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12. Digital Decoder R763826
The colour difference signals are first passing a low-pass filter, and then mutliplexed according the ITU standard. The Y, on the other
hand, passes a high pass filter and then a delay compensation.
In a last stage, a multiplexer "selects" the decoder output or the R/R-Y, G/Y or B/B-Y matrixed signals.
Digital processing - Scaling.
The digital processing consists of an acquisition control, pre-scaler for horizontal down-scaling, line buffer with asynchronous read
and write for vertical up-scaling, a vertical scaling section and output formatter.
The video scaler receives its input from the video decoder or from the expansion port (X-port, and not used here).It gets 16-bit
Y-CR-CB 4:2:2 input data at a continuous rate of 13.5MHz. It is sorted into a luminance path and time multiplexed chrominance
path. If it is a 4 : 1 : 1 format it is converted to 4:2:2 first.
The 8-bit Y-CR-CB output from the decoder, real time and unscaled ,is available at the bi-directional expansion port (X-port) from
where it is sent to the PMP board via the connector J3.
12.3.3 Power Supply
Power diagram for Digital decoder
Image 12-3
Power Supply for Digital decoder
GREEN LED D17: illuminates when the decoder is locked (Vertical & Horizontal lock and Colour detected)
Power Supply test points
Image 12-4
Power supply measurement points
84
LED D17
R5976820 SLM R12+ PERFORMER 08/03/2005
J3
30 60
1
31
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