Synchronising circuit for video recorder luminance and colour signals - uses trigger pulse derived from colour signal to clock luminance signal into charge coupled device serial register

摘要

Luminance and colour signals from separate tracks (S1, S2) of a magnetic tape (1) are read by separate recording heads (K1, K2) and passed to a pulse extractor (4) and a charge coupled device delay unit (8). The pulse extractor extracts a synchronising pulse (c) and passes it via an edge detector to a monostable (10) and an integrator (6). The monostable controls a switch (9) that passes the delay unit output (3) to a differentiator (14) that produces a trigger pulse (f) for a sample and hold unit (7). The latter holds the integrator valve at the level present when the trigger pulse is applied and uses it to drive the voltage controlled oscillator (11) that supplies clock signals to the delay unit, thus forming a feedback loop that synchronises the two tracks. USE/ADVANTAGE - Simple video synchronising circuit capable of being constructed from existing electronic components.