SU559459A1 - Device for generating a stereo broadcast signal - Google Patents

Description

The device is intended for use in modulators of stereo broadcasting with polar modulation.

A device for generating a stereo hanging signal is known, comprising a subcarrier frequency generator, connected to the first inputs of two key transducers, the outputs of which are connected to the inputs of the adder 11).

However, the known device has the difficulty of stabilizing and the resonant frequency of the Q value of the subcarrier suppression circuit. In order to achieve the necessary stability, it is necessary to produce those: “circuit depletion and apply control and adjustment schemes.

The purpose of the invention is to simplify the device by eliminating the thermosetting step.

For this, a device for forming a stereo broadcast with polar modulation comprising a subcarrier frequency generator, an output connected to the first inputs of two key transducers, the outputs of which are connected to the inputs of the adder, two high-pass filters are inputted to the inputs of which

the input signals, and the outputs are connected to the second inputs of the key converters, and an attenuator is inputted, the input of which is connected to the output of a low-frequency generator, and the output is connected through an adder to the input of the low-pass filter.

FIG. 1 shows the structural electrical circuit of the device; in fig. 2 - signal spectra at various X points of the circuit.

A device for generating a stereo broadcast signal with polar modulation contains two 1.2 high-pass filters, the input of which contains input signals, key transducers 3,4, a subcarrier frequency generator 5, an attenuator 6, whose input is connected to the output of a subcarrier frequency generator 5 and the output is connected through the adder 7 to the input of the low-pass filter 8, while the outputs of the key converters 3.4 are connected to the inputs of the adder 7, in addition, the first inputs of the key converters 3.4 are connected to the outputs of the generator 5, and the second inputs with the corresponding outputs of high-pass filters 1.2.

The proposed device operates as follows.

The low-frequency signals A and B entering the device's input in the left and right stereo channels are attenuated using filters 1.2 in the low-frequency region of the spectrum. As a result, the signals taken from the key converters 3,4 also have attenuated parts of the spectrum in the low-frequency region and in the region that attaches to the subcarrier. The subcarrier arriving at the adder is attenuated with attenuator 6 (five times). From the output of the adder 7, the signals arrive at the input of the filter 8, which compensates for the distortion of the spectrum in the low-frequency region. As a result, the output of the filter 8 produces a standard stereo broadcast signal, used (W 3) further, as usual, for the frequency mode of the transmitter carrier. Fig. 2 shows the conversion of the input signals into a standard stereo broadcast signal where; and the spectra of the input signals A and B; b, the spectra of ω als at the outputs of high-pass filters 1,2 ;; in the spectrum of the signal at the output of the adder; 7;

Thus, the proposed device forms a standard complex stereo signal without using the most complex and unstable element of a thermostatically controlled loop — in devices for generating a stereo broadcast signal with polar modulation.

Claims (1)

1. Kononovich L.M. Stereophonic broadcasting, M., Sv z, 1974, p. 128