SU1553913A1 - Frequency meter - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure the frequency of a current in a metro track circuit. A device for measuring the frequency contains a frequency sensor 1, trigger 2, element 4, generator 5 stable single pulses, single vibrators 7, 8, indicator 9, pulse counter 10. The introduction of the element NO 3 and the element OR-NE 6 made it possible to improve the frequency measurement accuracy by reducing the sampling error and increasing the synchronization accuracy. 2 Il.

Description

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with

FIG. one

The invention relates to measurement technology and can be used in devices controlling the frequency parameters of the equipment for automatically adjusting the speed on a railway to measure a frequency or period by counting the number of pulses placed in a certain time interval. i

The purpose of the invention is to improve the measurement accuracy by reducing the sampling error and increasing the synchronization accuracy.

FIG. 1 shows a diagram of a device for measuring frequency; figure 2 time. diagrams of his work.

The device contains frequency sensor 1, trigger 2, element HE 3, element I 4, generator 5 stable single pulses, element OR NOT 6, the first and second single vibrators 7, 8, indicator 9, and counter 10 pulses.

The output of the frequency sensor 1 is connected with the C-input of the trigger 2 and through the element NOT 3 to the first input of the element AND 4, the second input of which is connected to the output of the generator 5 stable single pulses, the first input of the element OR NOT 6 and the input of the first single-oscillator 7 connected to the output of the second one-shot 8, the second input element OR NOT 6 and the first input of the indicator 9, the second input of which is connected to the output of the counter 10 pulses. The first input of the counter 10 pulses is connected to the output of the element AND 4, and the second input to the output of the second one-shot 8 and the third input of the element OR NOT 6, the output of which is connected to the D-input of the trigger 2 connected to the output of the generator 5 stable single pulses .

The device works as follows.

The frequency measurement in the device is carried out by counting the number of pulses from frequency sensor 1, placed in a specific time interval specified by the generator 5 of stable single pulses.

Before the start of the measurement cycle, i.e. if the generator 5 is of stable single pulses, the first and second one-shot 7 and 8 are finished and the inputs of the element OR-HE 6 receive zero signals from their outputs, the output of the element OR-HE 6 is formed

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a single signal arriving at D- input of trigger 2. Measured frequency from frequency sensor 1 is fed to the element HE 3 and to the C input of trigger 2.

On the leading edge of the input frequency pulse from the frequency sensor 1, a single signal is generated at the output of the trigger 2, which triggers the generator 5 stable pulses, which sets the measurement time of the input frequency.

At the same time, the signal from its output, which arrives at the first input of the AND 4 element, permits the passage of the input frequency signals pre-inverted in the HE 3 element through the AND 4 element to the counter 10 pulses and simultaneously a zero signal is generated at the output of the OR-NE 6 element which, on the leading edge of the following input frequency pulses, is rewritten into trigger 2. Inverting provides a delay in switching the counter of 10 pulses per half-cycle of the input frequency in the case of a meander (frequency sequence from wells awn 2).

Thus, the methodical sampling error is reduced to 0.5 sampling, which is ensured by a phase shift in the beginning of the measurement of the input frequency signal by half the period of the measured input frequency relative to its beginning. After the end of operation of the generator 5 stable single pulses at the output of the element 4, a zero signal is generated, closing the input of the pulse counter 10, its state is fixed, the first one-oscillator 7 is started, with which the contents of the pulse counter 10 are written into indicator 9. The pulse from the one-oscillator output 7 keeps the element OR NOT b in the zero state, at the end it starts the second one-shot 8, the signal from the output of which returns to its original state the counter of 10 pulses and continues to hold in zero state element OR NOT 6. At the end of the second one-shot 8, the output of the element OR NOT 6 produces a single signal at the input of trigger 2. Switching to single state of trigger 2 takes place at the leading edge of the input frequency signal, ensuring a further trigger devices for a new measurement cycle.

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Claims (1)

Claims An apparatus for measuring a frequency, comprising a frequency sensor, an AND serially connected element, a pulse counter and an indicator, a trigger, a generator of stable single pulses, the output of which is connected to the first input of the And element and the input of the first one-oscillator, the output of which is connected to the control input indicator, the second one-shot, the output of which is connected to the control input of the pulse counter, characterized in that "1sh 3 2 S 7 8 6 4 ten I-I (-I I-I I-I G l P n P P one , 0 36 the height of measurement accuracy, the elements are NOT and OR-NOT, with; This element is NOT connected to the output of the frequency sensor and the trigger trigger input, and the output is connected to the second input of the AND element, the D-input of the trigger is connected to the output of the OR-NOT element, the first and second inputs of which are connected respectively to the outputs of the first and second single vibrators connected sequentially, and the third input - with the output of a generator of stable single pulses, the input of which is connected to the trigger output. P t t P t f 7 P one Phage. 2