SU438091A1 - Phase discriminator - Google Patents

Description

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The invention relates to the field of radio engineering and can be used in systems of automatic control of the speed of a magnetic carrier, as well as in systems of phase frequency auto-tuning.

The well-known phase discriminator, which consists of frequency dividers, a trigger with separate start and an output filter, has a low detection accuracy.

The purpose of the invention is to improve the detection accuracy.

In the proposed phase discriminator, this goal is achieved in that parallel to one of the frequency dividers are connected in series the frequency discriminator and the electronic relay.

The drawing shows a diagram of the proposed phase dyscreen.

Phase discriminator works as follows.

When the supply voltages Uni and U-az are switched on and the frequency dividers 1 and 2 are connected to the inputs of the master voltage frequency fo and voltage frequency fi, rectangular pulses of frequency and -i are formed at the output of the latter, respectively. These

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the pulses are differentiated by differentiating, strings assembled on capacitor 3 and diode 4 for the signal

frequency / o and on the capacitor 5 and the diode 6 for the signal frequency fi. Differentiated negative pulses through dividing diodes 7 and 8 are applied to the inverting and non-inverting inputs of the operational amplifier (OU) 9. Each negative pulse to the inverting input of the OA 9 sets a positive potential at its output, and

the negative impulse arriving at the non-inverting input of the op-amp 9 establishes a negative potential at its output, i.e., the square impulses are formed at the output of the op-amp 9 (flip-flop 10), the duration of which is proportional to the phase (time) shift between the signals from the outputs of frequency dividers 1 and 2 Resistors And and 12 provide positive feedback from the output of the OU 9 to its input in order to maintain

trigger 10 in the intervals between the input pulses in one of two stable states. The pulses of the output of the op-amp 9 are smoothed by the filter 13 assembled on the resistor 14 and the capacitor 15. Thus, the output voltage of the filter 13 forms a DC voltage proportional to the phase (temporal) shift between the pulses from the outputs of frequency dividers 1 and 2.

When changing the phase shift within

from O to 2n; frequency / i is equal to the reference frequency / 0. The additional frequency discriminator 16 is tuned to frequency / o, i.e. its output voltage is zero when voltage / o is applied to its input. When the phase shift increases by more than 2l, the frequency fi is less / o. Then, the output of the additional frequency discriminator 16 produces a negative voltage, the value of which is proportional to the frequency deviation fi relative to / o, and the output of the electronic relay 17 produces a positive voltage is fed to the non-inverting input of the op-amp 9. As a result, the output of the trigger 10 sets the maximum positive potential for the entire time during which the frequency is. As the phase shift decreases by less than zero, the frequency / i is greater than fo, and a positive voltage is generated at the output of the additional frequency discriminator 16. At the same time, a negative voltage appears at the output of the electronic relay 17, which is applied to the non-inverting

OU input 9. As a result, the output of the trigger 10 sets the maximum negative potential for the entire time during which the frequency / i / oThus, with equal frequencies fi and / o when their phase shift changes from O to 2, the output static characteristic of the phase discriminator linear. At fj / o, the output voltage of the phase discriminator is equal to the maximum negative, and at / 1 the fo is the maximum positive output voltage of the trigger 10.

Subject invention

Phase discriminator on a trigger with separate start, to the inputs of which frequency dividers are connected, characterized in that, in order to increase detection accuracy, serially connected frequency discriminator and electronic relay are connected in parallel with one of the frequency dividers.