JP2002168947A - Fm-cw radar system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an FM-CW radar system capable of detecting generation of interference by other radar. SOLUTION: An oscillator 2 generates a frequency-modulated transmission signal frequency-modulated by a frequency modulator 1 to be transmitted from a transmission antenna 4 as an electromagnetic wave. The electromagnetic wave emitted from the antenna 4 is reflected by an object to be received by a reception antenna 5. A mixer 6 mixes the received signal received by the antenna 5 with one portion of the transmission signal divided by a directional coupler 3, and a frequency of a mixer output is measured by a frequency measuring instrument 7. A signal processing part 8 calculates a distance and a relative distance with respect to the object based on a measured result by the measuring instrument 7. An interference detecting part 9 compares a level of an amplitude of an output signal of the mixer 6 with a level of a prescribed threshold value, and judges the generation of the interference by the other radar when the amplitude of the output signal exceeds the threshold value.

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 apparatus, and more particularly to an FM-C radar for measuring a distance of a short-distance object.
It relates to a W radar device.

[0002]

2. Description of the Related Art As an FM-CW radar apparatus of this type, an FM-CW radar apparatus which is mounted on an automobile and used for measuring an inter-vehicle distance or the like has been conventionally provided.

FIG. 13 is a schematic configuration diagram of a conventional FM-CW radar device. The FM-CW radar device includes a frequency modulator 1 for generating a modulation signal for modulating the frequency of a transmission signal, and a frequency modulator 1 according to the modulation signal. 2 that generates a transmission signal of a frequency that has been adjusted, a directional coupler 3 that branches a part of the transmission signal generated by the oscillator 2, and a transmission signal S1 input via the directional coupler 3 is radiated by electromagnetic waves. Transmitting antenna 4, a receiving antenna 5 for receiving a reflected wave of the emitted electromagnetic wave, and a mixer for mixing (mixing) a part of the transmitting signal branched by the directional coupler 3 and the receiving signal S 2 of the receiving antenna 5. 6 and an output signal of the mixer 6 (hereinafter, referred to as
This is called a beat signal. A) a frequency measuring device 7 for measuring the frequency of S3, and a signal processing unit 8 for obtaining the distance and the relative speed of the object from the measurement result of the frequency measuring device.

[0004] The modulated signal generated by the frequency modulator 1 is input to an oscillator 2, which generates a frequency-modulated transmission signal, and the transmission signal S 1 is radiated from a transmission antenna 4 by an electromagnetic wave. The reflected wave of the radiated electromagnetic wave is received by the receiving antenna 5, and the received signal S 2 is combined with a part of the transmission signal divided by the directional coupler 3 and a mixer 6.
Mixed by The frequency measuring device 7 measures the frequency of the output signal (beat signal) S3 of the mixer 6, and the signal processing section 8 detects the detection target distance and the relative speed from the frequency of the beat signal S3.

[0005] FIG. 14 shows a time change of the transmission signal S1 and the reception signal S2 when the relative distance to the object is zero.
FIG. 14A shows the time change of the frequency of the beat signal S3 in FIG.
FIG. 15B shows the time change of the transmission signal S1 and the reception signal S2 when the relative distance to the object is V, respectively.
FIG. 15A shows the time change of the frequency of the beat signal S3 in FIG.
(B) shows each. 14 (a) and FIG.
The solid line in (a) shows the signal waveform of the transmission signal S1, and the broken line in the figure shows the signal waveform of the reception signal S2.

When the relative speed with respect to the object to be detected is zero, the received signal S2 received by the receiving antenna 5 is delayed by the time Td with respect to the transmitted signal S1 due to a time delay due to the distance, and a part of the transmitted signal is transmitted by the mixer 6. And a beat signal S3 having a frequency fr is output. Here, assuming that the distance to the object is R and the speed of light is c, the delay time T
d is expressed as Td = 2 × R / c. On the other hand, when the relative speed with respect to the detection target is V, the beat signal S
The frequency of the beat signal is fr ± fd because the frequency of the frequency signal No. 3 changes by fd. Here, assuming that the period in which the frequency modulator 1 modulates the frequency of the transmission signal is Tm, the center frequency of the modulation is f0, and the modulation width is ΔF, the frequencies fr and fd are represented by the following equations.

Fr = 4 × ΔF × R / (c × Tm) (1) fd = 2 × f0 × V / c (2) Therefore, if the frequency of the beat signal S3 is measured, the equation (1) ( The distance to the target and the relative speed can be obtained using 2).

[0008]

By the way, as shown in FIG. 16, a vehicle A running on a road is equipped with the above-mentioned FM-CW radar device, and the distance and relative distance between the vehicle A running ahead and the vehicle B are determined. When measuring the speed, if the radar device is also mounted on another vehicle C running near the vehicle A,
A reflected wave due to a transmission signal radiated from another radar device mounted on the vehicle C is received by the FM-CW radar device mounted on the vehicle A, and interference between the FM-CW radar device and the other FM-CW radar device causes an inter-vehicle distance. There is a possibility that the distance or the relative speed is erroneously detected.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an FM-CW radar device capable of detecting occurrence of interference by another radar. .

[0010]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a frequency modulation section for generating a modulation signal for modulating a frequency of a transmission signal, and a transmission signal having a frequency corresponding to the modulation signal. An oscillation unit that generates a wave, a transmission unit that converts a transmission signal generated by the oscillation unit into a wave such as an electromagnetic wave or a sound wave and transmits the wave, a reception unit that receives a reflected wave due to the transmitted wave, and a reception unit. A mixer that mixes a part of the received signal and a part of the transmitted signal, a frequency measurement unit that measures the frequency of the output signal of the mixer, and a distance / speed measurement that calculates the distance and relative speed of the object from the measurement result of the frequency measurement unit Department and
By comparing the magnitude of either the output signal of the mixer or the signal received by the receiving unit with a predetermined threshold value, it is determined that interference from another radar has occurred if the signal amplitude exceeds the threshold value. When interference with other radars occurs, the receiver receives the reflected wave from the transmission signal of the other radar in addition to the reflected wave from the transmission signal of the own radar. Therefore, the output signal of the mixer that mixes the received signal of the wave receiving unit and the received signal and a part of the transmitted signal is increased as compared with the case where there is no interference. By comparing the magnitude of any one of the signals with the threshold value, it is possible to reliably detect interference from other radars.

According to a second aspect of the present invention, in the first aspect of the present invention, a threshold setting unit is provided which is mounted on the vehicle and changes a threshold value of the amplitude in accordance with speed information of the own vehicle input from the outside. Since the threshold value setting unit changes the threshold value of the amplitude according to the speed of the own vehicle, the threshold value of the distance can be appropriately set according to the speed of the own vehicle.

According to a third aspect of the present invention, in the first aspect of the present invention, a storage unit for storing a previous measurement result of the distance / speed measurement unit, and an amplitude threshold value according to the previous measurement result stored in the storage unit. The threshold setting unit that changes the amplitude is changed according to the information on the distance and the relative speed at the time of the previous measurement stored in the storage unit. The threshold value of the distance can be appropriately set with reference to the value.

According to a fourth aspect of the present invention, a frequency modulator for generating a modulation signal for modulating the frequency of a transmission signal, an oscillator for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillator. A transmitting unit that converts the transmitted wave into a wave such as an electromagnetic wave or a sound wave, and a receiving unit that receives a reflected wave due to the transmitted wave, and a mixer that mixes a received signal of the receiving unit and a part of a transmitted signal. And a frequency measurement unit that measures the frequency of the output signal of the mixer, and a distance / speed measurement unit that determines the distance and relative speed of the target object from the measurement result of the frequency measurement unit. A comparison is made between a magnitude relationship between the frequency of any one of the received signals and a predetermined threshold, and an interference detection unit that determines that interference by another radar has occurred when the frequency of the signal exceeds the threshold is provided. Features and of the mixer Since the frequency of the force signal is proportional to the distance to the object, if the frequency corresponding to the maximum value of the detection range is set as the frequency threshold, the frequency of the output signal of the mixer is changed to the frequency threshold by the interference detection unit. Because it exceeds
It can be determined that an abnormal signal has been input, and interference from other radars can be reliably detected.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, a threshold value setting unit is provided which is mounted on the vehicle and changes a frequency threshold value according to speed information of the own vehicle input from the outside. Since the threshold value setting unit changes the threshold value of the amplitude according to the speed of the own vehicle, the threshold value of the distance can be appropriately set according to the speed of the own vehicle.

According to a sixth aspect of the present invention, in the fourth aspect of the present invention, a storage unit for storing a previous measurement result of the distance / speed measurement unit, and an amplitude threshold according to the previous measurement result stored in the storage unit. The threshold setting unit that changes the amplitude is changed according to the information on the distance and the relative speed at the time of the previous measurement stored in the storage unit. The threshold value of the distance can be appropriately set with reference to the value.

According to a seventh aspect of the present invention, there is provided a frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation section. A transmitting unit that converts the transmitted wave into a wave such as an electromagnetic wave or a sound wave, and a receiving unit that receives a reflected wave due to the transmitted wave, and a mixer that mixes a received signal of the receiving unit and a part of a transmitted signal. And a frequency measuring unit for measuring the frequency of the output signal of the mixer, and a distance / speed measuring unit for obtaining the distance and relative speed of the object from the measurement result of the frequency measuring unit, and storing a signal waveform of the mixer output. Unit, a correlation value measuring unit for obtaining a correlation value indicating a similarity between the mixer output signal waveform stored in the storage unit and the currently measured mixer output signal waveform, and a correlation value obtained by the correlation value measuring unit being a predetermined value. Below the threshold of It is characterized by having an interference detection unit that determines that radar interference has occurred, and the correlation value measurement unit obtains a correlation value indicating the similarity between the signal waveform stored in the storage unit and the signal waveform measured this time. Therefore, when interference from other radars occurs, the signal waveform of the mixer output changes rapidly, and the correlation value decreases.
Since the correlation value obtained by the correlation value measurement unit is lower than the threshold value, it is possible to reliably detect interference from other radars.

According to an eighth aspect of the present invention, in the seventh aspect of the invention, when the correlation value obtained by the correlation value measuring section exceeds the threshold value, the storage section stores a mixer output signal whose storage content is measured this time. It is characterized by updating to a waveform, and when the correlation value obtained by the correlation value measurement unit exceeds the threshold value, it is considered that there is no interference from other radars, and during this time the mixer output stored in the storage unit is By updating the signal waveform, the latest signal waveform in a normal state can be stored in the storage unit.

According to a ninth aspect of the present invention, in the first to eighth aspects, when the interference detecting section detects interference, the frequency modulating section sets the upper limit of the frequency of the transmission signal so as to avoid interference by another radar. The frequency modulation unit changes the upper and lower limits of the frequency of the transmission signal when interference from other radars occurs. By shifting the band from another radar, a mixer output generated by interference with another radar and a mixer output by a transmission signal of the own radar can be distinguished, and interference with another radar can be avoided.

According to a tenth aspect of the present invention, in the first to eighth aspects, when the interference detection unit detects interference, the frequency modulation unit modulates the frequency of a transmission signal so as to avoid interference by another radar. The frequency modulating unit changes the period for modulating the frequency of the transmission signal when interference from other radars occurs. In this case, it is possible to distinguish between a mixer output generated by interference with another radar and a mixer output due to a transmission signal of the own radar, thereby avoiding interference with another radar.

[0020]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) Embodiment 1 of the present invention is shown in FIG.
This will be described with reference to FIG. FIG. 1 shows the FM of the present embodiment.
FIG. 2 is a schematic configuration diagram of a CW radar device, which is used, for example, to measure an inter-vehicle distance and a relative speed with a vehicle mounted on the vehicle and traveling ahead.

This FM-CW radar device includes a frequency modulator (frequency modulation unit) 1 for generating a modulation signal for modulating the frequency of a transmission signal, and an oscillator (modulation unit) for generating a transmission signal of a frequency corresponding to the modulation signal. ) 2, a directional coupler 3 for branching a part of the transmission signal generated by the oscillator 2, and a transmission antenna 4 (transmitting section) for radiating the transmission signal S1 input via the directional coupler 3 by electromagnetic waves. ) And a receiving antenna (wave receiving unit) 5 for receiving a reflected wave due to the emitted electromagnetic wave.
And a mixer 6 for mixing a part of the transmission signal branched by the directional coupler 3 and the reception signal S2 of the reception antenna 5
A frequency measuring unit (frequency measuring unit) 7 for measuring the frequency of the output signal (beat signal) S3 of the mixer 6; and a signal processing unit (distance / distance) for obtaining the distance and relative speed of the object from the measurement result of the frequency measuring device. Speed measuring section) 8 and beat signal S3
And an interference detector 9 for comparing the magnitude relationship between the amplitude of the signal and a predetermined threshold value and determining that interference by another radar has occurred when the signal amplitude exceeds the threshold value.

Here, the oscillator 2 outputs a transmission signal S1 having an amplitude a as shown in FIG. 2 (a), and when this transmission signal S1 is radiated from the transmission antenna 4, if there is no interference by another radar, As shown in FIG. 2B, the amplitude of the output signal (beat signal) S3 of the mixer 6 is equal to or smaller than a preset threshold ath. On the other hand, when the receiving antenna 5 receives a reflected wave due to a transmission signal radiated from another radar,
Since the reception signal S2 of the reception antenna 5 is larger than when there is no interference from other radars, the amplitude of the output signal (beat signal) S3 of the mixer 6 increases and becomes larger than a preset threshold ath.

The interference detector 9 compares the magnitude relationship between the amplitude of the beat signal S3 and the threshold value ath.
If the amplitude of 3 exceeds the threshold value ath, it is determined that interference by another radar has occurred, so that it is possible to reliably detect interference with another radar. Therefore, when the interference detection unit 9 detects interference from another radar, the signal processing unit 8 stops measuring the distance to the target and the relative speed in accordance with the detection result, thereby allowing the radar to communicate with another radar. It is possible to prevent erroneous detection due to the interference of light. Here, the threshold value ath of the distance is set to a value larger than the amplitude of the beat signal S3 when there is no interference by another radar and smaller than the amplitude of the beat signal S3 when interference by another radar occurs. ing.

In the present embodiment, the interference detector 9 detects the presence or absence of interference by another radar by comparing the magnitude of the output signal (beat signal) S3 of the mixer 6 with a predetermined threshold. However, the presence or absence of interference by other radars may be detected by comparing the magnitude relationship between the reception signal S2 received by the reception antenna 5 and a predetermined threshold value. The presence or absence of radar interference can be reliably detected.

(Embodiment 2) FIG. 3 shows Embodiment 2 of the present invention.
This will be described with reference to FIG. In the FM-CW radar apparatus according to the first embodiment, the threshold value ath of the amplitude of the beat signal S3 is set to a value larger than the amplitude when there is no interference from another radar and smaller than the amplitude when there is interference from another radar. And the amplitude threshold value ath is fixed to a predetermined value. However, in the FM-CW radar device of the present embodiment, the amplitude threshold value is determined in accordance with the speed signal S4 of the own vehicle input from outside the device. A threshold setting unit 10 for changing ath is provided. still,
Since the configuration other than the threshold value setting unit 10 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, the interference detector 9 detects the beat signal S3
Is compared with the threshold ath set by the threshold setting unit 10, and when the amplitude of the beat signal S3 exceeds the threshold ath, it is determined that interference by another radar has occurred.
Normally, when the speed of the own vehicle is high, the amplitude of the reception signal S2 received by the receiving antenna 5 is small. Therefore, the threshold value setting ath is reduced in the threshold setting unit 10, and the threshold value ath is reduced according to the speed of the own vehicle. An erroneous detection is prevented by appropriately setting the threshold value ath of the amplitude.

(Embodiment 3) FIG. 4 shows Embodiment 3 of the present invention.
This will be described with reference to FIG. In the FM-CW radar device according to the second embodiment, the threshold setting unit 10 changes the amplitude threshold ath according to the speed signal S4 of the vehicle input from the outside. In the present embodiment, the signal processing unit 8 Is provided with a storage unit 11 for storing the distance to the detected object and the relative speed, and the threshold value setting unit 10 provides an amplitude threshold ath according to the distance and the relative speed at the previous measurement stored in the storage unit 11. Is changing. Since the configuration other than the threshold value setting unit 10 and the storage unit 11 is the same as that of the second embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

The storage unit 11 stores information on the distance to the target and the relative speed detected by the signal processing unit 8 last time. Here, when there is no interference with other radars, the distance to the target and the relative speed do not change suddenly, so the threshold setting unit 10 sets the distance and relative speed to the previously measured target to The threshold value ath of the amplitude of the beat signal S3 is set in consideration of the normally expected variation in the distance and the relative speed. Therefore, the output signal of the mixer 6 (the beat signal S
If 3) exceeds the threshold value ath, the interference detection unit 9 determines that the fluctuation of the beat signal S3 has exceeded the normal fluctuation range, and determines that interference by another radar has occurred.

As described above, in the present embodiment, the threshold setting unit 1
0 assumes the distance and relative speed at the next detection from the distance and relative speed at the previous measurement stored in the storage unit 11,
Since the threshold value ath of the amplitude of the beat signal S3 is set,
By changing the threshold value ath in accordance with the detection state of the object, it is possible to reliably detect interference from other radars.

(Embodiment 4) Embodiment 4 of the present invention is shown in FIG.
This will be described with reference to FIG. In the first embodiment, the interference detection unit 9 detects the presence or absence of interference by another radar by comparing the amplitude of the output signal (beat signal S3) of the mixer 6 with a predetermined threshold ath. In the embodiment, the interference detection unit 9 detects the presence or absence of interference by another radar by comparing the frequency of the beat signal S3 measured by the frequency measuring device 7 with a predetermined threshold fmax. Since the configuration other than the interference detection unit 9 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, assuming that the maximum value of the detection distance of the radar apparatus is Rmax and the frequency of the beat signal S3 corresponding to the maximum range Rmax is fmax, the beat signal S3 of the beat signal S3 is expressed by the above-mentioned equation (1). Since the frequency is proportional to the detection distance R, the frequency of the beat signal S3 due to the object in the detection area becomes equal to or less than fmax, and the beat signal S3 having a frequency exceeding fmax, that is, the frequency range indicated by hatching in FIG. It is considered that the beat signal S3 is generated as a result of interference by another radar.

In the interference detecting section 9, the maximum range R
Using the frequency fmax of the beat signal S3 corresponding to the max as the frequency threshold, the beat signal S3
Is compared with the threshold value fmax. When the frequency of the beat signal S3 exceeds the threshold value fmax, it is determined that interference by another radar has occurred. When the interference detection unit 9 detects the interference from another radar, the signal processing unit 8 stops measuring the distance to the object and the relative speed according to the detection result, and the other radars It is possible to prevent erroneous detection due to the interference of light.

In this embodiment, the interference detector 9 compares the frequency of the output signal (beat signal) S3 of the mixer 6 with a predetermined threshold to detect the presence or absence of interference from another radar. However, the presence / absence of interference by another radar may be detected by comparing the frequency of the reception signal S2 received by the reception antenna 5 with a predetermined threshold value. The presence or absence of radar interference can be reliably detected.

(Embodiment 5) FIG. 7 shows Embodiment 5 of the present invention.
This will be described with reference to FIG. In the FM-CW radar device according to the fourth embodiment, the threshold value fmax of the frequency of the beat signal S3 is fixed to a predetermined value. However, the FM-CW radar device according to the present embodiment is used, for example, mounted on a vehicle. In addition, a threshold setting unit 10 that changes the frequency threshold fmax according to the speed signal S4 of the vehicle input from the outside of the apparatus is provided. Since the configuration other than the threshold value setting unit 10 is the same as that of the fourth embodiment, the same components are denoted by the same reference numerals, and
The description is omitted.

Here, the interference detector 9 is provided with a frequency measuring device 7
Compares the measured frequency of the beat signal S3 with the threshold fmax set by the threshold setting unit 10, and determines that interference by another radar has occurred when the frequency of the beat signal S3 exceeds the threshold fmax. Normally, when the speed of the own vehicle is high, the reception signal S2 received by the reception antenna 5
Becomes higher, and the frequency of the output signal (beat signal S3) of the mixer 6 becomes higher. Therefore, the threshold value setting unit 10 sets the frequency threshold value fmax higher, and appropriately sets the frequency threshold value according to the speed of the own vehicle. By setting, false detection is prevented.

(Embodiment 6) FIG. 8 shows Embodiment 6 of the present invention.
This will be described with reference to FIG. In the FM-CW radar device according to the fifth embodiment, the threshold value setting unit 10 changes the frequency threshold value fmax according to the speed signal S4 of the vehicle input from the outside, but in the present embodiment, the signal processing unit 8 Is provided with a storage unit 11 for storing the distance to the detected object and the relative speed, and the threshold setting unit 10 changes the frequency threshold fmax according to the distance and the relative speed stored in the storage unit 11. Note that the configuration other than the threshold setting unit 10 and the storage unit 11 is the same as that of the fifth embodiment, and therefore, the same components are denoted by the same reference numerals and description thereof will be omitted.

The storage unit 11 stores information on the distance to the target and the relative speed detected by the signal processing unit 8 last time. Here, when there is no interference with other radars, the distance to the target and the relative speed do not change suddenly, so the threshold setting unit 10 sets the distance and relative speed to the previously measured target to The threshold value fmax of the frequency is set in consideration of the normally expected fluctuation in the distance and the relative speed. Therefore, when the frequency of the output signal (beat signal S3) of the mixer 6 exceeds the threshold value fmax, the interference detection unit 9 determines that the fluctuation of the beat signal S3 has exceeded the normal fluctuation range, and sets another radar. It is determined that interference has occurred.

As described above, in the present embodiment, the threshold setting unit 1
0 assumes the distance and relative speed at the next detection from the distance and relative speed at the previous detection stored in the storage unit 11,
Since the frequency threshold fmax is set, interference with another radar can be reliably detected by changing the frequency threshold fmax in accordance with the detection state of the target object.

(Embodiment 7) FIG. 9 shows Embodiment 7 of the present invention.
This will be described with reference to FIG. In the FM-CW radar device according to the first embodiment, the interference detection unit 9 compares the amplitude of the beat signal S3 with a predetermined threshold ath, and when the amplitude of the beat signal S3 exceeds the threshold ath, the interference by another radar. However, in the FM-CW radar apparatus of the present embodiment, the storage unit 11 that stores the signal waveform and the spectrum of the beat signal S3, and the signal waveform and the spectrum of the beat signal S3 measured this time A correlator 12 for obtaining a correlation value indicating a similarity with the previous signal waveform and spectrum stored in the storage unit 11 is provided.
When the correlation value obtained in the step (b) falls below a predetermined threshold value, it is determined that interference by another radar has occurred. Since the configuration other than the interference detection unit 9, the storage unit 11, and the correlator 12 is the same as that of the first embodiment, the same components are denoted by the same reference numerals, and description thereof will be omitted.

Here, when there is no interference from other radars, the beat signal S3 does not fluctuate rapidly.
There is some correlation between the signal waveform and spectrum of the beat signal S3 detected this time and the signal waveform and spectrum of the beat signal S3 stored in the storage unit 11,
The correlation value obtained by the correlator 12 using a predetermined correlation function is higher than a predetermined threshold. On the other hand, when the correlation value obtained by the correlator 12 is lower than the predetermined threshold, the interference detection unit 9 determines that interference from another radar has occurred and the beat signal S3 has changed rapidly. When the interference detection unit 9 detects the interference from another radar, the signal processing unit 8 stops measuring the distance to the object and the relative speed according to the detection result, and the other radars It is possible to prevent erroneous detection due to the interference of light.

In the storage unit 11, when the correlation value obtained by the correlator 12 exceeds the threshold value and the interference detection unit 9 does not detect interference by another radar, the storage contents are updated sequentially. By storing the normal signal waveform and spectrum when there is no interference from the radar, the signal waveform and spectrum stored in the storage unit 11 can be updated to the latest one, and the sudden rise of the beat signal S3 due to the interference of another radar. Such a change can be reliably detected.

(Embodiment 8) Embodiment 8 of the present invention is shown in FIG.
This will be described with reference to FIGS. In the present embodiment, in the FM-CW radar apparatus according to the first embodiment, when the interference detection unit 9 detects interference by another radar, the frequency modulator 1 controls the frequency of the transmission signal S1 so as to avoid interference with another radar. Is changing. Since the configuration other than the frequency modulator 1 is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof will be omitted.

Here, when the interference detector 9 detects interference from another radar, the frequency modulator 1 sets the center frequency of the transmission signal (b in FIG. 11) output from the oscillator 2 as shown in FIG. The maximum value and the minimum value of the frequency of the transmission signal are made higher than the transmission signal before the change (a in FIG. 11), and the frequency band for modulating the transmission signal is made higher than that of other radars. Accordingly, the frequency of the beat signal obtained by mixing the reception signal obtained by receiving the reflected wave by the transmission signal of another radar and the transmission signal of the own radar by the mixer 6 becomes the same as that of the reception signal receiving the reflected wave by the transmission signal of the own radar. The frequency is sufficiently higher than the frequency of the beat signal obtained by mixing the transmission signal of the radar with the mixer 6. Therefore, the signal processing unit 8 can distinguish a beat signal generated by the transmission signal and the reception signal of the own radar from a beat signal generated by interference with another radar, and can determine a beat signal generated by interference with another radar. By ignoring the signal, erroneous detection due to interference with another radar can be prevented.

In the present embodiment, when the interference detector 9 detects interference from another radar, the frequency modulator 1 changes the center frequency of the transmission signal according to the detected signal, and modulates the transmission signal. Is shifted to avoid interference from other radars, but it is also possible to avoid interference from other radars by changing the frequency modulation cycle of the transmission signal. For example, C in FIG. 12 shows the transmission signal before the change, and D in FIG. 12 shows the transmission signal after the change. If the period for modulating the frequency of the transmission signal is made longer than before the change,
The frequency of the beat signal obtained by mixing the reception signal that has received the reflected wave of the transmission signal of the other radar and the transmission signal of the own radar with the mixer 6 is the same as that of the reception signal that has received the reflection wave due to the transmission signal of the own radar and the own radar. Transmitter and mixer 6
Since it becomes sufficiently higher than the frequency of the beat signal mixed in the above, it is possible to distinguish beat signals generated by interference with other radars, and by ignoring beat signals generated by interference with other radars, False detection due to interference with other radars can be prevented.

The FM-C according to the second to seventh embodiments described above.
In the W radar device, similarly to the present embodiment, when the interference detection unit 9 detects the interference by another radar, the transmission signal S is set so that the frequency modulator 1 avoids the interference with another radar.
1 may be changed, thereby avoiding interference with other radars and preventing erroneous detection.

[0047]

As described above, according to the first aspect of the present invention, there is provided a frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, A transmitting unit that converts a transmission signal generated by an oscillation unit into a wave such as an electromagnetic wave or a sound wave and transmits the wave, a receiving unit that receives a reflected wave due to the transmitted wave, and a reception signal and a transmission signal of the reception unit. A mixer for mixing a part of the mixer, a frequency measurement unit for measuring the frequency of the output signal of the mixer, and a distance / speed measurement unit for obtaining a distance and a relative speed of the object from the measurement result of the frequency measurement unit. Interference in which the magnitude of either the output signal or the signal received by the receiving unit is compared with a predetermined threshold value, and if the signal amplitude exceeds the threshold value, it is determined that interference from another radar has occurred. Characterized by having a detection unit If interference with other radar occurs, because in addition to the reflected wave by the transmission signal of its own radar, received by the reception section of the reflected wave by the transmission signal of the other radar,
Since the reception signal of the reception unit and the output signal of the mixer in which the reception signal and a part of the transmission signal are mixed are increased as compared with the case where there is no interference, the interference detection unit uses either the output signal of the mixer or the reception signal. By comparing the magnitude of the amplitude of one of the signals with the threshold value, there is an effect that the interference by another radar can be reliably detected.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a threshold setting unit mounted on the vehicle and changing a threshold value of the amplitude in accordance with the speed information of the own vehicle input from the outside. Since the threshold value setting unit changes the threshold value of the amplitude according to the speed of the own vehicle, there is an effect that the threshold value of the distance can be appropriately set according to the speed of the own vehicle.

According to a third aspect of the present invention, in the first aspect of the present invention, a storage unit for storing the previous measurement result of the distance / speed measurement unit, and a threshold value of the amplitude according to the previous measurement result stored in the storage unit. The threshold setting unit that changes the amplitude is changed according to the information on the distance and the relative speed at the time of the previous measurement stored in the storage unit. There is an effect that the threshold value of the distance can be appropriately set with reference to the value.

According to a fourth aspect of the present invention, there is provided a frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation section. A transmitting unit that converts the transmitted wave into a wave such as an electromagnetic wave or a sound wave, and a receiving unit that receives a reflected wave due to the transmitted wave, and a mixer that mixes a received signal of the receiving unit and a part of a transmitted signal. And a frequency measurement unit that measures the frequency of the output signal of the mixer, and a distance / speed measurement unit that determines the distance and relative speed of the target object from the measurement result of the frequency measurement unit. A comparison is made between a magnitude relationship between the frequency of any one of the received signals and a predetermined threshold, and an interference detection unit that determines that interference by another radar has occurred when the frequency of the signal exceeds the threshold is provided. Feature and mixer output Since the frequency of the signal is proportional to the distance from the object, if the frequency corresponding to the maximum value of the detection range is set as the frequency threshold, the frequency of the output signal of the mixer will be adjusted to the frequency threshold in the interference detection unit. As a result, it can be determined that an abnormal signal has been input, and there is an effect that interference from other radars can be reliably detected.

According to a fifth aspect of the present invention, in the fourth aspect of the present invention, there is provided a threshold setting unit mounted on the vehicle and changing a frequency threshold in accordance with the speed information of the own vehicle input from the outside. Since the threshold value setting unit changes the threshold value of the amplitude according to the speed of the own vehicle, there is an effect that the threshold value of the distance can be appropriately set according to the speed of the own vehicle.

According to a sixth aspect of the present invention, in accordance with the fourth aspect of the present invention, there is provided a storage unit for storing a previous measurement result of the distance / speed measuring unit, and an amplitude threshold value according to the previous measurement result stored in the storage unit. The threshold setting unit that changes the amplitude is changed according to the information on the distance and the relative speed at the time of the previous measurement stored in the storage unit. There is an effect that the threshold value of the distance can be appropriately set with reference to the value.

According to a seventh aspect of the present invention, there is provided a frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation section. A transmitting unit that converts the transmitted wave into a wave such as an electromagnetic wave or a sound wave, and a receiving unit that receives a reflected wave due to the transmitted wave, and a mixer that mixes a received signal of the receiving unit and a part of a transmitted signal. And a frequency measuring unit for measuring the frequency of the output signal of the mixer, and a distance / speed measuring unit for obtaining the distance and relative speed of the object from the measurement result of the frequency measuring unit, and storing a signal waveform of the mixer output. Unit, a correlation value measuring unit for obtaining a correlation value indicating a similarity between the mixer output signal waveform stored in the storage unit and the currently measured mixer output signal waveform, and a correlation value obtained by the correlation value measuring unit being a predetermined value. Below the threshold of The correlation value measurement unit determines the correlation value indicating the similarity between the signal waveform stored in the storage unit and the signal waveform measured this time. When interference from other radars occurs, the signal waveform of the mixer output changes abruptly and the correlation value decreases, so that in the interference detection unit, the correlation value obtained by the correlation value measurement unit is larger than the threshold value. The reduction has the effect of reliably detecting interference from other radars.

According to an eighth aspect of the present invention, in the seventh aspect of the present invention, when the correlation value obtained by the correlation value measurement section exceeds the threshold value, the storage section outputs the mixer output signal whose storage content has been measured this time. It is characterized by updating to a waveform, and when the correlation value obtained by the correlation value measurement unit exceeds the threshold value, it is considered that there is no interference from other radars, and during this time the mixer output stored in the storage unit is Updating the signal waveform has the effect that the latest signal waveform in a normal state can be stored in the storage unit.

According to a ninth aspect of the present invention, in the first to eighth aspects, when the interference detection unit detects interference, the frequency modulation unit sets an upper limit of the frequency of the transmission signal so as to avoid interference by another radar. The frequency modulation unit changes the upper and lower limits of the frequency of the transmission signal when interference from other radars occurs. By shifting the band from other radars, the mixer output generated by interference with other radars can be distinguished from the mixer output by the transmission signal of the own radar, and the effect of avoiding interference with other radars can be avoided. There is.

According to a tenth aspect of the present invention, in the first to eighth aspects, when the interference detection unit detects interference, the frequency modulation unit modulates the frequency of a transmission signal so as to avoid interference by another radar. The frequency modulating unit changes the period for modulating the frequency of the transmission signal when interference from other radars occurs. In this case, the mixer output generated due to interference with another radar can be distinguished from the mixer output generated by the transmission signal of the own radar, so that interference with other radars can be avoided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an FM-CW radar device according to a first embodiment.

FIGS. 2 (a) to 2 (c) are waveform diagrams of respective parts of the above.

FIG. 3 is a schematic configuration diagram of an FM-CW radar device according to a second embodiment.

FIG. 4 is a schematic configuration diagram of an FM-CW radar device according to a third embodiment.

FIG. 5 is a schematic configuration diagram of an FM-CW radar device according to a fourth embodiment.

FIG. 6 is a diagram showing a spectrum of a beat signal of the above.

FIG. 7 is a schematic configuration diagram of an FM-CW radar device according to a fifth embodiment.

FIG. 8 is a schematic configuration diagram of an FM-CW radar device according to a sixth embodiment.

FIG. 9 is a schematic configuration diagram of an FM-CW radar device according to a seventh embodiment.

FIG. 10 is a schematic configuration diagram of an FM-CW radar device according to an eighth embodiment.

FIG. 11 is a waveform diagram of a transmission signal of the above.

FIG. 12 is a waveform diagram of another transmission signal according to the embodiment.

FIG. 13 is a schematic configuration diagram of a conventional FM-CW radar device.

14A and 14B are waveform diagrams of respective parts when the above relative speed is zero, wherein FIG. 14A is a time waveform of a frequency of a transmission signal and a reception signal, and FIG. 14B is a time waveform of a frequency of a beat signal. .

15A and 15B are waveform diagrams of respective parts when the above relative speed is V, where FIG. 15A is a time waveform of the frequency of the transmission signal and the reception signal, and FIG. 15B is a time waveform of the frequency of the beat signal. .

FIG. 16 is an explanatory diagram illustrating a use state of the above.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Frequency modulator 2 Oscillator 3 Directional coupler 4 Transmitting antenna 5 Receiving antenna 6 Mixer 7 Frequency measuring device 8 Signal processing part 9 Interference detecting part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takashi Fujii 1048 Kazuma Kadoma, Kadoma City, Osaka Prefecture Inside Matsushita Electric Works Co., Ltd. Terms (reference) 5J070 AB17 AC02 AC06 AD02 AE01 AF03 AH14 AH23 AK02 AK06 AK32 BA01

Claims (10)

[Claims] A frequency modulator for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation unit for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation unit for converting an electromagnetic wave or a sound wave. A wave transmitting unit that converts the waves into waves and sends the waves, a wave receiving unit that receives a reflected wave due to the waves sent,
A mixer that mixes a part of a reception signal and a transmission signal of a reception unit, a frequency measurement unit that measures a frequency of an output signal of the mixer, and a distance that obtains a distance and a relative speed of an object from measurement results of the frequency measurement unit A speed measurement unit, and compares the magnitude relationship between the amplitude of any one of the output signal of the mixer and the reception signal of the reception unit with a predetermined threshold, and when the amplitude of the signal exceeds the threshold, another An FM-CW radar device comprising an interference detection unit for judging that radar interference has occurred. 2. The FM-CW radar device according to claim 1, further comprising a threshold setting unit mounted on the vehicle and configured to change a threshold value of the amplitude according to speed information of the vehicle input from outside. . 3. A storage unit for storing a previous measurement result of the distance / speed measurement unit, and a threshold setting unit for changing a threshold value of the amplitude according to the previous measurement result stored in the storage unit. The FM-CW radar device according to claim 1, wherein 4. A frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation section for transmitting an electromagnetic wave or a sound wave. A wave transmitting unit that converts the waves into waves and sends the waves, a wave receiving unit that receives a reflected wave due to the waves sent,
A mixer that mixes a part of a reception signal and a transmission signal of a reception unit, a frequency measurement unit that measures a frequency of an output signal of the mixer, and a distance that obtains a distance and a relative speed of an object from measurement results of the frequency measurement unit A speed measurement unit, and compares the magnitude relationship between the frequency of any one of the output signal of the mixer and the reception signal of the reception unit with a predetermined threshold, and when the frequency of the signal exceeds the threshold, the other An FM-CW radar device comprising an interference detection unit for judging that radar interference has occurred. 5. The FM-CW according to claim 4, further comprising a threshold value setting unit mounted on the vehicle and changing a frequency threshold value according to the speed information of the vehicle input from outside.
Radar equipment. 6. A storage unit for storing a previous measurement result of the distance / speed measurement unit, and a threshold setting unit for changing a threshold value of the amplitude according to the previous measurement result stored in the storage unit. The FM-CW radar device according to claim 4, wherein 7. A frequency modulation section for generating a modulation signal for modulating the frequency of a transmission signal, an oscillation section for generating a transmission signal having a frequency corresponding to the modulation signal, and a transmission signal generated by the oscillation section for converting an electromagnetic wave or a sound wave. A wave transmitting unit that converts the waves into waves and sends the waves, a wave receiving unit that receives a reflected wave due to the waves sent,
A mixer that mixes a part of a reception signal and a transmission signal of a reception unit, a frequency measurement unit that measures a frequency of an output signal of the mixer, and a distance that obtains a distance and a relative speed of an object from measurement results of the frequency measurement unit A storage unit that includes a speed measurement unit and stores a mixer output signal waveform, and obtains a correlation value indicating a similarity between the mixer output signal waveform stored in the storage unit and the currently measured mixer output signal waveform; An FM-CW radar apparatus, comprising: a correlation value measuring unit; and an interference detecting unit that determines that interference by another radar has occurred when the correlation value obtained by the correlation value measuring unit falls below a predetermined threshold. 8. The storage unit according to claim 7, wherein when the correlation value obtained by said correlation value measurement unit exceeds the threshold value, the storage unit updates the stored content to the signal waveform of the mixer output measured this time. The FM-CW radar device as described in the above. 9. The apparatus according to claim 1, wherein when the interference detecting section detects the interference, the frequency modulating section changes the upper limit value and the lower limit value of the frequency of the transmission signal so as to avoid interference by another radar. 9. The FM-CW radar device according to any one of 1 to 8. 10. The apparatus according to claim 1, wherein when the interference detecting section detects the interference, the frequency modulating section changes a cycle of modulating the frequency of the transmission signal so as to avoid interference by another radar. 8. The FM-CW radar device according to 8.