Video tape recorder recording every second half-frame - scans twice for replay without upsetting synchronisation by recording vertical sync. and compensating pulses

摘要

The video tape recorder records only every second half-frame and scans each recorded frame twice for replay without upsetting synchronisation. This is achieved by recording the vertical sync. pulses and the compensating pulses for both the recorded half-frame and the unrecorded half-frame. The vertical sync. pulses (5) and the compensating pulses for the recorded half-frame are recorded at the start of that frame's picture information (6). The corresponding pulses (7) for the unrecorded half-frame are recorded at the end of the recorded half-frame's picture information. The tracks are scanned by two switched replay heads.