JP3344368B2 - Radar equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention can measure the distance and relative speed of an obstacle or a running car located in the vicinity of a host vehicle, and can grasp and judge the surrounding conditions on behalf of a driver. Regarding the on-vehicle radar device, in particular, the on-vehicle radar device is a millimeter-wave radar system, which can not only simultaneously measure the distance and relative speed to an object, but also can greatly improve the failure detection performance.
The present invention relates to an FM-CW method using a continuous wave (CW) of a modulated wave.

[0002]

2. Description of the Related Art An on-vehicle radar device is capable of measuring the distance and relative speed of an obstacle or a running car located in the vicinity of a host vehicle, and grasping and judging the surrounding conditions on behalf of a driver. can do. for that reason,
A radar device installed in front of a vehicle is expected to be used as a device for preventing a collision accident of a vehicle beforehand or for reducing an impact at the time of a collision, and greatly contributing to a safe driving of the vehicle.

There are two types of on-vehicle radar systems: a laser radar system using a laser beam and a millimeter wave radar system using a radio signal in a millimeter wave band. Some laser radar devices have already been commercialized, but with the standardization of low-power millimeter-wave radar, the development of radar devices with a working frequency of 76 GHz has been active. Millimeter-wave radio waves have the advantage of being less affected by weather such as rain and fog than lasers, and the possibility of lowering prices due to an increase in production volume is more likely than that of laser systems, and commercialization is expected. The point that can be done lies in the background. Generally, as a millimeter wave radar device, a pulse method or a 2
A frequency CW method and an FM-CW method are known. Among them, FM-CW using a continuous wave (CW) of FM modulated wave
The method can be said to be particularly suitable for an in-vehicle radar device because the distance and the relative speed to an object can be measured simultaneously. FIG. 1 shows a configuration example of the FM-CW radar.

FIG. 2 shows signal waveforms and frequency transitions of respective parts of the circuit shown in FIG. The FM modulated wave is generated by the modulation control circuit 1 and the voltage controlled oscillator 2,
The transmission wave is sent to the transmission / reception antenna 4 via the circulator 3. The voltage control oscillator 2 is a modulation control circuit 1
Is converted into a frequency corresponding to the voltage value of the triangular wave having the repetition frequency fm shown in FIG. In this case, the free-running frequency fo of the voltage-controlled oscillator 2 becomes the modulation center frequency, and the transmission wave becomes F
FM modulation is performed with an M modulation width. 2, the horizontal axis represents time, the vertical axis V in FIG. 2A represents a triangular wave output voltage, and the vertical axes in FIGS. 2B to 2D represent transmission / reception frequency and beat frequency, respectively. , A beat signal.
The repetition frequency fm of the FM modulated wave is the reciprocal 1 / fm
Coincides with the cycle Tm of the triangular wave.

On the other hand, the reflected wave reflected by the object is received by the transmitting / receiving antenna 4 and sent to the mixer 5 as mixing means via the circulator 3. The mixer 5 mixes the transmission wave and the reception wave and extracts a beat signal having a frequency difference between the two waves. This peat signal is amplified by the intermediate frequency amplification circuit 6 and is converted from an analog signal to digital data by the A / D conversion circuit 7. Signal processing circuit 8
Separates the digital data subjected to A / D conversion between the rising section and the falling section of the modulation frequency in FIG. 2 (B), and individually performs frequency analysis to obtain a frequency spectrum. From the frequency spectrum, a peak frequency is detected from frequencies exceeding a threshold value in order to remove noise. Further, a non-existent object is excluded from information of the object obtained by the combination processing of the peak frequency in the ascending section and the peak frequency in the descending section, and the distance and the relative speed of the existing object are obtained.

Here, fo: transmission frequency Δf: FM modulation width Tm: modulation repetition cycle fb: transmission / reception beat frequency C: speed of light T: round trip time of radio waves to the object r: distance to the object v: object As shown in FIG. 2, the beat frequency fb is given by:
Modulation frequency rising section (fb1) and falling section (fb2)
And fb1 = (4 △ fr · C · Tm) − (2fo · v /
C) fb2 = (4 △ fr · C · Tm) + (2fo · v /
C) is given as Therefore, the distance to the reflecting object and the relative speed with respect to the reflecting object are given by r = C · Tm (fb1 + fb2) / (8 △ f) v = C · (fb1−fb2) / 4fo

In the above-mentioned conventional radar apparatus, when an object is present on a radar transmission / reception wave, the distance to the object and the relative speed with respect to the object can be obtained by the above operation principle. Therefore, the position of the object N seconds later can be predicted within a wide range from the obtained distance to the individual object and the relative speed. Therefore, some abnormalities could be detected by comparing the information obtained from the beat signal after N seconds with this prediction result.

[0008]

However, in this method, a long detection time is required for the determination, so that a large detection delay occurs. The delay from the occurrence of a failure becomes considerably large. Also, in order to avoid erroneous detection, it is necessary to have a wide threshold for determination, and there is a problem that the failure detection capability is low. Due to the detection delay or the low detection capability of the on-vehicle radar device, abnormal running caused by a failure cannot be prevented, which has been a safety problem. If the target does not exist on the radar transmission / reception wave, there is no reflected wave, and there is no peak frequency obtained by analyzing the frequency of the beat signal. Therefore, it is recognized that there is no target. However, in a state where a transmission wave is not output due to a failure or a state where detection is not possible due to an abnormality in a reception system, a beat signal cannot be obtained, and a failure cannot be detected from a state where there is no target object, and a failure cannot be detected. was there.

The present invention provides a radar device and a failure detection method capable of instantaneously detecting a failure in which a beat signal cannot be obtained regardless of the presence or absence of an object on a radar transmission / reception wave. Things.

Also, disclosed in Japanese Patent Application Laid-Open No. H10-62525,
The radar failure determination device performs failure detection by having a modulator dedicated to failure diagnosis in order to obtain a mixer output signal for detecting a failure, but in the present invention, the radar failure determination device is required for measurement of an object. With such a conventional configuration, a mixer output signal for failure detection can be obtained, which contributes to the realization of a low-cost and highly reliable radar device.

[0011]

SUMMARY OF THE INVENTION The present invention relates to a radar apparatus having an antenna which excites in a fixed band, oscillates at an exciting frequency at the time of measurement and deactivates the oscillator at a non-exciting frequency at the time of fault diagnosis. Oscillate. As a result, at a non-excitation frequency, reflection occurs due to impedance mismatch of the antenna, and a DC component is generated from the mixer. For this reason, at the time of failure diagnosis, if the output is normal, the mixer output is in a state where the DC component is increased. For example, if a failure occurs in the transmission system such that the output is cut off, the DC component decreases. Therefore, a failure can be detected by comparing with a set threshold value. As a result, the detection performance of a failure in which a signal is interrupted due to a failure in a component of the high-frequency circuit unit, bonding, or the like and a failure in which output is significantly reduced are improved.

The present invention not only increases the number of detectable fault locations and detectable fault modes, but also provides a diagnosis period within a measurement cycle, so that fault diagnosis can be performed almost simultaneously with measurement of an object, and a fault can be instantaneously detected. Can be detected, and the failure detection performance is improved without affecting the performance at the time of measurement. In addition, the number of components can be increased by a small amount or without increasing the number of components, thereby avoiding an increase in size and cost due to improved failure reliability. For this reason, a safe inter-vehicle distance maintaining traveling device, an automatic braking device, a collision impact mitigation device, and the like in a radar device mounted on an automobile can immediately detect a failure of the radar device.
The occurrence state of abnormal running due to failure can be suppressed,
Thereby, an excellent effect is exerted on the safe driving of the automobile.

The radar failure determination device disclosed in Japanese Patent Application Laid-Open No. H10-62525 detects a failure by providing a modulator dedicated to failure diagnosis in order to obtain a mixer output signal for detecting a failure. According to the present invention, a mixer output signal for failure detection can be obtained with a conventional configuration required for measuring an object, which contributes to the realization of a low-cost and highly reliable radar device.

According to the first aspect of the present invention , excitation is performed in a fixed band.
With an antenna that vibrates, and a FM-CW FM modulation
In radar equipment that transmits and receives high-frequency signals of continuous waves,
Along with the high-frequency signal for measuring objects,
Transmit other high frequency signals for fault diagnosis at different frequencies
Oscillator, and the transmitted and reflected waves of this oscillator are mixed
And the output signal of this mixer
Determination means, and the other high-frequency signal is
It is characterized by a frequency at which the impedance of the tenor becomes mismatched .

[0015]

According to a second aspect of the present invention, there is provided the radar apparatus according to the first aspect , further comprising an antenna for exciting in a fixed band, transmitting and receiving a high-frequency signal of an FM-modulated continuous wave (FM-CW system), It is characterized by having a modulation control circuit for generating a signal of a frequency for measurement and a signal of a frequency for diagnosis in an oscillator. According to a third aspect of the present invention, in the radar device according to the first or second aspect, an antenna for exciting in a fixed band is provided, and a high-frequency signal of an FM-modulated continuous wave (FM-CW system) is provided. And compares the difference between the threshold value set from the mixer output DC level before the failure (after manufacture, etc.) or a predetermined threshold value and the mixer output DC level at the time of failure or characteristic deterioration in the radar device. By doing so, a failure is detected.

According to a fourth aspect of the present invention, there is provided the radar apparatus according to the third aspect , further comprising an antenna for exciting in a fixed band, transmitting and receiving a high-frequency signal of a FM continuous wave (FM-CW system), For the measurement of the mixer output used for detecting a failure or characteristic deterioration in the radar device, the configuration for measuring the object is used as it is, and no additional circuit or the like is required. According to a fifth aspect of the present invention, in the radar device according to the third aspect or the fourth aspect, an antenna that excites in a fixed band is provided, and a high frequency signal of a continuous wave (FM-CW system) of FM modulation. Is transmitted and received, and a failure diagnosis is performed before or after one measurement of the target object irrespective of the presence or absence of a reflective object, so that a delay in detecting a failure does not occur.

According to a sixth aspect of the present invention, there is provided a modulation control circuit and a voltage-controlled oscillator, and a continuous wave (FM) of FM modulation.
It claims 2 to transmit and receive radio frequency signals -CW method)
6. The radar apparatus according to claim 5, wherein the modulation control circuit and the voltage-controlled oscillator are used to obtain a mixer output signal for detecting a failure, and no other modulator dedicated to failure diagnosis is required. It is characterized by. According to a seventh aspect of the present invention, in the radar apparatus according to the first to sixth aspects, the FM-modulated continuous wave (FM-C
Radar system for transmitting and receiving high-frequency signals (W system)
A modulation control circuit for generating a modulated wave, a voltage controlled oscillator, an antenna for transmitting the generated FM modulated wave and receiving a reflected wave, a circulator for sending the transmitted wave to the antenna, and sending a signal received by the antenna to a mixer A mixer as a means for mixing a transmitted wave and a received wave; an intermediate frequency amplifier circuit and a low frequency amplifier circuit for amplifying an output beat signal of the mixer; and an A / D converter for digitizing the signal amplified by the amplifier. And a signal processing circuit for performing a Fourier transform on the digitized discrete signal sequence.

According to the eighth aspect of the present invention, the distance to an object is measured by intermittently transmitting a radio wave in synchronization with a pulse signal and measuring a time interval between the received intermittent radio wave. In a pulse-type radar device, an interrupter that supplies an output of a voltage-controlled oscillator that generates a measurement wave to a transmitting / receiving antenna at regular intervals is provided, and the interrupter allows an object measurement period in which transmission and reception for distance measurement are performed. Between the next object measurement period, a failure diagnosis period for performing transmission and reception for failure diagnosis is inserted, and an oscillation control circuit that controls the oscillation frequency of the voltage-controlled oscillator, in the object measurement period, The transmission is performed at a frequency having a lower antenna excitation efficiency than the failure diagnosis period.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A radar apparatus according to an embodiment of the present invention and a method for detecting a failure thereof will be described. FIG. 3 is a block diagram showing a schematic configuration of the FM-CW radar apparatus according to one embodiment of the present invention. The FM modulated wave is generated by the modulation control circuit 1 and the voltage controlled oscillator 2 and sent to the transmission / reception antenna 4 via the circulator 3 as a transmission wave.
The transmission / reception antenna 4 radiates radio waves into space. Here, the voltage controlled oscillator 2 generates the modulation control circuit 1 as shown in FIG.
A triangular wave having a period Tm and a square wave having a period Ts shown in FIG. 3A are converted into frequencies corresponding to voltage values. At this time, the free-running frequency fo of the voltage controlled oscillator 2 becomes the modulation center frequency, and the transmission wave is FM-modulated with an FM modulation width of Δf around this modulation center frequency fo. Here, as shown in FIG. 5, the transmitting and receiving antenna 4 is an antenna that efficiently excites at a frequency between ± Δf / 2 with respect to the modulation center frequency fo. Further, the voltage of the square wave having the period Ts is set to a voltage corresponding to the frequency transmitted by the voltage controlled oscillator at the frequency where the return loss of the transmitting / receiving antenna 4 is large, as shown in FIG.

In FIG. 4, the abscissas of (A) to (C) and (E) represent time, and the abscissas of (D) and (F) represent frequency. Also, the vertical axis in FIG. 3A is a triangular wave output voltage, the vertical axis in FIG. 3B is the modulation frequency, and FIG.
The vertical axis of (E) is a beat signal, and FIGS.
The vertical axis indicates the frequency level. The transmitting / receiving antenna 4 receives a reflected wave reflected by the object. The electric wave received here is sent to the mixer 5 as the mixing means via the circulator 3. The mixer 5 mixes the transmission wave and the reception wave and extracts a beat signal having a frequency difference between the two waves.

On the other hand, the signal transmitted from the voltage controlled oscillator 2 during the period Ts is not radiated to the space from the antenna due to the impedance mismatch of the transmission / reception antenna 4, is reflected on the feeder line and is reflected through the circulator 3 to the mixer 5 It is led to. At this time, since there is no frequency difference between the transmission wave and the reception wave, the mixer 5 generates a signal including only a DC component as a beat signal. This beat signal is amplified by the intermediate frequency amplifier circuit 6 and is converted from an analog signal to a digital signal by the A / D converter circuit 7. Here, in the signal amplification between Tm, a high-pass filter is often inserted for the purpose of improving the characteristics. In this case, since the DC component is attenuated by the filter, the low-frequency amplifier circuit 9 for detecting the DC component is used. Is installed. The output of the low frequency amplifier 9 is
The A / D conversion circuit 7 is connected to another free channel,
It is digitally converted in the same way as the signal between them. Here, the output of the low frequency amplifying circuit 9 may be switched to the output of the intermediate frequency amplifying circuit 6 by a signal selector and taken into the A / D conversion circuit 7, or a dedicated voltage comparator may be used. Alternatively, a method may be used in which the signal is compared with a voltage set as a threshold value and is taken into the signal processing circuit 8 as a 1-bit signal. Further, a configuration in which the signal is not taken into the signal processing circuit 8 and transmitted to the outside as an output of the radar device may be adopted. The signal processing circuit 8 obtains the distance to the target and the relative speed from the data in the Tm section as a result of the frequency analysis. Also, T
The level of the DC component is obtained from the data in the s section,
A failure is detected by comparing the level of the C component with the set threshold value. When a dedicated voltage comparator is provided, a failure is determined based on the output of the circuit. In the case where a high-pass filter is not inserted in the intermediate frequency amplifying circuit, a special circuit is not required and can be realized by the conventional configuration of FIG.

The operation of the present invention shown in FIG. 3 will be described below. In a normal state, a signal transmitted to the transmission / reception antenna 4 in the Tm section in FIG. 4 is radiated into space from the antenna. Further, the power supplied to the Ts section is reflected by the impedance mismatch of the antenna 4 and guided to the mixer 5 via the circulator 3, so that there is no difference in the transmission / reception frequency and the power is output as a DC level. DC at this time
The level becomes a value higher than the level set in consideration of product variation, temperature drift, and the like, and is determined to be normal by the digital signal processing unit. On the other hand, if one or both inputs of the mixer 5 decrease due to a signal interruption or a significant decrease in the signal level due to a failure or the like, the DC level in the Ts section is set to the set threshold value. The value becomes lower, and is determined to be abnormal. As described above, the failure can be detected at the DC level in the Ts section by using the reflection caused by the impedance mismatch of the antenna 4.

Next, the operation of the signal processing circuit 8 for object recognition and fault detection in the embodiment of the present invention shown in FIG. 3 will be described with reference to the flowchart of FIG. Signal processing circuit 8
Captures data from the A / D conversion circuit 7 that converts a beat signal, which is an analog signal, into digital data (step S101). The acquired data is treated as three data groups of ascending section data, descending section data, and diagnostic section data. The ascending section data is subjected to frequency analysis such as Fourier transform and is converted into spectrum data. (Step S102). From this spectrum data, a peak frequency exceeding a threshold set in consideration of noise is detected (step S103). Next, the down-segment data is similarly converted into spectrum data (step S104) and the peak frequency is detected (step S105).

Next, an actual object is extracted from the combination of the peak frequencies detected by the peak frequency detection of the rising section data (step S103) and the peak frequency detection of the falling section data (step S105) (step S106). ). The distance to the target and the relative speed are calculated from the extracted peak frequency of the target, and each target is recognized (step S107). The process up to this point is the same as the conventional object recognition flow.

Next, frequency analysis is performed on the diagnostic section data to convert it into spectrum data (step S108). The frequency analysis here does not require frequency resolution accuracy unlike the processing for object recognition described above, and thus a simple frequency analysis method may be used. The level Ps of the DC component is detected from the converted spectrum data (step S109).

Next, a comparison is made between the DC level Ps and the threshold value Psh for failure determination which is set in consideration of product variation and temperature drift (step S11).
0). Here, when the DC level Ps exceeds the threshold value Psh, it is determined to be normal, and other control and arithmetic processing performed during normal time is performed (step S111).
Returning to the fetching of / D data (step S101), the repetition processing is performed. Here, the DC level Ps
Is smaller than the threshold value Psh, it is determined to be abnormal, and the information is transmitted to a control device or the like that performs control based on the information of the radar device, or the actuator is directly shut off, or an abnormal condition is generated by an alarm. Notification is performed (step S112).

For example, when the operation is normal, the object is recognized in the object recognition flow (step S113), and the DC level Ps is increased in the failure diagnosis flow (step S114), so that the operation is determined to be normal. On the other hand, assuming that a signal cannot be transmitted to the antenna 4 due to a failure of the circulator 3, for example, regardless of whether an object is present or not,
As a result of the object recognition flow (step S113), it is recognized that there is no object. At this time, the result of the failure diagnosis flow (step S114) indicates that the beat signal has the DC level Ps
Does not occur, and thus falls below the threshold value Psh. As a result, it is determined to be abnormal, and a failure is detected. In the above description, the processing of the diagnosis section may be performed before the processing of the ascending section and the processing of the descending section, or may be performed between the processing of the ascending section and the processing of the descending section.

FIG. 7 shows another embodiment applied to a pulse type radar apparatus. In a pulse-type radar device, a distance is calculated by synchronizing with a pulse signal, transmitting a radio wave intermittently, and measuring a time interval with a received intermittent radio wave. The output of the voltage controlled oscillator 2 is transmitted to the transmitting / receiving antenna 4 via the circulator 3 by the signal interrupter 10 for a fixed time. Here, after the period for transmitting the measurement signal of the object and receiving the reflected wave, a period for transmitting the failure diagnosis signal is inserted. During the object measurement period, the voltage control oscillator 2 is oscillated by the oscillation control circuit 1 ′ at a frequency that the antenna 4 efficiently excites. In the failure diagnosis period, oscillation is performed at a frequency at which the return loss of the antenna is large. Therefore, during the object measurement period, when the object exists, the radio wave transmitted from the transmitting / receiving antenna 4 is reflected by the object and received by the transmitting / receiving antenna 4. The received wave is guided to the mixer 5 via the circulator 3 and mixed with the transmitted wave. Here, the transmission wave and the reception wave have a frequency difference only by the Doppler of the speed of the object, and are output as low-frequency signals. This signal is amplified by the amplifier circuit 11 and shaped into a pulse signal by the waveform shaping circuit 12. By measuring the time difference between this pulse and the intermittent signal of the intermittent device 10 by the control / judgment circuit, the distance to the object can be obtained.

On the other hand, during the diagnosis period, a signal having a high DC level is output from the mixer 5 due to reflection due to impedance mismatch in the transmitting / receiving antenna 4 in a normal state. This signal is shaped into a pulse whose time difference from the intermittent transmission pulse is almost zero. At the time of failure, no pulse is generated because no DC level occurs. Thus, a failure can be detected by making a determination based on whether or not a pulse is generated for the failure diagnosis pulse.

[0031]

According to the present invention, by oscillating at a frequency at which the return loss of the antenna section increases, the fault detection performance can be greatly improved without increasing the number of components or the number of components. . For this reason, it is possible to avoid an increase in the size of the radar device due to the improvement in the failure detection performance, and to contribute to the realization of the radar device at low cost. In addition, the present invention expands the number of fault locations and states that can be detected and provides a diagnosis period within the measurement cycle,
The failure diagnosis can be performed almost simultaneously with the measurement of the object, and the failure can be detected instantaneously. For this reason, a safe inter-vehicle distance maintaining traveling device in a radar device mounted on an automobile,
In an automatic braking device, a collision impact reduction device, or the like, a failure of the radar device can be detected instantaneously, so that the occurrence of abnormal traveling due to the failure can be suppressed, thereby exerting an excellent effect on the safe traveling of the automobile.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a conventional FM-CW radar.

FIG. 2 is a diagram showing signal waveforms and frequency transitions of various parts of a conventional FM-CW radar.

FIG. 3 is a block diagram of an FM-CW radar according to one embodiment;

FIG. 4 is a diagram showing signal waveforms and frequency transitions of each circuit of the FM-CW radar according to one embodiment.

FIG. 5 is a frequency characteristic diagram of an antenna.

FIG. 6 is a flowchart of object recognition and failure diagnosis of the FM-CW radar according to one embodiment.

FIG. 7 is a block diagram of a pulse radar apparatus according to another embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Modulation control circuit 1 '... Oscillation control circuit 2 ... Voltage controlled oscillator 3 ... Circulator 4 ... Transceiving antenna 5 ... Mixer 6 ... Intermediate frequency amplification circuit 7 ... A / D conversion circuit 8 ... Signal processing circuit 9 ... Low frequency amplification circuit Reference Signs List 10 interrupter 11 amplifier circuit 12 waveform shaping circuit 13 control / judgment circuit

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-10-10227 (JP, A) JP-A-11-52052 (JP, A) JP-A-9-145824 (JP, A) JP-A-10- 62525 (JP, A) JP-A-50-140290 (JP, A) JP-A-7-198826 (JP, A) JP-A-57-59181 (JP, A) (58) Fields investigated (Int. ^7, DB name) G01S 7/00 - 7/42 G01S 13/00 - 13/95 G08G 1/16

Claims (8)

(57) [Claims] 1. An antenna for exciting in a certain band,
In a radar apparatus for transmitting and receiving a high-frequency signal of a continuous wave of FM-CW type FM modulation, an oscillator for transmitting a high-frequency signal for object measurement and another high-frequency signal for failure diagnosis of a frequency different from this frequency, , a mixer for mixing the transmission wave of the oscillator and the reflected waves, possess a determination means for performing failure judgment by the output signal of the mixer, said other high-frequency signal, the impedance of the antenna
Is a frequency that causes a mismatch . 2. A high-frequency signal for measurement in said oscillator.
Signal and another high frequency signal for diagnosis, different from the one high frequency signal
Having a modulation control circuit that generates a wave signal to an oscillator
The radar device according to claim 1, wherein: 3. Based on a mixer output DC level before a failure.
Threshold set or predetermined threshold,
Mixer output D at the time of failure or characteristic deterioration in radar equipment
Failure can be detected by comparing C level differences.
Claim 1 or Claim 2 characterized by the above-mentioned.
On-board radar equipment. 4. A failure or characteristic deterioration in the radar device.
The object measurement section measures the mixer output used for detection.
4. The radar device according to claim 3, wherein: 5. A single target, with or without a reflective object
Diagnosis of failure before or after measurement of an object
The radar according to claim 3 or 4, wherein
apparatus. 6. A mixer output signal for detecting a failure.
Use the modulation control circuit and the voltage controlled oscillator to obtain
The method according to any one of claims 2 to 5, wherein
Radar equipment. 7. A high frequency signal of a continuous wave of the FM modulation is transmitted.
The receiving radar apparatus performs modulation control for generating an FM modulated wave.
Circuit, voltage controlled oscillator, and the generated FM modulated wave
Antenna that receives the reflected wave
To the mixer and send the signal received by the antenna to the mixer.
A circulator Komu Ri, and mixing means of the transmitted wave and the received wave
And amplifies the output beat signal of the above mixer.
Intermediate frequency amplifier circuit and low frequency amplifier circuit,
A / D conversion circuit for digitizing the signal amplified by the amplifier
And the Fourier transform of the digitized discrete signal sequence.
7. The signal processing circuit according to claim 1, further comprising:
A radar device according to any of the above. 8. An intermittent transmission of radio waves in synchronization with a pulse signal.
Measure the time interval between intermittent and received radio waves
Pulse-type laser that measures the distance to the target
Output of a voltage controlled oscillator that generates a measurement wave
An interrupter for supplying power to the transmitting / receiving antenna at regular intervals,
A mixer for mixing a transmission wave and a reception wave, and an output of the mixer
Determining means for performing a failure determination by means of
The receiver is the object measurement period for transmitting and receiving for distance measurement
Between transmission and reception of the next object measurement period
A fault diagnosis period for performing communication, and
An oscillation control circuit for controlling an oscillation frequency is provided for measuring the object.
In the period, the antenna excitation effect is better than the fault diagnosis period.
A radar device for transmitting at a low frequency.
Place.