SU693294A1 - Device for calibrating seismic channels - Google Patents

Description

I

The invention relates to the field of measurement technology and is intended to calibrate seismometric channels using seismometers with magnetoelectric transducers and galvanometric recording using light-beam oscilloscopes.

A vibration electrodynamic stand is known, which is a table moved vertically by an electrodynamic driver I.

A disadvantage of the known device is its large size, which makes it impossible to use it in the measured points of high dams. Stand Limited in low frequencies; Calibration is possible in a band of 5 Hz, while it is necessary to obtain a frequency of 0.3-0.5 Hz. And, besides, in the famous stand one component is vertical, and it is necessary and horizontal.

A device for pulse calibration or control of an increase in a seismometric channel is known, comprising a generator of a single rectangular pulse, with which a calibration meter or operating coil of a seismometer master

a current pulse is given, a cih manus output from the equilibrium position, a time shifting circuit to select a measurement interval consisting of two series-connected waiting multivibrators, the first of which is started from the same generator, a key, a shunt and a galvanometer of a light beam oscilloscope. The increase is determined as the ratio of the oscilloscope recording ordinate to the velocity value of the seismometer master in the measurement selected with the help of the meter 2. The disadvantage of the device is that the velocity of the instrument in the measurement interval of the seismometer is measured by the emulator EMF

seismometer and at its known sensitivity. The latter, in turn, is performed only in statics with the known basic parameters of the seismometer, obtained by computational-experimental methods. This, as well as the need for photochemical oscillograms of the response of the seismometer and its subsequent use for measuring ordinates, greatly reduces the accuracy of scaling or scaling and increases the laboriousness of calibration, especially when multichannel recording of seismic vibrations at large hydraulic structures.

The aim of the invention is to improve the accuracy and simplify calibration.

The goal is achieved by the fact that the device for calibration of seismometers is. The channel also contains an indicator of moments of passage of the tonic near the zero position, an indicator of moments of passage near the zero position of the light point on the viewing screen of the oscilloscope reflected from the galvanometer mirror, a coincidence circuit, and each indicator is equipped with a photoresistor with a flap having two apertures with a threshold pulse shaper with mounted with a light bulb in the first indicator, a flap with a hole mounted on the master, and a second indicator mounted on the viewing screen not an oscilloscope, each indicator photoresistor connected to its own threshold pulse shaper, inputs from which are connected respectively to the second and third inputs of the coincidence circuit connected to the control input of a normally open switch connected between the seismometer coil and the device output, and the second multivibrator connected to the first permitting input of the coincidence circuit.

FIG. 1 shows a structural electrical circuit of the device; in fig. 2 - time diagrams illustrating his work.

The device contains a single pulse generator, waiting for multivibrators 2 and 3, a matching circuit 4, a light bulb 5, a valve with an opening 6, a coil 7 on a seismometer, a photoresistor 8 with a two-hole valve, a threshold driver 9 of a pulse, a key 10, a shunt II , galvanometer 12 and viewing screen 13 of the oscilloscope, photoresistor 14 with a two-hole gate, threshold pulse generator 15. FIG. 2a-3 show a timing diagram, where FIG. 2a shows a pulse at the output of the generator 1 of a single pulse, FIG. 26 shows the voltage of the response of the coil 7 of a seismometer to a pulse effect; FIG. 2b - time shift pulse at the output of the waiting multivibrator 2, FIG. 2d is a resolution pulse or measurement interval at the output of the waiting multibirator 3; FIG. 2e — pulses indicating the moments of passage of the master of the seismometer near the zero position at the output of the threshold driver 9; FIG. 2e — pulse indications of the moments passing close to the zero position of the light point on the viewing screen of the oscilloscope at the output of the threshold shaper 15; FIG. 2g - control pulses of the key 10 at the output of the coincidence circuit 4, fig. 2h - measured pulses at the output of the device.

A device for calibrating a seismometric channel works as follows.

A rectangular impulse from the output of a single impulse generator (Fig. 2a) simultaneously enters the coil of the 7th seismometer, its exit from the equilibrium position, and the input time of the shifting standby multivibrator 2. The trailing edge of the impulse removed from it (Fig. 2c) starts waiting multivibrator 3, which forms the resolution pulse or measurement interval (Fig. 2d), which is fed to the first enabling input of the coincidence circuit 4. Indicator of the moments of passage

0 of the tommy near the zero position, made in the form of a removable attachment to the seismometer, produces, using the threshold shaper 9, pulses (Fig. 2e) only when the photoresistor 8 valve hole coincides. At the same time, light from the electric bulb 5 is transmitted to it and its Resistance falls. The pulses of the threshold shaper 9 arrive at the second input of the coincidence circuit 4 and correspond in time to the maxima of the voltage of the response signal of the coil 7 (Fig. 26), since it is proportional to the speed of movement of the seismometer master. The indicator of the points of passage of the light point on the viewing screen of the oscilloscope, made in the form of a removable and position-adjustable attachment, produces pulses using the threshold shaper 15 (Fig. 2e) also only when the light point coincides with the holes of the photoresistor gate 14. The pulses of the threshold shaper 15 are received to the third input, the coincidence circuits 4 and correspond in time to the minimum and opposite polarity values of the response voltage (Fig. 26). Using the waiting multivibrators 2 and 3, the measurement interval is selected (Fig. 2d), at which

J control input key 10 from the output of the coincidence circuit 4 only two pairs of pulses are received (Fig. 2g). The key 10, being closed for the time of action of these pulses, passes to the output of the device or to the input of an external measuring device from the roller 7

o the seismometer of the signal pulses (Fig. 2h), the amplitudes and polarities of which are equal to the values of the output voltage of the coil 7 at the closing points.

5 The magnification or scale of the seismometric channel recording the oscillation speeds is determined by the formula

V, - l11d ± di. , d t,

Claims (2)

"(D X ° - / whereDi and A Ui are the amplitudes of the pulses proportional to the input voltage of the coil 7 of the seismometer at the moments when the master passes near the zero position; D ti is the interval between pulses. LH is the distance between the photoresistor gate openings 8 equal to the path that the wave goes through for the time L t; A and U D are the amplitudes of the pulses proportional to the output voltage of the coil 7 of the seismometer at the time the light point passes on the viewing screen 13 of the oscilloscope near the zero position D Y is the distance between from The photoresistor gate 14 is equal to the path that the light point passes on the oscilloscope viewing screen, near the zero position, In case A Ui D Uj. and / L Uj / / AUj (, /, and Dh Du, expression ( 1) simplifies and takes the form (2) Since it is necessary to determine the ratio D Ui to D Uj or D Ui + D Ua to / A. Us / + / D U, and not the values themselves, when using, for example, an electronic oscilloscope with an afterglow or the storage amplitude of the pulses are determined in mm or the number of grid points on its screen, and the need for voltage calibration is aet. At the same time, the complexity of the measurements is reduced, and their accuracy is increased. The distance between pulses D t is measured on the same oscilloscope. If it is necessary to improve the measurement accuracy, a digital pulse voltmeter and a digital time interval meter can be used. Claim 1. A device for calibrating a seismometric channel, including a single rectangular pulse generator, a working coil of a seismometer master, two waiting multivibrators in series, a key, a shunt and a galvanometer of a light beam oscilloscope, different in that in order to improve accuracy and simplify calibration channels, the schemes of coincidence and indicators of the moments of passage near the zero position of the model and the light point on the viewing screen of the oscilloscope are introduced into it, trazhennoy from galvanometer mirror, wherein the indicator outputs connected respectively to second and third inputs of coincidence circuits connected to control input of a normally open switch connected between the coil seismometer and output device, wherein the first multivibrator is connected to the enabling input of the coincidence circuit. 2. The device according to claim I, characterized in that the indicator of the moments of the passing of the model near the zero position contains a photoresistor with a valve having two holes connected to a threshold pulse shaper, a valve with a hole fixed on the model, and a light source. 3. The device according to claim 1, characterized in that the passage moment indicator near the zero position of the light point on the viewing screen of the oscilloscope contains a photoresistor with a flap having two holes connected to the threshold pulse shaper and mounted on the viewing screen of the oscilloscope. Sources of information taken into account in the examination 1.Sheinin I.S. Vibration measurement of a structure. L., Stroyizdat, 1974, p. 254. 2.Sb. Equipment and methods of seismometric observations in the USSR. M., “Science, 1974, p. 174-176 (prototype).