SU391490A1 - YOU-UNION - Google Patents

Description

one

The invention relates to the field of digital measurement technology and can be used in the rapid coding of low-frequency signals from sensors and transducers ..

Digital low-frequency meters are known, containing a reference oscillator and a signal source of a measured frequency, connected to the valve inlets, the output of which is connected to a subtractive counter.

The proposed meter differs in that between the valve and the subtracting counter there are two interconnection counters with common register and circuits for non-transferring its code into each of the two counters at the moment of overflow of the corresponding one, and the register is connected to the valve output through a divider. This makes it possible to increase the measurement accuracy.

The drawing shows a functional diagram of the proposed meter.

A digital low-frequency meter contains an on-off generator / with valve 2, two serially connected counters 3 and 4 with register 5 and transfer codes 6 of its code into counters 3 and 4 at the time of the appearance of pulses at their outputs, subtracting counter 7 of the measurement result and divider 8 frequency / 0. The measured frequency is fed to the input 9 of the imaging unit 10 of one or several non-periods of the input sequence. Frequency generator 1 / o can have two outputs shifted by i lperiod.

Digital low-frequency meter works as follows.

On the leading edge of the measured signal with a delay of Ti time, the numbers are quenched in counters 5 and 4 and the maximum number is set in counter 7. The same signal sets the initial state to divider 8 and register 5. The initial state of the divider and register may differ from zero. After the initial setup, the code in the Vp register changes linearly.

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L - Adi

P, DD

where g is the current time;

D is the division factor of divider 8.

The frequency fi at the output of counter 3 is determined by a register code, since each pulse fi translates the code into this counter.

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f - / o-D fo-t i g L DD DN ,, tf, -t / Set. g In counter 7, the NI code decreases from the maximum one, corresponding to 2, where n is the number of bits of the latter, therefore NI can be calculated how r dt. 1 + 1 If you select 2, then, where d. Of the above expression, you can see that the measurement result is proportional to the frequency, and all frequencies fx, the period of which will be represented by the maximum code. It also follows that the initial installation must be made

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61 not at the moment corresponding to the leading edge of the measured signal, but with a delay of time Ti corresponding to the maximum measured frequency. The measurement error Y is minimal at the highest input frequency and is equal to 7 -. Thus, the required accuracy can be selected depending on the V / A and .Vy. Subject of the Invention A digital low-frequency meter containing a reference oscillator and a measured frequency signal source connected to the valve inputs, the output of which is connected to a subtractive counter, characterized in that In order to increase the measurement accuracy, between the valve and the subtractive meter are connected two serially connected meters with a common register and circuits for transferring its code to each of the two meters at the moment of overflow, respectively Enikeev of them being connected to the output register through the divider valve.