SU1615630A1 - Method of measuring instantaneous values of electric signal - Google Patents

Abstract

The invention relates to a measurement technique and can be used, for example, in instrument making and automation in measuring electrical signal values at specified points in time. In order to increase the measurement accuracy, the method additionally performs a two-pole limitation of the total signal and carries out a second measurement of the monitored signal when the inputs of the adder are changed, to which the monitored and reference signals were applied in the first dimension. In the device implementing the method, a monitored signal is fed to the input terminal 1, which through the switching unit 4 is fed to one of the inputs of the adder 5, the output summing signal of which is limited by a two-pole limiter 7 and fed to the input of the oscilloscope 6. The other input of the adder 5 receives the reference a signal from a source 2 of an adjustable reference voltage, the reference signal being opposite in polarity to the monitored signal. By adjusting the reference signal, the total signal is equal to zero on the oscilloscope screen. The second measurement is carried out when the inputs of the adder are re-switched, and the measurement result is calculated as the geometric mean for the results of the first and second measurements. 1 il.

Description

The invention relates to electrical engineering and can be used, for example, in instrumentation and automation when measuring the values of an electrical signal at specified times,

The aim of the invention is to improve the accuracy of measurement.

According to the method for measuring the instantaneous values of an electric signal, the adjustable reference signals that are controlled and opposite in sign are applied to the corresponding inputs of the adder, the value of the adjustable reference signal is adjusted until the total signal is zero on the oscilloscope screen, the value of the reference signal is measured, and then the measurement operation of the controlled signal is repeated, by switching the controlled and reference signals to the opposite inputs of the adder. In both operations, the measurement of the monitored signal carries out two-sided limitation of the total signal, and the measurement result is determined as geometric mean according to the results of two measurements according to the formula U _x = v C · and? where Ui and U2 are the results of the first and second measurements of the monitored signal.

The drawing shows a block diagram of a device that implements the proposed method.

The device contains an input terminal Ί, a source 2 of an adjustable reference constant signal, the output of which is connected to the input of the reference unit 3 and the first input of the switching unit 4, the second input of which is connected to the input terminal 1, two inputs of the adder 5 are connected to the corresponding outputs of the switching unit 4, output the adder 5 is connected to the input of the oscilloscope 6 and the bipolar limiter 7 voltage level. The synchronization input of the oscilloscope 6 is connected to the input terminal 1. The adder 5 in a particular case can be built on resistors 8 and 9.

The device operates as follows.

In the first measurement, the input controlled signal enters through the switching unit 4 to the first input of the adder 5. From the output of the source 2 of the adjustable constant reference signal through the switching unit 4 to the second input of the adder 5, the voltage is supplied whose polarity is opposite to the polarity of the measured voltage at the measurement point. A limited in amplitude input signal shifted by a constant voltage is fed to the input of the oscilloscope. By adjusting the level of the constant reference voltage at the output of the source of the reference signal 2, combine the image of the total signal at the measurement point with the zero line on the screen of the cathode ray tube of the oscilloscope at the set maximum sensitivity of the vertical deviation path, while measuring the voltage Ui at the output of the source of reference 2 of the constant signal by the unit 3 counts. At the measurement point, the total signal at the output of the adder 5 is zero, thereby eliminating the error introduced by the input resistances of the oscilloscope 6 and the bipolar limiter 7 of the voltage level. The bipolar limiter 7 of the voltage level allows measurements at the maximum sensitivity of the vertical deviation path of the oscilloscope 6 in linear mode, as it limits the total signal symmetrically on both sides of the measurement point without changing it at the measurement point.

The second measurement differs from the first in that the monitored signal is fed through the switching unit 4 to the second input of the adder 5, and the DC reference voltage, the polarity of which is opposite to the polarity of the monitored signal at the measurement point, is supplied from the output of the reference signal source 2 through the switch 4 to the first adder input 5.

Claims (1)

Claim The method of measuring the instantaneous values of the electrical signal, which consists in supplying the controlled reference signal opposite to the sign to the corresponding inputs of the adder, regulate the magnitude of the reference signal until the total signal on the oscilloscope screen is equal to zero and measure the value of the reference signal, characterized by that, in order to improve the measurement accuracy, they additionally carry out a two-sided limitation of the total signal and conduct a second measurement of the magnitude of the reference signal, p At which monitored and regulated signals are fed to the opposite inputs of the adder, and the instantaneous value is calculated as the geometric mean from the results of two measurements.