SU720665A1 - Device for restoring carrier frequency - Google Patents

Description

I

The invention relates to radio engineering and can be used in transfer channels of discrete signals, as well as to separate a harmonic signal from a mixture of signal and additive noise.

A device for recovering a carrier frequency is known, comprising a quadrature phase shift keyed signal-to-video converter, a low-pass filter and a controlled oscillator ij.

However, in the known device, it is not possible to obtain a large capture band without degrading the noise immunity in the synchronism mode .;

The purpose of the invention is to increase the capture range.

To do this, in a carrier frequency restoration device containing a quadrature ringed transform of a phase-shift keyed signal into a video frequency, a low-pass filter and a controlled oscillator, between the output of the quadrature converter

phase-shifted signal in the video frequency and the input of the controlled generator are connected in series a differentiating circuit, an amplifier, an amplitude selector of positive pulses, the first driver - a pulse expander, an adder, between another input of which and the amplifier output are connected in series the amplitude selector of negative pulses and a second driver - a pulse extender , and optional low pass filter.

FIG. 1. a structural electrical circuit of the proposed device is given; in fig. 2 - time diagrams that show his work.

A device for restoring a carrier frequency contains a quadrature converter 1 of a phase-shift keyed signal, a low-pass filter (LPF) 2, a controlled oscillator 3, a differentiating circuit 4, an amplifier 5, amplitude selectors 6, 7 positive and negative pulses, two impregnator formers of 8.9 pulses, the adder 10, the low-pass filter 11, in addition, the quadrature converter 1 phase manipulator-. th signal contains multiplier 12, synchronous detector 13, power amplifier - limiting device 14, phase detector 15, phase shifter 16 to P / 2. The device works as follows. Let there be some detuning between the frequencies of the input signal and the controlled oscillator 3. A sinusoidal unmanipulated signal is fed to the input of the device. Since the voltage from the controlled oscillator 3 is supplied to the synchronous detector 13 and the phase detector 15 with a shift by П / 2, then at the outputs of the synchronous and phase detectors, 13 and 15 are sinusoids of the difference frequency (Fig. 2 a and 2 c) will also have a shift between P / 2 between them. Moreover, depending on the sign of the frequency detuning, this shift will be libr + P / 2, or - P / 2, i.e. with respect to the voltage (Fig. 26) at the output of the synchronous detector 13, the voltage at the output of the Phase detector 15 will have the form shown in FIG. 2c (with one frequency detuning sign) and 2c (with another frequency detuning sign). The voltage after multiplier 12 representations / ieHo, respectively, in FIG. , 2g and 2g. With one tae frequency detuning, the output of multiplier 12 shows voltage jumps from maximum negative to maximum positive (Fig. 2d), and on the other hand, vice versa, from maximum positive to maximum positive (2d). The difference in the rate of change of voltage at the output of the multiplier 12 OLE of the sinewave segments of the beat frequency and voltage spikes that occur when the beat voltage crosses the zero at the input of the synchronous detector 13, is proposed in the proposed device for expanding the capture band using 4-11 pulses next thus: differentiating circuit 4 produces pulses, the sign of which {fig. 2 d or c) is determined by the frequency offset sign. If these pulses miss the worm amplitude selector 6 and 7 of the pulses of the corresponding polarity, and hit the expander 8 or 9 pulses of the same polarity, a control signal is formed (see Fig. 2e, e, where solid lines The figure shows the voltage taken from the former of the one-stable relaxer type, and the dotted line shows the voltage taken from the former of the peak detector, which has a large constant component depending on the sign of the frequency detuning. This constant component passes through the additional low-pass filter 11 and adjusts the controlled oscillator 3, i.e., reduces the difference frequency. It is important to note that this adjustment mechanism operates at such large frequency detuning, when the usual capture mechanism of PLL systems, described, for example, in known devices, is not yet effective. Therefore, the introduction of additional nodes and links into the prototype leads to the expansion of the capture band. The operation of the device practically does not change when r a phase-manipulated signal is applied to the input, since the manipulation law is extracted by the synchronous detector 13 and amplifier 14, and then is removed by the multiplier 12 from the voltage supplied from the output of phase detector 15 to low pass filter 2 and differentiating chain 4. After beating, the proposed device works in the same way as the prototype device. The form of the invention A device for restoring a carrier frequency, comprising a ring-connected quadrature converter of a phase-shift keyed signal to a video frequency filter, a low-pass filter and a controlled oscillator, which is different in order to expand the capture band between the output phase-shifted quadrature converter video frequency and input of controlled oscillator including {1s serially connected differentiating circuit, amplifier and amplitude selector of positive pulses, ne vy formirovatel-) asshiritel pulse adder, between the other input and whose output are connected in series with the amplifier () dvnonnye amplitude selector negative pulses and a second pulse shaper-rasschiritel and an additional low pass filter.

Sources of information taken into account in the examination

1. Detection of binary FM signals. PLL system with decisive feedback, VINITI, Express information. Transfer of information, 1969, No. 22, (prototype).

Claims (1)

The claims are the place where the voltage jumps from the maximum negative to the maximum ₄ θ positive (Fig. 2d), and, on the other hand, from the maximum positive to the maximum negative (2g '). The difference in the rate of change of voltage at the output of the multiplier 12 for the segments of the sinusoid of the beat frequency and the voltage jumps that occur when the beat voltage passes through zero at the input of the synchronous detector 13, 4 generates pulses whose sign (Fig. 2 d or y \) is determined by the sign of the frequency rasst- ₅₅ Royko. If these pulses are passed through the amplitude selector 6 and 7 of the Pulses of the corresponding polarity, then they fall onto the shaper expander 8 A device for recovering a carrier frequency comprising a quadrature transducer of a phase-shift keyed signal into a video signal connected to a ring, a low-pass filter and a controllable generator, characterized in that, in order to expand the capture band, between the output of the quadrature transducer of the phase-shift keyed signal into a video frequency signal and the input of a controllable generator connected differentiating circuit, amplifier and amplitude selector of positive impulses, the first driver-expand pulses spruce, an adder, between the other input and the output of which amplifier includes series-connected amplitude selector negative pulses and a second generator-expander impul5 owls, and an additional low pass filter.