Application Note

TECHNICOLOR
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www.technicolor.com/mcs
Mega-Bits Per Second Section
Figure 3
The Mega-Bits Per Second section of the QAM page is purely informational. The information is
presented in a grid format with qam channels (Qam1 – Qam12) displayed in the vertical axis and sub
channels (-1 through -6) displayed in the horizontal axis. If you use sub channels beyond -6 the grid will
automatically increase in size to accommodate them.
Starting with the left most column we see it contains the QAM channels Qam1 through Qam12. These
QAM channels are not separated this way on the grid, but are in fact, 3 groups of 4 channels with each
group going through one of the 3 up convertor ICs on the QAM6 (A, B and C). Qam1-Qam4 belong to
group A, Qam5-Qam8 belong to group B and finally Qam9-Qam12 belong to group C. The importance of
this relationship will become obvious in the Control section text later on in your reading.
The next column to the right is the PortBase. The PortBase relates to the QAM channel immediately to
the left of the Portbase (the PortBase for Qam12 is 192). The PortBase value is there for your
convenience and can be used to quickly determine which port to send the transport stream to get the
programming on the Major-minor channel you want that program to be on. The formula to determine
the port value to use is Port = QamChannel X 16 + QamSubChannel. So for Qam2, QamSubChannel3 it