Quantum Data 802BT, User Manual

Page: 459 / 744

Video Test Generator User Guide 449
NCPP
Number Clocks Per Pixel
Class Format parameter setting - Digital video signal
Description Specifies the number of clocks per pixel (double-clocking factor for whole line). Some
industry standard formats (e.g. 480i) have pixel rates that are below the minimum pixel
rate restriction (of 25 MHz) required by the TMDS interface. In these cases, a feature
known as “double-clocking” is used to raise the TMDS clock rate to an acceptable
frequency.
Double-clocking is controlled by the NCPP format parameter. When NCPP is set to 1
(normal single-clocked), each pixel, output by the generator, is paired with one clock
pulse. In this case, the pixel rate is equal to the TMDS clock rate. By setting NCPP to 2
(double-clocked), two clocks are send during each pixel period and the TMDS clock rate is
raised to 2 times the pixel rate.
Note that double clocking with NCPP and pixel repetition (NPPP) cannot be applied at the
same time.
Command syntax NCPP factor
factor
1 or 2
Related commands NBPA , NPPP
Example
NCPP 2
FMTU