SU883770A1 - Frequency deviation meter - Google Patents

Description

The invention relates to a measurement technique and can be used in an automated frequency control and control system. The relative frequency, absolute, and reduced frequency error meter is known, which contains a driver, a key, controlled and scaled frequency dividers, a model frequency generator, a reversible counter, k, control and display circuit. The disadvantage of this device is low speed. periods of the investigated signal. The closest in technical essence to the present invention is a digital deviometer containing successively connected pulse generator and key, generator of exemplary frequency, control unit, registers and digital logometer 2. A disadvantage of the known devices is low speed, since the measurement is carried out over several periods the signal under study and the complexity of the hardware implementation. The purpose of the invention is to increase the speed of the device. This goal is achieved in that a frequency deviation meter comprising a series-connected amplitude ration unit, a pulse shaper and a key, a series-connected constant voltage source and a comparison unit, the second input of which is connected to the input of the pulse shaper, and the output to the second key input, the third input of which is connected to the generator output of the reference frequency, as well as a digital logometer, a reversible counter is entered, the first input of which is connected to the input of the digital logometer and the output of the key, while the second output of the reversible counter is connected to the second input of the digital logometer. The drawing shows a diagram of the proposed device. The device comprises an amplitude forming unit 1, a comparison unit 2, a constant voltage source 3, a pulse shaper 4, an exemplary frequency generator 5, a key 6, a reversible counter 7, a digital logometer 3. The device operates as follows.

The signal under study is fed to the input of the amplitude shaping unit 1, at the output of which the amplitude of the signal under study is: equal to the amplitude of the reference frequency signal. The task of maintaining a constant amplitude of the signal under study is greatly simplified if the proposed device is used in frequency control systems or in automatic control systems with frequency output, because in this case the amplitude of the monitored signal is known in advance. From the output of the amplitude shaping unit 1, the signal under study is fed to the inputs of the comparator unit 2 and the former 4. When the signal undergoes a zero crossing at the output of the former 4, a pulse is generated that opens the key 6. The pulses from the generator 5 of the reference frequency are transmitted to the first key The input of the reversible counter 7 and the second input of the digital logometer 8. At the moment of time t, when the instantaneous value of the investigated signal becomes equal to the threshold level specified by the source 3 of constant voltage to the output ode of the comparison unit 2, a pulse is formed that closes the key 6, thereby stopping the arrival of the pulses at the first input of the counter 7 and the second input of the logometer e

The principle of measuring the frequency deviation of the proposed device is as follows.

At the moment t of equality of the instantaneous value of the signal of the reference frequency to the voltage UQ, given by the constant voltage source, and for the moment of the Equality of the instantaneous, eigenvalue of the signal being investigated to the voltage UQ, the ratio 0 (5 u) (jt, Uo U sinCujQ-dii) tti , (1) Uj., Is the voltage source of a constant voltage; a.v, - signal amplitude reference

t

frequencies;

0 - the amplitude of the signal under study, and always

Urn and; H) | s - reference frequency; to) - urashirnie frequency. Transforming the time intervals t-, and tn into a number-pulse code, equality (1) can be written as

And about

 N and

D)

where N (j is some constant number that determines the measurement discreteness; N is the number of pulses proportional to time t; J (h is the number of pulses proportional to time t .. Putting and „U, j and, we determine from the relation (2) the deviation frequency d w pulses arriving at Q, the first input of the reversible counter 7 and the second input of the digital logometer 8. During this time, the number of pulses Nn equal to s N, j fo will be sent from the output of the key b to the first input of the reversible counter 7 and the second input of the digital logometer 8. t2.

The number of pulses N equal to N fgt, the value for the reference frequency signal, known in advance, is entered into a reversible counter when 0 preparing the device for operation. From the output of the reversible counter 7, the difference N N is fed to the first input of a digital logometer, the output of which corresponds to the desired value of the relative frequency deviation oftw.

Thus, the proposed device does indeed allow to determine the relative deviation of the Q frequency in a wide range of frequency variations in molar time.

Claims (2)

1. USSR author's certificate No. 587980, cl. G 01 R 23/06, 1978. 60 2. USSR author's certificate in application 2719672/21 (017129) (prototype),