SU1320784A1 - Device for registering first arrivals of elastic vibrations in echo sounding of rock - Google Patents

Abstract

The invention relates to the field of geophysical studies by the acoustic method and is intended to record the first arrival of elastic oscillations in acoustic sounding of rocks. The purpose of the invention is to increase accuracy and noise immunity. The signals are sent to the time selector in the form of a delayed prohibition scheme of a given duration, therefore signals with a visible frequency close to the expected one are passed through it, which increases the noise immunity. 2 Il. S (L: about N5 30

Description

11320784

The invention relates to geophysical research by acoustic method.

The purpose of the invention is to increase the accuracy and noise immunity of the device operation.

FIG. 1 shows a block diagram of the proposed device; Fig. 2 shows diagrams explaining the operation of the device.

The device consists of discriminator 1 zeros, the input is connected to the input pshnoy device, and the output - to the input of the first driver 2, the output connected to the input of the selector 3 pulses, besides the set ones, and to the first input of the waiting multivibrator 4, connected by the second input to the output of the selector 3 pulses and

The waiting multivibrator 4 is triggered by a positive front pulse from the output of the imaging unit 2 and reset to the initial state by the pulses themselves from the output of the selector 3 (Fig. 2, diagram 12).

Pulses from the output of the selector 3 pass the shaper 5 and enter one of the inputs of the anti-dump circuit 7 (Fig. 2, diagram 13). The rear front of the pulse of the waiting multivibrator 4 is fed to the driver where a short pulse is formed, equal in shape to the output pulse 5 of the driver 5 (FIG. 2, diagram 14), and then to another input of the anti-matching element 7.

In the absence of a useful signal, noise interference does not allow waiting

to

 input of the second driver 5, and the output multivibrator 4 to work out

house - with the entrance of the third shaper 6

 output connected to one of the inputs of the element / antismatching other

input connected to the output of the shaper 5, and the output with the output bus device.

The device works as follows.

The discriminator 1 captures in the incoming signal (Fig. 2, chart 8) all zero-crossing in the form of short pulses (chart 9). These pulses arrive at shaper 2, which expands them in duration T, which exceeds the return time of the waiting multivibrator 4 under the action of the forced return pulses returning to the initial multivibrator from the output of the selector 3.

From the output of the former 2, the expanded and inverted pulses (Fig. 2, diagram 10) are fed to the input of the selector 3 and the waiting multivibrator 4. The selector 3 selects the time intervals between the inverted pulses of the former and produces short pulses attached to the negative on the output. the front edges of the pulse of the imager 2, if the time interval between the positive front and the subsequent negative front of the pulse at the output of the imager differs from the expected period of the useful signal by the amount of e given (Fig. 2, graph 11).

The waiting multivibrator 4 is triggered by a positive pulse front from the output of the imaging unit 2 and reset to the initial state by pulses from the output of the selector 3 (Fig. 2, Diagram 12).

The pulses from the output of the selector 3 pass the driver 5 and are fed to one of the inputs of the anti-coincidence circuit 7 (Fig. 2, diagram 13). The rear edge of the pulse of the waiting multivibrator 4 is fed to the driver 6, where a short pulse is formed, equal in shape to the output pulse of the driver 5 (FIG. 2, diagram 14), and then to another input of the anti-matching element 7.

In the absence of a useful signal, noise interference prevents the waiting

five

momentum, equal to T ,. Since, in the absence of a signal, the period of the output pulses of the discriminator 1 differs completely from the half-period of the useful signal, the selector 3 passes pulses to the output, forcibly resetting the pending multivibrator 4, therefore, at the output of the formers 5 and 6, the pulses are simultaneously present. As a result, in the absence of a useful signal, the anti-coincidence element 7 does not let the - back front. Pulse of the waiting multivibrator 4 exit the device.

5 When a useful signal appears, the pulses from the discriminator output have gaps between them equal to the half-period of the useful signal. Therefore, they do not go to the output of the selector during the time T.

At the end of the pulse of the waiting multivibrator 4, a pulse is formed at the output of the shaper 6 (Fig. 2, diagram 14), which arrives at the anti-coincidence element 7 and passes through it to the device output (Fig. 2, diagram 2), as at the other input of the anti-coincidence element there is no pulse (Fig. 2, diagram 15). Thus, at the output of the device, an impulse appears that is delayed with respect to the first zero-crossing of the signal by time T, which is constantly and easily taken into account.

5 when processing measurements.

Use as a sign of a useful signal the appearance of a periodic component in noise, control

0

It is possible to increase the noise immunity of the device up to a signal-to-noise ratio of 5: 1 for several times over a time that exceeds several times the duration of the expected period.

The use of a zero discriminator instead of a threshold device allows one to improve the accuracy of fixation of the useful signal with a large dynamic range of variation of its amplitude.

Claims (1)

Formula A device for fixing the first arrivals of elastic oscillations in acoustic sounding of rocks, which contains a driver, an output connected to a selector, which is characterized by g O five 0 to improve the accuracy and noise immunity of the device operation, a discriminator zero, a waiting multivibrator, second and third drivers, an anti-coincidence element are introduced into Het o, the selector being designed as a waiting inhibitory circuit of a given activity, the discriminator with a zero input is connected to the device input pn, and the output to the input of the first imager, the output of which is connected to the first input of the waiting multivibrator, the second input of which is connected to the output of the selector and the input of the second imager, and the output - to the input of the third a driver, the output of which is connected to one of the inputs of the anti-coincidence element, which is connected to another output to the output of the second driver, and the output is connected to the output bus of the device. Bxoff output Ft J Q WITH )  L 00 SC Editor E. Kopcha Compiled by V. Krutin Tehred V. Kadar Proofreader M. Sharoshi Order 2657/50 Circulation 730 VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab, 4/5 Production and printing company, Uzhgorod, st. Project, 4 eN4 o N12 if Subscription