SU300838A1 - DIGITAL INTEREST FREQUENCY - Google Patents

Description

The invention relates to the field of electrical measuring equipment and can be used to extend the range of measurement of the relative deviation of the measured frequency from the nominal value and increase the speed of digital percentage frequency meters.

The known digital percentage frequency meter containing a pulse shaper, keys, an exemplary frequency generator, a pulse counter, a control unit, a pulse shaper limited in time by the measured frequency period, a period – conduction converter formed by a binary counter-register and a code – conductivity converter, a comparison circuit voltage, trigger, integrating capacitor and reference voltage source, characterized by a narrow measurement range of the relative deviation of the measured frequency from the nominal value and the reduced speed.

The proposed digital percentage frequency meter differs from the known ones in that it is equipped with an additional voltage comparison circuit and an exemplary RC circuit, an active voltage divider and a disturbing generator, the output of which is connected in parallel with an exemplary RC circuit, the RC circuit. conductivity and an integrating capacitor, and an active voltage divider, the midpoint of which is connected in parallel to the first inputs of the first and second voltage comparison circuits, the second inputs of which They are connected to the midpoints of the RC circuits, and the outputs to the trigger circuits of the trigger.

Such an embodiment of the device makes it possible to expand the range of measurement of the relative deviation of the measured frequency from the nominal value and to increase its speed.

The block diagram of the proposed device shown in the drawing.

The device consists of a pulse shaper 1, a control unit 2, keys 3-5, a generator of exemplary frequency 6, an auric converter- (conductor 7 formed by a binary counter-register5, keys and (Converter — od - conductivity 9, disturbance generator 10, integrating and reference capacitors, 12, reference resistor 13, comparison circuits 14, 15, voltage divider 16, trigger 17, and pulse counter 18.

2. The output signal of the control unit 2 opens the key 3 for a time equal to the period of the measured frequency, during which the pulses of the generator 6 are fed to the converter 7.

The impulses of the generator 6 are counted by a binary counter-register 5, which, acting on the keys 4, switches the conductivities connected in parallel in the converter 9. The conductivity values increase according to the binary law, starting with the least significant bit of the binary counter-register 8.

The total conductivity is proportional to the period of the measured frequency. After a period that has elapsed. Thus, pulse C of control block 2 starts generator 10, which produces a rectangular pulse or ramp voltage on an RC circuit formed by controlled conductivity with capacitor 11 and resistor 13 with capacitor 1/5. Capacitors 12, 11 are charged. Comparison schemes 14, 15, to the second inputs of which a part of the disturbing action f / c from the active voltage divider 16 is applied, are triggered when the voltage on the capacitors reaches a level equal to t / c.

The trigger 17 is transferred at the time of the operation of one of the comparison circuits 14, 15 and returns to the initial state at the time of the operation of the other scheme. During the time f, the trigger 17 opens the key 5, and the pulses from the generator 6 arrive at the counter 18 and are counted by it.

The number of pulses counted by the counter is equal to.

/ in

N + K

IX nom

t2- / o,

constant time of the circuit formed by resistor 13 and capacitor 12;

sample frequency; the deviation of the measured frequency from the nominal;

/ dgnom- nominal frequency. When L is numerically equal to the deviation of D / I in percent.

Indication of the deviation sign fei from / V.Ch. The number can be produced by an additional trigger that determines which of the comparison circuits will work before. When replacing an exemplary resistor 13 with a transducer for a period of a pulse sequence of a second measured frequency to conductance, the device measures the difference between two frequencies.

Subject invention

Digital percentage frequency meter containing pulse shaper, keys, reference frequency generator, pulse counter, control unit, pulse shaper, limited in time to the measured frequency period, period-to-conduct converter, part formed by a binary counter-register And a shredder code - conductivity, circuit voltage comparison, trigger, integrating capacitor and reference voltage source, characterized in that, in order to expand the range of measurement of the relative deviation from the nominal nogo values and speed, it is provided with additional circuit comparing voltages and exemplary RC-tsvpyu, active subgroup: na1I1r Yazheni and generator disturbing effect to vyhodukotorogo parallel connected Obrazcova COP-chain, CP-chain formed otreobrazovatelemkod-1provodimost "integrating capacitor, and an active voltage divider whose midpoint is connected in parallel to the first inputs

the first and second voltage comparison circuits, the second inputs of which are connected to the midpoints of the RC circuits, and the outputs to the trigger circuits of the trigger.