Learning Event 4:
DESCRIBE HOW VIDEO AND AUDIO FREQUENCIES ARE USED IN THE OPERATION OF VIDEO TAPE
MACHINES
1.
There are two major video frequency bands. One is the 3.5mHz band which is
referred to as low band and is used by most monochrome recorders. The other is the
5.5mHz to 6.6mHz band, the high band used by recorders with color capability.
Figure 1-5 illustrates that slanted 3€6' angle of the recorded video information
and other dimensions.
NOTE: The azimuth method of recording eliminates guard
bands between scan lines for recording each track at a
slightly different angle from the other.
Figure 1-5.
One-inch helical scan video tape showing scan tracks
2.
There are two categories of audio frequencies. Audio frequencies record the
narrative portion of the presentation and audio frequency establishes the control
track signal pulse.
a. The control track signal pulse is obtained from the vertical sync pulse.
In some instances, a third audio track is used as a cueing track or for other
pertinent information.
b. The third audio track may be on the edge of the tape near to the primary
audio track, or it may be on the side next to the control track.
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