JP2014202602A - Transmitter-receiver and transmitting/receiving method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To confirm operation, while minimizing an increase in device scale.SOLUTION: A transmitter-receiver which calculates a distance to a target on the basis of a transmission wave transmitted to the target and a reflection wave of the transmission wave from the target includes: a high-frequency circuit which transmits a first transmission wave from a transmission antenna to the target, and outputs a signal having a beat frequency generated by mixing the first transmission wave with a first transmission wave received via a receiving antenna; and a control signal processing circuit which detects a peak frequency component to be generated by antenna coupling on the basis of the signal having the beat frequency output by the high-frequency circuit, and determines normal operation on the basis of changes of the frequency component.

Description

  The present invention relates to a transmission / reception device.

  A function is known in which a vehicle running in an adjacent lane is detected by a radar and an indicator mounted on a door mirror is turned on when the vehicle enters an area that cannot be seen from a side mirror. This function is sometimes called a blind spot monitor. For example, a frequency-modulated continuous wave (FM-CW) radar is used as a radar that detects a vehicle.

  When the detected vehicle is in an area that cannot be seen from the side mirror and the side turn lamp blinks, the blind spot monitor alerts the driver by blinking the indicator.

  With regard to the millimeter wave transmission / reception module, a technique is known in which the modulation voltage and / or power supply voltage of a voltage controlled oscillation circuit is periodically monitored to monitor whether there is an abnormality in the transmission frequency (for example, see Patent Document 1).

Japanese Patent Laid-Open No. 2008-232528

  FM-CW radar controls the oscillation frequency by changing the control voltage applied to the voltage controlled oscillator. Therefore, it is preferable to monitor the control voltage in order to confirm the operation of the FM-CW radar.

  If the output signal of the voltage controlled oscillator is fed back by the phase synchronization circuit, and the oscillation frequency is monitored based on the fed back signal, the addition of the phase synchronization circuit increases the scale of the apparatus and increases the cost. It becomes.

  Further, even if the control voltage is converted into a digital signal by an AD converter and the digital signal is monitored, the addition of the AD converter increases the scale of the apparatus and increases the cost.

  The present invention is to confirm the operation while minimizing an increase in the scale of the apparatus.

A transmission / reception apparatus according to an embodiment of the disclosure includes:
A transmission / reception device that calculates a distance between the transmission wave transmitted to the target and a reflection wave of the transmission wave by the target,
A signal having a beat frequency generated by transmitting a first transmission wave from the transmission antenna to the target and mixing the first transmission wave and the first transmission wave received via the reception antenna A high-frequency circuit that outputs
A control signal that detects a peak frequency component due to antenna coupling based on a signal having a beat frequency output from the high-frequency circuit, and determines whether or not the device is operating normally based on fluctuations in the frequency component And a processing circuit.

The transmission / reception method of an embodiment of the disclosure is as follows:
A transmission / reception method in a transmission / reception apparatus that calculates a distance between a target and a transmission wave transmitted to a target and a reflection wave of the transmission wave by the target,
Transmitting a first transmission wave from the transmission antenna to the target;
Generating a signal having a beat frequency by mixing the first transmission wave and the first transmission wave received via a receiving antenna;
Based on a signal having the beat frequency, a peak frequency component due to antenna coupling is detected,
Based on the fluctuation of the frequency component, it is determined whether or not it is operating normally.

  According to the disclosed embodiment, it is possible to confirm the operation while minimizing an increase in the scale of the apparatus.

It is a figure which shows one Example of a transmission / reception apparatus. It is a figure which shows one Example of a high frequency circuit. It is a figure which shows one Example of a control signal processing circuit. It is a figure which shows one Example of a control voltage. It is a figure which shows one Example of a beat signal. It is a functional block diagram which shows one Example of a control signal processing circuit. It is a figure which shows the relationship between a transmission signal, a received signal, and a beat signal. It is a flowchart which shows one Example of operation | movement of a transmission / reception apparatus.

Next, the form for implementing this invention is demonstrated, referring drawings based on the following Examples. Examples described below are merely examples, and embodiments to which the present invention is applied are not limited to the following examples.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

<Example>
<Transmitting / receiving device>
FIG. 1 shows an embodiment of a transmission / reception device 100. The transmission / reception device 100 is a so-called radar that emits radio waves toward an object (target) and measures a reflected wave of the radio waves from the object. One embodiment of the transmission / reception apparatus 100 emits a quasi-millimeter wave toward an object and measures a reflected wave from the quasi-millimeter wave object. Not only the quasi-millimeter wave but also a radio wave different from the quasi-millimeter wave such as a millimeter wave can be emitted. The transmitting / receiving apparatus 100 emits a quasi-millimeter wave as a frequency-modulated continuous wave (FMCW). That is, the transmission / reception device 100 periodically and linearly increases and decreases the frequency of the quasi-millimeter wave and transmits it without interruption.

  The transmission / reception device 100 is preferably applied to a blind spot monitor. By applying it to a blind spot monitor, it is possible to detect a vehicle traveling in the adjacent lane. Moreover, the transmission / reception apparatus 100 can also be applied to cruise control. By applying it to cruise control, traveling control can be executed at a speed instructed by the driver. Further, by installing the cruise control function in the vehicle, it is possible to maintain the instructed speed without continuing to step on the accelerator pedal.

  The transmission / reception device 100 obtains a signal having a beat frequency (hereinafter referred to as “beat signal”) by mixing the reflected wave and the transmitted wave based on the reflected wave from the target. The beat frequency is proportional to the distance R between the transmission / reception device 100 and the target and the relative velocity V between the transmission / reception device 100 and the target. Based on the beat signal, the transmission / reception device 100 calculates a frequency corresponding to the distance (hereinafter referred to as “distance frequency”) and a frequency corresponding to the relative speed (hereinafter referred to as “relative speed frequency”). And the relative speed between the target and the target.

  Here, in addition to the reflected wave from the target, the transmission / reception device 100 may receive a radio wave transmitted without being reflected by the target. By receiving the transmitted radio wave as it is, so-called antenna coupling occurs. The occurrence of antenna coupling is undesirable because it corresponds to the target having a relative velocity of zero immediately before the antenna. On the other hand, it is known that the distance frequency obtained by receiving the transmitted radio wave as it is by antenna coupling is constant.

  Therefore, one embodiment of the transmission / reception device 100 determines whether or not it is operating normally by measuring a beat signal obtained by mixing a transmission wave and a reception wave. Here, the received wave is a reflected wave from the target and a received transmitted wave that is reflected by the target.

  The transmission / reception apparatus 100 includes a transmission antenna 102, a reception antenna 104, a high frequency circuit 106, and a control signal processing circuit 108.

  The transmission antenna 102 transmits a millimeter wave to the target as a frequency-modulated continuous wave.

  The high frequency circuit 106 is connected to the transmission antenna 102. The high frequency circuit 106 generates a transmission wave based on the control voltage from the control signal processing circuit 108. The high frequency circuit 106 generates a beat signal by mixing the reception wave from the reception antenna 104 and the transmission wave, and inputs the beat signal to the control signal processing circuit 108.

<High-frequency circuit 106>
FIG. 2 shows an embodiment of the high-frequency circuit 106.

  The high-frequency circuit 106 includes a voltage-controlled oscillator (VCO) 202, a directional coupler 204, amplifiers 206 and 208, and a mixer 210.

  The voltage controlled oscillator 202 is connected to the control signal processing circuit 108. The voltage control oscillator 202 receives a control voltage from the control signal processing circuit 108. The voltage controlled oscillator 202 controls the transmission frequency by the control voltage from the control signal processing circuit 108. The oscillation wave from the voltage controlled oscillator 202 is input to the directional coupler 204.

  The directional coupler 204 is connected to the voltage controlled oscillator 202 and the transmission antenna 102. The directional coupler 204 transmits the oscillation wave from the voltage controlled oscillator 202 from the transmission antenna 102 and inputs it to the amplifier 206.

  The amplifier 206 is connected to the directional coupler 204. The amplifier 206 amplifies the oscillation wave from the directional coupler 204. The amplifier 206 inputs the amplified oscillation wave to the mixer 210.

  The amplifier 208 is connected to the receiving antenna 104. The amplifier 208 amplifies the reception wave from the reception antenna 104. The amplifier 208 inputs the amplified received wave to the mixer 210.

  The mixer 210 is connected to the amplifiers 206 and 208. The mixer 210 mixes the oscillation wave amplified by the amplifier 206 and the reception wave amplified from the amplifier 208. The mixer 210 inputs a beat signal generated by mixing to the control signal processing circuit 108.

  The control signal processing circuit 108 is connected to the high frequency circuit 106. The control signal processing circuit 108 generates a control signal to be input to the voltage controlled oscillator 202 of the high frequency circuit 106. Further, the control signal processing circuit 108 calculates the distance frequency and the relative speed frequency based on the beat signal from the high frequency circuit 106, and calculates the distance and the relative speed between the target and the target. Further, the control signal processing circuit 108 determines whether or not the operation of the transmission / reception circuit 100 is normal based on the beat signal from the high frequency circuit 106.

<Control signal processing circuit 108>
FIG. 3 shows an embodiment of the control signal processing circuit 108.

  The control signal processing circuit 108 includes a main control unit (MCU) 302, a modulation control circuit 304, an intermediate wave processing circuit 306, and a signal capturing circuit 308.

  The main control unit 302 executes overall control of the transmission / reception device 100. Specifically, the main control unit 302 executes control of a D / A converter (not shown) mounted on the modulation control circuit 304. The main control unit 302 inputs a control signal for controlling the D / A converter of the modulation control circuit 304 to the modulation control circuit 304.

  The modulation control circuit 304 is connected to the main control unit 302 and the high frequency circuit 106. The modulation control circuit 304 includes an oscillation circuit (not shown) and a D / A converter (not shown). The oscillation circuit generates a frequency control voltage. The D / A converter operates in accordance with a control signal from the main control unit 302, and generates a control voltage by converting a digital voltage value of the frequency control voltage from the oscillation circuit into an analog voltage value. The modulation control circuit 304 inputs a control voltage to the voltage controlled oscillator 202.

  FIG. 4 shows an example of the control voltage output by the modulation control circuit 304. FIG. 4 shows the relationship between time and control voltage.

  As shown in FIG. 4, the control voltage is preferably a triangular wave. Further, the control voltage may be represented by a waveform other than a triangular wave.

  The intermediate wave processing circuit 306 is connected to the high frequency circuit 106. The intermediate wave processing circuit 306 amplifies the beat signal from the high frequency circuit 106 and performs filtering. The intermediate wave processing circuit 306 inputs the filtered beat signal to the signal reading circuit 308.

  The signal reading circuit 308 is connected to the intermediate wave processing circuit 306. The signal reading circuit 308 converts the filtered beat signal from the intermediate wave processing circuit 306 into a digital signal under the control of the main control unit 302. The signal reading circuit 308 converts the beat signal into a signal in the frequency domain by performing a fast Fourier transform (FFT) on the beat signal converted into the digital signal under the control of the main control unit 302. The beat signal revealed as a frequency domain signal by the signal reading circuit 308 is input to the main control unit 302.

  FIG. 5 shows an example of signals input from the signal reading circuit 308 to the main control unit 302. FIG. 5 shows the relationship between frequency and signal strength.

  As shown in FIG. 5, the output signal from the signal reading circuit 308 includes a peak due to the frequency component due to antenna coupling (hereinafter referred to as “first peak”) and a peak due to the frequency component due to the target (hereinafter referred to as “ Second peak ”).

  The main control unit 302 is connected to the signal capturing circuit 308. The main control unit 302 calculates the distance to the target and the relative distance to the target based on the beat signal from the signal capturing circuit 308.

<Main control unit 302>
FIG. 6 shows the main control unit 302. The main control unit 302 is preferably configured by a processor such as a digital signal processor (DSP) or an integrated circuit such as an FPGA (field-programmable gate array).

  The functions of the distance / relative speed calculation unit 402, the peak component detection unit 404, and the operation determination unit 406 are preferably executed by the processor in accordance with an application (firmware) stored in the processor. Further, the functions as the distance / relative speed calculation unit 402, the peak component detection unit 404, and the operation determination unit 406 may be executed by a processor according to an application stored in a storage unit (not shown).

  The main control unit 302 functions as the distance / relative speed calculation unit 402.

  The distance / relative speed calculation unit 402 calculates the distance to the target and the relative speed with respect to the target based on the beat signal.

  FIG. 7 shows the relationship between time and frequency (upper side) for transmission waves and reception waves, and the relationship between time and frequency (lower side) for beat frequencies.

In FIG. 7, “c” is the speed of light (m / s), “Δf” is the frequency modulation width (Hz), “T” is the modulation repetition period (s), “f ₀ ” is the center frequency (Hz), “R”. "Represents distance (m), and" V "represents relative velocity (m / s). “F _BD ” and “f _BU ” indicate beat frequency (Hz), “f _R ” indicates distance frequency (Hz), and “f _V ” indicates relative velocity frequency (Hz).

  In the relationship between time and frequency (upper side) for the transmission wave and the reception wave, the solid line indicates the transmission wave, and the broken line indicates the reception wave. The radio wave reflected by the target reciprocates between the transmission / reception device 100 and the target. Therefore, the reflected wave is received with a time delay corresponding to the distance (2R) for reciprocating between the transmission / reception device 100 and the target. In addition, when there is a relative speed V between the transmission / reception device 100 and the target, the reception frequency is shifted due to the Doppler effect.

Among the received waves, the one with a time delay of 2R _A / c with respect to the transmitted wave indicates the transmitted wave received without being reflected by the target, and the time delay with respect to the transmitted wave is represented with 2R / c. What is shown shows the reflected wave reflected by the target.

  Moreover, Formula (4) is formed from Formula (1).

f _R = (f _BD + f _BU ) / 2 (1)
f _V = (f _BD -f _BU ) / 2 (2)
R = f _R・ c ・ T / 4 ・ Δf （３）
V = f _V・ c / 2 ・ f ₀ （４）
The distance / relative speed calculation unit 402 calculates the distance to the target by Expression (5) obtained from Expression (1) to Expression (4), and calculates the relative speed by Expression (6).

R = (f _BD + f _BU ) ・ c ・ T / 4 ・ Δf (5)
V = (f _BD -f _BU ) ・ c / 2 ・ f ₀ (6)
The distance / relative speed calculator 402 outputs the distance R between the target and the relative speed V obtained by the calculation.

  The main control unit 302 functions as the peak component detection unit 404.

  The peak component detection unit 404 detects the first peak from the output signal from the signal reading circuit 308. As shown in FIG. 5, two peaks of a first peak and a second peak are detected in the output signal from the signal reading circuit 308. The peak component detection unit 404 preferably detects a peak on the lower frequency side of the two detected peaks as the first peak. The peak component detection unit 404 detects the detected frequency component of the first peak. The peak component detection unit 404 inputs the frequency component of the first peak to the operation determination unit 406.

  The main control unit 302 functions as the operation determination unit 406. The operation determination unit 406 is connected to the peak component detection unit 404. The operation determination unit 406 determines whether or not the transmission / reception device 100 is operating normally based on the frequency component of the first peak from the peak component detection unit 404. Specifically, the operation determination unit 406 determines whether or not the fluctuation of the frequency component of the first peak from the peak component detection unit 404 is within a predetermined threshold value, so that the transmission / reception device 100 operates normally. It is preferable to determine whether or not. Here, the normal operation of the transmission / reception device 100 means that the operation of the modulation control circuit 304 is normal.

  The operation determination unit 406 determines that the transmission / reception device 100 is operating normally when the variation in the frequency component of the first peak is within a predetermined threshold. When it is determined that it is operating normally, it is preferable that the operation of the transmission / reception device 100 is continued.

  The operation determining unit 406 determines that the transmission / reception device 100 is not operating normally when the fluctuation of the frequency component of the first peak is not within the predetermined threshold, that is, when the fluctuation of the frequency component of the first peak is large. judge. When it is determined that the transmission / reception apparatus 100 is not operating normally, the operation of the transmission / reception apparatus 100 is preferably stopped. If it is determined that the device is not operating normally, the transmitting / receiving device 100 may sound an alarm.

<Operation of Transmission / Reception Device 100>
FIG. 8 shows an embodiment of the operation of the transmission / reception device 100.

  In step S802, the transmission / reception device 100 transmits a quasi-millimeter wave as a frequency-modulated continuous wave. A quasi-millimeter wave is wirelessly transmitted from the high-frequency circuit 106 via the transmission antenna 102.

  In step S804, the transmission / reception device 100 receives a radio wave including a reflected wave reflected by the target. The reflected wave is received by the high frequency circuit 106 via the receiving antenna 104. Here, a transmission wave that is not reflected by the target may be received via the reception antenna 104.

  In step S806, the transmission / reception device 100 extracts a beat signal by mixing a transmission wave and a radio wave including a reflected wave. The mixer 210 generates a beat signal by mixing a transmission wave and a radio wave including a reflected wave.

  In step S808, the transmission / reception device 100 performs FFT processing on the beat signal. The beat signal is input to the control signal processing circuit 108. In the control signal processing circuit 108, the band of the beat signal is limited in the intermediate wave processing circuit 306. The signal reading circuit 308 converts the beat signal having a limited band into a frequency domain signal by performing an FFT conversion.

  In step S810, the transmission / reception device 100 obtains the frequency component of the first peak from the beat signal subjected to the FFT processing. The frequency domain signal generated by the FFT conversion by the signal reading circuit 308 is input to the main control unit 302. In the main control unit 302, the main control unit 302 functions as the peak component detection unit 404, thereby obtaining the frequency component of the first peak from the frequency domain signal.

  In step S812, the transmission / reception device 100 determines whether or not it is operating normally based on the fluctuation of the frequency component of the first peak. The main control unit 302 determines whether the main control unit 302 is operating normally by functioning as the operation determination unit 406.

  According to one embodiment of the transmission / reception device 100, it is possible to determine whether or not the control voltage applied to the voltage controlled oscillator is normal by monitoring the beat frequency due to antenna coupling. That is, it is possible to determine whether or not the modulation control circuit that applies the control voltage to the voltage controlled oscillator is normal based on the fluctuation of the peak frequency component due to the antenna coupling extracted from the beat signal. When the fluctuation of the peak frequency component due to antenna coupling is within a predetermined threshold, it is determined that the modulation control circuit is operating normally. Further, when the fluctuation of the peak frequency component due to the antenna coupling is larger than a predetermined threshold, it is determined that the modulation control circuit is not operating normally. Ideally, the peak frequency component due to antenna coupling takes a constant value.

  In addition to the function of detecting the peak frequency component, it can be realized by installing software that executes a function of monitoring whether or not the operation is normal in the transmission / reception apparatus 100. Therefore, it can be realized without newly installing hardware. For this reason, an increase in the scale of the apparatus can be minimized. In addition, an increase in cost can be suppressed.

  Although the present invention has been described above with reference to specific embodiments and modifications, each embodiment and modification is merely illustrative, and those skilled in the art will recognize various modifications, modifications, alternatives, and substitutions. You will understand examples. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be implemented in hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 100 Transmission / reception apparatus 102 Transmission antenna 104 Reception antenna 106 High frequency circuit 108 Control signal processing circuit 202 Voltage control oscillation circuit 204 Directional coupler 206 Amplifier 208 Amplifier 210 Mixer 302 Main control unit 304 Modulation control circuit 306 Intermediate wave processing circuit 308 Signal acquisition circuit 402 Distance / Relative Speed Calculation Unit 404 Peak Component Detection Unit 406 Operation Determination Unit

Claims (6)

A transmission / reception device that calculates a distance between the transmission wave transmitted to the target and a reflection wave of the transmission wave by the target,
A signal having a beat frequency generated by transmitting a first transmission wave from the transmission antenna to the target and mixing the first transmission wave and the first transmission wave received via the reception antenna A high-frequency circuit that outputs
A control signal that detects a peak frequency component due to antenna coupling based on a signal having a beat frequency output from the high-frequency circuit, and determines whether or not the device is operating normally based on fluctuations in the frequency component A transmission / reception device comprising: a processing circuit.   The transmission / reception apparatus according to claim 1, wherein the control signal processing circuit detects a peak frequency component due to antenna coupling from a signal having the beat frequency obtained by fast Fourier transform.   The transmission / reception apparatus according to claim 1, wherein the transmission signal is a frequency-modulated continuous wave.   4. The transmission / reception apparatus according to claim 1, wherein the control signal processing circuit detects a frequency component of a peak on a low frequency side among peaks of a signal having a beat frequency subjected to the fast Fourier transform. 5.   The control signal processing circuit determines that the operation is normal when the fluctuation of the peak frequency component due to the antenna coupling is within a predetermined threshold, and operates normally when the fluctuation is larger than the predetermined threshold. The transmission / reception apparatus according to claim 1, wherein the transmission / reception apparatus determines that the transmission / reception is not performed. A transmission / reception method in a transmission / reception apparatus that calculates a distance between a target and a transmission wave transmitted to a target and a reflection wave of the transmission wave by the target,
Transmitting a first transmission wave from the transmission antenna to the target;
Generating a signal having a beat frequency by mixing the first transmission wave and the first transmission wave received via a receiving antenna;
Based on a signal having the beat frequency, a peak frequency component due to antenna coupling is detected,
A transmission / reception method for determining whether or not the device is operating normally based on fluctuations in the frequency component.

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