SU1451869A1 - Stereophonic broadcasting system - Google Patents

Abstract

The invention relates to the field of radio communications. Pel invention - reducing transient distortion. The transmitter of the stereo broadcasting system contains the sensor 1 of the left channel signals, the sensor 2 of the signals of the right channel, the amplitude moduli of the torus 3 and 4, r-p 5 intermediate frequency, the phase shifter 6, the adder 7. Differential converters 8 and 9 are entered into the transmitter. The signals received at the outputs of the synchronous detectors of the receiver system are the original stereo signals and do not require further sum-difference conversion. Thus, a stereo broadcasting system allows the use of a simpler receiver without a sum-difference transducer, consisting of inverting gates, requiring a very accurate selection of coefficients. transform. 2 Il. (O (L SP 00 O) o

Description

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The invention relates to radio and can be used to build stereo broadcasting systems operating in the amplitude modulation mode at medium wavelengths, as well as to carry out stereo broadcasting in multiprogrammed wire broadcasting networks.

The aim of the invention is to reduce transitional distortion.

Fig. 1 shows a block diagram of a transmitter of a stereo broadcasting system; Fig. 2 is a block diagram of a receiver of a stereo broadcasting system.

The transmitter of the stereo broadcasting system contains sensor 1 of the signals of the left channel, sensor 2 of the signals of the right channel, the first 3 and second. Swarm A amplitude modulators, intermediate frequency generator 5, phase shifter 6, adder 7, first 8 and second 9 difference converters.

The receiver of the stereo broadcasting system comprises an intermediate frequency amplifier 10, the first 11 and second 12 synchronous detectors, phase detectors, a phase detector 13, a voltage controlled oscillator 14, a phase shifter 15.

The stereo broadcasting system operates as follows.

The signals from sensors 1 and 2 are fed to the inputs of the first 8 and second 9 differential converters. The signals combined with the σ-prescribed coefficients, taken from the outputs of the differential converters 8 and 9, go to the modulating inputs of the first and second amplitude modulators 3 and 4, respectively. From the intermediate frequency generator 5, the modulated signal is fed to the amplitude modulator 4 and through a phase shifter 6 to the amplitude modulator 3. The signals from the outputs of the amplitude modulators 3 and 4 are fed to the adder 7.

In the receiver, the stereo signal removed from the output of amplifier 10 of the intermediate frequency is fed to synchronous detectors 11 and 12 and to the input of the phase detector 13, the second input of which receives the intermediate frequency signal from the output of the voltage controlled oscillator 14. The voltage removed from the output of the phase detector 13 sets with accuracy d

ABOUT

Q

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phase generator frequency 14, equal to the frequency of the intermediate frequency signal fed to the first inputs of synchronous detectors 11 and 12. The second input frequency of the synchronous detector 12 receives the recovered intermediate frequency from the generator 14 directly. At the first input of the 7-detector detector 11, the reconstructed intermediate frequency from the generator 14 is fed through the phase shifter 15. From the left channel signal sensor 1, signal A and from the right channel sensor 2, signal B is fed to the first differential converter 8, from the output of which signal A is removed. In cos W, where I / is the phase angle between the high frequencies of the modulated oscillation fed to amplitude modulators 3 and 4. The angle M for reducing nonlinear ICs | Causes for monophonic reception is chosen to be 30 ... 60.

Similarly, from the sensors 1 and 2, the signals of the left and right channels come to the second differential converter 9, from the output of which the signal B A cos Z is taken

- These signals are modulated for amplitude modulators 3 and 4 from the outputs of which the signals are removed, respectively.

U (t) (1 + A - B cos Lf) cos (u) t + L;); ) (1 + B - A cos c) cos u) t,

where A shd sozd t; In L t. From the output of the adder 7, the signal is removed

and (t) (1 + A - B cos 1) cos (u) t + tf) + (1 + B - A cos c) cos u) t.

At the receiver in synchronous detectors 11 and 12, the received signal is multiplied by the harmonic oscillation.

At the output of the first synchronous detector 1 1, containing a multiplier and a low-pass filter, a signal of 2 A (1, - cos Y) is obtained, and after separating the constant component it is equal to

and 11 A (1 - cos h).

At the output of the second synchronous detector 12 containing a multiplier and a low pass filter, a signal is obtained

2 -t- B (1 - cos if),

a after separation of the constant component it is equal to

and l In (1 - cos Lf).

The received signals are source stereo signals and do not require further sum-difference conversion.

Thus, a stereo broadcasting system allows the use of a simpler receiver without a sum-difference converter consisting of inverting amplifiers and requiring a very accurate selection of conversion factors, which greatly increases the cost of mass production of receivers.

Claims (1)

Invention Formula A stereo broadcasting system contains a left channel signal sensor, a right channel signal sensor, and an intermediate frequency generator connected in series, a phase shifter, a first amplitude modulator, and an adder, whose output is the transmitter output, and the second adder input connected to the second amplitude modulator five 0 five 0 a torus, the first input of which is connected to the input of the phase shifter, in the receiver - serially connected intermediate frequency amplifier, phase detector, voltage controlled oscillator, phase shifter and first synchronous detector, the second input of which is connected to the first input of the second synchronous detector and the output of the intermediate frequency amplifier The input of which is the input of the receiver, and the input of the phase shifter is connected to the second input of the second synchronous detector, characterized in that, in order to reduce transient distortion, The first differential and second differential converters are input to the transmitting side, the first inputs of which are connected to the sensor outputs of the rpm channel signals, the second inputs are connected to the sensor output of the right channel signals, and the outputs are connected respectively to the second inputs of the first and second amplitude modulators, the first and The second receiver outputs are respectively the output of the first synchronous detector and the output of the second synchronous detector, the second input of which is connected to the second input of the phase detector. (fju8.2