SU1317693A1 - Method for checking parameters of television channel - Google Patents

Abstract

The invention relates to the field of television technology and provides increased control accuracy. On the transmission side of the monitored television path (TT), a test signal consisting of a reference sine-square pulse with a spectrum smaller than the TT bandwidth and a test rectangular pulse (IPI) with a spectrum exceeding the bandwidth of the TT are inserted into the transmitted video signal. The amplitudes of both pulses are equal. The main distortions are subjected to IPD, which is identified at the receiving side. The presence of nonlinearity of the frequency response will cause a change in the amplitude of the IPD, and. phase distortion will lead to its asymmetry. The nonlinearity is defined as the ratio of the amplitudes of the IPD and the reference pulse. The FPI amplitude is counted at a time half the length of the FPI front. The nonlinearity of the phase-frequency characteristic is defined as the ratio of the sums of the modules of the IPI areas located up to a point in time separated from the front by the IPI by half its duration and after this point. 3 il. with S (L OE -J G5 CO oo

Description

The invention relates to television technology and can be used to control the quality of television channels.

The purpose of the invention is to show the accuracy of the control.

FIG. 1 shows a block diagram of an electrical device for implementing a method for monitoring parameters of a television path; in fig. 2 is a plot of a test signal containing a reference sine-square pulse and a test rectangular pulse, before passing through a controlled, television path of FIG. 3 - the same, after passing through the controlled television and zion path.

The method of monitoring the parameters of the television path is carried out in the following way.

On the transmitting side of the monitored television path, a test signal consisting of a reference sine-square pulse with a spectrum smaller than the television bandwidth of the television path and a test rectangular pulse with a spectrum exceeding the bandwidth of the television path are introduced into the transmitted video signal. The amplitudes of both pulses are equal.

After passing through the controlled television path, the test signal was distorted in accordance with the non-linearity of the amplitude-frequency and 4) a-frequency characteristics of the television path. Since the reference sine-quadratic pulse has an aspect less than the bandwidth of the television path, its distortion will be negligible. In general, the test square-wave pulse, whose spectrum is wider than the transmission band of the television path, will be distorted.

At the receiving side of the monitored television path, a test signal is made from the received video signal. The presence of nonlinearity of the amplitude-frequency characteristics of the television path will cause a change in the amplitude of the test rectangular pulse, and the phase-frequency distortions will lead to its asymmetry. Therefore, the non-linearity of the amplitude-frequency characteristic of the television channel is estimated, computed. an attitude

amplitudes of the test rectangular impulse AUJJ to the amplitude of the reference sine-square impulse A; At the same time, the amplitude of the test rectangular impulse is measured at half a time from the front of this impulse. . Phase frequency distortions are estimated.

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calculating the ratio of the sums of the modules of the areas of the parts of the test rectangular impulse located up to a point in time separated from the front of the test rectangular impulse by half its duration S (and after this moment 5 "(see Fig. 2 and 3).

Thus, when monitoring the television path, the non-linearity of the amplitude-frequency and phase-frequency characteristics is estimated by numbers ranging from zero to one, and the higher the numbers, the better the corresponding characteristics of the TV / Vision path.

A device for implementing a method for monitoring parameters of a television path works as follows.

The master oscillator 1 generates pulses that trigger the generator 2 reference sine-square impulses and the generator 3 right angle, j test-impulses. From the generators 2 and 3 pulses arrive at the mixer. 4. From the output of the mixer 4, the received test signal, the states from the reference sine square pulse and the test direct coal pulse, is fed to the output amplifier 5 and further to the control television line 6. From the television output tract 6 the test signal arrives at

input amplifier 7 and further to the distribution unit 8,

From the first output of the distribution unit 8 test signal

Q enters the low-pass filter 9 where the high-frequency components of the test impulse are suppressed, which leads to an increase in its amplitude compared to the amplitude of the supports / J of the sine-quadratic impulse and facilitates the subsequent limitation of this impulse, which occurs in the next block 10 of the limitation from below After passing the limiter

31317693

10 a bounded reference pulse is applied to the block.

11 differentiation. At the output of block 11, we receive a signal, whose moment of passage of its amplitude through a zero value corresponds to the moment of reaching the maximum amplitude of the reference pulse. From the output of block 11, the signal enters the null body 12,

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t T. From the outputs of the BS 16 and 17, the signals arrive at dividing unit 20, where it is calculated

A / L ratio

From the third output of the distribution unit 8, the test signal is fed to the inputs of the keys 21 and 22. The key 21 is opened by timer 13 at the time t t,. At the same time, a generating rectangular impulse, tO, the test impulse arrives at the front of which coincides with the tegrator 23, where it is integrated by the time of passing through to t - T, when the key 21 closes the zero value of the input signal. null organ 12. Square impulse

when applying a signal from timer 13. At the output of the integrator 23 receive

from the output of the null organ 12 is applied to 5 signals: proportional to the area S.

Further, this signal arrives at the BR 24, which is transferred by the timer 13 to the recording mode at the moment of time and to the playback mode at t T. In the BR 24, a signal is proportional to the area 8d. Key 22 is opened by timer 13 at time t T and is locked at t t ,. . The signal from the output of the key 22 is the integrator 13, which produces a sequence of pulses whose leading edges are located at the following time intervals relative to the leading edge of the input pulse. 20 pulses, the first at the interval t, the second at the interval T, the third at the interval t.

From the second output of the distribution-25 routs in the integrator 25, the output

which receive a signal proportional to the area of 8 ". Further, this signal arrives at the BR 26, where it is remembered. The KB 26 is switched to the recording mode 30 at t T and to the playback mode at t t. From the outputs of the BRs 24 and 26, the signals arrive at block 27 for the generation, in which the ratios of

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unit 8 test signal. enters unit 14 sampling amplitude. In block 14, upon receipt of pulses from the strobe generator 15, controlled by timer 13, the amplitude of the test signal is sampled at a time t и and t T. Thus, at the output of sampling unit 14, the amplitude of the reference pulse AQU is obtained at a time t and the amplitude of the Auz test impulse at the time instant t T. The sampling amplitudes of the test signal from unit 14 are transmitted to test stations 16 and 17 (BR). The KB 16 is switched to the recording mode at t 0, and information about the amplitude of the reference pulse is recorded in it. After the end of the recording mode, the KB 16 is transferred to the playback mode by applying a pulse from the one-shot 18, which generates this pulse at a time interval relative to t 0, which is necessary for recording information. The overall operating mode of the vision path is that

Thus, at the output of block 20, the value of the coefficient Kd is obtained, and the value of the coefficient K is obtained at the output of the block 27 of division. Based on the values, these 4Q coefficients control the quality of the frequency response and phase response of the television path. These coefficients can vary from zero to one, and the closer to unit their value, the higher the quality of the corresponding characteristic.

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Claims (1)

The method of monitoring the parameters of the telepowers allows the RZ 16 to be in recording mode for the minimum necessary time interval, which reduces the noise level, the RV 17 is switched to the recording mode at t T, and the one-shot 19 switches the RZ 17 to the playback mode. In the BR 17, information is recorded on the amplitude of the test AC pulse on its axis of symmetry at that, when transmitting a test signal as a reference sine-quadratic pulse and a test imprint of a mogon impulse of the same amplitude, are transmitted to the television signal, and at reception a test signal is determined from the television signal, which determines the amplitude-frequency irregularity four t T. From the outputs of the BS 16 and 17, the signals arrive at dividing unit 20, where it is calculated A / L ratio From the third output of the distribution unit 8, the test signal is fed to the inputs of the keys 21 and 22. The key 21 is opened by timer 13 at the time t t,. At the same time, the test impulse arrives at the tegrator 23, where it integrates up to t - T, when the key 21 closes when applying a signal from timer 13. At the output of the integrator 23 receive Sign: proportional to the area S. Further, this signal arrives at the BR 24, which is transferred by the timer 13 to the recording mode at the moment of time and to the playback mode at t T. In the BR 24, a signal is proportional to the area 8d. Key 22 is opened by timer 13 at time t T and is locked at t t ,. . The signal from the output of the key 22 integrator receives a signal proportional to the area of 8 ". This signal is then fed to the BR 26, where it is memorized. The BR 26 is switched to the recording mode 30 at t T and to the playback mode at t t. From the outputs of the BRs 24 and 26, the signals arrive at dividing block 27, in which the ratio of the reference path is calculated, consisting of tion, if S „l if s. S A5 OR ZP / FOR Vision path, consisting in Thus, at the output of dividing unit 20, the value of coefficient Kd is obtained, and at the output of dividing unit 27, the value of coefficient K is obtained. The values of these coefficients control the quality of the frequency response and phase response of the television path. These coefficients can vary from zero to one, and the closer to unit value, the higher the quality of the corresponding characteristic. Vision path, consisting in The method of controlling parameters by the tele- phone, which, when transmitted to a television signal, introduces a test signal in the form of a reference sine-quadratic pulse and a test rectangular pulse of the same amplitude, and when received, the test signal, from which the signal is determined, is extracted from the television signal. amplitude-frequency irregularity 513 characteristics of the television path, characterized in that, in order to increase the control accuracy, when transmitting, the spectrum of the reference sine-square pulse is chosen to be less than the bandwidth of the television path, and the spectrum of the test rectangular impulse is greater than the bandwidth of the television path when receiving uneven amplitude-frequency response s as a ratio of the amplitudes of the test rectangular impulse and the reference sine quad7693 of the ramp pulse, where the amplitude of the test rectangular pulse is produced at a time away from the front of the test rectangular pulse by half of its duration, the non-linearity of the phase-frequency characteristic of the tagging path is determined as the ratio of the area modules of the parts of the test rectangular pulse located up to the time spaced from the front of the test rectangular pulse at half its duration and after this time. fil1 Lm tftuf Compiled by A. Fedotov Editor E. Sligan Tehred V. Kadar Proofreader M.Sharoshi, Order 2437/56 Edition 638 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4