SU362403A1 - DISCRIMINATOR OF ZERO BEATS - Google Patents

Description

The invention relates to the field of radio engineering and can be used in precision measuring devices, in AFC systems, in control circuits of range generators with automatic frequency stabilization, as well as in radio engineering devices requiring stabilized frequency-to-voltage conversion characteristics.

Zero-beat discriminators are known, consisting of two parallel channels, of which the first channel contains a series connected mixer, an amplifier-limiter, a phase inverter, a coincidence circuit and an integrating filter, and the second channel also contains a series-connected mixer, on one of the inputs of which a phase shifter is turned on, an amplifier-limiter, a differentiating circuit, a matching circuit, an integrating filter, the second input of the matching circuit of the first channel connected to the output of the differentiating circuit, and The second input of the coincidence circuit of the second channel is connected to the output of the limiting amplifier of the first channel.

However, the known discriminators are unstable. nonlinear characteristic of the output signal.

In order to obtain a stable and linear output voltage in the proposed discriminator between the coincidence circuit and the integrating filter, a trigger is connected to each channel, the second inputs of which are connected to the output of the differentiating circuit through a precision delay line.

FIG. 1 shows the block diagram of the proposed zero beat discriminator; in fig. 2 - the characteristic of the discriminator zero beats.

In the proposed zero-beat discriminator (see Fig. 1), the mixer output / is connected to the input of the amplifier-limiter 2, the output of which is connected to the phase inverter 3 and to one of the inputs of the coincidence circuit 4.

The output φ of the azo-inverter 3 is connected to one of the inputs of the matching circuit 5, and its output to one of the inputs of the trigger 6, the output of which through the integrating filter 7 is connected to the output of the integrating filter 8. The outputs of the integrating filters 7 and 5 are the outputs of the circuit.

One of the inputs of the mixers / and 9 are interconnected directly, and others through the phase shifter 10.

The output of the mixer 9 is connected to the second inputs of the coincidence circuits 4 and 5 and to the input of the precision delay line 11 via the limiting amplifier 12 and the differentiating circuit 13.

The output of the matching circuit 4 is connected to one of the inputs of the trigger 14, and the output of the latter is connected to the input of the integrating filter 8.

The discriminator zero beats works as follows.

The input signal and the signal of the reference generator are fed to the input of mixers 7 and 5, and to the mixer 9 it is supplied by a phase shifter 10 shifted by 90 °.

From the output of the mixer signals the frequency

G - / Signal / Supports to limit amplifiers, from the output of which we get square wavelets coming from amplifier 2 to input of coincidence circuit 4 and through phase inverter to match 5 of input. The meander from differential amplifier 12 differentiates into a differentiating circuit. 13, the differentiated pulses arrive at the second inputs of the matching circuits 4 and 5 and the precision delay line 11. If the differentiated pulse passes to the output of one of the matching circuits, then it triggers the corresponding trigger, tilting the initial state of the pulse passing through the delay line.

Thus, a sequence of pulses is formed with a duration equal to the delay time and is fed to the output through the appropriate filter, forming one branch of the discriminator characteristic. When the offset F is equal to the difference frequency lAf, the sign is reversed, as a result, the second arm of the circuit begins to work, forming the second branch of the discriminator characteristic (Fig. 2).

The integrated and summed signals from the output of the flip-flops provide a stable, linear, proportional to the detuning F, output voltage of the zero beat discriminator.

The width of the characteristics of the discriminator () is equal to

1, P ,,

3

where 3 is the delay time produced by the precision delay line in seconds.

Subject invention

Zero-beat discriminator consisting of two parallel channels, of which the first channel contains a series-connected mixer, an amplifier-limiter,

phase inverter, coincidence circuit, integrating filter, and the second channel also contains a serially connected mixer, at one of the inputs of which a phase shifter, an amplifier-limiter, a differentiating circuit, a coincidence circuit, an integrating filter are connected, the second input of the coincidence circuit of the first channel and the second input of the coincidence circuit of the second channel is connected to the output of the amplifier-limiter of the first channel, characterized in that, in order to obtain a stable and linear output n april between the coincidence circuit and the integrating filter for each channel

The second-to-one 1V X10y tr; I1Lge | po1v through a precision delay line connected to the output of the differentiating circuit.

+ Af

ig. 2