SU370537A1 - DIGITAL FREQUENCY - Google Patents

Description

one

This invention relates to electrical measuring technology.

A well-known digital frequency meter containing an input driver, an exemplary frequency generator, a counter control valve, a potential key system, a scaling circuit, a main counter, a decoder, an assembly circuit, a period number counter and a digital recording unit are characterized by a complicated structure.

The proposed frequency meter differs from the known ones in that it is equipped with a three-input key, the control input of which is connected to the output of the billing circuit, the signal input - to the output of the potential key system, prohibiting the input - to the output of the assembly circuit, and the output to the subtracting inputs of the controlling and main counters.

This embodiment of the device allows to simplify its design.

The drawing shows a block diagram of the proposed device.

The device consists of an input driver 1, a generator 2 of exemplary frequency, a valve 3, a control counter 4, a system of 5 potential keys, a recalculation circuit 5, an assembly circuit 7, a three-input key 5, a main counter 9, a digital registration block 10, a decoder // and counter 12 the number of periods.

The device works as follows. In the initial state, the number

 - ftxam

whereLo is the capacity of the scaling circuit 6;

fo is the frequency of the generator 2; -period corresponding to the laximal value of the frequency of the working portion of the measuring range.

Counter 4 records the number that is selected based on the specified accuracy and size of the work area of the desired frequency range. The counter 9 contains the Lomake number corresponding to the maximum frequency of the working section of the measuring range. The period number counter 12 and digital registration unit 10 are in the zero state. The valve 3 and key 8 are closed. The measurement is as follows. The first pulse of the measured frequency from the generator output / opens valve 3, through which the generator 2 of the reference frequency of the counting circuit 6 begins to fill with pulses. At the same time, the pulses of the measured frequency arrive at the input of the counter 12, which counts the number of pulses of the measured frequency. The output of the decoder 11 appears a signal corresponding to the arrival of each pulse in counter 12, the number of which is an integer power of 2, i.e. 1, 2, 4, 8, ..., t 2. Each pulse from the output of the decoder // switches the comma in digital registration block 10, respectively, to O, 1, 2, 3, ..., Id t binary bits to the right, where t is the number of pulses received in counter 12. Pulses from the output of the decoder 11 through circuit 7 The assemblies arrive at the input of the key S, closing it. As a block that implements an exponential dependence, a binary integrator with sequential transfer is used, covered by negative feedback. It consists of a scaling circuit 6, a system of 5 potential keys and a control counter 4. When pulses arrive at the input of circuit 6, it generates an overflow pulse opening key 8. Frequency pulses (i) varying exponentially. / W -fo-e of time, arrive t --- constant / o

to the subtractive inputs of the controlling 4 and main 9 meters. The measurement process continues until the next t-th pulse arrives at the input of counter 12 and a corresponding pulse appears from the output of the decoder 11 closing the key 8. The number recorded in the main counter 9 will be equal at this moment

L. Lomake-j / Wrf. (2)

Substituting in the equation (2) the value of the frequency f (t) from the expression (1), we get m, t

 - Lmax +

lg, ",

. jVo

P, r e d m et and z obrete n I1

A digital frequency meter containing an input, a driver, an exemplary frequency generator, a valve, a control counter, a potential key system, a scaling circuit, a main counter, a decoder, an assembly circuit, 5 a period number counter and a digital recording unit, characterized in that construction, it is equipped with a three-input key, the control input of which is connected to the output of the scaling circuit, the signal input - with the output of the system of potential keys, prohibiting the input - with the output of the assembly circuit, and the output - c) Discharge inputs Dami manager and main counters. + where is G.-; -Ghmin. Choosing the Lomake, .VH, // o, / o parameters that define the parameters of the exponent, one can achieve a match with a given degree of accuracy of this exponential function (Tx) with the required piperbolic dependence (-), i.e. N2 F {x). Thus, in the digital recording unit, by transferring the comma to the right by 1dm binary bits, the number Al is multiplied by m. Therefore, the final measurement result recorded in the digital recording unit will be Levy. The measurement time will be within T T mln them where T max is the maximum period corresponding to the end of the working section of the measuring range.

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