SU1195460A1 - Device for reception of stereophonic signals - Google Patents

Abstract

The invention relates to the field of radio engineering. The purpose of the invention is improving the reception quality of stereo signals. The device contains an audio frequency path 1, a supersonic frequency path consisting of a subcarrier frequency restorer 3, a bandpass filter 4 and an AM detector 5j as well as a decoder matrix 6, an amplitude-frequency equalizer 7 and a control unit 8 consisting of a noise analyzer 9, of the distortion detector 10 and the programmable matrix 11. In order to improve the reception quality, an amplitude-frequency equalizer 7 is inputted, the input of which is connected to the output of the AM detector 5, the frequency response of the amplitude-frequency equalizer 7 is linear in the entire audio frequency range, which is echivaet maximum crosstalk attenuation between the stereo channels. A control unit 8 has also been introduced, in which the noise analyzer 9 evaluates Pd, based on an analysis of the energy characteristics of the noise and the desired signal in the baseband for long time intervals. The distortion detector 10 estimates the distortion of the crosstalk between the stereo pair channels. A rectified voltage proportional to the magnitude of the distortion caused by the adjustment is used as the 2nd control signal. The programmable matrix 11 reproduces the functional dependence “x + y, and the coefficient L and m. are set either hard or vary in time according to some program from the outside. In the simplest case, programmable matrix 11 is an adder. 1 il.

Description

This invention relates to radio radio broadcasting with a polar mod.

The aim of the invention is to improve the quality of reception of stereo signals.

The drawing shows a structural electrical circuit of the device for receiving stereo signals.

The reception device is stereo. The signals contain the audio frequency path 1 and the supersonic frequency path 2, consisting of the subcarrier frequency reducer 3, the band-pass filter 4 and the AM detector 5, as well as. coding matrix 6, amplitude -. frequency equalizer 7 and control unit 8 consisting of a noise analyzer, a distortion detector 10 and a programmable matrix 11,

The device works as follows.

The noise analyzer 9 carries out an estimate of PRJ ,, J (based on an analysis of the energy characteristics of the noise and the useful signal in the base band for sufficiently long time intervals.

The distortion detector 10 estimates the distortion - crosstalk between the stereo pair channels by isolating the difference between the input and output signals of the amplitude-frequency equalizer. The rectified voltage, proportional to the magnitude of the distortion caused by the adjustment, is used as the 2nd control signal.

Programmable matrix 11 reproduces the functional dependence of the form Z - ofx. In this case, the coefficients iX and p can be set either rigidly or vary in time in accordance with some program from the outside by the operator or automatically. In the latter case, the proposed device together with the control processor forms an adaptive adjustment system of the stereo receiver. In the simplest case, the programmable matrix 11 is an adder.

Upper-tonal — part of the complex stereo signal (SSS) spectrum is subjected to a series of transforms in the 2 supersonic frequency path (reconstruction of the subcarrier frequency, detection of the envelope of the sup-tone component of the polar-modulated oscillation), which resulted in a difference stereo pair at the input of the amplitude-frequency equalizer 7 id-Ur, where U /, U, are, respectively, of the left and right channels,

Accordingly, a total signal U -t-Un is generated at the output of the audio frequency path 1 by filtering the KCC tone component. As a result, both signals, subjected to sum-difference conversion in the decoding matrix 6, form the signals of the left (UK) and right () channels at the outputs of the device. The nonlinearity of the RF path of the RF path, as well as the difference in the complex transmission coefficients of the audio 1 and supersonic 2 frequency paths, determine the presence of its own channel U. also the voltage (interference) of the opposite channel UQQ).

The degree of channel separation is one of the partial indicators of the quality of stereo reception, which is characterized by transient attenuation

 L 20 lg.l-dB pom

(for the perfect tract),

In the initial state of the device, characterized by a high signal-to-noise ratio at the output Pout, the ratio between the output voltages of the analyzer 9 of the V and U and the detector 10 of the distortions Ua is such that the amplitude-frequency characteristic of the amplitude-frequency corrector 7 is linear in the entire sound frequency range, which provides maximum crosstalk between stereo channels at all frequencies of the range, including it. top section (over 10 kHz),

By decreasing P,

below threshold

Claims (1)

The value of PLp, the output voltage of the noise analyzer 9, controls the amplitude-frequency equalizer 7, changes its gain at high frequencies so that its noise bandwidth is reduced. At the same time, the reduction of the band to 4–5 kHz has very little effect on the stereo effect, since human localization of sound sources with a frequency of 5 kHz is practically absent. With a significant decrease in P, either due to an increase in noise or due to a decrease in the radio transmission of the useful message (Up), the change in the amplitude-frequency characteristic of the amplitude-frequency corrector 7 as a result of tracking 1 can also occur at frequencies below 5 kHz (in the stereo range), To avoid overshooting, the device contains a distortion detector 10, the output of which, combined with the signal of the noise analyzer 9, has a stabilizing effect according to the distortion + noise integral criterion, i.e. When the difference between the input and output voltages of the amplitude-frequency equalizer 7, which exceeds a certain critical value, the amplitude-frequency characteristic of the amplitude-frequency equalizer 7 is equalized. Claims: A stereo signal receiving device comprising an audio frequency path, a supersonic frequency path comprising a series-connected subcarrier restorer, a band-pass filter and an AM detector, as well as a decoding matrix, the inputs of the audio frequency path and the subcarrier frequency restorer of the supersonic frequency path combined, The output of the audio frequency path is connected to the first input of a decoding matrix, characterized in that, in order to improve the reception quality of stereo signals, An amplitude-frequency equalizer and a control unit consisting of a sound analyzer, a distortion detector and a programmable matrix are configured, the output of the AM detector of the supersonic frequency path is connected to the first input of the distortion detector of the control unit and the input of the amplitude-frequency equalizer whose output is connected to the second input distortion detector of the control unit and the second input of the decoding matrix, the first and second outputs of the decoding matrix are connected respectively to the first and second inputs of the noise analyzer of the control unit The control inputs of which are connected to the input of the audio frequency path, while the output of the distortion detector of the control unit and the output of the noise analyzer of the control unit are connected respectively to the first and second inputs of the programmable matrix of the control unit whose output is connected to the control input of the amplitude-frequency equalizer.