SU1140223A1 - Phase modulator - Google Patents

Abstract

A PHASE MODULATOR containing a series-connected source of modulated signals, the first phase shifter, the first amplitude modulator and the first adder,. in series connected is-. the modulating signal point and the second phase shifter, as well as the second amplitude modulator, one input of which is connected to the output of the source of modulated signals and the output connected to the second input of the first adder, is also different in order to reduce the parasitic amplitude modulation of the output signal , between the output of the first adder and the second input of the first amplitude modulator entered in series the amplitude detector, amplifier and second adder, between the amplifier output and the second input of the second amplitude The third modulator has been entered into the third modulator, the second input of which is connected to the output of the source of modulating signals, and the output of the second phase-shifter is connected to the second input of the second adder.

Description

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The invention relates to radio engineering and can be used for generating phase-modulated signals in radio engineering devices for various purposes, in particular in radio transmitters, as well as in electrical measuring equipment.

A phase modulator with amplitude modulation conversion into a phase modulator is known, containing serially connected sources of modulated signals, a phase shifter and an adder, as well as serially connected sources of modulating signals and a balanced modulator, the other input of which is connected to the output of the modulated signal source and the output to the second input adder Cl.

However, the output signal has a relatively high level of spurious amplitude modulation (AMP).

The closest to the proposed is a phase modulator containing a series-connected source of modulated signals, a first phase shifter, a first amplitude modulator and a first summer adder, subsequently connected source of modulating signals and a second phase shifter, and a second amplitude modulator, one input of which is connected with the output of the source of modulated signals, and the output is connected to the second input of the first adder, while the second input of the second amplitude modulator is connected to the output of the source mod iruyuschih signals, and the output of the second phase shifter connected to the second input of the first amplitude modulator On 2 March.

When adding signals from the outputs of the first and second amplitude modulators in the first adder, the amplitude modulation is converted into phase modulation, and the phase modulation is accompanied by a PLA.

With a maximum phase modulation index, the depth coefficient of the SAM

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The purpose of the invention is to reduce the parasitic amplitude modulation of the output signal.

The goal is achieved by the fact that in a phase modulator containing

serially connected modulated signal source, first phase shifter, first amplitude modulator and first adder, serially connected base source and second phase shifter, as well as a second amplitude modulator, one input of which is connected to the output of the modulated signal source and the output connected to the second input of the first adder, between the output of the first adder and the second input of the first amplitude modulator entered in series connected amplitude detector, amplifier and second The adder, the output of the amplifier and the second input of the second amplitude modulator, is the third adder, the second input of which is connected to the output of the source of modulating signals, and the output of the second phase shifter is connected to the second input of the second adder.

The drawing shows a structural electrical circuit of the proposed phase modulator.

The phase modulator contains a source of modulated signals, a source of 2 modulating signals, the first 3 and second 4 phasers, the first 5 and second 6 amplitude modulators, the first, third adders 7–9, the amplitude detector 10 and the amplifier 11.

Phase modulator works as follows.

At the first input of the second amplitude; modulator 6 directly, and the first input of the first amplitude modulator 5 through the first phase shifter 3, giving a phase shift of 31/2, receives a signal from the output of source 1 of modulated signals, to the first, the input of the third adder 9, and to the second input of the second adder B through the second phase shifter 4 to the IC is fed a signal from the output of the source 2 modulating signals, from the second 8 and third 9 adders the signal is fed to the second inputs of the first 5 and second 6 amplitude modulators, respectively.

If the linear modulation characteristics of the first 5 and second 6 amplitude modulators have a slope S, the general normalized amplitude modulation characteristic of the phase modulator 3: К5.К (1; Зe) (5е) Г2-Л1 + (5е) 2. (, Phase modulation characteristic 4 o, rct4: a-Sej / (+ 5e), (2) where e is the modulating voltage from the modulating signal source 2. The change in amplitude is determined by the deviation of the characteristic Kg from the ideal Kjs consist (at). the output of amplifier 11 is a voltage proportional to l and M4K, (4) where N is the gain of the amplifier 11 and the amplitude detector 10. This voltage is applied to the first input of the second adder 8 and, to the second input of the third adder, 9. From (1) taking into account (3) we get () () Ml + ZNuK + NK +. (5) Resh (5) with respect to K and transform, you can get () tl / (N-1j2- (M - i | {Se) V (N4l. (Since N can be made much more than one, (6) 23 3Ku1 / (Nn) tl | l- (From (7) it follows that the change in the amplitude of the output signal decreases N times and can be made arbitrarily small. Phase modulation characteristic of the proposed phase modulator, rct .s (liVH) .Se. -s (ltlfM) 5 (8) with S "1 is reduced to the form (2), i.e. Introduction of the amplitude detector 10, amplifier 11 and second 8 and third 9 adders, creating negative amplitude feedback in the phase modulator, has almost no effect on the phase modulation characteristic. Thus, in the proposed phase modulator, the CAM is significantly (40 dB) reduced PAM without having a noticeable effect on the phase modulation of the output signal, as a result of which the additional distortions caused by the conversion in various devices in which the pre-Locked Phase Module can be eliminated torus, parasitic amplitude modulation in phase.

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Claims (1)

PHASE MODULATOR comprising a series-connected source of modulated signals, a first phase shifter, a first amplitude modulator and a first adder,. sequentially connected is-. a modulator of the modulating signals and \ a second phase shifter, as well as a second amplitude modulator, one input of which is connected to the output of the source of modulated signals, and the output is connected to the second input of the first adder, distinguishing it by the fact that, in order to reduce spurious amplitude modulation an output signal, between the output of the first adder and the second input of the first amplitude modulator, series-connected amplitude detector, amplifier and a second adder are introduced, between the output of the amplifier and the second input of the second amplitude Nogo modulator introduced a third adder, a second input coupled to an output source of modulating signals, and the output of the second phase rotator is coupled to a second input of the second adder. SU .1140223 1 1140223