SU1250972A1 - Method of measuring physical quantities - Google Patents

Abstract

The invention relates to electrical measuring technique and can be applied when measuring physical quantities containing additive interference in the form of a variable component. The purpose of the invention is to improve the measurement accuracy. Measuring Prox SP SP ffjus.3

Description

is wound as follows. An electrical signal containing a constant component U and a variable non-periodic component 11 is integrated for a fixed time duration t t by a command received at an arbitrary time. During the same interval, the variable component of the signal is integrated. The integration of both signals is carried out over the next time periods in which the sign of the current value of the variable is opposite to the sign of the integral value of the variable in the interval t, t. before

t 2

until the integral value of the variable component reaches zero. Integral value

The invention relates to electrical measuring technique and may find application in the measurement of physical quantities containing additive interference in the form of a variable component.

The aim of the invention is to improve the measurement accuracy by suppressing non-periodic, random and deterministic additive interference in a wide amplitude-frequency range and when the interference characteristics change during the measurement process.

FIG. 1 and 2 shows time diagrams illustrating the essence of the proposed method; in fig. 3 is a block diagram of a device for its implementation.

Measurement of physical quantities is performed as follows.

An electrical signal that displays a controlled physical quantity, containing a constant component and a variable non-periodic component U, which can be random or deterministic, but necessarily includes areas of positive and negative polarity relative to its zero value, integrates during the time interval fixed duration by command on

relative to the measured total duration of time intervals, corresponds to the value of the constant component of the signal. A device implementing this method contains a converter 1, a key 2, a pulse counter 3, a generator of 4 exemplary frequencies, a control block 5, keys 6, 13 and 19, a time meter 7, an arithmetic unit 8, an indication and output block 9, a block 10 in the variable component, the discriminator 11 characters of the signal, the discriminators 12 values of the signal, the analog integrator 14, the null-body 15, the parametric transducer 16, the inverter 17, the power source 18. 3 il.

measurement arriving at an arbitrary point in time. At the same time, the separated variable component of the signal is integrated within the same interval. By the time of graduation

This interval determines not only the magnitude but also the sign of the integral value of the variable component. Further integration of both signals is performed in the nearest time intervals, in which the sign of the current value of the variable component is opposite to the sign of the integral value of the variable component at the interval t t until the integral value of the variable is. component will not reach zero. FIG. 1 is the time tt. Tjtg and t.j tg. It also shows a diagram of the second dimension, containing a fixed duration interval and a time interval t t, which is necessary to bring the integral value of the variable component to zero. The integral value of the signal representing the physical magnitude, referred to the measured total duration of time intervals at which the integral value of the component variable is zero, corresponds to

3

constant signal component.

If the constant component U, which is the measured value, is distorted only by the variable component and "", then one measurement is minimally necessary, including intervals of fixed and measured duration. Subsequent measurements can be made to improve their accuracy. If the additive interference is not only a variable component, but also an uninformative constant component in the form of a parasitic thermo-emf, which must also be excluded, two measurements are necessary, each of which includes a fixed duration interval, and to determine The desired value of the measurement results must be summed up.

For example, when using parametric transducers with low-level signals, parasitic thermo-emf and induced type of network noise make a significant contribution to the total measurement error. The operations of the measurement method under consideration in this case are complemented by inverting the polarity of the power source while simultaneously inverting the sign of the output signal of the converter between pairs of measurements. A timing diagram of such a change is shown in FIG. 2. After integrating the signal, equal to the sum of the constant constituting And parasitic thermo-emf and the variable component U, during the interval. the fixed duration and length of time tt, and the measured physical dimension, on the sum of which the integral value of the variable component is zero, performs the specified inversion operations. In this case, the polarity of the parasitic thermo-emf and the phase of the induced disturbance change. Repeated measurement and summation of the results obtained before inversion and after it during the intervals of fixed and measured duration eliminate the influence on the measurement result of the parasitic thermo-EMF and the induced disturbance.

509724

A device that implements the proposed method; contains voltage converter 1 - frequency, the output of which is connected via switch 2 to signal input of a pulse counter 3, which together with converter 1 plays the role of an integrator. The output of the generator 4 of the reference frequency is connected directly to the input of the control unit 5, and through | key 6 - with the input of the meter 7 time intervals, the other input of which is connected to the control circuit, the output to the arithmetic unit 8, which, at the command of the control unit 5, performs dividing the result of integrating the signal of the measuring transducer by the total length - 20 nosti integration intervals. The result of the calculation is entered into the display and output unit .9. The signal from the output of the measuring transducer is fed not only to the input of the transducer 25 body 1 voltage - frequency, but also to the input of the variable component extraction unit 10, the output of which is directly connected to the inputs of the discriminator 11 of the variable signal component and the discriminator 12 values of this signal, and through the key 13 - with the input of the analog integrator 14. The output of the integrator 14 is connected to the inputs of the discriminator 11 35 characters and the zero-body 15, the output of which, like the outputs of discriminators 11 and 12, is connected to the circuit admin laziness. When using a parametric measuring converter 40, its output is connected to the inputs of converter 1 and unit 10 via an inverter 17. Other internal measuring converters are connected directly to them. The parametric converter power buses are connected to the power source 18 via a switch 19, the control input of which is combined with the same input of the inverter 17 n connected to the output of the control unit 5.

The device operates as follows: P430M.

The command to start the measurement from the output of the control unit 5 to the inputs 55 of the keys 2 and 6 is given control pulses, as a result of which the keys are closed and to the inputs of the counter 3 and the meter 7 time intervals are supplied the sequences formed by the voltage converter 1, respectively frequency and generator 4 exemplary frequency. At the same time, the key 13 closes and the variable component separated by the block 10 is fed to the input of the integrator 14. After a fixed duration interval, all the named keys are opened if the signs of the current and integral values of the variable component of the signal compared to the discriminator 11 characters are the same. With opposite signs, the keys remain in the closed state and the integration processes and measuring their duration continue until the integral value of the variable is not equal to zero or the current value of this component changes sign in both cases, the keys 2, 6, 13 is disconnected, but in the first of them the measurement will be completed, and in the second it will stop for a time of equality of signs and continue with opposite signs until the integral value of the variable component becomes zero. After that, a switch command is issued to the inputs of the key 19 and the inverter 17 by the control unit 5. After the establishment of transient processes, the parasitic thermo-emf changes its sign, and the induced disturbances change the phase. The polarity of the measured signal U will remain the same. The inputs of the keys 2B and I3 will receive a command from block 5 and close again. Further, the operation of the device proceeds as described. The results of both measurements from the outputs of the counter 3 and the meter 7 are fed to the input of the arithmetic unit. The result of the calculation, which is the half-sum of the integral values of the signal of the measuring transducer, related to the total duration of the time intervals in which the integral value of the variable component is zero, is given to the display unit 9 and the display. In order to increase the measurement accuracy, subsequent pairs of measurements can be made. If the value of the variable component of the signal of the measuring transducer does not exceed the threshold for triggering a 12 level discriminator, the device makes only two integral samples of a fixed duration.

Claims (1)

Invention Formula A method of measuring physical quantities containing an additive noise in the form of a variable component in which the signal corresponding to the measured physical quantity is integrated during shifted time intervals, the beginning of the first of which is arbitrarily fixed in duration, and the end of the last coincides in time with the moment of equality zero of the integral value of the variable component for a time equal to the total duration of the intervals, characterized in that, in order to increase the measurement accuracy, signal integration la at intervals subsequent to the first derivative T during the time segments, cha which the sign of the current value variable component opposite to the sign of the integral value of the variable component for the first integration interval. Compiled by V. Skomorokhov. Editor M. Kelemesh Tehred M. Khodanych. Corrector I. Erdeyi Order 4404/40 Circulation 728 Subscription Vshipi State Committee of the USSR for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4