JPS5858634B2 - Shingo Kenshiyutsu Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION For example, a method is used in which the distance to a remote location is measured using the arrival time of a pulse wave.

In this method, a paging pulse is usually transmitted from a measurement point to a remote location, and the remote location responds to the paging pulse by sending a response pulse back to the measurement location.

Then, at the measurement point, the distance to the remote location is measured by measuring the time from the transmission of the calling pulse to the return of the response pulse.

In this case, the call pulse and the response pulse are transmitted with a certain pulse width.

Therefore, the reception time of a calling pulse at a remote location or the return time of a response pulse at a measurement point is detected by detecting any position of the pulse wave, generally the rising position of the pulse wave.

Conventionally, detection of the rising position of a pulse wave is performed using an envelope waveform of the pulse wave.

For example, as shown in FIG. 5, when a pulse-modulated ultrasonic pulse is received, envelope detection is performed on this to obtain the envelope waveform shown in FIG.

This envelope waveform opening is sliced at a constant slice level Es to obtain the slice waveform shown in FIG.

However, the rising edge of the pulse wave shown in FIG. 5A tends to change due to the influence of the propagation path, the reception characteristics of the receiver, etc.

Therefore, the characteristics of the rising or falling portion of the envelope waveform change.

For example, if the envelope waveform is as shown in Fig. 5, the slice waveform will be as shown in Fig. 5 (c), and the waveform at the rising position will be sent out to a position that differs in time by △ as shown in 2. Ru.

This time change Δt occurs as an error in the measured distance.

As described above, this invention detects the rise or fall of a pulse wave using the carrier wave of the pulse wave, instead of detecting the rise or fall of the pulse wave using the envelope waveform of the pulse wave. The purpose of this is to eliminate measurement errors such as those mentioned above.

The present invention addresses the above drawbacks and provides a device that can always detect a specific position of a pulse wave without being affected by the propagation path of the pulse wave.

This will be explained below with reference to the embodiments shown in the drawings.

In FIG. 1, a reference oscillator 1 sends out an ultrasonic carrier frequency signal (FIG. 2a) transmitted from a wave transmitter 2. In FIG.

The output signal a of the reference oscillator 1 is sent to a frequency dividing circuit 3, and the frequency dividing circuit 3 divides the frequency of the output signal a and sends out output pulses at regular intervals.

The output pulses of the frequency dividing circuit 3 are sent to the pulse wave generating circuit 4.

The pulse wave generation circuit 4 sends out a pulse wave (FIG. 2b) that lasts for a fixed number of waves of the reference frequency signal a every time an output pulse is sent out from the frequency dividing circuit 3.

This pulse wave is sent to the integrating circuit 5 and at the same time, it is also sent to the phase inverting circuit 6.

The phase inversion circuit 6 controls the phase of the reference frequency signal a, and inverts the phase of the reference frequency signal a within the duration of the pulse wave as shown in FIG. 2C.

On the other hand, the integrating circuit 5 integrates the pulse wave and sends out a sawtooth wave whose rising edge changes linearly, as shown in FIG. 2d.

The integrating circuit 5 is set so that the falling period T' of the sawtooth wave d is relatively shorter than the rising period T.

The sawtooth wave d sent out from the integration circuit 5 is transmitted to the amplitude modulation circuit 7
be led to.

The amplitude modulation circuit 7 amplitude modulates the amplitude of the phase inverted waveform C sent out from the phase inversion circuit 6 using a sawtooth wave d, and sends out the modulated signal shown in FIG. 2e.

After this modulated signal is power amplified in the amplifier 8,
It is transmitted from the transmitter 2 to a remote location as an ultrasonic signal.

FIG. 3 shows a signal detection device installed at a remote location.

After the transmission signal e is received by the receiver 11, it is amplified by the receiver 12 and sent out as shown in e' in FIG.

The output signal e' of the receiver 12 is delayed by a half cycle to/2 of the reference frequency signal a (FIG. 2) in the delay circuit 13, and then guided to one input of the adder circuit 14.

FIG. 4g shows a delayed signal by the delay circuit 13.

Further, the output signal e' of the receiver 12 is introduced to the other input terminal of the adder circuit 14 via an attenuator 15.

The attenuator 15 compensates for the amount of attenuation of the delay circuit 13.
It is set equal to the attenuation amount of the delay circuit 13.

Therefore, both inputs of the adder circuit 14 have e' and g in FIG.
As shown in , the amplitudes are equal to each other and the phase is equal to the reference signal a
Signals that differ by a half cycle to/2, that is, signal waves having an antiphase relationship, are guided.

These signal waves e' and g are modulated so that their respective amplitudes vary linearly.

Therefore, the adder circuit 14 adds the amplitudes of these two signals e' and g to each other, and as a result, the adder circuit 14 outputs an added waveform as shown in the fourth diagram.

Since the delayed signal g is delayed by half the period of the reference frequency signal a compared to the received signal e', the final waveform G of the delayed signal g is
The reverse polarity waveform for n is not sent out.

Therefore, this final waveform Gn is directly sent out as an extremely wide amplitude waveform Hn during the output of the adder circuit 14.

The added output of the adder circuit 14 is amplified by an amplifier 18 and then sent to a rectifier circuit 16 .

The rectifier circuit 16 rectifies the added waveform as shown in FIG. 4i, and then sends the rectified waveform i to the slice circuit 17.

The slice circuit 17 extracts a thick amplitude waveform H from the addition waveform.
n is selected, and the slice level Es is set so that the slice operation is performed only on the extremely wide amplitude waveform Hn.

Therefore, a slice waveform as shown in FIG. 4 is sent out from the slice circuit 17.

As described above, the present invention detects the rising position or falling position of a pulse wave using the carrier wave of the pulse wave.

Therefore, even if the rise or fall characteristics of the pulse wave change somewhat, the rise or fall detection pulses will not fluctuate as in the prior art and can always be accurately detected.

Note that in FIG. 1, a phase inversion circuit 6 is used, but this is for preventing damped vibration due to inertia of the transmitter 2.

That is, the transmitter 2 is excited by the modulation signal e whose amplitude is modulated by the sawtooth wave d, but at the falling edge of the sawtooth wave d, the amplitude of the modulation signal e changes suddenly. , a damped vibration occurs in the transmitter 2 as shown by the dotted line in FIG. 2e.

At this time, if an excitation signal with a polarity opposite to the vibration waveform (dotted line) is applied to the transmitter 2 by the phase inverter 6, this damped vibration is suppressed, and the receiving side receives an ideal signal as shown in Fig. 4 e'. You can get a good reception signal.

Note that in the above explanation, the transmitting device (Fig. 1) is
I explained as if transmitting the sawtooth amplitude modulated wave in Figure e, but
The same result as above can be obtained even by transmitting an amplitude modulated wave as shown in FIG. 2 ε in which the direction of the sawtooth is reversed.

However, in this case, the maximum waveform Hn in Figure 4 occurs at the beginning of the signal wave (h in Figure 4), as is clear from the above description.

[Brief explanation of the drawing]

FIG. 1 shows a transmitting side device implementing the present invention, and FIG. 2 shows a waveform diagram for explaining its operation. Further, FIG. 3 shows a receiving side device implementing the present invention, and FIG.
The figure shows a waveform diagram for explaining the operation. Further, FIG. 5 shows a waveform diagram for explaining the operation of the conventional device.

Claims (1)

[Claims] 1. A receiver that receives an incoming signal from a remote location whose carrier wave is width-modulated in a sawtooth pattern, a delay circuit that delays the incoming signal received by the receiver by a half period of the carrier wave, and a delay of the delay circuit. It comprises an adder circuit that adds the output and the received signal of the receiver, and a slice circuit that slices the output signal of the adder circuit at a predetermined slice level, and the appearance of the waveform selected by the slice circuit is determined as described above. A signal detection device characterized in that it is used as a reference when an incoming signal arrives.