JP2020085867A - Distance velocity measurement device and distance velocity measurement method - Google Patents

Abstract

To provide a distance velocity measurement device and a distance velocity measurement method which enable measurement in a short period of time.SOLUTION: In the distance velocity measurement device, a first frequency modulation continuous wave generating circuit (101, 102 and 104) generates a first frequency modulation continuous wave, a second frequency modulation continuous wave generating circuit (101, 103 and 105) generates a second frequency modulation continuous wave having a fixed frequency difference with respect to the first frequency modulation continuous wave, a transmission circuits (107 and 108) transmits the first frequency modulation continuous wave, a reception circuit (113, 114 and 115) receives a reflection wave of the first frequency modulation continuous wave from the object, and a processing circuit (109, 110 and 111) generates a beat signal for calculating at least one of distance to the object and relative velocity of the object on the basis of the reflection wave and the second frequency modulation continuous wave.SELECTED DRAWING: Figure 1

Description

The present invention relates to a distance velocity measuring device and a distance velocity measuring method.

In recent years, research on automatic driving and driving assistance systems for automobiles has progressed, and vehicle-mounted radars have been attracting attention as sensing means. Among in-vehicle radars, the FMCW radar is widely used as a radar that can measure the distance to the object and the relative speed of the object, and as a radar that uses a heterodyne method that can detect weak reflected waves. Developments such as directivity and miniaturization of antennas are progressing.

Under such circumstances, for example, as in the radar device described in Patent Document 1, the research of FMCW Lidar aiming at improvement of directivity, downsizing, and low power consumption by replacing electromagnetic waves with laser light is under way. ..

FMCW Lidar calculates the distance to the object from the frequency difference between the transmitted wave and the reflected wave, which are frequency-modulated continuous waves. FMCW Lidar is the frequency difference between the transmitted wave and the reflected wave when the sweep slope is positive and the frequency difference between the transmitted wave and the reflected wave when the sweep slope is negative, which is caused by the frequency shift due to the Doppler effect. The relative speed of the object is calculated from the difference between and.

By the way, the smaller the relative velocity of the object, the smaller the frequency shift due to the Doppler effect. Generally, it is considered that at least one cycle or more is required to measure a waveform, and therefore the smaller the frequency shift, the longer the measurement time.
As a method of increasing the frequency shift, increasing the frequency of the transmitted wave can be considered. However, for example, in a vehicle-mounted FMCW radar, a millimeter wave of 24 GHz or 77 GHz is defined as a standard. In FMCW Lidar, the operating speed of LD is currently about 2GHz. Therefore, there is a limit in increasing the frequency of the transmitted wave.

An object of the present invention is to provide a distance velocity measuring device and a distance velocity measuring method capable of performing measurement in a short time.

In order to solve the above-mentioned problem, the distance velocity measuring apparatus of the present invention is provided with respect to a first frequency-modulated continuous wave generation circuit that generates a first frequency-modulated continuous wave and the first frequency-modulated continuous wave. A second frequency-modulated continuous wave generation circuit that generates a second frequency-modulated continuous wave having a constant frequency difference, a sending circuit that sends out the first frequency-modulated continuous wave, and the first frequency wave from the object. A receiving circuit for receiving a reflected wave of a frequency-modulated continuous wave, and a beat for calculating at least one of a distance to the object or a relative speed of the object from the reflected wave and the second frequency-modulated continuous wave. And a processing circuit that generates a signal.

According to the present invention, it is possible to measure in a short time.

The block diagram which shows an example of a structure of the distance velocity measuring device of 1st Embodiment. The figure which shows an example of a structure of general FMCW Lidar. The 1st figure which shows the relationship between a reference wave and a reflected wave in general FMCW Lidar, and their frequency difference (when an object is stopped). The second figure showing the relation between the reference wave and the reflected wave and their frequency difference in a general FMCW lidar (when the object is moving). FIG. 6 is a first timing diagram (in the case of a relative speed of 0 km/h) for explaining the operation of the distance/speed measuring device of the first embodiment. FIG. 6 is a second timing chart for explaining the operation of the distance velocity measuring device of the first embodiment (when the relative velocity is not 0 km/h). The flowchart which shows the operation|movement procedure of the distance velocity measuring device of 1st Embodiment. The block diagram which shows an example of a structure of the distance velocity measuring device of 2nd Embodiment. The block diagram which shows an example of a structure of the distance velocity measuring device of 3rd Embodiment. The timing diagram for demonstrating operation|movement of the distance velocity measuring device of 3rd Embodiment. The block diagram which shows an example of a structure of the distance velocity measuring device of 4th Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
First, a first embodiment of the present invention will be described.
FIG. 1 is a block diagram showing an example of the configuration of the distance velocity measuring device according to the present embodiment. In the present embodiment, it is assumed that the distance velocity measuring device of the present invention is realized as an FMCW lidar using laser light. Not limited to FMCW lidar, the distance velocity measuring device of the present invention can be realized as various types of radar using frequency continuous modulation waves. Further, hereinafter, the distance to the object means the distance between the distance velocity measuring device and the object, and the relative velocity of the object is the velocity when the object is viewed from the distance velocity measuring device. It shall mean the relative speed of the object to a certain distance measuring device.

This distance velocity measuring apparatus is composed of a reference oscillator (Xtal: crystal oscillator) 101, a phase synchronization circuit (PLL1_RAMP) 102 with a frequency sweep function (ramp function), and a voltage controlled oscillator (VCO1) 104. It has a frequency modulation continuous wave generation circuit. The distance velocity measuring device also has a second frequency-modulated continuous wave generation circuit including a reference oscillator 101, a phase-locked loop (PLL2_RAMP) 103 with a frequency sweep function, and a voltage-controlled oscillator (VCO2) 105. .

The output of the first frequency modulation continuous wave generation circuit is applied to the laser diode (LD) 108 together with the DC bias current from the constant current bias circuit (Bias) 107 via the capacitor 106 to output the transmitted wave a1. On the other hand, the output of the second frequency modulation continuous wave generation circuit is added to the multiplication circuit (MIX) 111 as the reference wave a2.

Here, as a comparative example, first, a configuration of a general FMCW Lidar and a method of measuring a distance and a relative speed by the general FMCW Lidar will be described with reference to FIGS. 2 to 5.
FIG. 2 is a diagram showing an example of the configuration of a general FMCW Lidar.

The transmitted light of FMCW Lidar is a linear frequency-modulated continuous wave, and is generated by a reference oscillator (Xtal: crystal oscillator) 901, a phase-locked loop (PLL_RAMP) 902 with a frequency sweep function, and a voltage-controlled oscillator (VCO) 903. To be done. The generated linear frequency-modulated continuous wave is added to the laser diode (LD) 906 as a transmission wave b1, converted into an optical signal and transmitted to the outside, and added to the multiplication circuit 909 as a reference wave b2. It is divided into what can be.

Of the optical signals sent to the outside, the optical signal reflected on the object and reflected is received by the avalanche photodiode (APD) 912 as a reflected wave b3, converted into an electrical signal, and then multiplied by the reference wave b2 by the multiplication circuit (MIX) 909. Is multiplied by. At this time, the reflected wave b3 has a time delay due to the distance from the object. In addition, when the object is moving, frequency shift due to the Doppler effect also occurs. Therefore, the beat signal (multiplication signal of the reflected wave and the reference wave) obtained from the multiplication circuit 909 includes the frequency difference between the reference wave b2 and the reflected wave b3. Therefore, by performing frequency analysis and finding the frequency difference, the distance to the object and the relative speed of the object can be obtained.

FIG. 3 and FIG. 4 are diagrams showing the relationship between the reference wave b2 and the reflected wave b3 in a general FMCW Lidar and their frequency differences.
FIG. 3 shows a case where the object is stopped. As shown in FIG. 3A, the frequency of the reflected wave b3 is delayed with respect to the reference wave b2 by the time required for the round trip to and from the object. There is. Since the slope of the frequency sweep is constant, as shown in FIG. 3B, the frequency difference c1 (reference wave-reflected wave) has a constant frequency, and the distance to the object can be obtained from this frequency difference.

On the other hand, FIG. 4 shows a case where the object is moving, and as indicated by reference sign c2 in FIG. 4A, the frequency is shifted due to the Doppler effect in addition to the delay due to the distance. Therefore, as shown in FIG. 4(B), the frequency difference c1 differs depending on whether the sweep slope is positive or negative, and the relative speed can be obtained from the difference in frequency difference at the positive/negative slope. ..

By the way, the frequency shift due to the Doppler effect for measuring the relative velocity as described above can be obtained by the following (Equation 1).
Frequency shift due to Doppler effect = 2 x relative velocity ÷ wavelength (Equation 1)
The wavelength in (Equation 1) can be obtained by the following (Equation 2).

Wavelength = speed of light ÷ frequency of reference wave (Equation 2)
Here, in (Equation 1) and (Equation 2), the relative velocity is set to 1 km/h (0.28 m/s), the frequency of the reference wave is set to 2 GHz, and the frequency shift due to the Doppler effect is calculated.
Wavelength=(3×10 ⁸ )÷(2×10 ⁹ )=0.15m
Frequency shift due to Doppler effect = 2 x 0.28 ÷ 0.15 ≒ 3.73Hz
Thus, when the relative speed is as slow as 1 km/h (0.28 m/s), the frequency obtained as the frequency shift due to the Doppler effect is low. Then, the slower the relative speed, the smaller the frequency shift.

Generally, it is considered that at least one cycle is required for waveform measurement, considering the signal offset error and waveform distortion. Therefore, if the frequency shift due to the Doppler effect is 3.73Hz, 270ms (1/3.73Hz ) Measurement time is required.
In order to shorten the measurement time, it is necessary to increase the frequency shift due to the Doppler effect, but the magnitude of the frequency shift due to the Doppler effect depends on the frequency of the reference wave according to (Equation 1) and (Equation 2). To do. In the FMCW Lidar assumed in this embodiment, the operating speed of the LD is currently about 2 GHz, and there is a limit to the high frequency of the reference wave.

Therefore, the distance velocity measuring device of the present embodiment is provided with a mechanism capable of measuring the relative velocity in a short time without being influenced by the relative velocity of the object such as when the relative velocity is slow. This will be described in detail below.
Returning to FIG. 1, the description of the distance velocity measuring device of this embodiment will be continued.

The phase synchronization circuit with frequency sweep function 102 and the phase synchronization circuit with frequency sweep function 103 can easily control the frequency sweep timing, the tilt frequency range, and the like by writing data. In addition, since they share the reference oscillator 101, timing errors, temperature characteristics, aging errors, etc. are reduced. A laser diode (LD) 108 is used as the light emitting unit. The light receiving section is composed of an avalanche photodiode (APD) 114, and the avalanche photodiode 114, the resistor 113, and the resistor 115. The processing circuit of the received signal (reflected wave a3) transferred via the capacitor 112 is composed of a multiplication circuit 111 to which the reference wave a2 and the reflected wave a3 are given, a low-pass filter (LPF) 110, and a variable gain amplifier (VGA) 109. is doing. The output from the processing circuit of the received signal is input to the signal processing unit 116 including an analog-digital conversion circuit (ADC), and the signal processing unit 116 performs processing such as calculation of distance and relative speed.

As the laser diode 108, an edge emitting laser, a vertical cavity surface emitting laser (VCSEL), or the like can be used. In particular, the VCSEL is advantageous in that it can be easily downsized and highly integrated and that it is suitable for high frequency driving as compared with the edge emitting laser.

5 and 6 are timing charts for explaining the operation of the distance velocity measuring device according to the present embodiment.
FIG. 5 shows a case where the peaks of the frequency of the transmitted wave and the frequency of the reflected wave are the same, and there is no relative frequency shift due to the Doppler effect, and the relative speed is 0 km/h.
In FIG. 5(A), reference numeral a1 indicates a transmitted wave by the output of the first frequency modulation continuous wave generation circuit, and reference numeral a2 indicates a reference wave by the output of the second frequency modulation continuous wave generation circuit. In the configuration of the distance velocity measuring device of the present embodiment, the frequency of the reference wave a2 of the multiplication circuit 111 is set to a frequency higher by a constant frequency (f _b0 ) than the frequency of the transmitted wave a1. The reflected wave indicated by reference sign a3 is delayed from the transmitted wave a1 in accordance with the distance to the object. FIG. 5B shows the beat signal d1(f _b ) which is the difference frequency between the reference wave a2 and the reflected wave a3. Between the frequency (f _b1 ) of the beat signal d1 in the up-modulation period in which the frequency of the transmitted wave a1 increases and the frequency (f _b2 ) of the beat signal d1 in the down-modulation period in which the frequency of the transmitted wave a1 decreases, There is a relationship of the following (Equation 3) and (Equation 4) including the difference frequency f _b0 between the transmitted wave a1 and the reference wave a2.

f _b1 =f _b0 +f _r (Equation 3)
_{f b2 = f b0 -f r ...} ( Equation 4)
Here, f _r is a frequency based on the delay time τ of the reflected wave.
In FIG. 5B, the intermediate value (broken line) between f _b1 and f _b2 indicates the difference frequency f _b0 between the transmitted wave a1 and the reference wave a2.

On the other hand, FIG. 6 shows a case where the relative speed is not 0 km/h. In this case, as shown in FIG. 6(A), the reflected wave a3 includes a frequency change due to the relative velocity, and in addition to the time delay caused according to the distance, the reflected wave a3 is caused by the Doppler effect as shown by a symbol d2. There is a positive or negative frequency shift. Then, as shown in FIG. 6B, the beat frequency f _b1 in the up modulation period and the beat frequency f _{b2 in the} down modulation period have the following relationships (Equation 5) and (Equation 6).

f _b1 =f _b0 + _fr −f _d (Equation 5)
_{f b2 = f b0 -f r -f} d ... ( Equation 6)
Here, f _d is the Doppler shift frequency.
In this example, the frequency shift occurs in the positive direction due to the Doppler effect, and the frequency peak of the reflected wave a3 is higher than the frequency peak of the transmitted wave a1. Compared to the case where the relative speed is 0 in FIG. 5, the beat frequency becomes lower by the positive shift due to the Doppler effect.

Next, a method of calculating the distance R to the measurement object and the relative velocity v in the distance velocity measuring device of the present embodiment will be described.
When the speed of light is c, the delay time τ of the reflected wave a3 is represented by τ=2R/c. Further, when the repetition frequency of the transmitted wave a1 is f _m and the frequency displacement width of the transmitted wave a1 is Δf, the frequency _fr is
f _r =τ·Δf·2f _m
f _r =4R·Δf·f _m /c
It is represented by.

Therefore, (Equation 5) and (Equation _6), since it is _{f r = (f b1 -f b2} ) / 2, it is possible to determine the distance R from the beat signal d1.
Further, assuming that the center frequency of the transmitted wave a1 is f ₀ , the Doppler shift frequency is represented by the following (formula 7) and (formula 8).
f _d =2v·f ₀ /c (Equation 7)
v=c·f _d /2f ₀ (Equation 8)
(Equation 5) and (Equation _{6), f d = f b0} - because it is _{(f b1 + f b2) /} 2, it is possible to determine the relative velocity v from the beat signal d1.

As can be seen from the above, in the distance velocity measuring device of the present embodiment, even if the relative velocity is 0 or close to 0, by appropriately setting f _b0 , f _d can be measured in a practical time. Can be Therefore, the relative speed can be measured in a short time without depending on the measurement time depending on the relative distance to the measurement object.

In this embodiment, it is preferable to set f _b0 so that the beat frequency (f _b ) does not have a negative value. That is, it is preferable to set f _b0 so that aliasing does not occur at 0 Hz. Since the beat frequency depends on the distance to the object and the relative speed of the object, f _b0 may be changed according to the range to be measured.

Further, the frequency of the reference wave a2 may be shifted in the negative direction with respect to the frequency of the transmitted wave a1, and at this time, the frequency difference may be obtained as “transmitted wave a1−reference wave a2”.
FIG. 7 is a flowchart showing an operation procedure of the distance/velocity measuring apparatus of this embodiment.
In the distance velocity measuring device of the present embodiment, the first frequency-modulated continuous wave (sending wave) is generated (step S1), and the second frequency-modulated continuous wave having a constant frequency difference is generated. The frequency-modulated continuous wave (reference wave) is generated (step S2).

The distance velocity measuring device transmits the first frequency-modulated continuous wave (step S3) and receives the reflected wave of the first frequency-modulated continuous wave from the object (step S4). Then, the distance velocity measuring device multiplies the reflected wave and the second frequency-modulated continuous wave to generate a beat signal (step S5).

Hereinafter, the distance velocity measuring device frequency-analyzes the beat signal obtained by the procedure of steps S1 to S4 to calculate the frequency difference between the reflected wave and the second frequency-modulated continuous wave (step S6), and The distance/relative velocity to the object is calculated from the frequency difference from the second frequency-modulated continuous wave (step S7).

As described above, in the distance/velocity measuring apparatus of this embodiment, the frequency range obtained as the beat signal can be set by giving a constant frequency difference between the transmitted wave and the reference wave. Thereby, the distance velocity measuring device of the present embodiment can measure the relative velocity in a short time without being influenced by the relative velocity of the object.

(Second embodiment)
Next, a second embodiment of the present invention will be described.
FIG. 8 is a block diagram showing an example of the configuration of the distance velocity measuring device according to the present embodiment. Similar to the first embodiment, it is assumed in the present embodiment that the distance velocity measuring device of the present invention is realized as an FMCW lidar using laser light. Further, as described above, the distance velocity measuring device of the present invention is not limited to the FMCW Lidar, and can be realized as various types of radar using frequency continuous modulation waves. Here, the same components as those in the first embodiment are designated by the same reference numerals, and duplicated description thereof will be omitted.

The distance-velocity measuring apparatus according to the present embodiment is different from the distance-velocity measuring apparatus according to the first embodiment shown in FIG. 1 in that a multiplication circuit (MIX) 203, a low-pass filter (LPF) 202, and a variable gain amplifier (VGA). ) 201 is added to the processing circuit for the received signal (the portion surrounded by the broken line). The output of the first frequency-modulated continuous wave generation circuit is added to the multiplication circuit 203 as a reference wave a2-2.

That is, the beat signal obtained by the multiplication circuit 203 is the same as the beat signal obtained by the general FMCW lidar described with reference to FIGS. 2 to 5. That is, in the distance/velocity measuring apparatus of this embodiment, it is possible to obtain two types of beat signals, that is, the beat signal obtained by the measuring method described in the first embodiment and the beat signal obtained by the conventional measuring method. I have to. Specifically, the distance/velocity measuring device of the present embodiment is configured so that one of the two types of beat signals can be selected according to the measurement state.

In the measurement method described in the first embodiment, the measurement result may include an error in the difference frequency between the phase synchronization circuit with frequency sweep function 102 and the phase synchronization circuit with frequency sweep function 103. Therefore, the signal processing unit 116 in the distance/velocity measuring apparatus of the present embodiment selects a conventional measurement method (for example, in the multiplication circuit 203) when there is no problem in the measurement time (the relative speed is sufficiently high). On the other hand, when the relative speed is small, the measurement method described in the first embodiment can be selected (using the output of the multiplication circuit 111).

Further, the signal processing unit 116 in the distance/velocity measuring device of the present embodiment selects a conventional measuring method (using the output of the multiplication circuit 203) in the distance measurement, while the first in the relative velocity measurement. It is also possible to select the measurement method described in the embodiment (use the output of the multiplication circuit 111).

As described above, in the distance velocity measuring device of the present embodiment, two beat signals having different frequencies of the reference waves are obtained, and further, an optimum beat signal can be obtained by, for example, selectively using the relative velocity measuring application and the distance measuring application. You will be able to select adaptively.
(Third Embodiment)
Next, a third embodiment of the present invention will be described.

FIG. 9 is a block diagram showing an example of the configuration of the distance velocity measuring device according to the present embodiment. Similar to the first and second embodiments, it is assumed in the present embodiment that the distance velocity measuring device of the present invention is realized as an FMCW lidar using laser light. Further, as described above, not only the FMCW lidar but also the distance velocity measuring device of the present invention can be realized as various types of radar using frequency continuous modulation waves. Here, the same reference numerals are used for the same components as those in the first and second embodiments, and duplicated description thereof will be omitted.

The distance-velocity measuring apparatus according to the present embodiment is different from the distance-velocity measuring apparatus according to the second embodiment shown in FIG. 8 in that instead of the phase synchronization circuit 103 with the frequency sweep function, the phase synchronization without the frequency sweep function is provided. The circuit (PLL2) 301 is arranged to be changed. As described above, the phase synchronization circuit 103 with the frequency sweep function can easily control the frequency sweep timing, the tilt frequency range, and the like by writing data. Therefore, the distance/velocity measuring apparatus according to the second embodiment. The second frequency-modulated continuous wave generation circuit in 1 may be used as the constant frequency continuous wave generation circuit.

In the case of distance measurement, since the delay of the time until the transmitted wave a1 hits the object and is received as the reflected wave a3 is measured, it is necessary to perform frequency sweep. On the other hand, in the case of the relative velocity measurement, since the frequency shift is measured by the Doppler effect, it is not necessary to perform the frequency sweep. Therefore, in the distance/velocity measuring device of the present embodiment, the reference wave a2-3 for obtaining the beat signal to be obtained in addition to the beat signal obtained by the conventional measuring method can be controlled simply and frequency stability can be expected. It is a constant frequency continuous wave.

FIG. 10 is a timing chart for explaining the operation of the distance/velocity measuring apparatus of this embodiment having such a configuration.
In the distance/velocity measuring apparatus of the present embodiment, as shown in FIG. 10A, the reference wave a2-3 of the multiplication circuit 111 is set to a constant frequency higher than the reference wave a2-2 of the multiplication circuit 203. Further, the reference wave a2-2 of the multiplication circuit 203 is a repetition of a positive frequency sweep and a constant frequency.

Then, in the case of the distance/velocity measuring apparatus of the present embodiment, the reference wave (a2-2)-reflected wave (a3) of the multiplication circuit 203 shown by reference numeral d1-2 in FIG. The measurement is performed (e1: distance measurement point). Further, in the reference wave (a2-3)-reflected wave (a3) of the multiplication circuit 111 indicated by reference numeral d1-3 in FIG. 10B2, the relative speed is measured in a constant frequency period (e2: relative). Speed measurement point).

As described above, in the distance/velocity measuring device of the present embodiment, when the relative velocity is measured, the frequency sweep error is eliminated as the control at a constant frequency, thereby making it possible to achieve both the measurement accuracy and the measurement speed.
(Fourth Embodiment)
Next, a fourth embodiment of the present invention will be described.

FIG. 11 is a block diagram showing an example of the configuration of the distance velocity measuring device according to the present embodiment. Similar to the first to third embodiments, it is assumed in the present embodiment that the distance velocity measuring device of the present invention is realized as an FMCW lidar using laser light. Further, as described above, not only the FMCW lidar but also the distance velocity measuring device of the present invention can be realized as various types of radar using frequency continuous modulation waves. Here, the same reference numerals are used for the same components as those of the first to third embodiments, and duplicated description thereof will be omitted.

The distance-velocity measuring apparatus according to the present embodiment is different from the distance-velocity measuring apparatus according to the first embodiment shown in FIG. 1 in that a multiplication circuit (MIX) 403, a low-pass filter (LPF) 402, and a variable gain amplifier (VGA). ) Add a correction data generating unit 401 (a portion surrounded by a broken line). The output (a1) of the first frequency modulation continuous wave generation circuit and the output (a2) of the second frequency modulation continuous wave generation circuit are added to the multiplication circuit 403.

That is, in the distance velocity measuring device of the present embodiment, the measurement data (data including the difference frequency between the reference wave a2 and the reflected wave a3) by the measurement method described in the first embodiment is generated, and the analog of the signal processing unit is generated. -Output to the digital conversion circuit (ADC1). Further, the multiplication circuit 403 generates correction data including the frequency difference between the output (transmitted wave) a1 of the first frequency modulation continuous wave generation circuit and the output (reference wave) a2 of the second frequency modulation continuous wave generation circuit. Then, the signal is output to the analog-digital conversion circuit (ADC2) of the signal processing unit. The signal processing unit 116 calculates the distance and the relative speed based on the output from the ADC1 and the output from the ADC2.

In the distance velocity measuring device of this embodiment, since the correction data including the frequency difference between the transmitted wave a1 and the reference wave a2 is input to the signal processing unit 116, the measurement data is corrected based on this correction data. It can be performed. The voltage-controlled oscillator 104 and the voltage-controlled oscillator 105 are feedback-controlled by the phase synchronization circuit 102 with frequency sweep function and the phase synchronization circuit 103 with frequency sweep function, but since they are adjusted by the analog voltage value, fluctuation may occur. There is. When fluctuation occurs, its frequency appears in the beat signal (beat frequency), so it is preferable to be able to correct this fluctuation.

In the distance-velocity measuring device of the present embodiment, the frequency difference between the voltage-controlled oscillator 104 and the voltage-controlled oscillator 105 can be measured by the correction data that is output in synchronization with the measurement data. Can be corrected.
As described above, in the distance velocity measuring device according to the present embodiment, the frequency difference is measured irrespective of the relative velocity and the distance, so that the influence of a circuit error or the like can be further reduced.

In addition, in the present embodiment, a multiplication circuit 403 and the like for multiplying the output of the voltage controlled oscillator 104 and the output of the voltage controlled oscillator 105 are added to the configuration of the distance velocity measuring device of the first embodiment. A multiplication circuit 403 or the like for multiplying the output of the voltage controlled oscillator 104 and the output of the voltage controlled oscillator 105 is added to the configuration of the distance velocity measuring device of the embodiment or the configuration of the distance velocity measuring device of the third embodiment. You can Even in this case, the influence of a circuit error or the like can be canceled.

As described above, in the distance velocity measuring devices according to some of the embodiments shown here, two continuous wave generating circuits are provided and the respective outputs are separately used for the transmitted wave and the reference wave. Further, these two continuous wave generation circuits are controlled in advance so that there is a constant frequency difference between the transmitted wave and the reference wave. As a result, even when the relative speed is 0 km/h and the distance is 0 m, a frequency difference occurs between the transmitted wave and the reference wave that are given to the beat signal in advance, and the frequency changes depending on the relative speed and the distance based on this frequency difference. It will be. As a result, it is possible to measure the relative speed in a short time without depending on the relative speed of the object.

The above description of some embodiments is not intended to limit the scope of the invention, and various modifications and changes can be made without departing from the scope of the invention.

101... Reference oscillator, 102, 103... Phase synchronization circuit with frequency sweep function, 104, 105... Voltage controlled oscillator, 106, 112... Capacitor, 107... Constant current bias circuit, 108... Laser diode, 109, 201, 401... Variable Gain amplifier, 110, 202, 402... Low pass filter, 111, 203, 403... Multiplication circuit, 113, 115... Resistor, 114... Avalanche photodiode, 116... Signal processing unit, 301... Phase synchronization circuit.

JP, 2005-129646, A

Claims (10)

A first frequency-modulated continuous wave generation circuit for generating a first frequency-modulated continuous wave;
A second frequency-modulated continuous wave generation circuit for generating a second frequency-modulated continuous wave having a constant frequency difference with respect to the first frequency-modulated continuous wave;
A transmission circuit for transmitting the first frequency-modulated continuous wave;
A receiving circuit for receiving a reflected wave of the first frequency-modulated continuous wave from an object;
A processing circuit for generating a beat signal for calculating at least one of a distance to the object or a relative velocity of the object from the reflected wave and the second frequency-modulated continuous wave;
Distance velocity measuring device comprising. The distance velocity measuring device according to claim 1, further comprising a second processing circuit that generates a second beat signal from the reflected wave and the first frequency-modulated continuous wave. A frequency-modulated continuous wave generation circuit that generates a frequency-modulated continuous wave;
A constant frequency continuous wave generating circuit for generating a constant frequency continuous wave;
A transmission circuit for transmitting the frequency-modulated continuous wave,
A receiving circuit for receiving a reflected wave of the frequency-modulated continuous wave from an object,
A first processing circuit for generating a first beat signal for calculating a distance to the object from the reflected wave and the constant frequency continuous wave;
A second processing circuit for generating a second beat signal for calculating the relative velocity of the object from the reflected wave and the frequency-modulated continuous wave;
Distance velocity measuring device comprising. The distance velocity measuring device according to claim 3, wherein the frequency-modulated continuous wave generation circuit generates a frequency-modulated continuous wave in which a positive frequency sweep section and a constant frequency section are alternately repeated. The distance velocity measurement according to claim 3 or 4, wherein the constant frequency continuous wave generation circuit is a phase synchronization circuit with a frequency sweep function in which frequency sweep timing and a tilt frequency range are set so as to generate the constant frequency continuous wave. apparatus. Second processing for generating data including a frequency difference between the first frequency-modulated continuous wave and the second frequency-modulated continuous wave from the first frequency-modulated continuous wave and the second frequency-modulated continuous wave The distance velocity measuring device according to claim 1, further comprising a circuit. 7. The third processing circuit according to claim 3, further comprising a third processing circuit that generates data including a frequency difference between the frequency-modulated continuous wave and the constant frequency continuous wave from the frequency-modulated continuous wave and the constant frequency continuous wave. The distance velocity measuring device according to item 1. 7. The constant frequency difference that the second frequency-modulated continuous wave has with respect to the first frequency-modulated continuous wave is set so that the value of the beat signal does not become a negative value. The distance velocity measuring device described in. The sending circuit converts the frequency-modulated continuous wave into an optical signal and radiates it.
The receiving circuit receives an optical signal reflected by an object and converts it into an electrical signal.
The distance velocity measuring device according to any one of claims 1 to 8. A distance velocity measuring method performed by an electronic device, comprising:
Generating a first frequency modulated continuous wave;
Generating a second frequency modulated continuous wave having a constant frequency difference with respect to the first frequency modulated continuous wave;
Sending out the first frequency modulated continuous wave;
Receiving a reflected wave of the first frequency modulated continuous wave from an object;
Generating a beat signal for calculating at least one of a distance to the object or a relative velocity of the object from the reflected wave and the second frequency-modulated continuous wave;
A distance velocity measuring method comprising:

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