Tuesday 11 September 2012

AUTOMATIC SCAN TRACKING [Film Technology]



AUTOMATIC SCAN TRACKING
[Film Technology]

In omega wrap: helical scan machines, to produce a sufficiently high head to tape speed and to record one held per head scan the tracks have to be long and oblique. It is difficult to follow such tracks accurately on replay, especially when using a machine other than the one on which the recording was made. Some machines are provided with a separate replay head which can be moved very slightly at right angles to the track by feeding a voltage to it; this is in addition to the main movement along the track. By sensing the signal level off the tape a voltage is fed to the head  so that the signal level off the tape is maximum. This facility is called automatic scan tracking. This particular format has been agreed as a standard for recording on 1 tape and is known as the tape A format. This format standard is internationally agreed by EBU & SMPTE.







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