SU1533010A1 - Stereo signal shaper - Google Patents

Abstract

The invention relates to radio engineering. The purpose of the invention is to improve the accuracy of the formation of a stereo signal. The former contains the adders 1 and 2, the sources 3 and 4 of the direct voltage, the filters 5 and 6 of the upper frequencies, the r-7 subcarrier and the modulator 8 of the difference signal. Signals enter the device, the difference of which allows current to flow through the filter 5, the input differential resistance of the modulator 8 and the filter 6. Modulation and correction only a difference signal is applied, and the device produces standard polar-modulated oscillations with a partially suppressed spectrum around subcarrier frequency. The occurrence of the subcarrier frequency at the output of the device is provided by an additional feed of different-sign DC voltages from sources 3 and 4 to adders 1 and 2. Shaper according to claims. 2-4 f-ly are different variants of the modulator 8. 3 Cp. F-ly, 3 Il.

Description

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The invention relates to radio engineering and communication and can be used in stereo broadcasting systems with polar modulation.

The purpose of the invention is to improve the accuracy of the formation of a stereo signal.

Figure 1 shows a structural electrical circuit of a stereo signal generator with a differential modulator implementation according to claim 2; Fig. 2 is a structural electrical circuit of a modulator of a difference signal implemented in accordance with Clause 3 of the claims; Fig. 3 is a structural electrical modulator of a differential signal modulator implemented according to claim 4 of the claims.

The stereo signal shaper contains the first and second adders 1 and 2, the first and second sources 3 and k DC, the first and second high-pass filters, the subcarrier frequency generator 7 and the modulator 8 of the difference signal, which contains resistor 9 and switches 10; according to item 3 of the formula - a chain of 11 series-connected resistors and a capacitor 12; According to claim A, the formulas are a resistor S and a digital-to-analog converter 13.

Shaper stereo signal works as follows.

The inputs of the device are signals of the left and right channels — signals 1 and Ave, respectively. The difference of the input signals leads to the corresponding current through the first filter b, the input differential resistance of the modulator 8, the second filter 6. The voltage drop across the input differential resistance of the modulator 8 is expressed as follows:

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- voltage at the first input of the shaper;

- voltage at the second input of the former;

-resistance of the resistors of the first and second filters b and 6;

- input differential resistance of the modulator 8.

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Only a difference signal is subjected to modulation and correction (it leads to a voltage drop across the input differential resistance of the modulator 8). The sum signal does not undergo any modulation or amplitude-frequency response correction, since it does not cause a voltage drop across the input differential resistance of the modulator 8. At the output of the device, standard polarized modulated oscillations with a partially suppressed spectrum around the subcarrier frequency are obtained.

By additionally supplying different sign voltages from the outputs of the first and second sources 3 and C to the inputs of the first and second adders 1 and 2 of the difference signal, the subcarrier frequency occurs at the device output. The resistance of the resistors of the circuit 11 (Fig. 2), the resistor 9 and the digital codes formed by the generator 7 are chosen in such a way as to ensure a sinusoidal change of the transmission coefficient over time of the modulator 8. The simplest version of the construction of the modulator 8 is shown in figure 1. where the number of its elements is minimized (resistor 9 and switch 10).

The operation of the switch 10, the keys 12 and the digital-to-analog converter 13 is controlled by the codes generated by the generator 7.

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Claims (1)

1. A stereo signal shaper comprising a subcarrier generator, a first adder and first and second high-pass filters, characterized in that, in order to improve the accuracy of stereo signal generation, a second adder, first and second constant voltage sources and a difference modulator are introduced signal, the first and second inputs of which through the corresponding first and second high-pass filters are connected to the outputs of the first and second adders, the inputs of which are connected to the outputs of the first and second and DC voltage sources, and the control input of the modulator of the difference signal is connected to the output of the subcarrier frequency generator, FIG. 2 5