SU370535A1 - -h ^^ UNIONAL - Google Patents

Description

The invention relates to the field of electrical measuring equipment and can be used to improve the accuracy and broaden the frequency range when measuring low frequency and infra-low frequencies during one of their periods.

The known digital method of measuring the pulse frequency, based on the subtraction during the period of the number corresponding to the maximum value of the measured frequency of the number of pulses, the frequency of which varies depending on the number in the subtracting counter, and fixing the remaining in the number counter, it is characterized by reduced accuracy and a narrow range of measured frequencies.

The proposed method differs from those known in that for a fixed time interval, measured from the beginning of the measured period and equal to the minimum pulse duration corresponding to the number recorded in the counter, the number recorded in the counter remains unchanged, and then the average frequency of the subtracted pulses is changed continuously directly proportional to the square of the current value of the number in the counter.

The method allows to increase the measurement accuracy and expand the range of measured frequencies.

The drawing shows a block diagram of one of the variants of the device for implementing the proposed method.

The device consists of a subtracting counter /, a converter "code - pulse frequency 2, and a control unit 3.

The device works as follows. Before the beginning of each measurement, a number is automatically recorded in the counter corresponding to the maximum value of the measured frequency max. OR the minimum value of the period Go

  KfttaKC -it t o

After the measurement has been started, the time interval / equal to

. - t -

  - - l

L o / max

During this interval, the number of counters stored in the counter remains unchanged, since no subtractive pulses are received at the input of the counter.

After fixing the interval t - T at the output of the control unit, a pulse of duration Gh-Go appears and the converter is turned on.

During this period of time, the subtraction of the recorded number of NQ pulses, which follow at an average frequency directly proportional to the square of the current value in the counter, is carried out. Since the number in the counter varies continuously, the frequency of the subtraction pulses also changes continuously. This is ensured by the presence of links between blocks 1 and 2, which are switched on by block 3 only after fixing Go for TX-TO time. After the end of Gx, block 3 fixes in the block / the remaining number NS, which is the result of measurement, expressed directly in frequency units. Subject of the Invention A digital method for measuring the pulse frequency, based on the subtraction of the number corresponding to the maximum value of the measured frequency of the pulses, the frequency of which changes depending on the number in the subtractive counter, and fixing the remaining a number counter, characterized in that, in order to increase the measurement accuracy and rasShifenm: the range of measured frequencies, during the flustible time interval, from the beginning of the measurement period and equal to the minimum duration of the pulse corresponding to the number recorded in the counter, the number recorded in the counter remains unchanged, and then the average follow frequency of the subtracted pulses is continuously directly proportional to the square of the current value of H | .