JP2012047578A - Frequency measurement device, frequency measurement method, speed measurement device, and speed measurement method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To measure a frequency in a short time by a simple device.SOLUTION: A micro wave reflected by a moving body to be measured is converted into an electric signal. Subsequently, using a first output circuit 13, an electric signal generated by amplifying the electric signal is converted into a DC signal SD13 of a voltage level corresponding to the attenuation characteristic of a high pass filter composing the first output circuit 13. At the same time, using a second output circuit 14, the electric signal is converted into a DC signal SD14 of a voltage level corresponding to the attenuation characteristic of a low pass filter composing the second output circuit 14. Then, using the value of the DC signal SD13 and the value of the DC signal SD14, a frequency of the electric signal is calculated.

Description

  The present invention relates to a frequency measurement device, a frequency measurement method, a speed measurement device, and a speed measurement method, and more particularly, a frequency measurement device that measures a frequency to be measured, a frequency measurement method for measuring a frequency to be measured, and a movement A speed measurement device that measures the speed of a moving object by measuring the frequency of an electric signal based on the reflected wave from the body, and measures the speed of the moving object by measuring the frequency of an electric signal based on the reflected wave from the moving body The present invention relates to a speed measurement method.

  In the field of structural vibration analysis and velocity measurement using the Doppler effect, for example, FFT (Fast Fourier Transform) processing is performed on the sampled signal to measure the sound pressure level for each frequency. In general, vibration analysis and speed measurement are performed using the measurement results (see, for example, Patent Document 1).

  The apparatus disclosed in Patent Document 1 collects noise generated from a measurement object using a microphone. Then, the frequency characteristic of the noise is calculated by performing FFT processing on the output signal from the microphone. The user of the apparatus can perform noise frequency analysis using the processing result.

JP-A-8-211986

  The FFT process is a process of calculating both the sound pressure level in the fundamental wave component of the signal to be processed and the sound pressure level in each of the harmonic components with respect to the fundamental wave component. For this reason, when the FFT process is performed on the distributed frequency signal, the time required for the arithmetic process increases.

  The present invention has been made under the above circumstances, and an object thereof is to measure the frequency of an electric signal generated based on a wave in a short time with a simple device. Moreover, it aims at measuring the moving speed of the moving body which reflects a wave in a short time by measuring the frequency of an electric signal in a short time.

In order to achieve the above object, a frequency measurement device according to the first aspect of the present invention provides:
Conversion means for converting the wave into an electrical signal;
First output means for outputting a first signal whose value increases in proportion to an increase in frequency of the electrical signal;
Second output means for outputting a second signal whose value decreases in proportion to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio of the value of the first signal and the value of the second signal, Computing means for calculating the frequency;
Have

  The increasing rate of the value of the first signal with respect to the frequency may be equal to the decreasing rate of the value of the second signal with respect to the frequency.

The first output means has a first filter that attenuates the electrical signal with an attenuation rate proportional to a decrease in the frequency of the electrical signal,
The second output means may include a second filter that attenuates the electrical signal with an attenuation rate proportional to an increase in frequency of the electrical signal.

The first output means includes
A first rectifier circuit that full-wave rectifies the electrical signal that has passed through the first filter;
A first smoothing circuit for smoothing an output from the first rectifier circuit and generating the first signal indicating a level of the electrical signal;
The second output means includes
A second rectifier circuit that full-wave rectifies the electrical signal that has passed through the second filter;
A second smoothing circuit that smoothes the output from the second rectifier circuit and generates the second signal indicating the level of the electric signal may be included.

The computing means sets the value of the first signal to P1, the value of the second signal to P2, and the frequency of the electrical signal when the value of the first signal and the value of the second signal match F _{0. When the} constant is k, the frequency F of the electrical signal may be calculated using the following equation.

In addition, the speed measuring device according to the second aspect of the present invention includes:
A frequency measuring device of the present invention for measuring the frequency of an electric signal based on a wave reflected from a moving body;
Speed calculation means for performing a calculation using the frequency measured by the frequency measuring device to calculate the speed of the moving body;
Is provided.

Moreover, the frequency measurement method according to the third aspect of the present invention includes:
Converting a wave into an electrical signal;
Generating a first signal indicative of a level of an output signal from a first filter that attenuates the passing electrical signal at an attenuation rate proportional to a decrease in the frequency of the electrical signal;
Generating a second signal indicative of a level of an output signal from a second filter that attenuates the passing electrical signal at an attenuation rate proportional to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio between the value of the first signal and the value of the second signal, Calculating the frequency of
including.

Moreover, the speed measurement method according to the fourth aspect of the present invention includes:
Converting the wave reflected from the moving body into an electrical signal;
Generating a first signal indicative of a level of an output signal from a first filter that attenuates the passing electrical signal at an attenuation rate proportional to a decrease in the frequency of the electrical signal;
Generating a second signal indicative of a level of an output signal from a second filter that attenuates the passing electrical signal at an attenuation rate proportional to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio between the value of the first signal and the value of the second signal, Calculating the frequency of
Performing a calculation using the calculated frequency of the electrical signal to detect the speed of the moving body;
including.

  According to the present invention, the center frequency of the wave is calculated based on the ratio between the value of the first signal and the value of the second signal corresponding to the frequency of the electrical signal generated by converting the wave. Therefore, it is not necessary to perform complicated processing such as FFT processing, and the frequency can be measured in a short time with a simple device. In addition, since the frequency of the wave can be measured in a short time, as a result, the moving speed of the measurement object that reflects the wave can be measured in a short time.

It is a block diagram of the speed measuring device concerning a 1st embodiment. It is a figure which shows an example of the electric signal output from an amplifier. It is a block diagram of a 1st output circuit. It is a block diagram of a 2nd output circuit. It is a figure which shows the attenuation characteristic of a high-pass filter and a low-pass filter. FIG. 6A is a diagram illustrating an output signal from the high-pass filter. FIG. 6B is a diagram illustrating an output signal from the low-pass filter. It is a figure which shows the DC signal output from a smoothing filter. It is a figure which shows the relationship between the voltage level of a DC signal, and a frequency. It is a block diagram of the speed measuring device which concerns on 2nd Embodiment. It is a figure which shows the attenuation characteristic of each filter which comprises the 1st-4th output circuit. It is a figure which shows the output characteristic of each of the 1st-4th output circuit.

<< First Embodiment >>
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a speed measuring device 10 according to the present embodiment. The speed measuring device 10 is a device that measures the moving speed of the moving body based on the frequency of the microwave reflected by the moving body as a measurement target. As shown in FIG. 1, the speed measuring device 10 includes a Doppler module 11, a signal amplifier 12, a first output circuit 13, a second output circuit 14, an A / D converter 15, an arithmetic circuit 16, and a speed calculation circuit 17. The display unit 18 is provided.

The Doppler module 11 includes, for example, a transmission circuit having a transmission frequency f ₀ , a transmission antenna that transmits microwaves, a reception antenna that receives microwaves reflected by the measurement object, and a detection circuit. The Doppler module emits a microwave having a frequency f ₀ generated by driving the transmission circuit toward a moving object as a measurement object via a transmission antenna. Then, a microwave reflected by the moving body (hereinafter simply referred to as a reflected wave) is received via the receiving antenna, and is represented by a difference between the frequency f ₀ of the microwave upon emission and the frequency f _{1 of the} reflected wave. An electric signal (Doppler signal) having a frequency of the Doppler shift frequency f _d (= | f ₀ −f ₁ |) to be generated is generated. The Doppler module 11 outputs this electrical signal to the amplifier 12.

When the traveling direction of the microwave and the traveling direction of the moving body are parallel, assuming that the speed of the moving body is v (m / s) and the wavelength of the microwave having the frequency f ₀ is λ ₀ (m), Doppler The deviation frequency f _d is 2 · V / λ ₀ . For example, when a microwave having a frequency of 24.15 GHz and a wavelength of 0.012414 m is reflected by a moving body that moves at a relative speed of 1 m / s with respect to the speed measurement device 10, 161. An electric signal having a frequency of 1 Hz (= 2 · 1 / 0.012414) is output.

The signal amplifier 12 amplifies the electrical signal output from the Doppler module 11. Then, the amplified electric signal S12 is output to both the first output circuit 13 and the second output circuit 14. FIG. 2 is a diagram illustrating an example of the electrical signal S12 output from the signal amplifier 12. As shown by the curve S0 in FIG. 2, the electrical signal S12 is an AC signal having a period of approximately 1 / _fd and an amplitude of V0, for example. Note that FIG. 2 is a diagram schematically showing the electric signal S12, but the actual electric signal S12 often includes a distribution frequency, a harmonic component, and a noise component due to the measurement object to some extent.

  Returning to FIG. 1, each of the first output circuit 13 and the second output circuit 14 outputs a signal having a voltage level corresponding to the electric signal S <b> 12 output from the signal amplifier 12. Hereinafter, the first output circuit 13 and the second output circuit 14 will be described with reference to FIGS. 3 and 4.

  FIG. 3 is a block diagram of the first output circuit 13. FIG. 4 is a block diagram of the second output circuit 14. As shown in FIG. 3, the first output circuit 13 includes a high-pass filter 13a, a full-wave rectifier 13b, and a smoothing filter 13c. As shown in FIG. 4, the second output circuit 14 includes a low-pass filter 14a, a full-wave rectifier 14b, and a smoothing filter 14c.

  FIG. 5 is a diagram illustrating the attenuation characteristics of the high-pass filter 13 a that constitutes the first output circuit 13 and the attenuation characteristics of the low-pass filter 14 a that constitutes the second output circuit 14. The high pass filter 13a is a filter having an attenuation characteristic in which the gain with respect to the input signal increases as the frequency of the input signal increases. Specifically, as shown in FIG. 5, the attenuation characteristic of the high-pass filter 13a is indicated by a straight line L1 that rises to the right in the coordinate system in which the horizontal axis is a logarithmic coordinate. As indicated by the straight line L1, the gain of the high-pass filter 13a becomes maximum at, for example, 100 kHz, and decreases as the frequency decreases.

  The low-pass filter 14a is a filter having an attenuation characteristic in which the gain with respect to the input signal decreases as the frequency of the input signal increases. More specifically, as shown in FIG. 5, the attenuation characteristic of the low-pass filter 14a is indicated by a straight line L2 that descends to the right. As indicated by the straight line L2, the gain of the low-pass filter 14a is maximum at 10 Hz, for example, and decreases as the frequency increases.

As shown in FIG. 5, in this embodiment, the gain (attenuation factor) of the high-pass filter 13a with respect to the input signal when the frequency is 1 KHz is equal to the gain (attenuation factor) of the low-pass filter 14a. For convenience of explanation, the gain of the high pass filter 13a, the frequency at which the gain of the low-pass filter 14a is equal to those of the reference frequency F _0. In the present embodiment, the gain increase rate indicated by the straight line L1 of the high-pass filter 13a is equal to the gain decrease rate indicated by the straight line L2 of the low-pass filter 14a.

6 (A) is a high frequency f _d electric signal S12 than the reference frequency F ₀ is when the input to the high pass filter 13a, a diagram showing an output signal S13 outputted from the high pass filter. Also, FIG. 6 (B), an electric signal S12 of a frequency f _d, when input to the low pass filter 14a, a diagram showing an output signal S14 output from the low-pass filter. If the frequency f _d of the electric signal S12 is higher than the reference frequency F _0, as seen with reference to FIG. 5, towards the gain of the high pass filter 13a is greater than the gain of the low pass filter 14a. Accordingly, the amplitude V1 of the output signal S13 from the high pass filter 13a is larger than the amplitude V2 of the output signal S14 from the low pass filter 14a.

Incidentally, when the frequency f _d of the electric signal S12 is lower than the reference frequency F _0, as seen with reference to FIG. 5, towards the gain of the high pass filter 13a is smaller than the gain of the low pass filter 14a. In this case, the amplitude of the output signal S13 from the high pass filter 13a is smaller than the amplitude of the output signal S14 from the low pass filter 14a.

  The full-wave rectifiers 13b and 14b have the same configuration. The full wave rectifier 13b performs full wave rectification on the output signal S13. The full wave rectifier 14b performs full wave rectification on the output signal S14.

  The smoothing filters 13c and 14c have the same configuration. The smoothing filter 13c smoothes the output signal S13 that has been full-wave rectified by the full-wave rectifier 13b. The smoothing filter 14c smoothes the output signal S14 that has been full-wave rectified by the full-wave rectifier 14b. As a result, the DC signal SD13 is output from the smooth fill et al 13c, and the DC signal SD14 is output from the smooth fill et al 14c.

  FIG. 7 shows a DC signal SD13 output from the smoothing filter 13c and a DC signal SD14 output from the smoothing filter 14c. As described above, the amplitude V1 of the output signal S13 output from the high pass filter 13a is larger than the amplitude V2 of the output signal S14 output from the low pass filter 14a. For this reason, the voltage value a1 of the DC signal SD13 is larger than the voltage value a2 of the DC signal SD14.

  If the amplitude V1 of the output signal S13 output from the high pass filter 13a is smaller than the amplitude V2 of the output signal S14 output from the low pass filter 14a, the voltage value a1 of the DC signal SD13 is It becomes smaller than the voltage value a2 of the DC signal SD14.

  Returning to FIG. 1, the A / D converter 15 converts the DC signal SD13 and the DC signal SD14 into digital signals. As a result, the voltage values a1 and a2 of the DC signal SD13 and DC signal SD14 are output to the arithmetic circuit 16 as digital data D13 and D14, respectively.

  The arithmetic circuit 16 calculates the frequency of the electric signal S12 based on the digital data D13 and D14 output from the A / D converter 15. FIG. 8 is a diagram showing the relationship between the voltage level and the frequency of the DC signals SD13 and SD14. A straight line L3 in FIG. 8 indicates the relationship between the voltage value a1 of the DC signal SD13 and the frequency of the electrical signal S12. A straight line L4 indicates the relationship between the voltage value a2 of the DC signal SD14 and the frequency of the electric signal S12. The characteristics indicated by the straight lines L3 and L4 are defined by the characteristics of the high-pass filter 13a and the low-pass filter 14a, and are similar to each other.

As shown in FIG. 8, when the relationship between the voltage level and the frequency of the DC signals SD13 and SD14 is indicated by straight lines L3 and L4 that are symmetrical with respect to a straight line parallel to the horizontal axis, the frequency F _{A of the} voltage signal S12. When, the reference frequency _{F 0,} the relationship between the voltage value a1, a2 of the DC signal SD13, SD14 is represented by the following formula (1). Note that k is a constant defined by the slopes of the straight lines L3 and L4.

The arithmetic circuit 16 specifies the voltage values a1 and a2 of the DC signals SD13 and SD14 from the received digital data D13 and D14. Then, a voltage value a1, a2 that this particular, by using the known reference frequency F _0, by performing the operation represented by the above formula (1), calculates the frequency F _A of the electrical signal S12.

Here, as shown in FIG. 7, the case where the voltage value a1 of the DC signal SD13 is larger than the voltage value a2 of the DC signal SD14 has been described. However, the above equation (1) represents the voltage of the DC signal SD13. This also holds when the value a1 is smaller than the voltage value a2 of the DC signal SD14. Therefore, if the voltage values a1 and a2 of the DC signal SD13 and the DC signal SD14 are known, the arithmetic circuit 16 can calculate the frequency F _A of the electric signal S12 regardless of the magnitude of each voltage value.

When the arithmetic circuit 16 calculates the frequency F _A of the electrical signal S 12, the arithmetic circuit 16 outputs information related to the frequency F _A to the speed calculation circuit 17.

The speed calculation circuit 17 calculates the moving speed v of the moving body based on the frequency F _A calculated by the calculation circuit 16. The moving speed v of the moving object can be expressed by the following equation (2) using the frequency F _A (≈f _d ) and the wavelength λ _{0 of the} microwave emitted from the Doppler module 11 toward the moving object. it can.

_{v = F A · λ 0/} 2 ... (2)

Therefore, the speed calculation circuit 17 calculates the moving speed v of the moving body by substituting the frequency F _A calculated by the calculation circuit 16 and the wavelength λ _{0 of the} microwave into the above equation (2). For example, when the wavelength λ _{0 of the} microwave is 0.012414 m and the frequency F _A detected as the Doppler shift frequency is 161.1 Hz, the moving speed v of the moving body is 1 m / S (= 161. 1 × 0.0124414 / 2). When calculating the moving speed v of the moving body, the speed calculating circuit 17 outputs information on the calculated moving speed v to the display unit 18.

  The display unit 18 has a liquid crystal display, for example. When the information about the moving speed v of the moving body is received from the speed calculating circuit 17, the information about the moving speed v is displayed.

As described above, in the velocity measuring device 10 according to the present embodiment, the reflected wave reflected by the moving body as the measurement target is received by the Doppler module 11. Then, the microwaves outputted from the Doppler module, based on the received reflected wave, an electric signal whose frequency coincides with the Doppler shift frequency f _d is generated. Next, the electric signal S12 generated by amplifying the electric signal is converted into a DC signal having a voltage level corresponding to the attenuation characteristic of the high-pass filter 13a constituting the first output circuit 13 by the first output circuit 13. Converted to SD13. At the same time, the second output circuit 14 converts it into a DC signal SD14 having a voltage level corresponding to the attenuation characteristic of the low-pass filter 14a constituting the second output circuit 14. Then, by using the voltage value a1 of the DC signal SD13 and the voltage value a2 of the DC signal SD14, the calculation shown in the above equation (1) is executed to calculate the frequency F _A of the electric signal (Doppler signal). Is done.

  For this reason, the speed measurement device 10 according to the present embodiment can measure the frequency of the electric signal in a short time without performing a calculation process having a relatively large calculation amount represented by the FFT process.

  Moreover, in the speed measuring device 10 according to the present embodiment, the moving speed of the moving body is measured based on the frequency measured in a short time. For this reason, the moving speed of the moving body can be measured in a short time.

  Further, in the speed measurement device 10 according to the present embodiment, since it is not necessary to perform complicated processing for frequency calculation, the structure of the device can be simplified. Thereby, the manufacturing cost and running cost of the apparatus can be reduced. Further, since the structure of the device is simplified, energy consumption in the device is not reduced. For this reason, it is possible to perform measurement over a long period of time using a power source such as a battery.

  In the present embodiment, the signal amplifier 12, the first output circuit 13, the second output circuit 14, the A / D converter 15, and the arithmetic circuit 16 constitute a frequency measuring device. In the present embodiment, the case where this frequency measurement device is used for detecting the moving speed of a moving body has been described as an example. The application of the frequency measurement device according to the present embodiment is not limited to this, and for example, the frequency of an electrical signal generated based on vibrations generated from a structure or ground such as a building or a plant may be measured. it can. In this case, the frequency characteristics of the high-pass filter 13a configuring the first output circuit 13 and the low-pass filter 14a configuring the second output circuit 14 are selected according to the frequency characteristics of the measurement target, depending on the application. Is preferred.

  In this embodiment, the gain of the high-pass filter 13a constituting the first output circuit 13 increases uniformly as the frequency of the input electric signal increases, and the low-pass filter 14a constituting the second output circuit 14 increases. The gain decreases uniformly as the frequency of the input electrical signal increases. The present invention is not limited to this, and the gain (attenuation rate) of each filter does not necessarily change uniformly, and the change rate does not necessarily have to be equal between the high-pass filter 13a and the low-pass filter 14a.

  Further, in the present embodiment, as illustrated in FIG. 2, the description has been made assuming that the frequency of the electric signal is a single frequency (sine wave). However, the electrical signal is not limited to a single frequency. In this case, by using the voltage value of the DC signal SD13 and the voltage value of the DC signal SD14, the calculation shown in the above equation (1) is executed to easily calculate the center frequency of the signal having a band. can do.

Moreover, although this embodiment demonstrated the case where the mobile body was moving to the advancing direction and the coaxial direction of the microwave inject | emitted from the velocity measuring apparatus 10, this invention is not limited to this. For example, when the moving body is moving in a direction that makes an angle of θ with the traveling direction of the microwave emitted from the velocity measuring device 10, the Doppler shift frequency f _d is expressed by the following equation (3). It is. Moreover, the moving speed v of the moving body is expressed by the following equation (4). In this case, the speed calculation circuit 17 can calculate the moving speed v using the following equation (4).

f _d = 2 · v / λ ₀ · COSθ (3)
v = F _A · λ ₀ / (2 · COSθ) (4)

For example, when the moving speed v of the moving body is 1 m / s, the wavelength λ _{0 of the} microwave is 0.012414, and θ is 45 degrees, the Doppler shift frequency f is obtained from the above equation (3). _d is 113.92 Hz. When the frequency F _A (≈f _d ) of the electric signal is 113.92 Hz, the moving speed v of the moving body is 1 m / s according to the above equation (4).

<< Second Embodiment >>
Next, a speed measuring device 10A according to a second embodiment of the present invention will be described. In addition, about the structure same or equivalent to 1st Embodiment, while using an equivalent code | symbol, the description is abbreviate | omitted or simplified.

  FIG. 9 is a block diagram of the speed measuring device 10A according to the present embodiment. The speed measuring device 10A is a first output circuit 21, a second output circuit 22, a third output circuit 23, and a fourth output circuit 24. It differs from the speed measuring device 10 according to the first embodiment in that it has two output circuits.

FIG. 10 is a diagram illustrating the attenuation characteristics of the filters constituting each of the first output circuit 21, the second output circuit 22, the third output circuit 23, and the fourth output circuit 24. A mountain-shaped broken line S1 indicated by a solid line in FIG. 10 indicates an attenuation characteristic of a filter (hereinafter referred to as a first filter) constituting the first output circuit 21. The first filter with respect to the center frequency F _1, and has a damping characteristic that the gain is reduced uniformly. A mountain-shaped broken line S2 indicated by a one-dot chain line indicates an attenuation characteristic of a filter (hereinafter referred to as a second filter) constituting the second output circuit 22. The second filter is based on the center frequency F _3, and has a damping characteristic that the gain is reduced uniformly. A mountain-shaped broken line S3 indicated by a two-dot chain line indicates an attenuation characteristic of a filter constituting the third output circuit 23 (hereinafter referred to as a third filter). The third filter, with respect to the center frequency F _5, and has a damping characteristic that the gain is reduced uniformly. A mountain-shaped broken line S4 indicated by a broken line indicates an attenuation characteristic of a filter (hereinafter referred to as a fourth filter) constituting the fourth output circuit 24. The fourth filter is a reference to the center frequency F _7, and has a damping characteristic that the gain is reduced uniformly.

As seen with reference to FIG. 10, a first filter gain (attenuation factor), the second filter gain (attenuation factor) is equal to the input signal of the frequency F _2. Further, the first filter gain (attenuation factor), third filter gain (attenuation factor) is equal to the input signal of the frequency F _3. Further, the first filter gain (attenuation factor), fourth filter gain (attenuation factor) is equal to the input signal of the frequency F _4. Further, the second filter gain (attenuation factor), third filter gain (attenuation factor) is equal to the input signal of the frequency F _4. Further, the second filter gain (attenuation factor), fourth filter gain (attenuation factor) is equal to the input signal of the frequency F _5. Also, a third filter gain (attenuation factor), fourth filter gain (attenuation factor) is equal to the input signal of the frequency F _6.

  FIG. 11 is a diagram illustrating output characteristics of the first output circuit 21, the second output circuit 22, the third output circuit 23, and the fourth output circuit 24. As described in the first embodiment, the output characteristics of the first output circuit 21, the second output circuit 22, the third output circuit 23, and the fourth output circuit 24 depend on the characteristics of the filters constituting each output circuit. It is prescribed. For this reason, the output characteristics of each output circuit are indicated by broken lines S5 to S8 similar to the broken lines S1 to S4.

  The arithmetic circuit 16 according to the present embodiment determines whether the frequency of the electrical signal S12 to be frequency-measured is included in the first range A1, the second range A2, or the third range A3. to decide. This determination is made based on, for example, the speed of the moving body and the frequency of the microwave used for measurement.

The first range A1 is in the range from the center frequencies F ₁ of the first filter, and the center frequency F ₃ of the second filter. The second range A2 is in the range from the center frequency F ₃ of the second filter, to the center frequency F ₅ of the third filter. The third range A3 is a range from the center frequency F ₅ of the third filter, to the center frequency F ₇ of the fourth filter.

When the arithmetic circuit 16 determines that the frequency of the electrical signal S12 belongs to the first range A1, the arithmetic circuit 16 uses the voltage values of the DC signals from the first output circuit 21 and the second output circuit 22 to calculate the above formula ( By performing the calculation shown in 1), the frequency F _A of the electrical signal S12 is calculated. When the arithmetic circuit 16 determines that the frequency of the electric signal S12 belongs to the second range A2, the arithmetic circuit 16 uses the voltage values of the DC signals from the second output circuit 22 and the third output circuit 23 to The frequency F _A of the electric signal S12 is calculated by performing the calculation shown in Expression (1). When the arithmetic circuit 16 determines that the frequency of the electric signal S12 belongs to the third range A3, the arithmetic circuit 16 uses the voltage value of the DC signal from the third output circuit 23 and the fourth output circuit 24 to The frequency F _A of the electric signal S12 is calculated by performing the calculation shown in Expression (1).

For example, as shown in FIG. 11, when it can be estimated that the frequency of the electric signal S12 belongs to the second range A2, the voltage value b2 of the DC signal from the second output circuit 22 and the third output circuit On the basis of the voltage value b1 of the DC signal from 23, the frequency F _A of the electric signal S12 is calculated. When the frequency of the electric signal S12 can be estimated to belong to the third range A3, the voltage value c2 of the DC signal from the third output circuit 23 and the voltage of the DC signal from the fourth output circuit 24 Based on the value c1, the frequency F _A of the electric signal S12 is calculated.

Returning to FIG. 9, the speed calculation circuit 17 calculates the moving speed v of the moving body by executing the calculation represented by the above formula (2) for the frequency F _A. And the display unit 18 displays the information regarding the moving speed v of a moving body.

  As described above, in the present embodiment, a DC signal used for frequency calculation is selected according to the frequency of the electric signal S12, and the frequency of the electric signal S12 is determined based on the voltage value of the selected DC signal. Calculated. A filter having an attenuation characteristic indicated by a mountain-shaped broken line generally has a high SN ratio in the vicinity of the center frequency. In the present embodiment, a DC signal is generated from an AC signal that has passed through a filter having a center frequency close to the frequency of the electrical signal 12. Then, based on the voltage value of the DC signal, the frequency of the electric signal S12 is calculated. Therefore, an error generated when calculating the electric signal is reduced, and an accurate frequency can be calculated. Further, by using a plurality of output circuits having different output characteristics, measurement in a wide frequency range is possible.

  In addition, 10 A of speed measuring devices which concern on this embodiment have the four output circuits 21-24. Not only this but you may have five or more output circuits.

  As mentioned above, although embodiment of this invention was described, this invention is not limited by the said embodiment. For example, in the above-described embodiment, a case has been described in which a frequency measurement device including a signal amplifier, an output circuit, an A / D converter, and an arithmetic circuit is used for a speed measurement device. However, the present invention is not limited to this, and the frequency measuring device of the present invention may be used for a frequency analyzing device for measuring the frequency of an input electric signal.

  In addition, the frequency band of the electrical signal and the frequency band of each filter in the above embodiment are examples, and the same effect can be obtained even when a filter having a frequency band other than the above frequency band is used in combination.

  Various embodiments and modifications can be made to the present invention without departing from the broad spirit and scope of the present invention. Further, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention. That is, the scope of the present invention is shown not by the embodiments but by the claims. Various modifications within the scope of the claims and within the scope of the equivalent invention are considered to be within the scope of the present invention.

  The frequency measuring device and frequency measuring method of the present invention are suitable for measuring the center frequency of a wave. Moreover, the speed measuring device and the speed measuring method of the present invention are suitable for measuring the speed of a moving body.

10, 10A Speed measurement device 11 Doppler module 12 Signal amplifier 13 First output circuit 13a High pass filter 13b Full wave rectifier 13c Smoothing filter 14 Second output circuit 14a Low pass filter 14b Full wave rectifier 14c Smoothing filter 15 A / D converter 16 Calculation Circuit 17 Speed calculation circuit 18 Display unit 21 First output circuit 22 Second output circuit 23 Third output circuit 24 Fourth output circuit A1 First range A2 Second range A3 Third range D13 Digital data D14 Digital data L1, L2 Linear S1-S8 broken line S12 electrical signal S13, S14 output signal SD13, SD14 DC signal

Claims (8)

Conversion means for converting the wave into an electrical signal;
First output means for outputting a first signal whose value increases in proportion to an increase in frequency of the electrical signal;
Second output means for outputting a second signal whose value decreases in proportion to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio of the value of the first signal and the value of the second signal, Computing means for calculating the frequency;
A frequency measuring device having:   The frequency measurement device according to claim 1, wherein an increase rate of the value of the first signal with respect to the frequency is equal to a decrease rate of the value of the second signal with respect to the frequency. The first output means has a first filter that attenuates the electrical signal with an attenuation rate proportional to a decrease in the frequency of the electrical signal,
3. The frequency measurement device according to claim 1, wherein the second output unit includes a second filter that attenuates the electrical signal with an attenuation rate proportional to an increase in the frequency of the electrical signal. The first output means includes
A first rectifier circuit that full-wave rectifies the electrical signal that has passed through the first filter;
A first smoothing circuit for smoothing an output from the first rectifier circuit and generating the first signal indicating a level of the electrical signal;
The second output means includes
A second rectifier circuit that full-wave rectifies the electrical signal that has passed through the second filter;
The frequency measurement device according to claim 3, further comprising: a second smoothing circuit that smoothes an output from the second rectifier circuit and generates the second signal indicating a level of the electric signal. The computing means sets the value of the first signal to P1, the value of the second signal to P2, and the frequency of the electrical signal when the value of the first signal and the value of the second signal match F _0. The frequency measurement device according to claim 1, wherein when the constant is k, the frequency F of the electrical signal is calculated using the following equation.

The frequency measurement device according to any one of claims 1 to 5, which measures a frequency of an electric signal based on a wave reflected from a moving body,
Speed calculation means for performing a calculation using the frequency measured by the frequency measuring device to calculate the speed of the moving body;
A speed measuring device comprising: Converting a wave into an electrical signal;
Generating a first signal indicative of a level of an output signal from a first filter that attenuates the passing electrical signal at an attenuation rate proportional to a decrease in the frequency of the electrical signal;
Generating a second signal indicative of a level of an output signal from a second filter that attenuates the passing electrical signal at an attenuation rate proportional to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio between the value of the first signal and the value of the second signal, Calculating the frequency of
Frequency measurement method including Converting the wave reflected from the moving body into an electrical signal;
Generating a first signal indicative of a level of an output signal from a first filter that attenuates the passing electrical signal at an attenuation rate proportional to a decrease in the frequency of the electrical signal;
Generating a second signal indicative of a level of an output signal from a second filter that attenuates the passing electrical signal at an attenuation rate proportional to an increase in frequency of the electrical signal;
Based on the frequency of the electrical signal when the value of the first signal and the value of the second signal match, and the ratio between the value of the first signal and the value of the second signal, Calculating the frequency of
Performing a calculation using the calculated frequency of the electrical signal to detect the speed of the moving body;
Speed measurement method including

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