a. The tape then passes the video head, which is rotating at
a high speed
(approximately 3600 rpm).
This combination of tape speed and head
speed gives a
tape-to-head speed of approximately 1000 ips.
This is the speed
at which the
picture and horizontal sync information is placed on the tape after
modulating an
FM signal, as previously indicated.
b. Following the rotating head and its signal application, the tape passes a
fixed head where a control track pulse is applied near the edge.
This control
track record head is preceded by an erase head which clears a track for the
recording of the control track pulses and a path for the audio track. However, on
some recorders, the other edge of the tape may be used for audio recording, and
therefore, the erase is on the opposite end of this fixed head stack.
c. In still another variation, two audio record tracks are present and
consequently, erase and record heads for audio are required on both ends of fixed
head stack. Once the path has been erased for the audio recording path, the audio
may be recorded in the usual manner.
The audio tracks are positioned to prevent
interference with the video control track pulses and the video signal which is
already recorded.
3.
The quadruplex recorder has a head that rotates in a plane 90 degrees to the
tape travel and therefore records a track approximately 90 degrees to the
longitudinal axis of the tape. The helical scan recorder head rotates in a plane
just a few degrees from the parallel of the direction of tape travel.
The video
tracks are applied to the tape in a pattern approximately 3 degrees to 4 degrees
from the longitudinal axis of the tape, depending upon the basic design by the
manufacturer.
39
Previous Page
