SU1188848A1 - Phase modulator - Google Patents

Abstract

A PHASE MODULATOR containing series-connected controlled analog input and output phase shifters, characterized in that, in order to reduce non-linear distortion. A quantizer and a subtractor are connected in series, the second input of which is connected to the input of the quantizer and the output to the control input of a controlled input analog phase shifter, an analog-to-digital converter is inserted between the output of the quantizer and the control input of the controlled output phase rotator, In this case, the controlled output phase shifter is implemented as a controlled discrete phase shifter, and the connection point of the second input of the subtractor with the input of the quantizer is the input of I drove. (L 00 00 00 g li 00

Description

The invention relates to radio engineering and can be used to form phase-modulated oscillations in radio engineering devices for various purposes.

The purpose of the invention is to reduce nonlinear distortion.

FIG. Figure 1 shows the structural electrical circuit of the proposed phase modulator; in fig. 2 time diagrams of his work.

; L Phase modulator contains controlled input analog phase shifter 1, controlled output discrete phase shifter 2, subtractor 3, analog-to-digital converter (ADC) 4o

Phase modulator works as follows.

The input of the controlled input analog phase shifter 1 receives a modulated high-frequency voltage O, and the second input of the subtractor 3 receives the modulating low-frequency voltage C. In FIG. 2a shows the form of the modulating voltage. This voltage is applied to the amplitude quantizer 5, the quantization step of which is chosen to be equal to the linear (with a given deviation) solution of the modulation characteristic of the controlled input analog phase shifter 1. The level-quantized modulating voltage (Fig. 26) from the input of the quantizer 5 is applied to the first input of the analog subtractor 3, to the second input of which the modulating voltage is applied. At the output of the subtractor 3, a difference signal or a quantization error signal (Fig. 2c) is generated, which is then fed to the control input of the analog phase shifter 1 and modulates the phase of the carrier oscillation in O- - rad, where N is the integer limits of a - Jf discrete the phase number corresponding to the working solution of the modulation characteristic of the controlled input analog phase shifter 1. The controlled input analog phase shifter 1 is the simplest phase shifting circuit, for example, a single oscillating circuit or RC circuit, and by the output digital phase shifter

a set of phase-shifting chains providing the phase shift of the carrier oscillation in the range O - 2F rad with sampling / sV according to the control signal (Fig. 2d) received from the ADC 4. Since the periodicity of the phase of the carrier oscillation is 277 rad and the solution of the modulation characteristic of the controlled output Since the discrete phase shifter 2 is equal to 2; G rad, then it is possible to reuse the modulation characteristic if the required deviation of the phase of the carrier oscillation is more than 2J rad. FIG. Figure 2 shows the case when under the influence of Up (Fig. 2a) the phase should change to 4F rad, therefore the control voltage applied to the controlled output discrete phase shifter 2 is converted to the form shown in FIG. 2d, where N 4, corresponding to 2/7 Jf

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N - G The phase of the modulated oscillation is changed by a controlled input analog phase shifter 1, respectively, FIG. 2c, and a controlled output discrete phase shifter 2 according to FIG. 2ii, with the total phase change corresponding to FIG. 2a, i.e. completely coincides with the modulating signal. In the proposed device, the controlled output discrete phase shifter 2 changes the phase of the modulated oscillations in exact accordance with some spurious levels of the modulating signal, and the controlled input analog phase shifter 1 serves to continuously change the phase of the carrier wave within these intervals. Since the magnitude of these intervals can be small, it is possible to obtain the required small value of cG, which determines the distortion during modulation. Since the controlled output discrete phase shifter 2 changes the phase of the carrier wave in exact accordance with the control voltage (Fig. 2b), the deviation of the modulation characteristic from the straight line will be determined by the properties of the controlled input analog phase shifter 1, i.e. will remain equal (G.

FIG. 2

Claims (1)

'' PHASE MODULATOR containing serially connected controlled input analog and output phase shifters, characterized in that, in order to reduce non-linear distortions, sequentially connected quantizer and subtracter are introduced into it, the second input of which is connected to the quantizer input, and the output to the control input of the controlled input analog phase shifter, between the quantizer output and the control input of the controlled output phase shifter, an analog-to-digital converter is introduced, while the controlled output The second phase shifter is designed as a controlled discrete phase shifter, and the connection point of the second input of the subtractor with the quantizer input is the input of the modulating signal.