7700 MultiFrame Manual
7736CEM Composite Encoder with Monitoring
Revision 1.5
Page - 73
*Grey background indicates un-implemented or un-tested features
8.8.2. Loss of Video
The user can either have the output video go to black or freeze the last good video picture at the input
with this control.
8.8.3. Genlock Source
This parameter allows you to select the reference video for the frame synchronizer output timing. The
reference may either be an externally supplied colour black or you may use the input video as a
reference. Optionally, the synchronizer can be free-run if the "
none
" option is selected.
8.8.4. Free-Running Frequency
This parameter allows you to calibrate the free-running frequency of the on-board Voltage Controlled
crystal Oscillator (VCXO). This oscillator provides the time-base when either operating without a reference
input (free-running) or when running with a reference and the reference video is removed.
To calibrate the free-running frequency, use this or a similar procedure:
•
Turn off genlocking with the "Genlock source" control or remove reference video from the
reference input. Wait for the VCXO to stabilize at its free-running frequency.
•
Apply the composite analog monitoring output video to a vector scope that is externally referenced
to the signal (usually plant reference black) that you are trying to frequency match.
•
Adjust this control until the vectors spin slowly.
•
Turn genlocking back on or apply reference video.
8.8.5. Fine Phase 525
With this parameter, you can set the horizontal fine phase timing of the output video with respect to the
Genlock when operating in NTSC/525 or PAL-M/525 video mode and locking to the reference input (this
control is not available when locking to the input video). Increasing the value will delay the output video.
There is approximately 250 ns range on this control.
Warning: For a set output horizontal phase, there are a few
fine phase/H phase
combinations that will
achieve the same position. For best results, set this control to 0, set the H phase to get within 37ns of the
desired position, then adjust this control to get closer.
8.8.6. Fine Phase 625
With this parameter, you can set the horizontal fine phase timing of the output video with respect to the
Genlock when operating in PAL/625 video mode and locking to the reference input (this control is not
available when locking to the input video). Increasing the value will delay the output video. There is
approximately 250 ns range on this control.
Warning: For a set output horizontal phase, there are a few
fine phase/H phase
combinations that will
achieve the same position. For best results, set this control to 0, set the H phase to get within 37ns of the
desired position, then adjust this control to get closer.
