SU440781A1 - Pulse-phase discriminator - Google Patents

Description

one

The invention relates to a pulse technique.

A phase discriminator is known, which contains a trigger, the inputs of which are supplied with compared signals, a C-integrator with a bit switch and an operational amplifier.

However, the known discriminator has a high level of output ripple.

The aim of the invention is to reduce the output pulsation level.

For this, an additional switch and an additional capacitor are introduced into the discriminator, with the additional switch being connected between the / C generator and the input of the operational amplifier, in parallel with which an additional capacitor is connected.

The drawing shows the block diagram of the discriminator.

The pulse-phase discriminator contains a trigger 1, an integrator containing a resistor 2 and a capacitor 3, a discharge switch 4, an additional switch 5, an additional capacitor 6, resistors 7, 8, and an operational amplifier 9.

The discriminator works as follows.

At one of the inputs of the trigger 1, a pulsing sequence of pulses is applied. The same pulses control the keys 4 and 5. In this case, the command to turn on the key 4

must come with some delay when key 5 is already turned off. Two control pulses separated in time are obtained for controlling keys 4 and 5 as follows: a pulse Tzad is differentiated on a pulse transformer (not shown), the leading edge gives a pulse for key 5, and the falling edge for key 4.

The second input of the trigger 1 receives another sequence of Toc pulses (for example, feedback), which is phase-shifted relative to Tzad.

When applying to trigger 1 of both sequences shifted in phase, trigger 1 will switch. In this case, a variable rectangular voltage is generated at its output, which is fed to the integrator. If the feedback pulse is located symmetrically between two adjacent Tzad pulses, then the voltage on the capacitor 3 at the time of closing the key 5 is zero, i.e., at the output of the entire device, the signal is zero. Such arrangement of pulse sequences is most favorable for the stable operation of the discriminator in a closed-loop control system. This phase shift is initially conditionally equal to zero. With a different mutual arrangement of pulses on

the capacitor 3 at the time of locking keys

5 and 4, the voltage direction is not zero, and its magnitude and sign uniquely characterizes the phase shift between the signals relative to the conditional zero.

At the moment of arrival of the pulse tzad, key 5 is first turned on, the capacitor b is connected briefly to capacitor 3, and, since the capacitance of capacitor 6 is an order of magnitude smaller, it is practically charged to a voltage equal to the voltage on capacitor 3 at this moment.

Then the key 5 is opened, and the key 4 is short-circuited by discharging the capacitor 3 to zero. Then again the capacitor 3 is charged, a 1 time TOO pulse arrives at the trigger, and so on.

The voltage from the capacitor 6 is fed through an input resistor 7, which has a relatively large resistance, to the input of the operational amplifier 9.

The pulsation at the output of the discriminator with linear feedback of the amplifier 9 and a fixed phase shift depends on the degree of discharge of the capacitor 6 through the resistor 7 during the time between two pulses Tzad. The pure delay introduced by the discriminator is no more than one half period

Tzad The invention

A pulse-phase discriminator containing a trigger, to the inputs of which lodans are compared signals, and the output of which is connected to an A / C integrator with a discharge key, and an operational amplifier, characterized in that, in order to reduce the output ripple level, an additional key is introduced and an additional capacitor, the additional switch being connected between the C-integrator and the input of the operational amplifier, in parallel with which an additional capacitor is connected.