SU406289A1 - DEVICE AUTO ADJUST FREQUENCY - Google Patents

Description

one

This invention relates to radio receiving equipment. The device can be used in radio relay stations with temporary channel compaction and pulse-phase modulation.

A device for frequency control is known that contains a series-connected adjustable local oscillator, a mixer, an intermediate frequency amplifier, a frequency detector, a phase inverter, and an adder, connected to a control input-heterodip.

The purpose of the invention is to increase the noise immunity of the device.

The proposed device is characterized in that between each phase inverter output and. the input of the corresponding rectifier is a sequential connection of the key scheme, the selection scheme, the amplifier and the rectifier.

The invention is illustrated in block diagram form.

The frequency control device contains a series-connected adjustable oscillator 1, a mixer 2, the second input of which is supplied with a reference signal, an intermediate frequency amplifier 3, a frequency control amplifier 4, a frequency detector 5, a phase inverter 6 and an adder 7 connected to the local oscillator control input. Between the first and second outputs of the phase inverter 6 and the corresponding input of the adder 7, serially connected key circuits 8i and 83, selection circuits 9i and Eg, amplifiers lOi and 102, and rectifiers llj and I are entered.

When the difference between the frequency of the signal and the frequency of the local oscillator deviates from the nominal value of the intermediate frequency, an error signal appears in the output of frequency detector 5 — video pulses, whose amplitude is proportional to the detuning value and the polarity depends on its sign.

Since the error voltage from the output of the frequency detector has either a negative or a positive polarity, the phase-inverter 6 is turned on at the input of the signal processing channels, outputting simultaneously the opposite-polarity impulses to both channels. Depending on the frequency detuning sign, only the channel amplifier 10 that receives the negative pulses is operated. From the phase inverter outputs, the error signal enters the key circuit 8 of each drip, which is open to negative polarity pulses. However, if the signal

errors on the output of the frequency detector 5 have a positive polarity, the phase inverter turns it over, and the first channel is working; if the error signal on the output of the frequency detector has a negative polarity, the signal of the negative polarity is also removed from the phase inverter, and the second channel is operating.

Next, the negative polarity pulses are fed to a selection circuit 9i or 92, which extracts the first harmonic from a periodic sequence of pulses. The first harmonic then passes through the amplifier of a sinusoidal voltage 10 or 102 and the rectifier 111 or 112. The rectified voltage of the error signal in the nerve channel is opposite to the polarity of the rectified voltage of the error signal in the second channel.

The resulting voltage on the adder 7 is equal to the voltage difference at the output of each rectifier and depends on the sign of the detuning of the intermediate frequency relative to the nominal value.

The error signal from the adder in the form of a constant voltage is applied to the control

LO element 1 for adjusting efti frequency.

Subject invention

An automatic frequency control device containing a series-connected adjustable local oscillator, a mixer whose second input is supplied with a reference signal, an intermediate frequency amplifier, a frequency detector, a phase inverter, and an adder connected to the local oscillator control input, and there are separate rectifiers between the phase inverter output and the adder input. the fact that, in order to increase the noise immunity, between each output of the phase inverter and the input of the corresponding rectifier are in series connected to Key scheme, selection scheme and amplifier.