Crystal Vision
Using the front panel
DEC104S User Manual R1.0
22
29/10/04
The active output timing reference
The horizontal and vertical timing adjustments operate relative to one of three analogue
timing references. These are an external reference, the composite or YC input or an
internal free-running clock. Which of these is the active reference is dependent on the
presence of an external reference or whether an 8 bit or 10 bit mode is in operation.
When an external analogue timing reference is present serial output timing is maintained
relative to the external analogue reference.
When no external analogue timing reference present the serial output timing depends on
whether the decoder is in 10 or 8 bit mode. In 10 bit mode the serial output is timed to the
composite or Y/C input. In 8 bit mode the output is timed to a free running clock.
The following tables summarises the possible output timing reference sources:
Active timing reference
Ext Ref
Mode
External analogue input
Present
10 or 8 bit
Composite or Y/C input
Not present
10 bit
Free running internal clock
Not present
8 bit
Adjusting horizontal and vertical timing
Increasing the vertical position setting will delay the output relative to the reference in
increments of one video line. Press the F1 button to allow the shaft encoder to adjust the
vertical output timing. The shaft encoder LED will illuminate and an asterisk will appear
on the display next to ‘VPOS'. The range of adjustment is one video frame. When the
maximum adjustment is reached the value wraps around to zero.
Increasing the horizontal position setting will delay the output relative to the reference in
increments of 37ns. Press the F2 button to allow the shaft encoder to adjust the horizontal
output timing. The shaft encoder LED will illuminate and an asterisk will appear on the
display next to 'HPOS'. The range of adjustment is one video line.
With an external analogue timing reference present the delay through the board depends
on these adjustments and the relative timing of the serial input and the analogue reference.
When both horizontal and vertical position settings are zero the delay thorough the board
will be minimum and the serial output will be timed to the analogue reference as per ITU-
R BT.601. The minimum delay through the board is approximately 1.7 lines in 10 bit
mode and 0.7 lines in 8 bit mode.
Adjusting chroma phase
Press the F3 button to the shaft encoder to adjust the chroma phase relative to burst. This
adjustment is available in 10 bit mode only. The shaft encoder LED will illuminate and an
asterisk will appear on the display next to 'PHSE'. The range of adjustment is 360 degrees,
in steps of roughly 0.1degrees. When the maximum adjustment is reached the value wraps
around to zero.
