JP2000147112A - Correlation-type probing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a correlation-type probing apparatus by which a precise correlation value can be obtained even when temperature, power-supply voltage or the like is changed. SOLUTION: This probing apparatus is provided with a fixed-cycle oscillator 32 which generates a pulsed signal 32A at every fixed cycle, a variable-time delay device 38 by which a variable time to be added to a fixed time by every very short time is delayed whenever the pulsed signal 32A is inputted and by which a delay pulsed signal 38A is generated, a promise-signal generator 34 which generates a promise signal 34A whenever the delay pulsed signal 38A is inputted, a correlation-signal generator 39 which generates a correlation signal 39A whenever the pulsed signal 32A is inputted, and a correlator 40 to which a reflection signal 36A obtained by transmitting the promise signal 34A and the correlation signal 39A are inputted so as to be correlated. In this case, it is provided with a fixed-time delay device 33 by which a fixed-delay pulsed signal 33A delayed by the same time as the fixed time is generated whenever the pulsed signal 32A is input. The correlation-signal generator 39 generates the correlation signal 39A whenever the fixed-delay pulsed signal 33A is inputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correlation type search device for searching for a different derivative in a concealed portion.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 5, there is known a correlation type search device which obtains a required detection signal by obtaining a correlation using a promised waveform at the time of transmission (Japanese Patent Laid-Open No. Hei 5-28).
8844, JP-A-5-313938).

[0005] A correlation type search apparatus 1 shown in FIG. 5 includes a fixed period circuit 2 for generating a pulse wave 2 A having a fixed period.
A transmission circuit 3 for generating a transmission signal 3A having a promised waveform using the pulse wave 2A as a trigger signal, a transmission antenna 4 for transmitting the transmission signal 3A to the outside, and receiving a reflected signal 5A from an underground pipe. Variable time (T + Δt × n) in which a small delay time Δt is added to the fixed time T every time a pulse wave 2A is input from the fixed period circuit 2 and the receiving circuit 5 that amplifies the reflected signal 5A. ), Which generates a delayed pulse wave 7A with a delay time of
And the transmission signal 3A using the delayed pulse wave 7A as a trigger signal.
A correlation signal circuit 8 for generating a correlation signal 8A having the same waveform as
A multiplying circuit 9 for receiving the reflected signal 5A and the correlation signal 8A and multiplying the amplitude values of both signals in the same phase;
And an integrating circuit 10 for integrating the multiplied amplitude value obtained by

[0006] As shown in FIG. 6, when a pulse wave 2 A is generated from the fixed period circuit 2, a transmission signal 3 A is output from the transmission circuit 3, and the transmission signal 3 A is directed from the transmission antenna 4 to the ground. Sent. This transmission signal 3A
Is reflected by an underground pipe or the like under the ground and received by the receiving antenna 5 as a reflected signal 5A. The received signal 5A is received with a time corresponding to the distance between the reflector and the transmitting antenna 4 and the receiving antenna 5 with a delay from the output point of the pulse wave 2A, and the delay time is the same for each time of the fixed period. Become. On the other hand, since the delayed pulse wave 7A output from the variable delay circuit 7 is delayed by a time obtained by adding the small delay time Δt to the fixed time T each time, the correlation signal 8A output from the correlation signal circuit 8 is: It shifts by Δt every fixed period. Then, the correlation between the correlation signal 8A and the received signal 5A, which are shifted by Δt, is obtained.

[0005]

In order to obtain an accurate correlation value, the delay time (T + .DELTA.t.times.n) by the variable delay circuit 7 is accurately delayed by a minute time .DELTA.t. It is desirable to go.

However, in an actual device, the variable delay circuit 7
Has a variable time (T
+ Δt × n) may not be accurate. Even in such a case, in order to obtain an accurate correlation value, a variable delay circuit having a high precision is used to reduce the delay time of the variable time so as not to affect the correlation value even if the delay time varies. There is a need.

In the exploration apparatus actually used, the fixed cycle is 1000 ns, the minute delay time Δt is 1 ns, and the delay time of the variable delay circuit 7 (T + Δt × n)
Is a fixed time T of 1000 ns which is the same as the fixed period. In order to obtain the time difference between the transmission signal 8A and the transmission signal 3A in units of 1 ns, an accuracy of 1 ns / 1000 ns is required. Further, if it is required that the reflection signal has a precision of 10 times, an accuracy of 0.1 / 1000 and 1/10000 is required.

However, it is difficult to provide such a high precision in the variable delay circuit 7, and it is difficult to reduce the variation in the variable time so as not to affect the correlation value in the conventional search device. .

The present invention has been made in view of the above-described problems, and provides a correlation-type search device capable of obtaining an accurate correlation value even when a temperature change, a power supply voltage change, or the like occurs. The purpose is to do.

[0010]

According to a first aspect of the present invention, there is provided a fixed-period pulse signal generating means for generating a pulse signal at a constant fixed period, and comprising: A promise signal generating means for generating a promise signal having a predetermined promise waveform, a transmitting means for transmitting the promise signal as a transmission signal, a receiving means for receiving a reflected signal obtained by the transmission, and the pulse A delay pulse signal generating means for generating a delay pulse signal delayed by a preset time every time a signal is input, and a correlation signal for generating a correlation signal having the same waveform as the promise signal each time the delay pulse signal is input Generating means, comprising a correlating means for inputting and correlating the reflected signal and the correlation signal,
The set time is a correlation search device which is a delay time obtained by adding a fixed delay time and an increase delay time that increases by a small amount every time the pulse signal is input. A fixed delay pulse signal generating means for generating a fixed delay pulse signal delayed by the same time as the fixed time every time the fixed delay pulse signal is input. Is generated.

According to a second aspect of the present invention, there is provided a fixed-period pulse signal generating means for generating a pulse signal at every fixed period, and generating a delayed pulse signal delayed by a preset time every time the pulse signal is inputted. Delay pulse signal generation means, and a promise signal generation means for generating a promise signal having a predetermined promise waveform each time the delay pulse signal is input,
A transmitting unit that transmits the promised signal as a transmission signal, a receiving unit that receives a reflected signal obtained by the transmission, and a correlation signal having the same waveform as the promised signal is generated each time the pulse signal is input. Correlation signal generation means, and correlation means for inputting and correlating the reflected signal and the correlation signal, wherein the set time is increased by a small amount of time each time a fixed delay time and the pulse signal are input. A fixed delay pulse that generates a fixed delay pulse signal delayed by the same time as the fixed time every time the pulse signal is input. Signal correlation means, wherein the correlation signal generation means generates the correlation signal every time the fixed delay pulse signal is input.

[0012]

According to the first aspect of the present invention, there is provided a fixed delay pulse signal generating means for generating a fixed delay pulse signal delayed by the same time as a fixed time every time a pulse signal is inputted. The time difference between the fixed delay pulse signal and the delay pulse signal can be maintained at a predetermined value irrespective of a temperature change or a power supply voltage change. Therefore, an accurate correlation value can be obtained even if the variable time delay means does not have high accuracy.

According to the second aspect of the present invention, there is provided a fixed delay pulse signal generating means for generating a fixed delay pulse signal delayed by the same time as a fixed time every time a pulse signal is inputted. The time difference between the fixed delay pulse signal and the delay pulse signal can be maintained at a predetermined value irrespective of a temperature change or a power supply voltage change. Therefore, an accurate correlation value can be obtained even if the variable time delay means does not have high accuracy.

[0014]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of a correlation type search apparatus according to the present invention.

(Embodiment 1) A correlation type exploration apparatus 30 shown in FIG. 1 includes a fixed period oscillator 32 which is a fixed period pulse signal generating means for generating a pulse signal 32A at every fixed period, and a pulse signal 32A. A fixed time delay unit 33 which is a fixed time delay means for generating a fixed delay pulse signal 33A obtained by delaying the fixed delay pulse signal 33A by a fixed time T;
Signal generator 34, which is a promise signal generating means for generating a promise signal 34A by using
Antenna 3 which is a wave transmitting means for transmitting the wave toward the outside
5, a receiving antenna 36 which is a receiving means for receiving a reflected signal 36A from the outside, an amplifying circuit 37 for amplifying the reflected signal 36A to obtain a received signal 37A, and a fixed period oscillator 3
2 each time the pulse signal 32A is input, the fixed time T
Variable time (T + Δt) in which a minute delay time Δt is added to
.Times.n) to generate a delayed pulse signal 38A by generating a delayed pulse signal 38A, and a correlation that generates a correlation signal 39A having the same waveform as the promised signal 34A by using the delayed pulse signal 38A as a trigger signal. Correlation signal generator 39, which is a signal generation means, and correlator 40, which is a correlation means for inputting and correlating received signal 37A and correlation signal 39A.
It is composed of

The fixed-period oscillator 32 is a time generating circuit, for example, a circuit that counts a predetermined amount of unit time pulses to obtain a periodic signal, and is a pulse signal 32 having a fixed fixed period.
A, and a fixed time delay 33 and a variable time delay 38
To enter.

The fixed time delay unit 33 outputs a pulse signal 32A.
, For example, a delay circuit using a monostable multivibrator, and applies a delayed pulse signal 33A to the promised signal generator 34.

The promised signal generator 34 generates a signal of a promised waveform, for example, a monocycle signal, using the fixed delay pulse signal 33A as a trigger signal, amplifies the signal to a required voltage, and supplies the signal to the transmitting antenna.

The transmission antenna 35 is a dipole antenna, for example, a fan-shaped dipole antenna, and transmits the promised signal 34A as a transmission electromagnetic wave toward the ground surface or the like.

The receiving antenna 36 is a fan-shaped dipole antenna similar to the transmitting antenna 35, and receives a reflected signal 36A based on a reflected electromagnetic wave.

The amplifying circuit 37 is a high frequency amplifying circuit, and converts the reflected signal 36A into a required amplitude value and inputs it to the correlator 39.

The variable time delay unit 38 is, for example, a pulse generating circuit in which a counting circuit and a clock circuit are combined. The variable time delay unit 38 stores the counted value of the pulse signal 32A and counts the counted value when a predetermined counted value is reached. Is reset, and the counting is repeated again. The time length obtained by reducing the time length of the promised signal 34A to 1 / m by the count value n of the counting circuit is set as a unit time, and a delayed pulse signal is given to the correlation signal.

The correlation signal generator 39 includes the promised signal generator 3
4 has the same pulse generation circuit as that of FIG.
Using A as a trigger signal, a signal having the same waveform as the promised signal 34A is delayed from the pulse signal 32A by a delay time and input to the correlator 40.

The operation of the correlation type search device 30 having the above configuration will be described.

As shown in FIG. 2, a pulse signal 32A is output from the fixed-period oscillator 32 every 1000 ns and is input to the fixed time delay unit 33 and the variable time delay unit 38. Each time the pulse signal 32A is input, the fixed time delay unit 33 generates a fixed delay pulse signal 33A delayed by a fixed time of 100 ns from the input of the pulse signal 32A. The fixed delay pulse signal 33A is input to the promised signal generator 34, and the promised signal generator 34 generates the promised signal 34A every time the fixed delay pulse signal 33A is input. This promise signal 34A
Is transmitted from the transmitting antenna 35 toward the ground. The promised signal 34A is reflected by an underground pipe or the like, and is received by the receiving antenna 36 as a reflected signal 36A. The reflected signal 36A is received after a time corresponding to the distance between the underground reflector and the transmitting antenna 35 and the receiving antenna 36 from the output time point of the pulse signal 32A. Is the same as

On the other hand, the delay pulse signal 38A output from the variable delay unit 38 is delayed by a time obtained by adding a small delay time 1 ns to the fixed time 100 ns each time.
The correlation signal 39A output from the correlation signal generator 39 is
It shifts by 1 ns from the generation of the pulse signal 32A every fixed period. Then, the correlation signal 39 shifted by 1 ns.
A is correlated with the received signal 37A.

Thus, the fixed time delay unit 33 is provided,
Fixed delay pulse signal 33 generated by fixed time delay unit 33
Since the promised signal 34A is generated based on A, a shift of ΔT occurs in the variable time (100 + 1 × n) ns due to a change in temperature, a change in the power supply voltage, or the like in the variable time delay unit 38 (100 + ΔT + 1 × n). ns, the fixed time delay device 33 is similarly affected, and the fixed time
Since ns fluctuates to (100 + ΔT) ns, the time difference between the fixed delay pulse signal 33A and the delay pulse signal 38A can be kept at (1 × n) ns. Therefore, it is not necessary to consider the variation ΔT of the fixed time 100 ns, and the accuracy of the variable time delay unit 38 is 1/1000, which is sufficient. Further, the fixed delay pulse signal 33A and the delay pulse signal 38A
Can be maintained at (1 × n) ns, so that a stable correlation signal 39A can be obtained without being affected by a change in temperature, a power supply voltage, or the like.

(Embodiment 2) Next, Embodiment 2 of the present invention will be described.

The correlation type search device 50 according to the second embodiment shown in FIG. 3 includes a fixed period transmitter 52 which is a fixed period signal transmitting means for generating a pulse signal 52A at every fixed period.
Each time the pulse signal 52A is input from the fixed-period oscillator 52, the delay time (T + Δt × n) obtained by adding the minute delay time Δt to the fixed time T is delayed to produce a delayed pulse signal 58.
A variable time delay device 58 which is a delay pulse signal generating means for generating A, a promise signal generator 54 which is a promise signal generation means for generating a promise signal 54A using the variable delay pulse signal 58A as a trigger signal, and a promise signal 54A. A transmitting antenna 55 which is a transmitting means for transmitting to the outside, a receiving antenna 56 which is a receiving means for receiving a reflected signal 56A from the outside, an amplifier 57 which amplifies the reflected signal 56A to obtain a received signal 57A, A fixed time delay unit 53 which is a fixed time delay means for generating a fixed delay pulse signal 53A obtained by delaying the signal 52A by a fixed time;
A correlation signal generator 59, which is a correlation signal generator for generating a correlation signal 59A having the same waveform as the promised signal 54A using 3A as a trigger signal, and a correlation means for inputting the received signal 57A and the correlation signal 59A to obtain a correlation value. And a certain correlator 60.

The correlation type search device 50 differs from the correlation type search device 30 in that the variable delay pulse signal 58A is input to the promise signal generator 54 and the fixed delay pulse signal 53A is input to the correlation signal generator 59. However, the other points are the same as those of the correlation type search device 30, and therefore detailed description is omitted.

The operation of the correlation type search device 50 having the above configuration will be described.

The correlation signal 59A is a fixed delay pulse signal 53
A and the promised signal 54A is generated based on the delayed pulse signal 58A.
Except for the differences, the detailed description is omitted because it is handled in the same manner as the correlation-type search device 30.

Thus, the fixed time delay unit 53 is provided,
Fixed delay pulse signal 53 generated by fixed time delay unit 53
Since the correlation signal 59A is generated based on A, a shift of ΔT occurs in the variable time (100 + 1 × n) ns due to a change in temperature, power supply voltage, or the like in the variable time delay unit 58, resulting in (100 + ΔT + 1 × n). ns, the fixed time delay unit 53 is similarly affected, and the fixed time
Since ns fluctuates to (100 + ΔT) ns, the time difference between the fixed delay pulse signal 53A and the delay pulse signal 58A can be kept at (1 × n) ns. For this reason, it is not necessary to consider the variation ΔT of the fixed time 100 ns, and the accuracy of the variable time delay unit 58 is 1/1000, which is sufficient. Further, the fixed delay pulse signal 33A and the delay pulse signal 38A
Can be maintained at (1 × n) ns, and a stable promise signal 54A can be obtained without being affected by a change in temperature, a change in power supply voltage, or the like.

(Third Embodiment) Next, a third embodiment of the present invention will be described. Correlation type search device 7 shown in FIG.
0 is a variable period pulse signal generation that generates a pulse signal 72A for each variable period TE (that is, represented by TE = X + Δt × n) that is sequentially extended by a minute time Δt each time in the initial period X. A fixed period oscillator 72 as a means, a fixed time delay unit 73 as a fixed time delay means for generating a fixed delay pulse signal 73A obtained by delaying the pulse signal 72A by a fixed time 1000ns, and a pulse signal 72A delayed by a fixed time 1000ns. A second fixed time delay unit 7 serving as fixed time delay means for generating a fixed delay pulse signal 74A.
The fixed delay pulse signal 73A is input to the promised signal generator 75 to generate the promised signal 75A. Except that the second fixed delay pulse signal 74A is input to the correlation signal generator 39 to generate the correlation signal 76A, the configuration is the same as that of the correlation type search device 30, and the description thereof is omitted.

[0035]

As described above, according to the first aspect of the present invention, there is provided a fixed-period pulse signal generating means for generating a pulse signal at a fixed fixed period, and a predetermined signal every time the pulse signal is inputted. Promising signal generating means for generating a promise signal having a waveform, transmitting means for transmitting the promise signal as a transmission signal, receiving means for receiving a reflected signal obtained by the transmission, and the pulse signal being input. A delayed pulse signal generating means for generating a delayed pulse signal delayed by a preset time every time, a correlation signal generating means for generating a correlation signal having the same waveform as the promised signal each time the delayed pulse signal is input, Correlating means for inputting and correlating the reflection signal and the correlation signal, wherein the set time increases by a fixed fixed delay time and a small amount of time each time the pulse signal is input. A fixed delay pulse that generates a fixed delay pulse signal delayed by the same time as the fixed time every time the pulse signal is input. Signal generating means, wherein the promised signal generating means generates the promised signal every time the fixed delay pulse signal is input, so that the time difference between the fixed delay pulse signal and the delayed pulse signal is changed to a temperature change or a power supply voltage change. Regardless, it can be maintained at a predetermined value. Therefore, an accurate correlation value can be obtained even if the variable time delay means does not have high accuracy.

According to the second aspect of the present invention, a fixed-period pulse signal generating means for generating a pulse signal at every fixed period, and a delayed pulse signal delayed by a preset time every time the pulse signal is inputted A delayed pulse signal generating means for generating a promised signal having a predetermined promised waveform each time the delayed pulse signal is input, and a transmitting means for transmitting the promised signal as a transmission signal. Receiving means for receiving a reflected signal obtained by this transmission, correlation signal generating means for generating a correlation signal having the same waveform as the promised signal each time the pulse signal is input, and the reflection signal and the correlation signal And a correlating means for inputting and correlating.The set time is a fixed delay time and an increased delay time that increases by a small amount of time every time the pulse signal is input. A correlation type exploration device which is an added delay time, comprising a fixed delay pulse signal generating means for generating a fixed delay pulse signal delayed by the same time as the fixed time every time the pulse signal is inputted, Since the correlation signal generating means generates the correlation signal each time the fixed delay pulse signal is input, the time difference between the fixed delay pulse signal and the delay pulse signal is maintained at a predetermined value regardless of a temperature change or a power supply voltage change. be able to. Therefore, an accurate correlation value can be obtained even if the variable time delay means does not have high accuracy.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a correlation type search device according to Embodiment 1 of the present invention.

FIG. 2 is an operation waveform diagram of a main part of the correlation search device according to the first embodiment of the present invention;

FIG. 3 is a block diagram showing a configuration of a correlation type search device according to a second embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of a correlation type search device according to Embodiment 3 of the present invention.

FIG. 5 is a block diagram showing a configuration of a conventional correlation search device.

FIG. 6 is an operation waveform diagram of a main part of a conventional correlation type search device.

[Explanation of symbols]

 32 Fixed period oscillator 33 Fixed time delay unit 34 Promised signal generator 38 Variable time delay unit 39 Correlation signal generator

Claims (2)

[Claims] A fixed-period pulse signal generating means for generating a pulse signal at every fixed fixed period; a promised signal generating means for generating a promised signal having a predetermined promised waveform each time the pulse signal is inputted; A transmitting means for transmitting the promised signal as a transmission signal; a receiving means for receiving a reflected signal obtained by the transmission; and a delay pulse signal delayed by a preset time every time the pulse signal is input. A delayed pulse signal generating means, a correlated signal generating means for generating a correlated signal having the same waveform as the promised signal every time the delayed pulse signal is input, and a correlation for inputting and correlating the reflected signal and the correlated signal. Means, wherein the set time is a delay time obtained by adding a fixed delay time and an increase delay time that increases by a small amount of time each time the pulse signal is input. The exploration apparatus, comprising: a fixed delay pulse signal generating unit that generates a fixed delay pulse signal delayed by the same time as the fixed time every time the pulse signal is input, wherein the promised signal generating unit includes: A correlated exploration apparatus, wherein said promise signal is generated each time a fixed delay pulse signal is input. 2. A fixed-period pulse signal generating means for generating a pulse signal every fixed period, and a delayed pulse signal generating a delayed pulse signal delayed by a preset time every time the pulse signal is inputted. Means, a promise signal generation means for generating a promise signal having a predetermined promise waveform each time the delayed pulse signal is input, a transmission means for transmitting the promise signal as a transmission signal, and transmission means. Receiving means for receiving a reflected signal, correlation signal generating means for generating a correlation signal having the same waveform as the promised signal each time the pulse signal is input, and correlation for inputting and correlating the reflected signal and the correlation signal Means, wherein the set time is a delay time obtained by adding a fixed delay time and an increase delay time that increases by a small amount of time each time the pulse signal is input. An exploration apparatus, comprising: a fixed delay pulse signal generating unit that generates a fixed delay pulse signal delayed by the same time as the fixed time every time the pulse signal is input, wherein the correlation signal generating unit includes: A correlation-type search device, wherein the correlation signal is generated each time a fixed delay pulse signal is input.