SU1026086A2 - Device for measuring non-linear distortions introduced by transmission circuits to the stereophonic signal modulation law - Google Patents

Abstract

DEVICE FOR MEASURING} NONLINEAR DISTORTIONS, VOICE OF TPAK-f THERE ARE TRANSFER TO THE LAW OF MODULATION. STEREOPHONIC for AVT. St. 905880, about T l and h and y "e EC by the fact that, with Eyel, the accuracy of Jeremiah increased, in series, additional Egghel phase-shifters, an attenuator, a stereo driver and an FM tuner were introduced; The TOFwe is connected between the output of the second source modulating the oscillation and the second input of the frequency deviation meter, with the second input of the additional stereo module connected to the third output of the two-channel stereo module.

Description

This invention relates to radio measurements, in particular to measuring nonlinear distortion factors.

A device is known which consists of two sources of modulating oscillation, a two-channel stereo modulator, two frequency modulated oscillators, a mixer, a frequency deviation meter, a stereo decoder, an attenuator phase shifter, an adder and a haomonics analyzer l.

A disadvantage of the known technique is the low resolution of the measurement of non-linear distortions due to the influence of non-linear distortions introduced by the frequency deviation meter and the stereo decoder.

The purpose of the invention is to increase the measurement accuracy.

This goal is achieved by the fact that in a device for measuring nonlinear distortions introduced by transmission paths into the law of modulation of a stereo signal, according to the author. St. No. 905880, serially connected additional phase shifter, attenuator, stereo modulator and FM generator, which are connected between the output of the second modulating oscillator source and the second input of the frequency deviation meter, with the second input of the additional stereo modulator connected to the third output of the two-channel stereo modulator.

The drawing shows a block diagram of the proposed device.

The device contains sources 1 and 2 of modulating oscillation, two-channel stereo module TPP 3, FM oscillators 4 and 5, mixer 6, Tested signal transmission path 7, meter 8 of frequency deviation, stereo decoder 9, phase shifter 10, attenuator 11, adder 12, analyzer 13 the harmonics, the second phase shifter 14, the second attenuator 15, the additional stereo module 16, and the FM generator 17.

Sources of modulating oscillations 1 and 2 are connected to the inputs of a two-channel stereomodulator 3. The outputs of a two-channel stereomodulator are connected to the modulating inputs of FM generators 4 and 5, the outputs of which are connected to the inputs of a mixer 6, the output of which is connected in series with the tested transmission path 7, a meter 8 frequency deviations, by the steardecoder 9 and the first input of the adder 12. A phase shifter 10 and an attenuator 11 are connected in series between the output of the source 2 of the modulating ring and the second input of the adder 12, the output cat This is connected to a 13-harmonic analyzer. Consistently connected phase shifter 14, attenuator 15, add. The main stereo modulator 16 and the FM generator 17 are connected between the output of the modulating oscillator source 1 and the second input of the frequency deviation meter 8, the second input of the additional stereo module is connected to the third output of the two-channel stereo modulator. Measurements with this device are carried out as follows.

Using sources 1 and 2 of the modulating voltage of a two-channel stereomodulator 3, two synchronous and in-phase with respect to the subcarrier frequency, polar-modulated oscillations and, E {ha 5n (52 t + (,) + + 1) are formed at the two outputs of the two-channel stereo modulator. - | -n1, sin (S (t-Cf, for sin fCJotf Po) 5 .;

U (+ 0.8 + m sin Cft., T + (fgl X s in f coo t + (po 15, which are fed to the modular inputs of the FM oscillators 4 and 5. From the outputs. The FM oscillators 4 and 5 h. -modulated oscillations, in the modulation laws of which oscillations and and U2 are incorporated, are fed to the inputs of the mixer 6. The signal at the mixer output has an oscillation in the law of frequency modulation

From and, - and, 2 R {(m, sin (TH t +

+ (f.) - t + Cfi) +

+ 0, sin t + (p) -

- in (5 t + () sin fCOo t

  )five

If the mixer 6 is made more broadband than the tested transmission path, then its own non-linear distortions of the law of modulation of the stereo oscillation can be neglected compared to the distortions of the tested transmission path. Nonlinear distortions of sources 1 and 2 of modulating oscillations, two-channel stereo modulator 3 and FM generators 4 and 5 lead to the appearance of harmonics of the main modulating oscillations in the envelope of the complex stereo signal embedded in the frequency modulation at the mixer output 6.

Thus, in the envelope of the complex stereo signal embedded in the frequency modulation of the oscillation at the input of the tested transmission waste 7, only the components with the main modulating frequencies and their harmonics are contained. When this oscillation progresses through the checked transmission path in the modulation law of a complex stereo signal, apart from components with main modulating frequencies and their harmonics, components with combinational frequencies arise that are caused by nonlinear distortions introduced by the verifiable transmission path into the modulus law stereo signal.

From the output of the tested transmission path 7, the signal goes to the meter 8 of the frequency deviation. At a time, the frequency-modulated signal from the output of the FM oscillator 17 arrives at the heterodyne input of the meter 8 of the frequency deviation.

U4 Е Cmt S in (SI, t (f)

+ m.s in (L t Cf,) sin ("o t

 (fo). formed using source 1

modulating oscillation, phase shifter 14, attenuator 35 ft of additional stereo modulator 16, to the second input of which a subcarrier frequency is applied from the third output of a two-channel stereomodulator. At the output of the meter 8, the frequency deviation of the measuring signal is converted so that the resulting signal has a component in the law of frequency modulation

Us Sh - U4 Ef-nigsin (52 t + + Pr) Co, 2 - mjS in (g t "

+ (()) J sin (“gt, +%).

The exact setting of the required initial phase and the amplitude of the oscillations necessary to compensate for one of the components with the main modulating frequency is carried out using a phase shifter 14 and an attenuator 15.

Thus, at the input of the frequency deviation meter 8, the resulting signal has, in the law of frequency modulation, a complex stereo signal modulated by only one fundamental modulating frequency. Therefore, nonlinear distortions of the modulation law of the stereo signal of the frequency deviation meter 8, stereodecoder 9 and the harmonic analyzer 13 will not lead to the emergence of combinational components due to the absence of the fundamental frequency. Using a source 2 of modulating voltage, a phase shifter 10 and an attenuator 11, the second is compensated.

5, the main modulating frequency in the adder 12, which allows to expand the dynamic range of the measurement of the Raman components by means of: an analyzer of 13 harmonics and to increase the measurement resolution.

Claims (1)

DEVICE FOR MEASUREMENT OF I NON-LINEAR DISTORTIONS OF THE TRACKED UNITS * * BY THESE TRANSFER TO THE MODULATION LAW STEREOPHONIC SIGNAL by ed. St. »905880, the fact is that, in order to increase the measurement accuracy, additional phase shifter, attenuator, stereo modulator and FM generator are connected in series, which are connected between the output of the second modulating source oscillations and the second input of the frequency deviation meter, and the second input of the additional stereo modulator is connected to the third output of the two-channel stereo modulator.