SU90062A1 - The method of recording seismic vibrations using the variable width method - Google Patents

Description

A conventional seismic oscilloscope is designed to record seismic Oscillations by the deviation method.

In order to obtain, using such an oscilloscope, also records using the variable width method, which are necessary in some cases of seismic exploration, in the present invention, oscilloscope galvanometers simultaneously with seismic vibrations transformed into low frequency alternating current are supplied with alternating current frequency 1000- 2000 Hz from the sound generator. The imposition of low-frequency vibrations on the sonic one causes a change in the degree of overlap by the light beams of the cutting slits installed in the oscilloscope reflected from the galvanometer mirrors, so that the recording of the recorded low-frequency vibrations will take the form of a variable-width recording.

The drawing shows a block / cutting shells, which is illuminated by beams of light reflected from the mirrors of galvanometers 2 as an image of the filament of the lamp of the illuminator 3.

An alternating audio current (1000-2000 Hz) is applied to the galvanometers, which means that light beams fixed on the slits will be deflected at the frequency of the alternating current supplied. The amplitudes of the deflection of the light beams are selected along the length of the slits and fixed so that the overlap occurs at half the slits.

A beam of light that has passed through the slit and the cylindrical lens 4 will fall on the photo paper 5.

When moving photographic paper at a speed of 20-25 cm1sec with a frequency of oscillations of light beams of 1000-2000 Hz, the photo paper will be recorded in the form of a dark strip on a white background.

When leading to low-frequency AC galvanometers of the seismic range, the low frequency will be superimposed on the sound one, which will cause a change in the degree of overlap of the cutting slits by the oscillations of the light beams.

Thus, the recording of the recorded low-frequency oscillations will take the form of a variable-width recording.

The transition from the usual method of recording by the method of deviation to recording by the method of variable width does not require serious alterations of the seismic survey.

For this purpose, the seismic station should be equipped with a recessed gap module and a sound generator.

In order to avoid effects between channels through a generator during multichannel recording, the alternating voltage (from the generator) is fed to the grids of the output stages of the amplifiers of the seismic station through the resistance of the grid loops.

The amplitude of oscillations of light beams is adjusted by potentiometers connected in parallel with the generator output. Subject invention

The method of recording seismic vibrations, but with the variable width method, characterized in that, in order to obtain registration with a conventional, seismic oscilloscope, on the latter galvanometers simultaneously with seismic vibrations, a transformed one. Baths are delivered to alternating current of low frequency, alternating current of frequency 1000-2000 Hz is supplied from the sound generator, and the imposition of low frequency oscillations on the sound one causes a change in the degree of overlap of the light beams installed in the oscilloscope of the cutting slits reflected from the mirrors of the galvanometers.