SU402810A1 - MEASURING DEVICE - Google Patents

Description

one

Known measuring instruments containing a switching device for the measured value and a reference, a frequency sensor, a selector controlled by the time interval circuit, and a counter are characterized by a low measurement accuracy when subjected to periodic noise interference.

To improve the measurement accuracy when subjected to periodic noise in the proposed device, a binary frequency multiplier is introduced between the input of the counter and the output of the selector through a key circuit, the code inputs of which are connected to the code outputs of the counter through memory devices.

The drawing shows the block diagram of the described device.

Through switch 1, either the source 3 of the reference voltage or the source 4 of the measured voltage is connected to the input of the frequency sensor 2.

The output of sensor 2 is connected through a selector 5 and through a switch 6, synchronous with switch 1, or with the input of a counter .7, or with a input of a binary multiplier 8, the output of which is connected with the input of a counter 7.

The code inputs of the binary multiplier - 8 through the storage device 9 is connected to the code outputs of the counter 7.

The frequency sensor in the described circuit is a voltage-to-frequency converter made, for example, in the form of an LC generator with a voltage-controlled varicap capacitor. Binary multiplier 8 is a device that allows frequency multiplication with a fractional multiplication factor inversely proportional to the number written in the code. The device works as follows.

In the first cycle, frequency sensor 2 is connected via switch 1 to the source 3 of the reference voltage, and the frequency from its output is selected through the selector 5, controlled by pulses synchronized by the frequency of the network, through switch 6, to counter 7.

At the end of the first cycle, the code from counter 7 is copied to the memory of the binary frequency multiplier, and switches 1 and 6 are moved to the opposite position.

To the beginning of the second cycle to the sensor input

applied voltage measured and output

selector via binary multiplier linked

with the entrance of the counter.

Frequency from sensor 2 output through selector

and the binary multiplier is fed to the counter during the time for which the selector is opened in the second cycle, i.e. during the same time as in the first cycle.

The result accumulated during the second

cycle at the counter, is used as output.

Thus, due to the possibility of setting the frequency measurement time both in the first and in the second cycle, multiple to the interference period, the error caused by the effect of periodic interference on the frequency sensor during the action of the measured and reference value is eliminated.

Subject invention

A measuring instrument containing a switching device for measuring and reference

magnitude, frequency sensor, selector, controlled by the time interval circuit, and a counter, characterized in that, in order to improve the measurement accuracy under the influence of periodic noise, a binary frequency multiplier is entered between the counter input and the selector output, the code inputs which is connected to code outputs through zanomapping devices

counter.

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