RU6653U1 - DEVICE FOR SUPPRESSING PARASITIC PHASE MODULATION - Google Patents

Abstract

A device for suppressing parasitic phase modulation, comprising a series-connected first controlled amplifier, a first phase shifter at π / 2 and a first adder, as well as a first phase discriminator with a sinusoidal characteristic, a second phase shifter at π and a second controlled amplifier, characterized in that, for the purpose of complete suppression of spurious phase modulation with the index Φ≅ π / 4, the second phase discriminator with the cosine characteristic, the second and third adders, the output of the first phase di the discriminator is connected to the first input of the second adder and through the second phase shifter with the first input of the third adder, the output of the second phase discriminator is connected to the second inputs of the second and third adders, the outputs of which are connected respectively to the control inputs of the first and second controlled amplifiers, the signal inputs of the first and second phase discriminators combined, and the output of the second controlled amplifier is connected to the second input of the first adder, the output of which is the output of the device.

Description

Iolese model refers to radio engineering and can be used to suppress spurious phase modulation in transceiver equipment and measuring instruments.

A device for suppressing spurious phase modulation is known. containing a linear adder connected in series., an amplitude limiter and a resonant amplifier, for example, a signal with parasitic phase modulation (PFM) arrives at the first input of the lipid from the mmagor directly., and to the second through a series-connected adjustable amplifier and phase shifter to 7G / 2 ( see USSR AS No. 653750, N 04 B 1 10.1979). The input signal from the IFM also goes to the input of the phase discriminator, the output of which is connected to the control input of the adjustable amplifier.

And at the output of the adjustable amplifier, a compensation signal is formed with the IFM and with amplitude modulation (AM) proportional to the IFM of the input signal. As a result of the linear summation of the input signal with the IFM and the compensation signal phase-shifted by tg 2 relative to the input signal with the IFM, a signal with partially suppressed IFM and with spurious amplitude modulation (IAM) proportional to the IFM of the input signal is generated at the output of the linear adder. To eliminate the IAM, the signal from the output of the linear adder is passed through a limiter and a resonant amplifier.

Thus, in the known device, the IFM of the input signal is converted to the IAM of the output signal of the adder, which is eliminated by the limiter and filter. However, due to the fact that, firstly, there is a residual IFM in the output signal of the linear adder. secondly, when the IAM is eliminated by the limiter, a partial conversion of the IAM into the IFM occurs, in the known device in the output signal there is a residual IFM at any IFM index fp (0 fp 71/4).

The closest in technical essence to the proposed one is a device for suppressing parasitic phase modulation (see USSR AS No. 674223, I 04 V 1/10, I 03 C 3/06, 1979), in which they are formed from the input signal with the IFM using two controlled amplifiers, a phase discriminator, and two phase shifters, two quadrature compensation signals with amplitudes changing in accordance with the IFM 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 IFM at small indices of the PFM of the input signal (fp "1).

Mathematically, this process can be represented 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 voltage at the output of the first phase shifter FVZ is equal to t t7 (l + фJcos (ro / + ф „- 71/2), (1)

where ω is the carrier frequency of the input signal. FP-PFM input signal.

The pairing at the output of the second controlled amplifier UU2 is equal to m, (co / -NF „), (2)

In this case, at the output of the SUM6 adder, we get co8 (co / + f.), (3)

gae

and Vf / Chl + φJ + f / (l-фJ + 2 (l + фJ (l-фJcos (-я / 2У

 / С7Ч1 + Ф „) + / Ч1-ф„) l / 2С / + 2ф:

f-afr / g Щ1 + ф „) с08 (ф„ -Я / 2) + / (1-ф „) с08ф„

 grc / g + P) (I + ф „) 8тф„ + (1 - ф С08ф „

From (4) and (5) it follows that if Φη 0, then MS 1.41 Φ arctan (-) -7C / 4 (see the vector diagrams in FIG. 2).

For φη <1, when it is possible in (5) to take 81pfp (Pn - ω8φn and L then

Fj. arctgl - -i arctg (-1) - 7s / 4. V 1 + Ф „У

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

With an increase in the fp value, in addition to the PAM, the residual PFM of the output signal also appears, which follows from (5), when 81pfp Fp, so8pf 1.

Thus, in the known device, the complete suppression of PFM is possible only with fp "1. With increasing fp, the suppression of PFM is significantly reduced.

The aim of the proposed technical solution is to completely suppress the PFM of the input signal with modulation index fp 7i / 4.

This goal is achieved in that in a device for suppressing spurious phase modulation, containing a series-connected first controlled amplifier, a first phase shifter on p / 2. the first adder, as well as the first phase discriminator with a synoidal characteristic, the second phase shifter at 7t and the second controlled amplifier, the second phase discriminator with a cosine characteristic, the second and third adders are introduced. The output of the first phase discriminator is connected to the first input of the second adder and through the second phase shifter to the first input of the third adder, the output of the second phase discriminator is connected to the second inputs of the second and third adders, the outputs of which are connected respectively to the control inputs of the first and second controlled amplifiers. The signal inputs of the first and second phase discriminator, the first and second controlled amplifier are combined, and the output of the second controlled amplifier is connected to the second input of the first adder, the output of which is the output of the device.

Characteristic here is that, with the help of the introduced new elements, combined by the corresponding links with the remaining nodes of the circuit, the parasitic phase modulation of the input signal is completely suppressed at the PFM index srp 7t / 4.

Applicants are not aware of solutions with similar features and properties. Therefore, we can conclude that the proposed technical solution has significant differences.

Pa fig.Z shows a block diagram of the proposed structure to suppress PFM.

A device for suppressing spurious phase modulation contains serially connected first controlled amplifier U1. the first phase shifter on It / 2 FV2, the first adder SUMZ, as well as the first phase discriminator FD4 with a sinusoidal characteristic, the second phase shifter on the TS FV5, the second controlled amplifier UU6, the second phase discriminator FD7 with a cosine characteristic, the second and third adders SUM8 and SU9. In this case, the output of the first PD4 is connected to the first input of the second SUM8 and through the second PV5 with the first input of the third SUM9, the output of the second PD7 is connected to the second input of the second SUM8 and third SUM9, the outputs of which are connected to the control inputs of the first U1 and second UU6. The signal inputs of the first PD4 and second PDT, the first UU1 and the second UU6 are combined, and the output of the second UU6 is connected to the second input of the first SUMZ. The output of the device is the output of the first adder SUMZ.

A device for suppressing spurious phase modulation works as follows.

The input signal with spurious phase modulation is fed to the signal inputs of the first and second controlled amplifiers UU1 and UU6 and to the signal inputs of the first and second phase discriminators FD4 and FD7. Pa output FD4

voltage is formed, non-proportional 81pfp. those. fd4 b81pfp. and at the output of ФД7 - voltage proportional to sozfp. those. / fd - Lcos9n.

Then, at the output of the second phase shifter on I ФВ5, the voltage МФВ5 - is obtained; 81pfp, and on the output of the second adder SUM8 or on the right: the first input of the first controlled amplifier UU1 the signal is summed

  Tss08fp + 81pfp).

At the output of the third adder SUM9 or at the control input of the second controlled amplifier UU6

  (S05fp - 81pfp).

At the output of the first controlled amplifier UU

  6T (s08fp - 51pfp) sO8 (s / + fp).

At the output of the first phase shifter on tg 2 FV2

MPF2 T (s08fp - 81pfp) s08 (sO / + fp 71: 2).

At the output of the second controlled amplifier UU6

Muub 6 (soO8fp - 81pfp) СО8 (soO / + fp).

As a result of the linear summation of the signals from the outputs of the first phase shifter to 7С / 2 ФВ2 and the second controlled force УУ6, the signal + Iiub 6T is generated at the output of the first adder SUMZ (or at the output of the device); (s8fp + 81pfp) co8 (co / - fp - t : 2) + and (com <8111 fp) co8 (co / + fp) 1.41 L cosCco / - 4).

Thus, the full PFM in the output signal of the device, which has a constant amplitude, with the PFM of the input signal with the modulation index fp i / 4.

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, EI Manaev, Fundamentals of Radioelectronics. Textbook for universities. - 2nd ed., Revised and additional - M. : Radio and communications. 1985. p. 403-405, fig. 16.3646.41), or on the basis of phase discriminators - balanced converters when the reference signal is sticky (see, for example, radio receivers. Node edited by A.N. Zhukovsky. M.: "Higher School. 1989. p. 142. 143. Fig. 7.29. 7.31).

The adder can be made passive on the resistors. The controlled amplifier is a high-frequency xsilylle with a gain coefficient close to unity, and this selepius coefficient can be changed from external bias voltage. Phase shifter on π 2 is a resonant circuit (nanomeasurement, circuit), into which an unambiguous selection of reactive elements (L, C) achieves a phase shift by π 2 of the output signal relative to the input.

Thus, the use of the proposed device allows you to completely suppress spurious phase modulation of the input signal with the modulus index and FP 71, 4.

Claims (1)

A device for suppressing parasitic phase modulation, comprising a series-connected first controlled amplifier, a first phase shifter at π / 2 and a first adder, as well as a first phase discriminator with a sinusoidal characteristic, a second phase shifter at π and a second controlled amplifier, characterized in that, for the purpose of complete suppressing parasitic phase modulation with index Φ _n ≅ π / 4, it entered the second phase discriminator with cosine characteristic, second and third adders, and the output of the first phase the discriminator is connected to the first input of the second adder and through the second phase shifter with the first input of the third adder, the output of the second phase discriminator is connected to the second inputs of the second and third adders, the outputs of which are connected respectively to the control inputs of the first and second controlled amplifiers, signal inputs of the first and second phase discriminators combined, and the output of the second controlled amplifier is connected to the second input of the first adder, the output of which is the output of the device.