri / c (9)

Therefore, the distance Ri to the target object i
Can be calculated by equation (10).

Ri = Tdi · c / 2 (10)

In the present embodiment, the isolator 8 is provided to suppress a leakage signal in the circuit of the up-converter 4. However, an amplifier having a large reverse loss may be used. When an amplifier is used, the direction of amplification is from the attenuator 7 to the up-converter 4. In order to further suppress the leakage signal, an attenuator may be provided between the distributor 6 and the down converter 11.

The intermediate frequency is set to 0 (that is, DC), the modulator 3, the IF oscillator 16, and the demodulator 17 are removed, and the PN signal generated by the PN signal generator 2 is input to the up converter 4, and the mixer 15 May be input to the correlation calculator 19. In this case, it goes without saying that the stop band of the band stop filter 14 is a direct current.

In this embodiment, the leakage signal in the circuit of the up converter 4 is suppressed by utilizing the isolation of the isolator 8, the attenuation by the attenuator 7, and the isolation between the output terminals of the distributor 6. So
The detection signal can be detected without the reception signal due to the reflection from the target object existing in a short distance overlapping the leak signal.

Further, since the power of the leak signal is suppressed, the influence of the (1 / N) correlation value of the leak signal on the correlation value of the received signal due to the reflection of the target object can be reduced, and the detection becomes easy. .

Embodiment 2 FIG. 10 is a block diagram showing a radar device according to Embodiment 2 of the present invention. In the figure, 21 is a circulator (signal transmission means), 22 is a transmitting / receiving antenna, and 23 and 24 are unnecessary signal removing circuits. The unnecessary signal removing circuit 23 and the unnecessary signal removing circuit 24
Is as shown in FIG. The other parts are the same as those described in the first embodiment, and a description thereof will be omitted.

Next, the operation of the radar apparatus shown in FIG. 10 will be described. The transmission signal frequency-converted by the up-converter 4 is transmitted to the transmission / reception antenna 22 by the circulator 21, and the signal is transmitted toward the target object. The signal transmitted by the transmitting / receiving antenna 22 is reflected by the target object and received by the transmitting / receiving antenna 22. The signal received by the transmission / reception antenna 22 is transmitted to the down converter 11 by the circulator 21.

When the transmission signal frequency-converted by the up-converter 4 is transmitted to the transmission / reception antenna 22 by the circulator 21, the transmission signal is actually transmitted directly to the down-converter due to leakage (isolation) of the circulator 21. Will be done.

Further, there is a reflection gain due to the mismatch of the connection portion of the transmission / reception antenna 22, and a reflection signal due to the reflection gain is input to the circulator 21 and transmitted to the down converter 11.

For the above reason, the down converter 11
The signal input to the unnecessary signal elimination circuit 23 includes a signal obtained by frequency-converting a received signal reflected from a target object, a signal obtained by frequency-converting a leak signal resulting from leakage of the circulator 21, The signal obtained by frequency conversion of the reflected signal reflected by the mismatch is synthesized.

In the removal delay circuit 13 in the unnecessary signal removal circuit 23, a delay amount according to the leakage signal due to the leakage of the circulator 21 is set, and the leakage signal due to the leakage of the circulator 21 is suppressed by the same operation as in the first embodiment. Is done. Further, in the removing delay circuit 13 in the unnecessary signal removing circuit 24, a delay amount according to the reflected signal reflected by the mismatch of the transmitting / receiving antenna 22 is set. The reflection signal reflected by the matching is suppressed.

Other operations are the same as those in the first embodiment, and a description thereof will be omitted.

In the present embodiment, the leakage signal in the circuit of the up-converter 4 is suppressed by utilizing the isolation of the isolator 8, the attenuation by the attenuator 7, and the isolation between the output terminals of the distributor 6. However, in addition to these, an unnecessary signal removing circuit may be added to further suppress a leak signal in the circuit of the upconverter 4.

In this embodiment, the circulator 21 is used as a common transmitting / receiving antenna for the transmitting and receiving antennas, so that the radar device can be downsized. Further, by using a plurality of unnecessary signal elimination circuits of the unnecessary signal elimination circuit 23 and the unnecessary signal elimination circuit 24, unnecessary signals due to different factors can be eliminated, and reception by reflection from a target object existing in a short distance is performed. The signal can be detected without overlapping the unnecessary signal. Further, since the power of the unnecessary signal is suppressed, the influence of the (1 / N) correlation value of the unnecessary signal on the correlation value of the received signal due to the reflection of the target object can be reduced, and the detection becomes easy.

[0060]

According to the first aspect of the present invention, a transmitting PN signal generating means for generating a transmitting PN signal, a modulating means for modulating a carrier with the transmitting PN signal, and a transmitting PN signal modulated by the modulating means are provided. Transmitting means for transmitting a signal to an object, receiving means for receiving a signal transmitted from the transmitting means reflected by the object, and demodulating the received signal received by the receiving means Means, and signal blocking means for blocking or attenuating a leak signal leaking from the modulation means in the direction of the demodulation means, so that a reception signal due to reflection from a target object located in a short distance leaks from the modulation means to the demodulation means. It is possible to detect the signal without overlapping with the leak signal. Further, since the power of the leak signal is cut off or attenuated, the influence of the (1 / N) correlation value of the leak signal on the correlation value of the received signal due to the reflection of the target object can be reduced, and the detection is facilitated. effective.

According to the second aspect of the present invention, the carrier wave inputted to the modulating means and the demodulating means is generated by the same generating means, and the carrier wave is provided to the modulating means and the demodulating means. It becomes possible to use only one carrier generation means, and the cost can be reduced. The signal cutoff means passes a signal from the distribution means to the modulation means,
Since it is an irreversible means for blocking or attenuating a signal from the modulation means to the distribution means, there is an effect that a leakage signal from the modulation means connected by the distribution means to the demodulation means can be suppressed.

According to the third aspect of the present invention, at least one of the distribution means and the modulation means or the distribution means and the demodulation means is provided with the attenuation means for attenuating the signal. There is an effect that the effect of suppressing the leakage signal to the means is increased.

According to the fourth aspect of the present invention, a transmitting PN signal generating means for generating a transmitting PN signal, a modulating means for modulating a carrier with the transmitting PN signal, and a transmitting signal modulated by the modulating means. A transmitting / receiving means for transmitting to an object and receiving a received signal reflected back from the object, and a received signal received by the transmitting / receiving means being demodulated and leaked or reflected by a signal other than the received signal received by the receiving means Demodulating means provided with signal removing means for removing or attenuating unnecessary signals, and transmitting a transmission signal from the modulating means to the transmitting / receiving means,
Signal transmission means for transmitting a reception signal from the transmission / reception means to the demodulation means, so that miniaturization is possible, and unnecessary signals due to leakage and reflection can be removed;
There is an effect that detection of a target object is facilitated.

According to the fifth aspect of the present invention, since the demodulating means includes the signal removing means for removing or attenuating signals other than the received signal received by the receiving means, unnecessary signals due to leakage or reflection are removed. This makes it easier to detect a target object.

According to the sixth aspect of the present invention, the demodulating means includes a frequency converting means for converting the frequency of a received signal received by the receiving means or the transmitting / receiving means into an intermediate frequency band, and a signal other than the received signal received by the receiving means. Signal removing PN signal generating means for generating a signal removing PN signal corresponding to an unnecessary signal due to leakage or reflection, and unnecessary signal multiplying means for multiplying the signal converted PN signal by the frequency converting means with the signal removing PN signal. And a frequency removing means for removing or attenuating the intermediate frequency from the signal multiplied by the unnecessary signal multiplying means, eliminating the need for amplitude adjustment and intermediate frequency phase adjustment to remove the unnecessary signal. This has the effect of reducing noise.

According to the seventh aspect of the present invention, the signal removing means comprises a receiving signal restoring means for multiplying a signal from the frequency removing means by a restoring PN signal corresponding to a signal other than the received signal received by the receiving means. Since it is provided, there is an effect that the correlation calculation becomes easy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a radar apparatus using a spread spectrum system according to Embodiment 1 of the present invention.

FIG. 2 is a diagram showing an autocorrelation characteristic of a PN signal (M sequence).

FIG. 3 is a diagram showing that a transmitting and receiving antenna is connected by a circulator.

FIG. 4 is a diagram showing a spectrum waveform obtained by modulating an intermediate frequency with a PN signal.

FIG. 5 is a diagram showing a spectrum waveform in which a leak signal and a received signal are combined.

FIG. 6 is a diagram illustrating a spectrum waveform obtained by multiplying a combined signal by a removal PN signal.

FIG. 7 is a diagram showing a spectrum waveform from which a leak signal component has been removed by a band rejection filter.

FIG. 8 is a diagram showing a spectrum waveform obtained by restoring a received signal with a restoration PN signal.

FIG. 9 is a diagram showing a correlation value calculated by a correlation calculator.

FIG. 10 is a block diagram showing a radar apparatus using a spread spectrum system according to Embodiment 2 of the present invention.

FIG. 11 is a block diagram illustrating a structure of an unnecessary signal removing circuit.

FIG. 12 is a configuration diagram showing a radar apparatus using a conventional spread spectrum method.

[Explanation of symbols]

1 clock generator, 2 PN signal generator, 3 modulator, 4 up-converter, 5 carrier oscillator,
6 distributor, 7 attenuator, 8 isolator,
9 transmitting antenna, 10 receiving antenna, 11 down converter, 12 mixer, 13 delay circuit for removal, 14 band rejection filter, 15 mixer,
16 IF oscillator, 17 demodulator, 18 reception delay circuit, 19 correlation calculator, 20 distance calculator, 2
1 circulator, 22 transmitting / receiving antenna, 23,
24 Unwanted signal removal circuit.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tadamasa Fukae 2-3-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) 5J070 AB10 AC02 AD02 AH01 AH04 AH33 AH34 AH39 AJ04 AJ10 AK02 AK06

Claims (7)

[Claims] 1. A transmission PN signal generation unit for generating a transmission pseudo noise (PN) signal, a modulation unit for modulating a carrier with the transmission PN signal, and a transmission signal modulated by the modulation unit. Transmitting means for transmitting to the object; receiving means for receiving a received signal in which the signal transmitted by the transmitting means is reflected by the object and returning; demodulating means for demodulating the received signal received by the receiving means And a signal blocking means for blocking or attenuating a leakage signal leaking from the modulation means toward the demodulation means. 2. A carrier input to the modulator and the demodulator is generated by the same generator, and a distributor for distributing and inputting the carrier to the modulator and the demodulator is provided. 2. A radar apparatus using a spread spectrum system according to claim 1, wherein said irreversible means is a means for passing a signal in the direction of the modulating means and blocking or attenuating a leak signal leaking from the modulating means toward the distribution means. . 3. A carrier wave input to the modulation unit and the demodulation unit is generated by the same generation unit, and the distribution unit distributes the carrier wave to the modulation unit and the demodulation unit and inputs the carrier wave. 3. The radar apparatus according to claim 1, further comprising an attenuator for attenuating a signal in at least one of the distributor and the demodulator. 4. A transmitting PN signal generating means for generating a transmitting PN signal, a modulating means for modulating a carrier with the transmitting PN signal, and transmitting the transmitting signal modulated by the modulating means to an object. Transmitting / receiving means for receiving a received signal reflected back from the object, demodulating means for demodulating a received signal received by the transmitting / receiving means, and transmitting a transmission signal from the modulating means to the transmitting / receiving means And a signal transmission means for transmitting a signal received from the transmission / reception means to a demodulation means. 5. The spread spectrum apparatus according to claim 1, wherein the demodulation means includes signal removal means for removing or attenuating a signal other than the received signal received by the reception means. Radar system using the system. 6. A demodulation means for frequency-converting a reception signal received by the reception means or the transmission / reception means to an intermediate frequency band, and a signal removing means for removing a signal other than the reception signal received by the reception means. Signal removing PN signal generating means for generating a PN signal; unnecessary signal multiplying means for multiplying the signal converted PN signal by the frequency-converted signal by the frequency converting means; 6. The radar apparatus according to claim 5, further comprising frequency removing means for removing or attenuating an intermediate frequency from the signal obtained. 7. The demodulating means includes a received signal restoring means for multiplying a signal from the frequency removing means by a restoring PN signal according to a signal other than the received signal received by the receiving means. Item 7. A radar device using the spread spectrum method according to Item 6.