SU410325A1 - DEVICE FOR MEASURING FREQUENCY - Google Patents

Description

one

This invention relates to a radio measuring technique.

Frequency measurement devices are known that contain a delay circuit, a trigger, output signal drivers, a low-pass filter, and a measuring instrument.

The purpose of the invention is to improve the measurement accuracy and expand the range of measured frequencies. It is achieved by the fact that the proposed device is equipped with a switch of measurement limits and two comparators.

FIG. 1 is a block diagram of the facility; in fig. 2 is a comparator circuit based on a transistor circuit versus emitter coupling.

The input of the delay / connected to the terminal of the input signals 2. The inputs of the trigger 3 are connected to terminal 2 and to the output of the delay circuit, and its outputs through the drivers 4 and the low-pass filter 5 are connected to the measuring device 6. The output of the filter through comparators 7 and S, the second the inputs of which are connected to the inputs 9 and 10 of the signals of multiple range values, are connected to the control inputs of the range switch // whose outputs are connected to the control inputs of the delay circuit 1.

The comparator shown in FIG. 2, contains a comparison circuit with a transistor connection. A threshold voltage is applied to the base of transistor 12, and a signal from the output of low-pass filter 5 is applied to the base of transistor 13. Transistor 13 opens, and the range switch signal is removed from circuit output 14 if the voltage at the base of transistor 13 exceeds the threshold level at the base of transistor story 12.

The input signals are sent to the trigger 3 directly, and through the delay circuit /, the value of which is determined by the state of the switch /). If the input frequency corresponds to the range determined by the delay value, then the readings of instrument 6 correspond to the middle sections of the scale. When the frequency of the input signals changes, the voltage at the output of the low-pass filter also changes. If it reaches one of the extreme values determined by the potentials at terminals 9 and 10, corresponding to

0 the extreme points of the measuring range, at the output of the comparator 7 or 8, a signal appears that switches the switch lil to one of the neighboring states, thereby changing the measurement range, since the last 5 is determined by the delay value according to the C / s dependence - / rj, where

one

delay time, a / (:

frequency, owner

fixed with a given range,

30, the deviation from which is measured.

For example, when the input signal frequency increases, the value of U decreases, and the comparator's output signal, for example, 7, must switch the switch 1-1 to that state, which is associated with a decrease in the delay in the circuit. Conversely, lowering the input frequency is associated with reverse switching of the switch and, accordingly, with increasing delay. The measurement range number is identified by indicating a single signal at the switch output.

The switch can be performed, for example, in the form of a ring circuit, a counting trigger circuit with a decoder, etc. To control the amount of the delay, the threshold voltage can be changed if the delay circuit is based on some kind of trigger circuit (sawtooth generator, multivibrator, etc.), change

the length of the delay line, if it is, for example, magnetostatic | change the initial state of the counter or the frequency of the reference oscillator, if the delay circuit is a device for counting by a given module.

Subject invention

A frequency measuring device comprising a series-connected delay circuit, a trigger, output signal drivers, a low-pass filter and a measuring device, characterized in that, in order to expand the frequency range and improve the measurement accuracy, the sensor is provided with a measuring limits switch and two comparators, inputs which are connected to the output of the low-pass filter, and the outputs through the switch are connected to the control input of the delay circuit.

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