burst multivibrator MV1 on; this multivibrator is set to produce a pulse width of
about 7 microseconds, as are all following multivibrators.
(2) The leading edge of the pulse from MV1 gates the signal from oscillator 1
on, and the trailing edge gates the same signal off. The trailing edge also gates
MV2 on, and so forth. Thus, the output signal consists of the white-flag and six
sine wave bursts on a time-shared basis during each line interval.
c. The signal and frequencies from left to right consist of white-flag, 0.5,
1.5, 2, 3, 3.58, 4.2 megahertz signals as illustrated in Figure 3-2.
The
multiburst test signal is inserted on the odd field of line 17 of the vertical
blanking interval.
The frequencies shown are those normally used for a standard
multiburst signal.
However, some multiburst signal generators facilitate
multiburst test signals with frequencies as high as 12 MHz.
Figure 3-2.
Standard multiburst signal
2. The transmission of video information over long lengths of cable degenerates
the signal through frequency-dependent losses of the cable. One application of the
multiburst signal is to set equalization controls on distribution amplifiers with
provision for compensating cable losses.
3. Another frequently used application of the multiburst signal is in the
evaluation of common carrier transmission. The multiburst signal is VITS keyed in
the vertical interval for insertion into a televised program. This allows for in-
service testing of the transmission path.
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