JPH0926475A - Fm-cw radar - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve NF(noise figure) and to enhance distance performance in the receiving system of an FM-CW radar mounted on a moving body such as automobile or the like. SOLUTION: The FM-CW radar accommodates an oscillator 1, a directional connector 2, a double multiplier 9, first and second antennas 3a, 3b and an anti-parallel diode pair in which two diodes having reversed poles are connected in parallel and it is equipped with an even-harmonic wave mixer 10 that outputs signals having frequencies of sum and difference of two times of frequency of a local signal and frequency of a signal wave, an A/D converter 7 and a signal processing section 8 that obtains distance and relative velocity with respect to a target. A leakage noise of the local signal involved in a video signal is attenuated and noise figure of the receiving system is reduced so that a distance performance of the FM-CW radar is enhanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an FM-CW radar which is mounted on a moving body such as an automobile and detects electric people, vehicles and obstacles existing around the vehicle by using radio waves.

[0002]

2. Description of the Related Art FIG. 11 is a configuration block diagram showing a conventional FM-CW radar. In the figure, 1 is an oscillator, 2 is a directional coupler, 3a and 3b are first and second antennas, 4 is a fundamental mixer, 5 is a filter, 6 is an amplifier, 7
Is an A / D converter, and 8 is a signal processing unit.

Next, the operation will be described. In FIG. 11, the oscillator 1 outputs a high frequency modulation signal (of the frequencies F _RF ± ΔF, F _RF is a high frequency component and ± ΔF is a modulation frequency component). The directional coupler 2 outputs a part of the high frequency modulation signal as a local oscillation signal and the rest as a transmission signal to the first antenna 3a. The first antenna 3a outputs a transmission signal toward a target (not shown in the figure), and the second antenna 3b receives a reflection signal from the target and outputs a reception signal. The fundamental wave mixer 4 receives the reception signal and the local oscillation signal, and outputs a video signal having a sum and difference frequencies of the two frequencies. The filter 5 suppresses the harmonic component of the video signal output from the fundamental mixer 4. The amplifier 6 amplifies the video signal. The A / D converter 7 converts the amplified video signal into a digital signal. Signal processing unit 8
Obtains information such as the distance to the target and the relative speed from the digitized signal.

Here, the operation will be supplementarily described. FIG.
Shows a principle diagram of the operation of a conventional FM-CW radar. FIG.
The curve a in (a) shows a transmission signal and a local oscillation signal (frequency F _RF ±
Of ΔF, F _RF is a high frequency component and ± ΔF is a modulation frequency component), and a curve b is a received signal. In the case of FM-CW radar, the target is irradiated with the frequency-modulated transmission signal,
The received signal has a delay time of twice the distance to the target, the received signal is frequency-converted (homodyne detection) by the local signal, and corresponds to the target distance / speed as shown by the curve c in FIG. 13 (b). The video signal has the beat frequency component F _b . Next, the signal processing unit 8 calculates the distance to the target and the relative speed from the frequency F _b . In order to simplify the description, the case where the own speed and the target speed are the same, that is, the case where the relative speed = 0 is shown. FIG. 12 shows the fundamental wave mixer 4 and the opposite polarity 2
The noise voltage contained in the video signal output from the even harmonic mixer with a built-in anti-parallel diode pair in which two diodes are connected in parallel is shown. In FIG. 12, the curve a
Is a noise voltage included in the video signal output from the fundamental wave mixer 4. As shown in FIG. 12, since the noise voltage included in the video signal output from the fundamental mixer 4 is very large, the noise figure (hereinafter referred to as NF) of the receiving system is deteriorated, and the range performance of the FM-CW radar is reduced. Will lower it.

[0005]

SUMMARY OF THE INVENTION The above conventional F
In the M-CW radar, since the noise voltage included in the video signal output from the fundamental mixer is large, the NF of the receiving system is deteriorated, and the distance performance of the FM-CW radar is deteriorated.

The present invention has been made to solve the above problems, and constitutes an FM-CW radar using an even harmonic mixer having an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel. By doing so, it is intended to improve the NF of the receiving system and improve the range performance of the FM-CW radar.

[0007]

In the FM-CW radar according to the first embodiment of the present invention, an oscillator, a directional coupler, a doubler, first and second antennas, and two opposite polarities. An even parallel mixer that has a built-in anti-parallel diode pair in which two diodes are connected in parallel, and that outputs a signal of the sum and difference frequency of the double frequency of the local oscillation signal and the frequency of the signal wave, an A / D converter, And a signal processing unit for obtaining the distance to the target and the relative speed.

In the FM-CW radar according to the second embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a second oscillator that outputs a frequency modulation signal, a fundamental wave mixer, and a directivity Built-in combiner, doubler, first and second antennas, and anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and the sum of the double frequency of the local oscillator signal and the frequency of the signal wave. And an even harmonic mixer that outputs a signal of a difference frequency, an A / D converter, and a signal processing unit that obtains a distance to a target and a relative speed.

In the FM-CW radar according to the third embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a second oscillator that outputs a frequency modulation signal, and two diodes of opposite polarities are provided. A first even harmonic mixer that incorporates an anti-parallel diode pair connected in parallel and that outputs a signal of the sum and difference frequency of the local oscillation signal and the frequency of the signal wave, a directional coupler, and 2 The multiplier, the first and second antennas, the second even harmonic mixer having the same configuration and function as the first even harmonic mixer, the A / D converter, and the distance and relative to the target. And a signal processing unit for obtaining speed.

In the FM-CW radar according to the fourth embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a first directional coupler, and a second oscillator that outputs a frequency modulation signal. , A second directional coupler, and an anti-parallel diode pair in which two diodes of opposite polarity are connected in parallel are built-in, and the signal of the frequency of the double frequency of the local oscillation signal and the frequency of the signal wave and the difference frequency is generated. A first even harmonic mixer for outputting, a first and a second antenna, a second even harmonic mixer having the same configuration and function as the first even harmonic mixer, a fundamental wave mixer, and A The / D converter and the signal processing unit for obtaining the distance to the target and the relative speed are provided.

In the FM-CW radar according to the fifth embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a first directional coupler, and a second oscillator that outputs a frequency modulation signal. , A second directional coupler, and an anti-parallel diode pair in which two diodes of opposite polarity are connected in parallel are built-in, and the signal of the frequency of the double frequency of the local oscillation signal and the frequency of the signal wave and the difference frequency is generated. A first even harmonic mixer for output, first and second antennas, a fundamental mixer,
The second even harmonic mixer having the same configuration and function as the first even harmonic mixer, the A / D converter, and the signal processing unit for obtaining the distance to the target and the relative speed are provided.

In the FM-CW radar according to the sixth embodiment of the present invention, a modulation frequency generator that outputs a signal having a first modulation frequency component and a high frequency modulation signal that has first and second modulation frequency components are output. Built-in oscillator, directional coupler, doubler, first and second antennas, and anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, A first even harmonic mixer that outputs signals of the sum and difference frequencies of the signal waves, a filter whose center frequency is N times the first modulation frequency component, an N multiplier, and a first even number. The second even harmonic mixer having the same configuration and function as the harmonic mixer, the A / D converter, and the signal processing unit for obtaining the distance and the relative speed to the target were provided.

In the FM-CW radar according to the seventh embodiment of the present invention, a modulation frequency generator for outputting a signal having a first modulation frequency component and a high frequency modulation signal having first and second modulation frequency components are output. Built-in oscillator, directional coupler, doubler, circulator, antenna, and anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel. A first even harmonic mixer that outputs signals of the sum and difference frequencies, a filter whose center frequency is N times the first modulation frequency component, an N multiplier, and a first even harmonic mixer The second even harmonic mixer having the same configuration and function as the above, the A / D converter, and the signal processing unit for obtaining the distance to the target and the relative speed are provided.

In the FM-CW radar according to the eighth embodiment of the present invention, an oscillator, a directional coupler, a doubler, first and second antennas, a distributor, a 90 ° hybrid, and an inverse. First and second even harmonic mixers, each having a built-in anti-parallel diode pair in which two diodes having polarities are connected in parallel, and which output a signal having a sum and a difference between the frequency of a local oscillation signal and the frequency of a signal wave And the first and second A
The / D converter and the signal processing unit for obtaining the distance to the target and the relative speed are provided.

[0015]

According to the first embodiment of the present invention, the oscillator, the directional coupler, the doubler, the first and second antennas,
An anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel is built-in, and an even harmonic mixer that outputs a signal of the sum and difference frequency of the frequency of the local oscillation signal and the frequency of the signal wave, and A / D By including the converter and the signal processing unit that obtains the distance and the relative speed to the target, it is possible to reduce the leak noise of the local oscillation signal included in the video signal and to reduce the noise figure of the receiving system. FM-CW because it can
The distance performance of the radar can be improved.

According to the second embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a second oscillator that outputs a frequency modulation signal, a fundamental wave mixer, a directional coupler, Built-in anti-parallel diode pair in which a doubler, first and second antennas, and two diodes of opposite polarities are connected in parallel, and the sum and difference frequencies of the double frequency of the local oscillator signal and the frequency of the signal wave. Since the even harmonic mixer that outputs the signal of A, the A / D converter, and the signal processing unit that obtains the distance and the relative speed to the target are provided, the leak noise of the local oscillation signal included in the video signal can be reduced. Since it is possible to reduce the noise figure of the receiving system, it is possible to improve the range performance of the FM-CW radar.

According to the third embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a second oscillator that outputs a frequency modulation signal, and an anti-parallel diode having two diodes of opposite polarities are connected in parallel. Built-in parallel diode pair,
A first even harmonic mixer that outputs a signal having a sum and difference frequency of a frequency of a local oscillation signal and a frequency of a signal wave, a directional coupler, a doubler, and first and second antennas And a second even harmonic mixer having the same configuration and function as the first even harmonic mixer, an A / D converter, and a signal processing unit for obtaining a distance and relative speed to a target. Reduces the leak noise of the local signal included in the video signal,
Since the noise figure of the receiving system can be reduced, the FM
-The distance performance of the CW radar can be improved.

According to the fourth embodiment of the present invention, a first oscillator that outputs a signal having a constant frequency, a first directional coupler, a second oscillator that outputs a frequency modulation signal, and a second oscillator The directional coupler and the anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and the signal of the sum of the frequency of the local oscillation signal and the frequency of the signal wave and the frequency of the difference is output. Even harmonic mixer, first and second antennas, second even harmonic mixer having the same configuration and function as the first even harmonic mixer, fundamental mixer, and A / D converter And a signal processing unit for obtaining the distance to the target and the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the intermediate frequency signal and to reduce the noise figure of the receiving system. Therefore, the distance performance of the FM-CW radar can be improved. .

According to the fifth embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a first directional coupler, a second oscillator that outputs a frequency modulation signal, and a second oscillator The directional coupler and the anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and the signal of the sum of the frequency of the local oscillation signal and the frequency of the signal wave and the frequency of the difference is output. Even harmonic mixer, first and second antennas, fundamental wave mixer, second even harmonic mixer having the same configuration and function as the first even harmonic mixer, and A / D converter And the signal processing unit for obtaining the distance to the target and the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the video signal and to reduce the noise figure of the receiving system. Can improve range performance of FM-CW radar

According to the sixth embodiment of the present invention, a modulation frequency generator for outputting a signal of a first modulation frequency component, an oscillator for outputting a high frequency modulation signal having first and second modulation frequency components, Built-in directional coupler, doubler, first and second antenna, anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and double frequency of local signal and frequency of signal wave A first even harmonic mixer that outputs signals of sum and difference frequencies, a filter whose center frequency is N times the first modulation frequency component, an N multiplier, and a first even harmonic mixer Since the second even harmonic mixer having the same configuration and function, the A / D converter, and the signal processing unit for obtaining the distance to the target and the relative speed are provided, the local oscillation signal included in the video signal is obtained. Reduces the noise leaked into the reception system It is possible to reduce the noise figure can be improved range performance of FM-CW radar.

According to the seventh embodiment of the present invention, a modulation frequency generator that outputs a signal having a first modulation frequency component, an oscillator that outputs a high frequency modulation signal having first and second modulation frequency components, Built-in directional coupler, doubler, circulator, antenna, anti-parallel diode pair in which two diodes of opposite polarity are connected in parallel,
A first even harmonic mixer that outputs a signal having a sum and difference frequency of a frequency of a local oscillation signal and a frequency of a signal wave; a filter having a center frequency N times the first modulation frequency component;
An N multiplier, a second even harmonic mixer having the same configuration and function as the first even harmonic mixer, an A / D converter,
By providing the signal processing unit for obtaining the distance to the target and the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the video signal and to reduce the noise figure of the receiving system. -The distance performance of the CW radar can be improved.

According to the eighth embodiment of the present invention, an oscillator,
A directional coupler, a doubler, first and second antennas, a distributor, a 90 ° hybrid, and an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and a local oscillator signal is generated. And a second even harmonic mixer that outputs a signal of a frequency that is the sum and difference of the double frequency and the frequency of the signal wave, the first and second A / D converters, and the distance between the target and By providing the signal processing unit for obtaining the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the video signal and to reduce the noise figure of the receiving system. Therefore, the distance of the FM-CW radar can be reduced. Performance can be improved.

[0023]

【Example】

Embodiment 1 FIG. FIG. 1 shows an FM-in the first embodiment of the present invention.
The block diagram of a CW radar is shown. In FIG.
3, 5 to 8 are the same as those of the conventional FM-CW radar, 9 is a doubler, and 10 is an even harmonic mixer having an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel. .

Next, the operation will be described. In FIG. 1, the oscillator 1 is a transmission signal (corresponding to a curve a in FIG. 13A, which irradiates a target (not shown in the drawing) from the first antenna 3a. The frequency is F _RF ± ΔF. 1 /
A high frequency modulated signal having a frequency of 2 is output. The directional coupler 2 outputs a part of the high frequency modulation signal output from the oscillator 1 as a local oscillation signal and the rest as a transmission reference signal. The doubler 9 receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. First antenna 3a
Irradiates a target with a transmission signal. Second antenna 3b
Receives the reflected signal from the target and receives the received signal (see FIG.
It corresponds to the curve b in (a). ) Is output. The even harmonic mixer 10 receives the local oscillator signal and the received signal, and corresponds to the sum and difference frequencies of the double frequency of the local oscillator signal and the frequency of the received signal (f _b and curve c in FIG. 13B). .) Is output. The filter 5 and the amplifier 6 filter and amplify the harmonic components of the video signal. The A / D converter 7 digitally converts the amplified video signal. The signal processing unit 8 receives the output of the A / D converter 7 and calculates the distance to the target and the relative speed. FIG. 12 shows the noise voltage contained in the video signal output from the fundamental wave mixer 4 in the conventional FM-CW radar and the even harmonic mixer 10 in this embodiment. In the figure, the curve a is the fundamental wave mixer 4, and the curve b is the noise voltage contained in the video signal output from the even harmonic mixer 10. Thus, the noise voltage of the even harmonic mixer 10 becomes
It can be seen that it is much smaller than the noise voltage of the fundamental wave mixer 4. Therefore, the NF of the receiving system constituting the FM-CW radar is improved, and the distance performance of the FM-CW radar can be improved.

Embodiment 2 FIG. 2 is a block diagram of an FM-CW radar according to the second embodiment of the present invention. In FIG. 2, 2 to 8 are the same as those of the conventional FM-CW radar, 1a and 1b are first and second oscillators, 9 is a doubler, and 10 is two diodes of opposite polarities connected in parallel. It is an even harmonic mixer with a built-in anti-parallel diode pair.

Next, the operation will be described. In FIG. 2, the first oscillator 1a corresponds to the transmission signal (curve a in FIG. 13A) that irradiates the target from the first antenna 3a. Of F _RF ± ΔF, F _RF is a high frequency component, ± ΔF is a modulation frequency component), and outputs a high frequency signal having a frequency of 1/2 of F _RF . The second oscillator 1b uses ± ΔF of the transmission signal emitted from the first antenna 3a to the target.
A frequency-modulated signal having a frequency of ½ of is output. The fundamental wave mixer 4 includes a first oscillator 1a and a second oscillator 1
The output of b is frequency-converted and a high frequency modulation signal is output. The directional coupler 2 outputs a part of the high frequency modulation signal output from the fundamental wave mixer 4 as a local oscillation signal and the rest as a transmission reference signal. The doubler 9 receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. The first antenna 3a irradiates a target with a transmission signal. The second antenna 3b receives the reflected signal from the target and outputs the received signal (corresponding to the curve b in FIG. 13A).
The even harmonic mixer 10 receives the local oscillation signal and the reception signal,
The frequency of the sum and difference of the double frequency of the local signal and the frequency of the received signal (corresponding to f _b and curve c in FIG. 13B).
Output a video signal with. Filter 5 and amplifier 6
Filter and amplify the harmonic components of the video signal. The A / D converter 7 digitally converts the amplified video signal. The signal processing unit 8 receives the output of the A / D converter 7 and calculates the distance to the target and the relative speed. Thus, by using the even harmonic mixer 10 for detection in the receiving system, the noise voltage included in the video signal can be reduced, the NF of the receiving system can be improved, and the distance performance can be improved. Further, by outputting only the modulation frequency component of the transmission signal output from the first antenna 3a from the second oscillator 1b, it is possible to improve the linearity of the transmission signal. The measurement accuracy of can be improved.

Embodiment 3 FIG. FIG. 3 shows a block diagram of an FM-CW radar according to a third embodiment of the present invention. In FIG. 3, 2, 3, 5 and 8 are the same as the conventional FM-CW radar, 1a and 1b are the first and second oscillators,
Reference numeral 9 is a doubler, and 10a and 10b are first and second even harmonic mixers each having a built-in anti-parallel diode pair in which two diodes having opposite polarities are connected in parallel.

Next, the operation will be described. In FIG. 3, the first oscillator 1a corresponds to the transmission signal (curve a in FIG. 13A) that irradiates the target from the first antenna 3a. Of F _RF ± ΔF, F _RF is a high frequency component, ± ΔF is a modulation frequency component), and outputs a high frequency signal having a frequency of ¼ of F _RF . The second oscillator 1b uses ± ΔF of the transmission signal emitted from the first antenna 3a to the target.
A frequency-modulated signal having a frequency of ½ of is output. The first even harmonic mixer 10a outputs a high frequency modulation signal having a sum and difference frequency of the double frequency of the output of the first oscillator 1a and the frequency of the output of the second oscillator 1b. The directional coupler 2 outputs a part of the high frequency modulation signal output from the first even harmonic mixer 10a as a local oscillation signal and outputs the rest as a transmission reference signal. The doubler 9 receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. The first antenna 3a irradiates a target with a transmission signal. The second antenna 3b receives the reflected signal from the target and outputs the received signal (corresponding to the curve b in FIG. 13A).
The second even harmonic mixer 10b receives the local oscillation signal and the reception signal, and sums and doubles the frequency of the local oscillation signal and the frequency of the reception signal (f _b and curve c in FIG. 13B). Corresponding to) is output. The filter 5 and the amplifier 6 filter and amplify the harmonic components of the video signal. The A / D converter 7 digitally converts the amplified video signal. The signal processing unit 8 receives the output of the A / D converter 7 and calculates the distance to the target and the relative speed. As described above, by using the second even harmonic mixer 10b for detection in the receiving system, the noise voltage included in the video signal can be reduced, the NF of the receiving system can be improved, and the distance performance can be improved. Furthermore, the first antenna 3a
By outputting only the modulation frequency component of the transmission signal output from the second oscillator 1b, the linearity of the transmission signal can be improved, and thus the measurement accuracy of the distance to the target and the relative speed can be improved. You can

Embodiment 4 FIG. Fourth Embodiment FIG. 4 shows a block diagram of an FM-CW radar according to a fourth embodiment of the present invention. 4, 3 to 8 are the same as the conventional FM-CW radar, 1a and 1b are first and second oscillators, 2a and 2b are first and second directional couplers, 10a and 10b
Are first and second even harmonic mixers having an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel.

Next, the operation will be described. In FIG. 4, the first oscillator 1a corresponds to a transmission signal (curve a in FIG. 13A) that irradiates the target from the first antenna 3a. Of F _RF ± ΔF, F _RF is a high frequency component, ± ΔF is a modulation frequency component), and outputs a high frequency signal having a frequency of 1/2 of F _RF . The first directional coupler 2a is
A part of the high frequency signal output from the first oscillator 1a is used as a first local oscillation signal, and the rest is output as a high frequency signal for transmission. The second oscillator 1b outputs a frequency modulation signal having a frequency of ± ΔF, out of the transmission signals emitted from the first antenna a to the target. The second directional coupler 2b outputs a part of the frequency modulation signal output from the second oscillator 1b as a second local oscillation signal and outputs the rest as a transmission modulation signal. The first even harmonic mixer 10a outputs a transmission signal having a sum of and a difference between the double frequency of the transmission high frequency signal and the frequencies of the transmission modulation signal. First antenna 3a
Irradiates a target with a transmission signal. Second antenna 3b
Receives the reflected signal from the target and receives the received signal (see FIG.
It corresponds to the curve b in (a). ) Is output. The second even harmonic mixer 10b receives the first local oscillator signal and the received signal, and outputs an intermediate frequency signal having a frequency that is a sum and difference frequency of the double frequency of the first local oscillator signal and the frequency of the received signal. Output. The fundamental wave mixer 4 receives the second local oscillation signal and the intermediate frequency signal, frequency-converts them, and outputs a video signal (corresponding to f _b and curve c in FIG. 13B). The filter 5 and the amplifier 6 filter and amplify the harmonic components of the video signal. The A / D converter 7 digitally converts the amplified video signal. The signal processing unit 8 receives the output of the A / D converter 7 and calculates the distance to the target and the relative speed. As described above, by using the second even harmonic mixer 10b for detection in the reception system, the noise voltage included in the intermediate frequency signal can be reduced, the NF of the reception system can be improved, and the distance performance can be improved. . Furthermore, by outputting only the modulation frequency component of the transmission signal output from the first antenna 1a from the second oscillator 1b, it is possible to improve the linearity of the transmission signal. The measurement accuracy of can be improved.

Embodiment 5 FIG. FIG. 5 shows a block diagram of an FM-CW radar according to a fifth embodiment of the present invention. In FIG. 5, 3 to 8 are the same as those of the conventional FM-CW radar, 1a and 1b are first and second oscillators, 2a and 2b are first and second directional couplers, 10a and 10b
Are first and second even harmonic mixers having an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel.

Next, the operation will be described. In FIG. 5, the first oscillator 1a corresponds to the transmission signal (curve a in FIG. 13A) that irradiates the target from the first antenna 3a. Of F _RF ± ΔF, F _RF is a high frequency component, ± ΔF is a modulation frequency component), and outputs a high frequency signal having a frequency of 1/2 of F _RF . The first directional coupler 2a is
A part of the high frequency signal output from the first oscillator 1a is used as a first local oscillation signal, and the rest is output as a high frequency signal for transmission. The second oscillator 1b outputs a frequency modulation signal having a frequency of ± ΔF, out of the transmission signals emitted from the first antenna a to the target. The second directional coupler 2b outputs a part of the frequency modulation signal output from the second oscillator 1b as a second local oscillation signal and outputs the rest as a transmission modulation signal. The first even harmonic mixer 10a outputs a transmission signal having a sum of and a difference between the double frequency of the transmission high frequency signal and the frequencies of the transmission modulation signal. First antenna 3a
Irradiates a target with a transmission signal. Second antenna 3b
Receives the reflected signal from the target and receives the received signal (see FIG.
It corresponds to the curve b in (a). ) Is output. The fundamental wave mixer 4 receives the second local oscillation signal and the reception signal, frequency-converts them, and outputs an intermediate frequency signal. Second even harmonic mixer 1
0b receives the first local oscillator signal and the intermediate frequency signal, and has a video signal having a sum and difference frequency of the double frequency of the first local oscillator signal and the frequency of the intermediate frequency signal (Fig. 13 (b)). f _b and curve c) are output. The filter 5 and the amplifier 6 filter and amplify the harmonic components of the video signal. The A / D converter 7 digitally converts the amplified video signal. The signal processing unit 8 receives the output of the A / D converter 7 and calculates the distance to the target and the relative speed. As described above, by using the second even harmonic mixer 10b for detection in the receiving system, the noise voltage included in the video signal can be reduced, the NF of the receiving system can be improved, and the distance performance can be improved. Furthermore, the first antenna 1a
By outputting only the modulation frequency component of the transmission signal output from the second oscillator 1b, the linearity of the transmission signal can be improved, and thus the measurement accuracy of the distance to the target and the relative speed can be improved. You can

Embodiment 6 FIG. 6 is a block diagram of an FM-CW radar according to a sixth embodiment of the present invention. In FIG. 6, 1 to 3, 7 and 8 are the same as those of the conventional FM-CW radar, 5a and 5b are first and second filters, 6a and 6b are first and second amplifiers, and 9 Is a doubler, 10a and 10b are first and second even harmonic mixers having anti-parallel diode pairs in which two diodes of opposite polarities are connected in parallel, 11 is a modulation frequency generator, and 12 is an N multiplier. is there.

Next, the operation will be described. In FIG. 6, the modulation frequency generator 11 has a first modulation frequency component ±
Output a frequency modulated signal with ΔF _AM . The oscillator 1
The first antenna 3 receives the output of the modulation frequency generator 11.
Transmission signal to irradiate target from a (frequency component F _RF ± ΔF
Of ± ΔF _AM , F _RF is a high frequency component, ± ΔF is a second modulation frequency component, and ± ΔF _AM is a first modulation frequency component. Output a high frequency modulation signal having a frequency of 1/2. The directional coupler 2 outputs a part of the high frequency modulation signal output from the oscillator 1 as a local oscillation signal and the rest as a transmission reference signal. The doubler 9 receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. The first antenna 3a irradiates a target with a transmission signal. The second antenna 3b receives the reflected signal from the target and outputs the received signal. The first even harmonic mixer 10a receives the local oscillator signal and the received signal, and outputs a first video signal having a frequency that is the sum and difference of the double frequency of the local oscillator signal and the frequency of the received signal. The first filter 5a receives the first video signal and receives N times the first modulation frequency component ± ΔF _AM (N is an integer).
Filter with the center frequency as. The first amplifier 6a amplifies the output of the first filter 5a. The N multiplier 12 is the output frequency of the modulation frequency generator 11 ± ΔF _AM
Is multiplied by N. The second even harmonic mixer 10b outputs a second video signal having a sum and difference frequency of the double frequency of the output of the N multiplier 12 and the frequency of the output of the first amplifier 6a. The second filter 5b and the second amplifier 6b filter and amplify the harmonic components of the second video signal. The A / D converter 7 digitally converts the amplified second video signal. The signal processor 8 is the A / D converter 7
Then, the distance to the target and the relative speed are calculated. As described above, by using the first even harmonic mixer 10a and the second even harmonic mixer 10b for detection in the receiving system, the noise voltage included in the first and second video signals can be reduced, and the receiving system can be reduced. NF can be improved. Further, the first filter 5a and the second even harmonic mixer 10b detect the second video signal with respect to the frequency N times the frequency F _M , thereby avoiding noise deterioration due to isolation between transmission and reception. As a result, the NF of the receiving system can be improved and the distance performance can be improved.

Here, the operation will be supplemented. FIG. 9 shows the operating principle of this embodiment. A curve a in FIG. 9A indicates a transmission signal and a local oscillation signal (of the frequency components F _RF ± ΔF ± ΔF _AM , F _RF is a high frequency component, ± ΔF is a second modulation frequency component, and ± ΔF _AM is the first Curve b)
Is the received signal. In the case of FM-CW radar, a target is irradiated with a frequency-modulated transmission signal, the reception signal has a delay time of twice the distance to the target, and the reception signal is frequency-converted (homodyne detection) by a local oscillation signal. Figure 9
The first video signal has the beat frequency component F _b corresponding to the target distance and speed as shown by the curve c in (b).
In FIG. 10, a curve d is a noise component caused by transmission / reception isolation, and a curve e is a spectrum of the first video signal. As shown, the first video signal is n ×
It has a target spectrum at ΔF _AM + f _b (n is an integer). However, since the spectrum of 0 × ΔF _AM + f _b may be buried in the curve d, the target may not be detected in some cases. Then, the first video signal is filtered by the first filter with N times ΔF _AM as the center frequency, so that the spectrum that is not buried in the curve d becomes
It becomes possible to calculate the target distance and the relative speed.
In this way, since the deterioration of noise due to transmission / reception isolation is suppressed, the detectable target distance performance can be improved.

Embodiment 7 FIG. FIG. 7 shows a block diagram of an FM-CW radar according to a seventh embodiment of the present invention. In FIG. 7, 1, 2, 7, and 8 are the same as the conventional FM-CW radar, 3 is an antenna, 5a and 5b are first and second filters, and 6a and 6b are first and second filters. Amplifier, 9 is a doubler, 10a and 10b are first and second even harmonic mixers having an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, 11 is a modulation frequency generator, and 12 is N multiplier.

Next, the operation will be described. In FIG. 7, the modulation frequency generator 11 has a first modulation frequency component ±
Output a frequency modulated signal with ΔF _AM . The oscillator 1
The first antenna 3 receives the output of the modulation frequency generator 11.
A transmission signal for irradiating a target from a (corresponding to the curve a in FIG. 9A.) Of the frequency components F _RF ± ΔF ± ΔF _AM , F _RF is a high frequency component, ± ΔF is a second modulation frequency component, ± ΔF _AM
Is the first modulation frequency component. Output a high frequency modulation signal having a frequency of 1/2. The directional coupler 2 outputs a part of the high frequency modulation signal output from the oscillator 1 as a local oscillation signal and the rest as a transmission reference signal. Doubler 9
Receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. The antenna 3 irradiates the target with the transmission signal, receives the reflection signal from the target, and receives the reception signal (FIG. 9A).
Corresponding to the curve b. ) Is output. Circulator 1
3 guides the transmission signal from the doubler 9 to the antenna 3 and the reception signal from the antenna 3 to the first even harmonic mixer 10a. The first even harmonic mixer 10a receives the local oscillator signal and the received signal, and has a first video signal (FIG. 9) having a frequency equal to the sum of the frequency of the local oscillator signal and the frequency of the received signal.
It corresponds to the curve c in (b). ) Is output. The first filter 5a receives the first video signal and filters it with the center frequency being N times (N is an integer) the first modulation frequency component ± ΔF _AM . The first amplifier 6a amplifies the output of the first filter 5a. The N multiplier 12 multiplies the output frequency ± ΔF _AM of the modulation frequency generator 11 by N times. The second even harmonic mixer 10b outputs a second video signal having a sum and difference frequency of the double frequency of the output of the N multiplier 12 and the frequency of the output of the first amplifier 6a. The second filter 5b and the second amplifier 6b filter and amplify the harmonic components of the second video signal. The A / D converter 7 digitally converts the amplified second video signal. The signal processing unit 8 receives the output of the A / D converter 7,
The distance to the target and the relative speed are calculated. Thus, by using the first even harmonic mixer 10a and the second even harmonic mixer 10b for detection in the receiving system, the noise voltage included in the first and second video signals can be reduced, and the receiving system can be reduced. NF can be improved. Further, the first filter 5a and the second even harmonic mixer 10b detect the second video signal with respect to the N times frequency of the frequency F _M , thereby avoiding noise deterioration due to isolation between transmission and reception. And consequently improve the NF of the receiving system,
The distance performance can be improved. Furthermore, by performing transmission and reception with one antenna, the FM-CW radar itself can be miniaturized.

Embodiment 8 FIG. FIG. 8 shows a block diagram of an FM-CW radar in Embodiment 8 of the present invention. In FIG. 8, 1 to 3 and 8 are the same as those of the conventional FM-CW radar, 5a and 5b are the first and second filters, and 6
a and 6b are first and second amplifiers, 7a and 7b are first and second A / D converters, 9 is a doubler, and 10a and 10b are antiparallel in which two diodes of opposite polarities are connected in parallel. The first and second even harmonic mixers have a diode pair built therein, 14 is a distributor, and 15 is a 90 ° hybrid.

Next, the operation will be described. In FIG. 8, the oscillator 1 corresponds to a transmission signal (curve a in FIG. 13A) that irradiates the target from the first antenna 3a.
The frequency is F _RF ± ΔF. Output a high frequency modulation signal having a frequency of 1/2. The directional coupler 2 outputs a part of the high frequency modulation signal output from the oscillator 1 as a local oscillation signal and the rest as a transmission reference signal. Doubler 9
Receives the transmission reference signal, doubles the frequency, and outputs it as a transmission signal. The first antenna 3a irradiates a target with a transmission signal. The second antenna 3b receives the reflection signal from the target and outputs a reception signal (corresponding to the curve b in FIG. 13A). The divider 14 divides the received signal into two powers having substantially the same phase. 90 ° hybrid 1
Reference numeral 5 divides the power of the local oscillation signal output from the directional coupler into two substantially in opposite phases. First even harmonic mixer 10a
Receives the power-divided reception signal and the local oscillation signal, and has a frequency (corresponding to f _b in FIG. 13B) of the sum and difference of the double frequency of the local oscillation signal and the frequency of the reception signal. The first video signal for the I channel is output. The first filter 5a and the first amplifier 6a filter and amplify the harmonic components of the first video signal. The first A / D converter 7a digitally converts the amplified first video signal. The second even harmonic mixer 10b, the second filter 5b, the second amplifier 6b, and the second A / D converter 7b are connected to the first even harmonic mixer 10a by the first A / D converter.
It operates similarly to the D converter 7a and outputs the second video signal for the Q channel. The signal processing unit 8 uses the first A / D
The first and second video signals (for I and Q channels) output from the converter 7a and the second A / D converter 7b are received, and the distance to the target and the relative speed are calculated. As described above, the first even harmonic mixer 10 is used for detection in the receiving system.
By using a and the second even harmonic mixer 10b, the noise voltage included in the first and second video signals can be reduced, the NF of the receiving system can be improved, and the distance performance can be improved. Furthermore, by providing two I and Q channels as video signals, it is possible to improve the measurement capability such as detection of multiple targets.

[0040]

According to the first embodiment of the present invention, an oscillator, a directional coupler, a doubler, a first and a second antenna, and an anti-parallel circuit in which two diodes of opposite polarities are connected in parallel. The built-in diode pair, the even harmonic mixer that outputs a signal of the sum and difference frequency of the local oscillation signal and the frequency of the signal wave, the A / D converter, and the distance and relative speed to the target By having a signal processing unit to obtain,
Since it is possible to reduce the leak noise of the local oscillation signal included in the video signal and reduce the noise figure of the receiving system,
Distance performance can be improved.

According to the second embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a second oscillator that outputs a frequency modulation signal, a fundamental wave mixer, a directional coupler, Built-in anti-parallel diode pair in which a doubler, first and second antennas, and two diodes of opposite polarities are connected in parallel, and the sum and difference frequencies of the double frequency of the local oscillator signal and the frequency of the signal wave. Since the even harmonic mixer that outputs the signal of A, the A / D converter, and the signal processing unit that obtains the distance and the relative speed to the target are provided, the leak noise of the local oscillation signal included in the video signal can be reduced. Since it is possible to reduce the noise figure of the receiving system, it is possible to improve the distance performance. Furthermore, since the linearity of the transmission signal can be improved, the accuracy of measuring the distance to the target and the relative speed can be improved.

According to the third embodiment of the present invention, a first oscillator that outputs a signal having a constant frequency, a second oscillator that outputs a frequency modulation signal, and an anti-parallel diode having two diodes of opposite polarities are connected in parallel. Built-in parallel diode pair,
A first even harmonic mixer that outputs a signal having a sum and difference frequency of a frequency of a local oscillation signal and a frequency of a signal wave, a directional coupler, a doubler, and first and second antennas And a second even harmonic mixer having the same configuration and function as the first even harmonic mixer, an A / D converter, and a signal processing unit for obtaining a distance and relative speed to a target. Reduces the leak noise of the local signal included in the video signal,
Since the noise figure of the receiving system can be reduced, the distance performance can be improved. Furthermore, since the linearity of the transmission signal can be improved, the accuracy of measuring the distance to the target and the relative speed can be improved.

According to the fourth embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a first directional coupler, a second oscillator that outputs a frequency modulation signal, and a second oscillator The directional coupler and the anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and the signal of the sum of the frequency of the local oscillation signal and the frequency of the signal wave and the frequency of the difference is output. Even harmonic mixer, first and second antennas, second even harmonic mixer having the same configuration and function as the first even harmonic mixer, fundamental mixer, and A / D converter And a signal processing unit for obtaining the distance to the target and the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the intermediate frequency signal and to reduce the noise figure of the receiving system. Therefore, the distance performance can be improved. Furthermore, since the linearity of the transmission signal can be improved, the accuracy of measuring the distance to the target and the relative speed can be improved.

According to the fifth embodiment of the present invention, a first oscillator that outputs a signal of a constant frequency, a first directional coupler, a second oscillator that outputs a frequency modulation signal, and a second oscillator The directional coupler and the anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and the signal of the sum of the frequency of the local oscillation signal and the frequency of the signal wave and the frequency of the difference is output. Even harmonic mixer, first and second antennas, fundamental wave mixer, second even harmonic mixer having the same configuration and function as the first even harmonic mixer, and A / D converter And the signal processing unit for obtaining the distance to the target and the relative speed, it is possible to reduce the leak noise of the local oscillation signal included in the video signal and to reduce the noise figure of the receiving system. The distance performance can be improved. Furthermore, since the linearity of the transmission signal can be improved, the accuracy of measuring the distance to the target and the relative speed can be improved.

According to the sixth embodiment of the present invention, a modulation frequency generator for outputting a signal of a first modulation frequency component, an oscillator for outputting a high frequency modulation signal having first and second modulation frequency components, Built-in directional coupler, doubler, first and second antenna, anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and double frequency of local signal and frequency of signal wave A first even harmonic mixer that outputs signals of sum and difference frequencies, a filter whose center frequency is N times the first modulation frequency component, an N multiplier, and a first even harmonic mixer Since the second even harmonic mixer having the same configuration and function, the A / D converter, and the signal processing unit for obtaining the distance to the target and the relative speed are provided, the local oscillation signal included in the video signal is obtained. The noise that leaks in the And since it is possible to avoid the influence of isolation between the receiving, it can improve NF of the receiving system, range performance can be improved.

According to the seventh embodiment of the present invention, a modulation frequency generator that outputs a signal having a first modulation frequency component, an oscillator that outputs a high frequency modulation signal having first and second modulation frequency components, Built-in directional coupler, doubler, circulator, antenna, anti-parallel diode pair in which two diodes of opposite polarity are connected in parallel,
A first even harmonic mixer that outputs a signal having a sum and difference frequency of a frequency of a local oscillation signal and a frequency of a signal wave; a filter having a center frequency N times the first modulation frequency component;
An N multiplier, a second even harmonic mixer having the same configuration and function as the first even harmonic mixer, an A / D converter,
By including the signal processing unit that obtains the distance and the relative speed to the target, it is possible to reduce the leak noise of the local oscillation signal included in the video signal, and to avoid the influence of the isolation between the transmission and the reception. The NF of the receiving system can be improved, and the distance performance can be improved. Further, by performing transmission and reception with one antenna, the FM-CW radar itself can be miniaturized.

According to the eighth embodiment of the present invention, an oscillator,
A directional coupler, a doubler, first and second antennas, a distributor, a 90 ° hybrid, and an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built in, and a local oscillator signal is generated. And a second even harmonic mixer that outputs a signal of a frequency that is the sum and difference of the double frequency and the frequency of the signal wave, the first and second A / D converters, and the distance between the target and Since the signal processing unit that obtains the relative speed is provided, the leak noise of the local oscillation signal included in the video signal can be reduced and the noise figure of the receiving system can be reduced, so that the distance performance can be improved. Further, by providing two video signals, I channel and Q channel, it is possible to improve the measurement capability such as detection of multiple targets.

[Brief description of drawings]

FIG. 1 is a configuration block diagram of an FM-CW radar according to a first embodiment of the present invention.

FIG. 2 is a configuration block diagram of an FM-CW radar according to a second embodiment of the present invention.

FIG. 3 is a configuration block diagram of an FM-CW radar according to a third embodiment of the present invention.

FIG. 4 is a configuration block diagram of an FM-CW radar according to Embodiment 4 of the present invention.

FIG. 5 is a configuration block diagram of an FM-CW radar according to a fifth embodiment of the present invention.

FIG. 6 is a configuration block diagram of an FM-CW radar according to a sixth embodiment of the present invention.

FIG. 7 is a configuration block diagram of an FM-CW radar according to a seventh embodiment of the present invention.

FIG. 8 is a configuration block diagram of an FM-CW radar according to Embodiment 8 of the present invention.

FIG. 9 shows an FM according to embodiments 6 and 7 of the present invention.
FIG. 6 is a diagram illustrating the operating principle of a CW radar.

FIG. 10 is a diagram showing a spectrum of a video signal in Example 6 and Example 7 of the present invention.

FIG. 11 is a configuration block diagram of a conventional FM-CW radar.

FIG. 12 is a diagram showing an example of output noise levels of a fundamental wave mixer and an even harmonic mixer.

FIG. 13 is an operation principle diagram of the FM-CW radar.

[Explanation of symbols]

1 Oscillator, 1a 1st oscillator, 1b 2nd oscillator, 2 directional coupler, 2a 1st directional coupler, 2
b second directional coupler, 3 antenna, 3a first antenna, 3b second antenna, 4 fundamental wave mixer, 5
Filter, 5a 1st filter, 5b 2nd filter, 6 amplifier, 6a 1st amplifier, 6b 2nd amplifier, 7 A / D converter, 7a 1st A / D converter, 7b 2nd A / D converter, 8 signal processor, 9 2
Multiplier, 10 even harmonic mixer, 10a first even harmonic mixer, 10b second even harmonic mixer, 11 modulation frequency generator, 12 N multiplier, 13 circulator, 14 distributor, 15 90 ° hybrid.

Claims (8)

[Claims] 1. An oscillator which outputs a high frequency modulated signal, a directional coupler which uses a part of the output of this oscillator as a local oscillation signal and the rest as a transmission reference signal, and doubles the frequency of this transmission reference signal. And a second antenna for irradiating the target with the transmission signal, and a second antenna for receiving a reflection signal from the target and outputting a reception signal,
And an even-harmonic mixer which incorporates an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel and outputs a video signal having a sum and difference frequency of the frequency of the local oscillation signal and the frequency of the reception signal. An FM-CW radar comprising: an A / D converter for digitally converting this video signal; and a signal processing unit for obtaining the distance and relative speed to the target from the output of the A / D converter. . 2. A first oscillator that outputs a high-frequency signal having a constant frequency, a second oscillator that outputs a frequency-modulated signal, and a frequency conversion that receives the outputs of the first and second oscillators to perform high-frequency modulation. A fundamental wave mixer that outputs a signal, a directional coupler that uses a part of the output of the fundamental wave mixer as a local oscillation signal and the rest as a transmission reference signal, and a transmission signal that doubles the frequency of this transmission reference signal. , A first antenna that irradiates a target with this transmission signal, a second antenna that receives a reflection signal from the target and outputs a reception signal, and two diodes having opposite polarities are connected in parallel. And an anti-parallel diode pair, which outputs a video signal having a frequency of the sum and difference of the frequency of the local signal and the frequency of the received signal, and this video signal is digitally converted. An FM-CW radar, comprising: an A / D converter that obtains a distance and a relative speed from the output of the A / D converter. 3. A first oscillator that outputs a high-frequency signal of a constant frequency, a second oscillator that outputs a frequency-modulated signal, and an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel are built-in. A first even harmonic mixer that outputs a signal having a frequency of a sum of and a difference between the frequency of the output of the second oscillator and the double frequency of the output of the first oscillator, and the output of the first even harmonic mixer A directional coupler in which a part of the signal is a local oscillation signal and the rest is a transmission reference signal, and the transmission signal is output by doubling the frequency of the transmission reference signal.
A multiplier, a first antenna for irradiating a target with this transmission signal, a second antenna for receiving a reflection signal from the target and outputting a reception signal, and a built-in anti-parallel diode pair, the local oscillation signal Second even harmonic mixer for outputting a video signal having a frequency equal to the sum of the frequency of the received signal and the frequency of the received signal, an A / D converter for digitally converting this video signal, and this A / D An FM-CW radar, comprising: a signal processing unit that obtains the distance to the target and the relative speed from the output of the converter. 4. A first oscillator that outputs a high-frequency signal having a constant frequency, and a first oscillator that outputs a part of the output of the first oscillator as a first local oscillator signal and the rest as a high-frequency signal for transmission. Directional coupler, a second oscillator that outputs a frequency modulation signal, and a second direction that outputs a part of the output of this second oscillator as a second local oscillation signal and the rest as a transmission modulation signal. Of a parallel signal and an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and a transmission signal having a sum frequency of the transmission high frequency signal and a frequency of the transmission modulation signal A first even harmonic mixer that outputs, a first antenna that irradiates a target with this transmission signal, a second antenna that receives a reflection signal from the target and outputs a reception signal, and the antiparallel diode pair Built in A second even harmonic mixer that outputs an intermediate frequency signal having a sum and difference frequency of the double frequency of the first local oscillation signal and the frequency of the reception signal, and the intermediate frequency signal and the second It receives a local signal and frequency modulates it,
A fundamental wave mixer that outputs a video signal, an A / D converter that digitally converts this video signal, and a signal processing unit that obtains the distance and relative speed to the target from the output of this A / D converter An FM-CW radar characterized by the following. 5. A first oscillator that outputs a high-frequency signal of a constant frequency, and a first oscillator that outputs a part of the output of the first oscillator as a first local oscillator signal and the rest as a high-frequency signal for transmission. Directional coupler, a second oscillator that outputs a frequency modulation signal, and a second direction that outputs a part of the output of this second oscillator as a second local oscillation signal and the rest as a transmission modulation signal. Of a parallel signal and an anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and a transmission signal having a sum frequency of the transmission high frequency signal and a frequency of the transmission modulation signal A first even harmonic mixer that outputs, a first antenna that irradiates a target with this transmission signal, a second antenna that receives a reflection signal from the target and outputs a reception signal, the reception signal and the above In response to the second local signal A fundamental wave mixer that converts the frequency and outputs an intermediate frequency signal, and the anti-parallel diode pair are built in, and have a double frequency of the first local oscillation signal and a sum and difference frequency of the frequencies of the intermediate frequency signal. A second even harmonic mixer that outputs a video signal, an A / D converter that digitally converts this video signal, and a signal processing unit that obtains the distance and relative speed to the target from the output of this A / D converter An FM-CW radar comprising: 6. A modulation frequency generator which outputs a frequency modulation signal having a first modulation frequency component, and a high frequency modulation signal which receives the frequency modulation signal and has a first modulation frequency component and a second modulation frequency component. , A directional coupler that outputs a part of the output of this oscillator as a local oscillation signal and the rest as a transmission reference signal, and a transmission signal that is obtained by doubling the frequency of this transmission reference signal. A multiplier, a first antenna for irradiating a target with this transmission signal, a second antenna for receiving a reflection signal from the target and outputting a reception signal, and an anti-parallel diode in which two diodes of opposite polarities are connected in parallel. A first even harmonic mixer which incorporates a pair and outputs a first video signal having a frequency that is the sum and difference of the double frequency of the local oscillator signal and the frequency of the received signal, and the first video signal. A filter that receives a signal and filters by using a frequency (N is an integer) of the first modulation frequency component as a center frequency, and N that multiplies the first modulation frequency component output from the modulation frequency generator by N times. Built-in multiplier and anti-parallel diode pair,
A second even harmonic mixer that outputs a second video signal having a frequency that is the sum and difference of the double frequency of the output of the N multiplier and the frequency of the output of the filter, and a digital signal of the second video signal. An FM-CW radar, comprising: an A / D converter for conversion; and a signal processing unit for obtaining a distance to the target and a relative speed from an output of the A / D converter. 7. A modulation frequency generator which outputs a frequency modulation signal having a first modulation frequency component, and a high frequency modulation signal which receives the frequency modulation signal and has a first modulation frequency component and a second modulation frequency component. , A directional coupler that outputs a part of the output of this oscillator as a local oscillation signal and the rest as a transmission reference signal, and a transmission signal that is obtained by doubling the frequency of this transmission reference signal. A multiplier, a circulator that outputs the transmission signal and the reception signal from the antenna to the antenna and the even harmonic mixer, respectively, and an antenna that irradiates the target with the transmission signal and outputs a reception signal that receives a reflection signal from the target. , A built-in anti-parallel diode pair in which two diodes of opposite polarities are connected in parallel, and the sum and difference frequencies of the double frequency of the local oscillator signal and the frequency of the received signal. A first even harmonic mixer for outputting a first video signal having a number, and filtering with the N times frequency (N is an integer) of the first modulation frequency component as a center frequency in response to the first video signal Filter, an N multiplier for multiplying the first modulation frequency component output from the modulation frequency generator by N, and the anti-parallel diode pair are built in, and the double frequency of the output of the N multiplier and the above A second even harmonic mixer that outputs a second video signal having a frequency of the sum and difference of the frequencies of the output of the filter, and A that digitally converts the second video signal.
An FM-CW radar, comprising: an A / D converter and a signal processing unit that obtains a distance and a relative speed to the target from an output of the A / D converter. 8. An even harmonic mixer for receiving a received signal
All the configurations up to the D / D converter are provided for I channel and Q channel, the received signal output from the antenna is divided into two in phase, and even harmonics for I channel and Q channel are provided. It is provided with a distributor for outputting to the mixer and a 90 ° hybrid for dividing the local oscillation signal of the directional coupler into two with opposite phases and outputting to the even harmonic mixer for I channel and Q channel. The FM-CW radar according to any one of claims 1 to 7, which is characterized.