SU463926A1 - Frequency measuring device - Google Patents

Description

one

The invention relates to the field of measurement technology.

A device for measuring the frequency is known, comprising a reference frequency generator, a phantomizer, an electric key, an ImulsoB counter, and a control unit.

The device measures the frequency according to the duration of the period, and the counter is set to the state corresponding to twice the number of pulses produced by a stable generator for a given number of periods at the nominal value of the measured frequency, and the pulses fed to the counter are subtracted from the original recorded number, and the counter readings thus obtained correspond to the frequency value.

The known device for frequency measurement has a method error, increasing in proportion to the square of the frequency out of the memorial value.

The aim of the invention is to increase accuracy with significant frequency deviations from the nominal value.

In the proposed device, this is achieved by introducing a correction with the help of a controllable delay unit and the "OR.

The drawing shows a block diagram of the described device, comprising a driver 1, a control unit 2, an electronic switch 3, a generator 4 of the reference frequency, a counter 5, a block 6 of a controlled delay, a logic circuit "OR 7.

The device works as follows.

The voltage source U, the frequency of which must be measured, is connected to the input of the imaging device 1, which forms time intervals proportional to the measurement period of its own voltage. The device can be switched on manually or automatically from the control unit 2. The electronic key 3 receives pulses from the generator 4. If the key 3 is open, these pulses are passed to the input of the counter 5. The block 6 is connected to the output of the counter 5 via the start) according to the generator, with the output of the forcing device 1n the first input of the logic circuit "OR 7.

Before the start of the work cycle, the counter 5 is set to the position corresponding to the Lo number. The shaper 1 generates a signal and through the “OR 7” circuit opens the electronic key 3. At the same time, pulses with a frequency F from the reference frequency generator arrive at the input of counter 5. Counter 5 works on subtraction. Each incoming pulse reduces the number written into counter 5 by one. During the time period of the selected interval G, F-T pulses will arrive at the counter and at the end of the interval T in the counter 5 the number will be written

. У (Г). У „-ГГ.

The frequency F and the Lo number are chosen so that if the maximum (/ max) and the frequency range (/ Nil ,,,) is measured, the contents of the counter at the end of the Nernod .V (T) will exactly match the frequencies / ma .- with and / min. For intermediate values of frequency / m11n; /; / ma1, h: NUMBER L (t) will be somewhat larger than the necessary number L (7 + t) corresponding to frequency /.

From the output of the block, the delay unit 6, after the end of the interval T, lasts for some time the signal, which through the logic circuit OR 7 leaves the clamp 3 in the open state. Correction is introduced due to the fact that the PA input of the counter 5 receives the impulses from the generator 4 for some time more than the end of the interval T. The delay t, which ensures the passage of the required number of correction signals, depends on the state of the counter at the end of interval 7 ( the numbers L (r)).

Subject invention

A device for measuring the frequency, comprising a reference frequency generator, a driver, an electronic key, a counter and a control unit for the steppe, characterized in that, in order to increase accuracy with significant frequency deviations from the nominal value, it is equipped with an OR circuit and a control unit delay, one of the inputs of which is connected to one of the inputs of the logic circuit "OR and the output of the imager, the second input is connected to the output of the counter, and the output is connected to the second input of the logic circuit" OR, the output of which n with one of the inputs of the electronic key.