SU612585A1 - Method of shaping tv test signals - Google Patents

Abstract

METHOD FOR FORMING televis-torrid TESTING SIP1ALOV, Oszko tubs on vschelenii sinhrosignaloviz television signal by amplitude selektirovani, forming 'gating signal by counting clock signals of vschelennym line number, characterized in, • that, in order to reduce distortion of the television signal, the high-]-frequency the television signal is additionally modulated at the moments of the strobe signal with a test signal ”

Description

The invention relates to television and can be used to control television channels transmitting high-frequency image signals.

A known method of generating television test signals is based on extracting clock signals from a television signal by amplitude selection, generating a strobe signal by counting the line number of the selected clock signals.

However, the known method gives significant distortion of the television signal.

The purpose of the invention is to reduce the distortion of the television signal during the formation of the executive signals directly in the intervals of the high-frequency television signal frame snuffing, as well as the sequential formation of these signals to control any part of the path.

For this, in the method of generating television test signals based on extracting clock signals from a television signal by amplitude selection, generating a strobe signal by counting the line number on the selected clock signals, the high-frequency television signal is additionally modulated with a test signal at the strobe signal moments

Figure 1-2 shows the structural electrical circuits of devices that implement the proposed method; the time diagrams explaining this method.

The device (FIG. 1) contains a modulator 1 and a detector 2, the shape of a1vated 3 pulses and a driver 4 test signals.

The device (FIG. 2) contains a carrier generator 5, a key circuit 6, a modulator 7, as well as a detector 8,

shaper 9 pulses and shaper 10 test signals.

The device (figo) works as follows.

The high-frequency image signal (Fig. 3a) is detected in detector 2 and pulse 3 is separated by shaper (Fig. 36), the location of which corresponds to the input intervals of the test signals. These pulses drive shaper 4 test signals (Fig. 3b). Then the test signals re-modulate the high-frequency image signal, thereby introducing the test signals into the high-frequency image signal (Fig. 3g). The modulation depth carrying the corresponding elements of the test signals is selected taking into account the accuracy requirements of measuring the characteristics of the transmission channel of the high-frequency signal. So, to eliminate the effect of quadrature distortions in the transmission channels of the high-frequency signal with a limited sideband on the measurement accuracy of the transient characteristics, the carrier modulation depth is

test signals should be no more than 50%.

The device (figure 2) works as follows.

The high-frequency image signal (FIG. 3) is fed to carrier generator 5, ensuring its synchronization in frequency and phase, as well as through key circuit 6 to modulator 7 and directly to detector 8.

The video signal from the detector is fed to the pulse shaper 9 (Fig. 36), which controls the operation of the shaper 10 test signals (Fig.8).

Key circuit 6 suppresses the high-frequency signal (Fig. A) in the required interval and introduces a synchronous and in-phase carrier (Fig. Ze) from oscillator 5 into it. Then, the test signal re-modulates the high-frequency image signal (phigo).

The proposed method provides the possibility of monitoring a television channel for transmitting a high-frequency image signal and its individual sections with direct use of the received signal.

1

FIG. 2

Claims (1)

METHOD FOR FORMING TELEVISION TEST SIGNALS, based on the selection of clock signals from a television signal by amplitude selection, the formation of a 'strobe signal by counting the line number from the selected clock signals, characterized in that, in order to reduce distortion of the television signal, the high-frequency television signal is additionally modulated at times strobe signal test signal.