RU8857U1 - DEVICE FOR SUPPRESSING PARASITIC PHASE MODULATION - Google Patents

Abstract

A device for suppressing parasitic phase modulation, comprising a first phase discriminator with a sinusoidal characteristic, a phase shifter on π / 2 and an adder, characterized in that a second phase discriminator with a cosine characteristic and a first signal multiplier, as well as a second signal multiplier, are introduced in series whose input is connected to the output of the first phase discriminator with a sinusoidal characteristic, the second input to the output of the phase shifter at π / 2, and the output to the first input the adder, while the second input of the adder is connected to the output of the first signal multiplier, the second input of which, the input of the phase shifter at π / 2 and the signal inputs of the first and second phase discriminators are combined and connected to the input of the device, the output of the adder is the output of the device.

Description

DEVICE FOR SUPPRESSING A PARASITIC PHASE

MODULATIONS

The utility model relates to radio engineering and can be used to suppress spurious phase modulation in transceiver equipment and measuring instruments.

A device for suppressing stray phase modulation, comprising a series-connected linear adder, an amplitude limiter and a resonant amplifier, while the first input of the linear adder signal with spurious phase modulation (PFM) is supplied directly, and the second through a series-connected adjustable amplifier and phase shifter to w2 (see A.S. USSR No. 653750, H 04 B 1/10, 1979). The input signal from the PFM also goes to the input of the phase discriminator, the input of which is connected to the control input of the adjustable amplifier.

At the output of the adjustable amplifier, a compensation signal is generated with a PFM with amplitude modulation (AM) proportional to the PFM of the input signal. As a result of the linear summation of the input signal from the PFM and the compensation signal shifted in phase by 7 g2 relative to the input signal from the PFM, a signal with partially suppressed PFM and with spurious amplitude modulation (PAM) proportional to the PFM of the input signal is generated at the output of the linear adder. To eliminate PAM, the signal from the output of the linear adder is passed through a limiter and a resonant amplifier.

Thus, in the known device, the PFM of the input signal is converted to the PAM of the output signal of the adder, which is eliminated by the limiter and filter. However, due to the fact that, firstly, the output signal of the linear adder contains residual PFM, and secondly, when the PAM is eliminated by the limiter, partial conversion of PAM to PFM occurs, in the known device, there was a residual PFM in the output signal at any PFM index fp (0 (rp 4).

The closest in technical essence to the proposed one is a device for suppressing parasitic phase modulation (see AS USSR No. 674223, Н 04 В 1/10, Н 03 С 3/06, 1979), in which they are formed from the input signal with PFM using two controlled amplifiers, a phase discriminator and two phase shifters, two quadrature compensation signals with amplitudes that vary in accordance with the PFM of the input signal. As a result of the linear summation of these signals at the output of the adder, a signal is formed that is free of PFM at small indices of the PFM of the input signal (fp "1).

MW-H04B1 / 10 H 03 s 3/06

This process can be represented mathematically as follows (see Fig. 1).

If the voltage at the output of the phase discriminator ФД5 is proportional to the PFM of the input signal, and also, if the increase in the amplitude at the output of the first controlled amplifier UU1 is proportional to the voltage at the output of the phase discriminator ФД5, i.e. proportional to the PFM of the input signal, and also, if the decrease in amplitude at the output of the second controlled amplifier UU2 is proportional to the voltage at the output of the second phase shifter ФВ4, i.e. proportional to the PFM of the input signal, the output voltage of the first phase shifter FVZ is

(1 + FP) cos ((ot + (pn -), (1)

where ω is the frequency of the carrier oscillation of the input signal, (pn is the stray phase shift of the input signal.

The voltage at the output of the second controlled amplifier UU2 is

M2 C / (1 -9n) COS (03t + (|) n). (2)

In this case, the output of the adder SUM6 will

MB i / sCos (cc) t + 95 :), (3)

Mz-l, 41t / vTT; (4)

(1-f) (1 + f „) С08ф„

fu arctg- ----)

(1 + ф „) 8тф„ + (1-ф „) С08ф„

From (4) and (5) it follows that, if, then MS 1.4SH; f arctg (-l) -7c / 4 (see vector diagrams in figure 2). For Φ «1, when it is possible to take in (5)

Zhfp "(rp, sozfp" 1, then f "arcjfg - arctg (-l) - 7t / 4.

V l + 9j

However, even with fp «1, the PAM of the output signal appears, which follows from (4).

With increasing value of (rp, in addition to PAM, the residual PFM of the output signal also appears, which follows from (5), when sin (pn fp, co8 (rp 1.

Thus, in the known device, the complete suppression of PFM is possible only at (pn "1. With increasing (pp, the suppression of PFM is significantly reduced.

Another disadvantage of the known device is that the initial phase of the output signal differs from the initial phase of the input signal by -71/4. Therefore, such a device is not possible to use in synchronous phase systems.

The aim of the proposed technical solution is to completely suppress the PFM of the input signal at any PFM index and to ensure that the output signal is in phase with respect to the input.

with a sinusoidal characteristic, a 7t / 2 phase shifter and an adder, a second phase discriminator with a cosine curve and a nerve signal multiplier, as well as a second signal multiplier, the first input of which is connected to the first phase discriminator with a sinusoidal characteristic, and the second input to the phase rotation output, are introduced on, and the output - to the first input of the adder, while the second input of the adder is connected to the output of the first signal multiplier, the second input of which, the phase rotation input The receiver for t and the signal inputs of the first and second phase discriminators are connected and connected to the input of the device, and the output of the adder is the output of the device.

A distinctive feature of the proposed technical solution is that with the help of the introduced new elements, combined by appropriate links with certain nodes of the circuit, the parasitic phase modulation of the input signal is completely suppressed at any PFM index. In addition, the initial phase of the output signal does not differ from the initial phase of the input signal. Therefore, such a device can also be used in synchronous systems, where the phase shift of the output signal relative to the input is unacceptable.

Decisions with similar features and properties are not known to the applicant. From this we can conclude that the proposed technical solution has significant differences.

On Fig.3 shows a block diagram of the proposed device for suppressing PFM.

A device for suppressing spurious phase modulation comprises a first phase discriminator ФД1 with a sinusoidal characteristic, a phase shifter on a type ФВ2, an adder SUMZ, series-connected second phase discriminator ФД4 with a cosine characteristic and a first signal multiplier PS5, as well as a second signal multiplier PS5, the first input of which is connected to PS6, the output of the first phase discriminator FD1, the second input to the output of the phase shifter FV2, and the output to the first input of the adder SUMZ. In this case, the second input of the SUMZ adder is connected to the output of the first PS5 signal multiplier, the second input of which, the input of the phase shifter ФВ2 and the signal inputs of the first ФД1 and second ФД4 are combined and connected to the input of the device. The output of the adder SUMZ is the output of the device.

A device for suppressing spurious phase modulation works as follows.

The input signal with spurious phase modulation is fed to the input of the first PS5 signal multiplier, to the input of the phase shifter on l FV2 and to the signal inputs of the first PD1 and second PD4 phase discriminators. Mi t7cos (cot + q) n). (6)

(cot + (pn). (7)

At the output of the first phase discriminator PD1 with a sinusoidal characteristic, a signal is generated proportional to the PFM of the input signal

.(eight)

At the same time, the output of the second PD4 is

M4 S08fp. (9)

Then, at the output of the first PS5 M5 signal multiplier, Mi5 MiM4 C / cos (rot + 9n) cos (rp. (10)

At the output of the second PS6 6 6 MsMz f / sin (rot + 9n) sin%. (11)

As a result of the linear summation of the signals from the outputs of PS5 and PS6, the signal tij MS + We Ucos (o) t + q) n) cosfp + t / sin (cot + (pn) smfc Ucoscot is generated at the output of the SUMZ adder (12)

Thus, the PFM is completely absent in the output signal of the device at any PFM index of the input signal. There is no constant phase shift of the output signal relative to the input.

Proof of the feasibility of the proposed device is that the input blocks are typical.

Phase discriminators with sinusoidal and cosine characteristics can be performed either on the basis of phase-frequency discriminators (see, for example, Manaev EI Fundamentals of Radio Electronics. Textbook. Textbook for High Schools.-2- ed., Revised and additional - M .: Radio and communication, 1985. Pages 403-405, Fig. 16.36-16.41), or based on phase discriminators - balanced converters in the presence of a reference signal (see, for example. Radio receivers. Edited by A.P. Zhukovsky. M .: "Higher School, 1989, pp. 142.143, Fig. 7.29, 7.31). The phase shifter on l / 2 is a resonant circuit (for example, a circuit) in which a phase shift of 71/2 of the output signal relative to the input signal is achieved by a certain selection of reactive elements (L, C). Multipliers of signals can be performed on microcircuits 174 PS1, the adder can be made passive on resistors.

Thus, the use of the proposed device allows you to completely suppress spurious phase modulation of the input signal at any modulation index. The phase of the output signal coincides with the phase of the input signal, which allows the proposed device to be used also in synchronous systems.

Claims (1)

A device for suppressing parasitic phase modulation, comprising a first phase discriminator with a sinusoidal characteristic, a phase shifter on π / 2 and an adder, characterized in that a second phase discriminator with a cosine characteristic and a first signal multiplier, as well as a second signal multiplier, are introduced in series whose input is connected to the output of the first phase discriminator with a sinusoidal characteristic, the second input to the output of the phase shifter at π / 2, and the output to the first input the adder, while the second input of the adder is connected to the output of the first signal multiplier, the second input of which, the input of the phase shifter at π / 2 and the signal inputs of the first and second phase discriminators are combined and connected to the input of the device, the output of the adder is the output of the device.