SU581562A1 - Method of automatic frequency tuning of reference generator - Google Patents

Description

The invention relates to a radioelectric conductor and can be used to isolate a reference voltage when implementing coherent methods of receiving signals, preferably signals with a phase shift value chain.

A known method for automatically adjusting the frequency of a reference oscillator, mainly for phase-shifting signals, involves converting the input signal to video by quadrature components, removing manipulation, filtering, and feeding a filtered video frequency signal to control the frequency of the reference signal generator 1.

However, with this method, it is impossible to obtain a large acquisition bandwidth of the automatic tuning of the frequency of the reference oscillator, since the bandwidth of the low-pass filter in the auto-tuning ring for the increased capture-bandwidth simultaneously reduces the noise immunity of the auto-tuning ring, and consequently reduces the noise immunity of signal reception .

The purpose of the invention is the expansion of the capture band.

To do this, in order to automatically adjust the frequency of the reference oscillator, mainly for phase-shifted sigiioioB, which consists in converting the input signal into an off-frequency quadrature component with relieving manipulation, filtering, and running a filtered video signal to control the frequency of the reference signal generator before filtering the video signal changes exceeding the threshold.

Due to the introduction of a nonlinear operation of threshold limiting the rate of change of a demanipulated video signal at the input of a low-pass filter in the beat mode (entering into synchronization of an auto-tuning ring when there is an initial frequency detuning between the input and reference signalX

An additional constant stress appears, the magnitude and sign of which is determined by the magnitude and sign of the frequency detuning, respectively. This additional voltage adjusts the reference oscillator,

reducing its frequency detuning with respect to the input signal, i.e. Spreads the self-tuning ring trap.

The possibility of frequency discriminatory research institutes by introducing a limitation on the rate of change of the video signal at the filter input is due to the specific shape of this signal in the beat mode when implementing the known method of auto-tuning. In this signal, the regions of smooth voltage variations and surges and voltages, whose frequency is determined by the beat frequency, and the polarity is a sign of frequency detuning.

FIG. 1 is a block diagram of a device for implementing the proposed method for automatically adjusting the frequency of a reference voltage generator for coherently receiving signals with a single phase difference modulation (O -JT); FIG. 2-time diagrams explaining the operation of the device in the beat mode.

The device comprises a Topor voltage generator, the output of which is connected to the input of Phase detector 2 directly, and to the input of a synchronous detector. 3, connected by the second input to the input of the entire device, through the phase shifter 4 to / 2. & the control of the frequency of the generator I is connected to the output of the threshold limiter 5 of the rate of change of the signal through the low-pass filter 6. The input limiter 5 through phase detector 2 is connected to the output of multiplier 7, one input of which is connected to the input of the device, and the second through the amplifier-limiter 8 is connected to the output of the synchronous detector 3.

The device works as follows. An input signal with a single phase difference manipulation and a non-manipulated harmonic signal is fed to the input of a synchronous detector 3, to the second input of which a reference signal passes. In the beat mode in the auto-loop ring, the video signal envelope at the output of the detector 3 has a sinusoidal shape of the beat frequency. Correspondingly, the binary signal at the output of the limiting amplifier 8 repeats the law of manipulation of the phase of the input signal with a change of sign every half-period of the beat frequency. As a result of multiplying this binary signal with the input of the output of the multiplier 7, the initial phase shift keying is removed and the phase beat frequency (O or TG) appears. The same signal will be at the multiplier output

7 yr to the input of the device of a non-manipulated harmonic signal. The voltage at the output of the phase detector 2 in the beat mode has the form of a sinusoidal beat frequency with phase manipulation at 5G every half-period (see Fig. 2a). With a different sign of the frequency detuning, the voltage at the output of phase detector 2 will have the form shown in FIG. 26. The voltage from the output of the phase detector 2 is fed to the threshold limiter 5 of the rate of change of the signal, the output of which produces a permanent negative (see Fig. 2c) or a positive one (see

FIG. 2d) voltage depending on the sign of the frequency detuning. This constant voltage passes through the low-pass filter 6 to adjust the oscillator 1 and reduces its voltage tuning relative to the input signal. When the frequency detuning is reduced to a value close to the capture band, the mevanism of capturing the usual PLL starts - the half-wave and the beat-up voltage corresponding to a decrease in the capture band are stretched, and the half-wave of the other sign is compressed. After the device enters the synchronism of the beats, there is no device, and the device that implements the proposed method works in the same way as the device, which implements the well-known method.

Thus, the proposed method allows to expand the capture band of the self-tuning ring.

Claims (1)

Invention Formula A method of automatically adjusting the frequency of the reference oscillator, mainly for phase-shifted signals, which consists in converting the input signal into video frequency by quadrature components with relieving manipulation, filtering, and applying a filtered video signal for controlling the frequency of the reference signal generator, characterized in that capture, before filtering the video signal, reduce its rate of change, exceeding the threshold. Sources of information taken into account in the examination: I. USSR author's certificate Poison 180644, M. Kl. H 04 L 27/22, 18.05.64. to: / t / I / I M I / xl / V / IVX I v iv /  .. - I. L. x1