JP3657063B2 - Speed measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, when the sound wave received by the receiver is a sound wave reflected by a moving object or a stationary object, the sound wave signal from the moving object is extracted and the speed of the moving object is accurately determined. The present invention relates to a speed measuring device that measures.
[0002]
Conventionally, there is a case where a speed measuring device using the Doppler effect is used for measuring the speed of a moving object. FIG. 9 is a block diagram showing the configuration of the speed measuring device. In the following, for convenience of explanation, the speed measuring device is roughly classified into a transmission system, a reception system, and a signal processing system.
[0003]
The transmission system includes a reference oscillator that generates a reference signal having a frequency Fout, an output amplifier that amplifies the reference signal 2, and a transmitter 3 that emits ultrasonic waves based on the signal from the output amplifier 2.
[0004]
The wave receiving system includes a wave receiver 4 that receives an ultrasonic wave of frequency Fin and converts it into an electric signal, and a preamplifier 5 that amplifies the signal from the wave receiver 4 and outputs the amplified signal as a received signal. Has been.
[0005]
Further, the signal processing system receives the reference signal and the received signal, detects the signals from the mixer 6 and the mixer 6 that mix them, and outputs the signal of the difference frequency Fd between the reference signal and the received signal as the difference frequency signal. A frequency detector 12 that outputs a signal as a Doppler signal, and a measurement result from the frequency meter 12 Based on the velocity of the moving object
Fd = 2 · V · Fout / (C−V) (1)
And a display 14 for displaying the speed of the moving object calculated by the calculator 13. In Equation 1, V indicates the speed of the moving object, and C indicates the speed of sound.
[0006]
FIG. 10 shows a band-pass filter 801 for passing a signal of the Doppler frequency band from the differential frequency signal output from the detector 7 between the detector 7 and the arithmetic unit 13 instead of the low-pass filter 601 in FIG. , A frequency measuring device 12 for measuring the frequency of the signal from the bandpass filter 801 is provided, and a noise band bandpass filter 802 for filtering noise that is a frequency component higher than the Doppler frequency from the difference frequency signal from the detector 7. In addition, a signal detector 901 is provided to improve measurement accuracy.
[0007]
[Problems to be solved by the invention]
However, in the above-described configuration, for example, when measuring the ball speed of the ball thrown by the pitcher, the frequency Fin of the received signal is not a single frequency, so that there is a problem that accurate speed measurement is difficult for the reason described later.
[0008]
That is, the ultrasonic wave emitted from the transmitter 3 is reflected by any part such as a stationary object or the body of the pitcher other than the ball and received by the receiver 4 and emitted from the transmitter 3. A part of the ultrasonic wave directly enters the receiver 4 (hereinafter referred to as a direct wave) and is received.
[0009]
Therefore, the received signal includes a plurality of signals having different frequencies, and the signal level of the ultrasonic wave or direct wave reflected by the stationary object has a high signal level. Therefore, the S / N ratio (signal-to-noise ratio) of the Doppler signal is high. As a result, the signal waveform is distorted or the waveform of the signal is distorted, making it difficult to measure the normal frequency, that is, to measure the velocity of the moving object.
[0010]
Accordingly, an object of the present invention is to provide a speed measuring device capable of measuring speed with high accuracy by extracting only the Doppler signal even when the received signal is composed of a plurality of signals having different frequencies. To do.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the invention according to claim 1 includes a sound wave emitting means for emitting a sound wave based on a reference signal having a predetermined frequency, a wave receiving means for receiving a sound wave and outputting it as a received signal, In a speed measuring device having speed calculating means for calculating the speed of a moving object from a reference signal and a received signal, the speed calculating means obtains a difference in frequency between the received signal and the reference signal to obtain a difference frequency signal. A differential frequency detection unit that outputs the differential frequency signal as a band signal by band-separating the differential frequency signal into two or more preset frequency bands, and a detection signal of the band signal or the band signal When the time exceeds the threshold or the time that can be considered to have exceeded the preset first judgment time, a detection signal of a superior level is output and the threshold is exceeded. If the second judgment time longer than the first judgment time continues for a time that can be regarded as being between or exceeded, a band signal judgment unit that outputs a valid signal, and the band signal and the detection signal are input and the detection is performed. A band signal selection unit that selects one band signal from a plurality of band signals based on a signal, and measures the frequency of the band signal selected by the band signal selection unit, and whether or not the measured frequency is valid And a measurement calculation unit for calculating the speed of the moving object based on the effective frequency.
[0012]
That is, from the received signal including various frequencies, only the signal from the sound wave reflected by the moving object is processed and the received signal is divided into a plurality of frequency bands by the frequency band separation unit in order to measure the speed of the moving object with high accuracy. Is separated into a band signal.
[0013]
When the time that the band signal is determined to be greater than or greater than the threshold by the band signal determination unit is longer than the preset first determination time, a detection signal having a superiority level indicating that is output, If the time when the band signal exceeds the threshold or the time when it can be considered to exceed the threshold is longer than the preset second determination time by a predetermined amount, an effective signal indicating that is output.
[0014]
The first determination time is set shorter than the second determination time, and is set to be longer by a predetermined amount than the time in the region when a frequency disturbance or the like occurs in the start region of the band signal.
[0015]
The second time is a determination time for measuring the frequency by removing the region from the frequency measurement when the frequency of the end region of the band signal is disturbed.
[0016]
When at least one or more detection signals having a superior level are present by the band signal selection unit, the band signal corresponding to the detection signal with the highest frequency is selected.
[0017]
The frequency of the band signal is measured by the measurement calculation means, and whether or not the band signal measured by the frequency is valid is judged from the valid signal. When the frequency signal is valid, the speed of the moving object is calculated based on the frequency measurement result. It is characterized by performing.
[0018]
The above-described superior level refers to an effective signal level in the subsequent determination processing. For example, when a pulse signal of “High” level is output when the band signal is larger than the threshold value, the “High” level is It becomes a superior level.
[0019]
The invention according to claim 2 is characterized in that the frequency band separation unit is divided into two or more frequency bands with respect to the frequency band of the measurement range of the speed measuring device.
[0020]
The invention according to claim 3 is characterized in that the band signal selection unit selects a band signal corresponding to a detection signal having the highest frequency band among the plurality of detection signals having a superiority level.
[0021]
According to a fourth aspect of the present invention, when the start region and the end region of the band signal are at least frequency modulated due to the transient characteristic of the frequency band separation unit, the first determination time is the start of the band signal. The second determination time is set to be a predetermined amount longer than the modulation time of the region, and the sum of the time during which the measurement calculation unit can measure the frequency of the band signal and the modulation time of the end region of the band signal It is characterized by being set longer by a predetermined amount.
[0022]
The modulated time is the duration of a region that is modulated by transient characteristics.
[0023]
According to a fifth aspect of the present invention, there is provided a sound wave emitting means for emitting a sound wave based on a reference signal having a predetermined frequency, a wave receiving means for receiving a sound wave and outputting it as a received signal, and a moving object from the reference signal and the received signal. A speed measuring device having a speed computing means for computing the speed of the differential frequency detector, wherein the speed computing means obtains a frequency difference between the received signal and a reference signal and outputs the difference as a differential frequency signal; The differential frequency signal is band-separated into two or more preset frequency band signals, and the time when the band signal or its detection signal exceeds or exceeds the preset threshold is obtained. It is determined whether or not a first determination time set in advance and a second determination time longer than the first determination time are longer, and when there are a plurality of band signals longer than the first determination time, The frequency measurement is performed by selecting the band signal having the highest frequency band from a number of the band signals and moving based on the frequency measurement result only when the band signal measured for the frequency continues for the second determination time. And a signal processing unit that calculates the velocity of the object.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a block diagram of a speed measuring device according to the present embodiment. The velocity measuring device includes a sound wave emitting means for emitting ultrasonic waves based on a reference signal, a wave receiving means for receiving ultrasonic waves reflected by a moving object, etc., and outputting a received signal, and a received signal from the wave receiving means. Based on the speed calculation means for calculating the speed of the moving object based on this.
[0025]
In addition, the speed calculation means includes a difference frequency detection unit that obtains a difference frequency signal between the received signal and the reference signal, a frequency band separation unit that separates the difference frequency signal into band signals of a plurality of frequency bands, and outputs the band signal. A band signal determination unit that determines whether or not a predetermined condition is satisfied and outputs a detection signal and a valid signal, and a band signal selection unit that selects a band signal corresponding to a specific detection signal from detection signals having a plurality of superior levels The frequency of the band signal selected by the band signal selection unit is measured, and it is determined whether the band signal measured by the effective signal is valid. Only when the band signal is valid, the frequency of the moving object is determined. It consists of a measurement calculator that calculates speed.
[0026]
The above configuration will be described in detail. The wave transmitting means emits a reference oscillator 1 that generates a reference signal S1 having a frequency Fout, an output amplifier that amplifies the reference signal S1, and an amplified reference signal S1 as an ultrasonic wave S2. It consists of a transmitter 3.
[0027]
The wave receiving means receives the ultrasonic wave S3, converts it into an electric signal and outputs it, a receiver 4, a preamplifier 5 that amplifies the signal from the wave receiver 4 and outputs it as a received signal S4. It is composed of
[0028]
The differential frequency detector in the speed calculation means extracts the frequency difference between the received signal S4 and the reference signal S1 from the mixer 6 and the mixer 6 that mix the received signal S4 and the reference signal S1, and uses this to extract the difference frequency signal S5. As shown in FIG.
[0029]
The frequency band separation unit separates the differential frequency signal S5 from the detector 7 into five adjacent narrowband frequency components and outputs the band signal Se (SeHH to SeLL) as a bandpass filter 8 (8a to 8a). 8e). Note that the number of divisions of the bandpass filter 8 is not limited to five and can be set as appropriate.
[0030]
The band signal determination unit has signal detectors 9 (9a to 9e) provided corresponding to the respective bandpass filters 8, and has a superior level when each band signal Se satisfies a condition 1 described later. The detection signal Sf (SfHH to SfLL) is output, and if the condition 2 is satisfied, the valid signal Si is output.
[0031]
The band signal selection unit selects and outputs the band signal Se corresponding to the detection signal Sf having the highest frequency band among the plurality of detection signals Sf having the superiority level from the signal detection unit 9. The selected band signal Se is referred to as a band signal Sh.
[0032]
The measurement calculation unit only measures the frequency measured by the frequency measuring instrument 12 based on the effective signal Si from the frequency measuring instrument 12 and the signal detector 9 that measures the frequency of the selected band signal Sh. And an arithmetic unit 13 for calculating the speed of the moving object.
[0033]
In addition, the measurement calculation unit is provided with a temperature measuring device 15 that measures the outside air temperature in consideration of the change in sound speed depending on the temperature, and performs a temperature correction as appropriate, and a display unit 14 that displays the speed of the moving object. Is provided.
[0034]
In the following description, with regard to a device comprising a plurality of means having the same function, such as the bandpass filter 8 (8a to 8e) and the signal detector 9 (9a to 9e), individual configurations are referred to. Unless otherwise specified, general numbers are used to appropriately describe the bandpass filter 8, the signal detector 9, and the like.
[0035]
FIG. 2 shows the output signal of each block, and the operation will be described with reference to FIG. A reference signal S1 having a frequency Fout is oscillated from the reference oscillator 1 and amplified by the output amplifier 2. Then, the ultrasonic wave S <b> 2 is emitted from the transmitter 3.
[0036]
The emitted ultrasonic wave S2 is reflected by a moving object and is subjected to the Doppler effect, thereby being reflected by the receiver 4 as a reflected wave S3 having a frequency Fin.
[0037]
Note that the ultrasonic wave S3 received by the wave receiver 4 is reflected by an ultrasonic wave reflected under various conditions, so that the frequency of the received signal S4 is not a single frequency, and the emitted ultrasonic wave Note that it is not a clean waveform as shown in the sound wave S2.
[0038]
For example, when measuring the ball speed of the ball thrown by the pitcher, the ultrasonic wave S3 received by the wave receiver 4 includes a reflected wave from the ball, a reflected wave from a moving object other than the ball, such as the pitcher's body, The direct wave that the ultrasonic wave emitted from the transmitter 3 directly wraps around and receives and the reflected wave reflected by the stationary object are included. For the purpose of measuring the ball speed, all the ultrasonic waves reflected by the ball become noise.
[0039]
The signal from the receiver 4 is amplified by a preamplifier 5 to be a received signal S4, then mixed with a reference signal S1 by a mixer 6, detected by a detector 7 and converted to a differential frequency signal S5, and a bandpass filter 8 To enter.
[0040]
The band-pass filter 8 is divided into five bands (HH, HL, M, LH, LL) from the high frequency side, and the input differential frequency signal S5 is separated into each band signal Se (SeHH to SeLL) to detect signals. Output to the device 9 and the signal selector 10.
[0041]
Incidentally, since the bandpass filter 8 has transient characteristics, the frequency of the start region and the end region of the band signal Se is modulated to a frequency different from the original frequency. Therefore, if measurement / calculation processing is performed using such a band signal Se, an accurate result cannot be obtained. Therefore, the signal detector 9 makes various judgments in order to eliminate the influence of such transient characteristics.
[0042]
That is, the signal detector 9 determines whether or not the input band signal Se is larger than a threshold value set in advance in the signal detector 9, and if the time or the time when the band signal becomes larger than the threshold value is larger. When the time that can be considered continues for longer than the first determination time (condition 1), the detection signal Sf (SfHH to SfLL) having the superiority level is output to the signal selector 10.
[0043]
In addition, when the time when the band signal is larger than the threshold or the time when it can be regarded as larger than the second determination time (condition 2), the band signal Se is not at least a non-original signal such as noise, and the above The effective signal Si indicating that the frequency measurement is possible without including the modulated region in the end region of the band signal Se due to the transient characteristics is output to the calculator 13.
[0044]
FIG. 3 is an example of a Bode diagram showing the signal level of the band signal Se input to the signal detector 9 with respect to the band frequency. In the case of this example, the band signals SeHL, SeM, SeLH of the bands HL, M, LH have a signal level larger than a threshold value preset in the signal detector 9, and among these, the band signal SeLH of the band LH is the most. Have a large signal level.
[0045]
The band signal SeHH in the band HH has a signal level substantially equal to the threshold value, and the band signal SeLL in the band LL has a signal level smaller than the threshold value. The band signals SeHH and SeLL of the bands HH and LL can be determined as noise.
[0046]
Therefore, among the band signals Se from the band pass filter 8, the band signals SeHL, SeM, SeLH of the bands HL, M, LH having a signal level larger than the threshold value preset in the signal detector 9 are the dominant levels. This is a detection signal having However, in this case, it is assumed that the condition 1 described above is satisfied.
[0047]
Then, the signal selector 10 determines the band signal Sh having the highest frequency band from the detection signal Sf having the superior level and outputs it to the frequency measuring device 12.
[0048]
The reason for selecting a high-frequency band signal from a plurality of band signals Se is, for example, when the frequencies of the ultrasonic wave reflected from the pitcher and the ultrasonic wave reflected from the ball are compared, This is because the ultrasonic frequency is high (the Doppler frequency is high).
[0049]
Therefore, if the relationship is not as described above, a criterion for selection by the signal selector 10 may be appropriately set.
[0050]
A signal from the frequency measuring device 12, an effective signal Si from the signal detector 9, and an outside air temperature signal from the temperature measuring device 15 are input to the calculator 13. Based on these, the calculator 13 sets the sound speed C as the outside temperature t,
C = 331.5 + 0.6t (2)
And the velocity V of the moving object is calculated according to Equation 1, and the display 14 displays this result.
[0051]
Next, the transient characteristics of the bandpass filter 8 will be described in detail with reference to FIG. When the intermittent difference frequency signal S5 is input to the bandpass filter 8, the bandpass filter 8 modulates the band signal Se to a frequency different from the original frequency in the start region and the end region of the difference frequency signal S5 due to transient characteristics. Output as. Therefore, the frequency of the start region and the end region of the band signal Se is modulated by the transient characteristic and becomes a frequency different from the original frequency.
[0052]
Hereinafter, the signal region transiently modulated by the bandpass filter 8 is referred to as a transient modulation region, and in particular, the modulation region at the start of the signal is referred to as a start modulation region, and the modulation region at the end is referred to as an end modulation region. The durations of the start modulation area and the end modulation area are denoted as Δts and Δte, respectively.
[0053]
4A shows the differential frequency signal S5 input from the detector 7 to the band pass filter 8, and FIG. 4B shows the band signal Se output from the band pass filter 8. FIG. FIG. 4C is a diagram for facilitating understanding of the frequency characteristics of the transiently modulated band signal Se, and shows a waveform when the band signal Se is subjected to frequency / voltage conversion (F / V conversion). Is shown.
[0054]
Now, let Fc be the center frequency in a certain band of the bandpass filter 8, and F be the frequency of the differential frequency signal S5.
[0055]
At this time, when the frequency F of the differential frequency signal S5 is lower than the center frequency Fc (F <Fc), the frequency Fe of the band signal Se output from the bandpass filter 8 gradually increases with the input of the differential frequency signal S5. A region that gradually increases to a frequency close to the center frequency Fc and then gradually settles down to the frequency F of the differential frequency signal S5 (start modulation region), and when the differential frequency signal S5 ends, gradually reaches a frequency that is close to the center frequency Fc. After that, the output ends gradually (end modulation area).
[0056]
Accordingly, the F / V converted band signal Se has peaks at both ends of the signal as shown in FIG.
[0057]
When the frequency F of the difference frequency signal S5 is higher than the center frequency Fc (F> Fc), the frequency Fe of the band signal Se gradually passes through the center frequency Fc as the difference frequency signal S5 is input. Frequency F (start modulation region), and thereafter, when the differential frequency signal S5 ends, it gradually decreases through the center frequency Fc (end modulation region), and the output ends.
[0058]
Accordingly, the F / V-converted band signal Se becomes a mountain-shaped signal where both ends of the signal are gentle as shown in FIG.
[0059]
On the other hand, when the frequency F of the difference frequency signal S5 is equal to the center frequency, the band signal Se gradually becomes the center frequency Fc (start modulation region), and gradually decreases with the end of the difference frequency signal S5 (end). (Modulation region) is not output.
[0060]
Since the bandpass filter 8 has a transient characteristic in this way, a transient modulation start modulation region and an end modulation region are generated, and it is accurate to perform frequency measurement using a signal region including these modulation regions. Frequency measurement is not possible. Therefore, the speed error of the moving object becomes large and the reliability is significantly lowered.
[0061]
Therefore, the signal detector 9 determines whether or not signal processing is possible by excluding the influence of transient characteristics. This will be described with reference to FIG.
[0062]
FIG. 5A is a block diagram showing a schematic configuration of the signal detector 9, and compares the band signal Se with a preset threshold value Vth and outputs a predetermined pulse signal (determination signal) S11. And a determination block 9B that outputs a detection signal Sf having a superior level when the band signal Se satisfies the condition 1, and outputs a valid signal Si when the condition 2 is satisfied, based on the determination signal from the comparison block 9A. ing.
[0063]
FIG. 5B shows each signal waveform in the comparison block 9A, and FIG. 5C shows each signal waveform in the decision block 9B.
[0064]
The comparison block 9A receives the band signal Se and the threshold value Vth, and outputs a trigger signal S10 when the band signal Se becomes larger than the threshold value Vth. A determination signal S11 having a predetermined width corresponding to the trigger signal S10. Is constituted by a retrigger type circuit (retriggerable one-shot circuit) 9b.
[0065]
The retrigger type circuit 9b also responds to the trigger signal S10 input when the retrigger type circuit 9b is in a metastable state, and each time the retrigger type circuit 9b enters a new metastable state. Therefore, if a plurality of trigger signals S10 are continuously input at intervals within the metastable state of the retrigger type circuit 9b, one wide square wave pulse signal S11 is output. This metastable state is characterized by a time constant τ, which is set to be a predetermined amount larger than the period of the lower cut-off frequency of each bandpass filter 8.
[0066]
The determination signal S11 obtained in this way is input to the determination block 9B. The determination block 9B is composed of a first determination system and a second determination system, and the respective operations are the same, but since the set values are different, finally different operations are obtained.
[0067]
These first and second determination systems output first and second integrators 9c (9ca, 9ca, 9db) that output an integration signal S15 (S15a, S15b) obtained by integrating the determination signal S11 to the first and second Schmitt trigger circuits 9d (9da, 9db). 9cb) and first and second one-shot circuits 9e (9ea, 9eb) for outputting a pulse having a predetermined width in response to a trigger signal S16 (S16a, S16b) from the first and second Schmitt trigger circuits 9d.
[0068]
In the above configuration, the first integrator 9ca integrates the determination signal S11 and outputs an integration signal S15a. When the integration signal S15a becomes equal to or higher than a predetermined level V1, the first Schmitt trigger circuit 9da outputs the trigger signal S16a, and the first one-shot circuit 9ea outputs the detection signal Sf with the rising of the trigger signal S16a as a trigger.
[0069]
The time width of the detection signal Sf is t2, and this time is a time required for the frequency measuring device 12 to measure the frequency of the band signal Se (hereinafter referred to as a frequency measurement time).
[0070]
Of course, when the output of the first integrator 9ca does not reach the level V1, since the trigger signal S16a is not output from the first Schmitt trigger circuit 9da, the detection signal Sf becomes a signal of an insignificant level.
[0071]
The integration constant of the first integrator 9ca is set so that the time t1 until the integration signal S15a reaches the predetermined level V1 is slightly longer than the duration Δts of the start modulation region.
[0072]
Accordingly, the trigger signal S16 output from the first Schmitt trigger circuit 9da is output after the start modulation region has elapsed since the band signal Se was input. Therefore, at the time of frequency measurement by the frequency measuring device 12, it is possible to exclude at least signals in the start modulation region.
[0073]
However, in this case, the end modulation region may be included in the frequency measurement time t2. Therefore, in the second determination system, it is determined whether or not the end modulation region is included in the frequency measurement time t2, and if it is not included, the valid signal Si is output.
[0074]
That is, the second integrator 9cb integrates the determination signal S11 and outputs an integration signal S15b. When the integration signal S15b becomes equal to or higher than a predetermined level V2, the second Schmitt trigger circuit 9db outputs a trigger signal S16b. The second one-shot circuit 9eb outputs a valid signal Si having a predetermined width, triggered by the rise of the trigger signal S16b.
[0075]
The time t3 from when the detection signal Sf ends until the integration signal S15b reaches the predetermined level V2 is set to be slightly longer than the duration Δte of the end modulation region.
[0076]
Therefore, if the time t3 can be secured during the time width t0 of the band signal Se, the end modulation region is not included in the frequency measurement time t2.
[0077]
In summary, when t0 ≧ t1 (condition 1), the detection signal sf having the superiority level of the time width t2 is output, and when t0 ≧ t1 + t2 + t3 (condition 2), the valid signal Si is output.
[0078]
Next, the signal selector 10 will be described in detail with reference to FIG. The signal selector 10 has priority input terminals D1 to D5, and selects a specific band signal Se based on a signal from the priority encoder 10A to which the detection signal Sf is input to the input terminals D1 to D5 and the priority encoder 10A. And an analog multiplexer 10B for output.
[0079]
The detection signal Sf from the signal detector 9 is configured to be input to an input terminal having a higher priority in order from the detection signal Sf in the higher frequency band.
[0080]
For example, since the detection signal SfHH has the highest frequency band, it is input to the input terminal D5 having the highest priority, and the detection signal SfLL has the lowest frequency band and is input to the input terminal D1 having the lowest priority.
[0081]
With respect to the input having the priority as described above, the output is output as a control signal to the analog multiplexer 10B according to the logic table shown in FIG. Select the band signal for output. In FIGS. 6B and 6C, the superiority level is “H”.
[0082]
As described above, even if a reflected wave other than the original reflected wave from a stationary object or the like is input to the receiver, the reflected wave signal from the target moving object is extracted and a highly accurate moving object is extracted. Can be obtained.
[0083]
As a method of avoiding the transient characteristics of the bandpass filter 8, the avoiding means is configured using a delay circuit, a one-shot circuit, or the like. According to the method according to the present embodiment, for example, in FIG. Even when the signal level is substantially equal to the threshold value Vth of the signal detector 9 as in the band signal SeHH, and as a result, the pulse width of the detection signal SfHH is narrow and noise-like (shown by a dotted line in FIG. 2), the detection signal Sf There is a feature that is not output as.
[0084]
The frequency of each band divided by the bandpass filter 8 is appropriately set depending on the reference frequency Fout of the reference oscillator 1 and the measurement speed range of the apparatus. For example, the frequency Fout of the reference signal is 40 kHz, and the speed range is If the speed is 20 to 150 km / h, the frequency of the reflected wave reflected by the moving object is about 41.3 to 50.93 kHz, and the frequency of the differential frequency signal S5 is 1.3 to 10.93 kHz.
[0085]
In such a case, if the frequency range of the differential frequency signal is equally divided by the five bandpass filters 8 (8a to 8e), the frequency width of each band is about 2 kHz. The center frequencies of 8a to 8e may be 2.3 kHz, 4.2 kHz, 6.1 kHz, 8.0 kHz, 10.0 kHz.
[0086]
Further, the comparison block 9A in the signal detector 9 may be composed of, for example, a detector 9f and a comparator 9g as shown in FIG. FIG. 7 (a) is a schematic block diagram of the signal detector 9, and FIG. 7 (b) illustrates each signal waveform at that time.
[0087]
The detector 9f outputs an envelope signal S13 obtained by detecting the band signal Se from the bandpass filter 8 to the comparator 9g. The comparator 9g compares the envelope signal S13 with a preset threshold value Vth ′, and outputs a determination signal S11 having a pulse width as a time when the envelope signal S13 becomes larger than the threshold value Vth ′.
[0088]
This makes it possible to obtain a determination signal similar to that of the comparison block 9A shown in FIG.
[0089]
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a block diagram showing the configuration of the speed measuring apparatus according to the present embodiment. Note that the same components as those in the first embodiment are denoted by the same reference numerals and description thereof is omitted.
[0090]
The speed measuring device according to the present embodiment includes a bandpass filter 8, a signal detector 9, a signal selector 10, a frequency measuring device 12, and a computing unit 13 of the speed measuring device according to the first embodiment shown in FIG. Is replaced by the digital signal processor 20.
[0091]
As the digital signal processor 20, a microcomputer or DSP including an analog / digital converter can be applied.
[0092]
In the digital signal processor 20, for example, the signal from the detector 7 is amplified by high gain, and analog / digital conversion is performed on the amplified signal. Thereafter, by performing digital filter processing such as Fourier transform, the same action as the bandpass filter 8 can be obtained.
[0093]
The frequency V of the moving object can be calculated according to the equations 1 and 2 by obtaining the frequency of the signal satisfying the above conditions 1 and 2 from the signal subjected to such filter processing.
[0094]
In the present embodiment, the range to be replaced with the digital signal processor 20 is the above-described range, but it goes without saying that the range is appropriately selected according to the processing capability of the digital signal processor 20.
[0095]
【The invention's effect】
According to the present invention, since the differential frequency signal is converted into a plurality of band signals by the differential frequency detection unit, one band signal is selected from the band signals, and the band signal is used as the speed calculation signal of the moving object. As the N ratio is improved, the distortion of the signal waveform is reduced, and the speed of the moving object can be measured with high accuracy.
[0096]
In addition, when selecting one band signal from a plurality of band signals, the band signal of the maximum frequency band is selected, so even if various sound waves with different frequencies are received, It is possible to extract a high-frequency (high-speed) component buried in a frequency (low-speed) component, and it is reflected from any part of the pitcher's body other than the ball, for example, when measuring a ball thrown by the pitcher. The ball speed can be measured with high accuracy even in the presence of sound waves.
[Brief description of the drawings]
FIG. 1 is a block diagram of a speed measuring device applied to the description of a first embodiment of the present invention.
FIG. 2 is a timing chart showing output waveforms from each block of the speed measuring device.
FIG. 3 is a Bode diagram showing an example of a frequency distribution of a band signal.
4A and 4B are diagrams illustrating transient characteristics of a bandpass filter, where FIG. 4A is a difference frequency signal, FIG. 4B is a band signal, and FIG. 4C is a diagram illustrating an F / V waveform.
5A and 5B are diagrams applied to the description of the signal detector, where FIG. 5A is a block diagram, FIG. 5B is a signal waveform of a comparison block, and FIG. 5C is a diagram illustrating a signal waveform of a determination block;
6A and 6B are diagrams applied to the description of the signal selector, where FIG. 6A is a block diagram, FIG. 6B is a logic table of a priority encoder, and FIG. 6C is a logic table of an analog multiplexer.
7A and 7B are diagrams showing another configuration example of the signal detector, where FIG. 7A is a block diagram and FIG. 7B is a diagram showing signal waveforms.
FIG. 8 is a block diagram of a speed measuring device applied to the description of the second embodiment of the present invention.
FIG. 9 is a block diagram of a speed measuring device applied to the description of the prior art.
FIG. 10 is a block diagram of a speed measuring device applied to the description of the prior art.
[Explanation of symbols]
1 Reference oscillator
2 Output amplifier
3 Transmitter
4 Receiver
5 Preamplifier
6 Mixer
7 Detector
8 Bandpass filter
9 Signal detector
10 Signal selector
12 Frequency measuring instrument
13 Calculator
14 Display
15 Temperature measuring instrument
20 Digital signal processor

Claims (5)

Sound wave emitting means for emitting a sound wave based on a reference signal of a predetermined frequency, wave receiving means for receiving a sound wave and outputting it as a received signal, and speed calculating means for calculating the speed of a moving object from the reference signal and the received signal In a speed measuring device having
A differential frequency detector that calculates a frequency difference between the received signal and the reference signal and outputs the difference as a differential frequency signal;
A frequency band separating unit that band-separates the differential frequency signal into two or more preset frequency bands and outputs the band signal as a band signal;
When the time when the band signal or the detection signal of the band signal exceeds the threshold or the time that can be regarded as exceeding the threshold continues for the first determination time set in advance, a detection signal of a superior level is output and the threshold is set. A band signal determination unit that outputs a valid signal when the time exceeds or the time that can be regarded as exceeding has continued for a second determination time longer than the first determination time;
A band signal selector that receives the band signal and the detection signal and selects one band signal from the plurality of band signals based on the detection signal;
The frequency of the band signal selected by the band signal selection unit is measured, whether the measured frequency is valid is determined based on the valid signal, and the speed of the moving object is calculated based on the valid frequency. A speed measuring device having a measurement calculation unit. The speed measuring device according to claim 1, wherein the frequency band separation unit is divided into two or more frequency bands with respect to a frequency band in a measurement range of the speed measuring device. The speed measuring device according to claim 1, wherein the band signal selecting unit selects a band signal corresponding to a detection signal having the highest frequency band among the plurality of detection signals having a superiority level. When the start region and the end region of the band signal undergo at least frequency modulation due to the transient characteristics of the frequency band separation unit, the first determination time is a predetermined amount from the modulated time of the start region of the band signal. The second determination time is set longer by a predetermined amount than the sum of the time during which the measurement calculation unit can measure the frequency of the band signal and the modulation time of the end region of the band signal. The speed measuring device according to any one of claims 1 to 3, wherein Sound wave emitting means for emitting a sound wave based on a reference signal of a predetermined frequency, wave receiving means for receiving a sound wave and outputting it as a received signal, and speed calculating means for calculating the speed of a moving object from the reference signal and the received signal In a speed measuring device having
A differential frequency detector that calculates a frequency difference between the received signal and a reference signal and outputs the difference as a differential frequency signal;
The differential frequency signal is band-separated into band signals of two or more preset frequency bands, and a time when the band signal or its detection signal exceeds or exceeds a preset threshold is obtained. Is longer than a preset first determination time and a second determination time longer than the first determination time, and when there are a plurality of band signals longer than the first determination time, The band signal having the highest frequency band is selected from the band signal and frequency is measured, and only when the band signal that has been frequency-measured continues for the second determination time, based on the frequency measurement result, A speed measuring device comprising: a signal processing unit that calculates a speed.

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