SU653769A1 - Device for measuring modulation of television signal - Google Patents

Description

The invention relates to television technology, in particular to devices measuring the parameters of a television signal, and can be used to examine a video signal element for the presence of phase modulation. A device for measuring phase modulation in a television signal is known, comprising a series-connected first switch, the input of which is supplied with a standard television video signal, a sync selector connected with an output to the first input of the second switch, a reference generator, a third switch, the second input of which is supplied with a television sync signal, block variable delay and phase detector, the second input of which is connected to the output of the second switch, and the output of the phase detector is connected to the measuring Indicator 1. However, in such a device it is impossible to measure phase modulation of video signal drops. The aim of the invention is to improve the accuracy of measurement of phase modulation of video signal differences. For this purpose, the device for measuring phase modulation in a television signal, containing in series the first switch, the input of which is supplied with a standard television video signal, the sync selector connected with the output to the first input of the second switch, the reference oscillator, the third switch, the second signal of which is supplied the television sync signal , variable delay unit and phase detector, the second input of which is connected to the output of the second switch, and the output of the phase detector is connected to the meter The first indicator, pulse generator, gating unit and second pulse shaper, the output of which is connected to the second input of the second switch, and the input of the first pulse shaper are connected to the second indicator, and the output of the variable delay block is connected to the second entrance block gating. In such a device, it is possible to measure the phase modulation of the video signal drops.

The drawing shows the structural electrical circuit of the proposed device for measuring phase modulation in a television signal.

A device for measuring phase modulation in a television signal contains a first switch 1, a sync selector 2, a second switch 3, a reference generator 4, a third switch 5, a variable delay unit 6, a phase detector 7, a measuring indicator 8, a first pulse shaper 9, a gating unit 10 the second shaper 11 pulse.

The device works as follows.

When measuring the phase modulation of the sync signal, the input signal at the input of the first switch 1 passes to the sync selector 2, where the sync signal is extracted. The selected clock signal is fed to the reference oscillator 4 and via the second switch 3 to the phase detector 7. The phase detector compares the phases of the signals at the input of the first switch 1 with the signal supplied to the second input of the third switch 5, or with the signal of the reference generator 4, incoming alternately through the second switch 5 and the block. 6 of the variable delay with which the signals are phased. The error signal is recorded by the measuring indicator 8. To measure the phase modulation in the video signal element, the input signal passes through the first switch 1 to the first pulse shaper 9, then goes to the gating unit 10. From the pulse of the reference generator 4 or from the television clock signal, the generated strobe pulse passes through the third switch 5 to a variable delay block 6, where it is phased and then input to the gate unit 10. Using the variable delay unit 6, it is possible to change the temporal position of the strobe pulse, which allows the gating unit 10 to isolate the video element under investigation. The selected pulse is then formed by the second pulse shaper 11 and passes through the second switch 3 to the phase detector 7. The selected and formed pulse from the video signal is compared on the phase detector, as in the measurement of modulation in the clock signal, either with a pulse of the reference generator 4 or with a pulse,

formed from the signal arriving at the second input of the third switch 5. The error signal selected by the phase detector 7 is recorded by the measuring indicator 8.

The proposed device allows not only to measure phase modulation in a television clock signal, but also to select a separate element in it and measure it, thus obtaining a comprehensive idea of phase modulation in a full television signal.

Claims (1)

Invention Formula A device for measuring phase modulation in a television signal, containing a sequentially connected first switch, the input of which is fed to a standard television video signal, a sync selector connected to the output of the first input of the second switch, a reference oscillator, a third switch to the second input of which is fed to a synchronous television signal blbk variable delay and phase detector, the second input of which is connected to the output of the second switch, and the output of the phase detector is connected to the measuring indicator the kator, characterized by a & m, which, in order to improve the accuracy of measurement of phase modulation of video signal drops, is entered into it included the first pulse shaper, the gating unit and the second pulse shaper, the output of which is connected to the second input of the second switch, and the input of the first pulse shaper is connected to the second output of the first switch, and the output of the variable delay unit is connected to the second input of the gating unit. Sources of information taken into account in the examination I.Harris, A.T. V. V. Tara Time Stability. Wireless World 1962, No. 11, p. 516-520,