L – Video D.O.


The circuit on this module takes care of drop-out compensation of the demodulated video signal and of generation of the MTF signal. The drop-out detector circuit measures a negative going drop- out and in case of a drop-out it will give a  pulse to switch over the DO switch to have the delayed video as output signal. This will be the case as long as there is drop-out. The drop-out pulses can be blocked by the DO-INH signal. This is necessary to prevent drop-out correction during the data part of the video signal. Drop-out correction is only done with the luminance signal. The luminance signal is fed to the CCD memory part, which takes care of the 64μs delay (one line-time).

The DC RESTORER will take care of clamping of the DC-level of the delayed video to the DC-level of the direct video with the aid of the burst key pulses. The MTF signal is also created on this module. This MTF signal is a DC voltage which will vary in value depending on the read-out diameter of the disc. This voltage is used to adapt the frequency response of the HF signal on the HF PROC module (K).

Top-view of PCB

Bottom-view of PCB