Comtech EF Data CDM-Qx, Installation And Operation Manual

Page: 70 / 224

CDM-Qx Satellite Modem Revision 6
Front Panel Operation MN/CDMQx.IOM
The FEC type takes the highest configuration priority, and the selection
here depends on what, if any, optional plug-in Codecs are installed. The
choice of FEC type then determines what demodulation types, code
rates, and data rates are available. The order of hierarchy is therefore:
IMPORTANT
FEC type
► Demodulation type ► Code Rate ► Data Rate
(Highest) (Lowest)
If the user changes a parameter within this hierarchy, the other parameters may become
invalid. In this case, the software will change those other parameters, in order that the
configuration remains valid at all times.
Example
: Suppose the user has selected V Reed-Solomon, QPSK, Rate 1/2.
Now, the user changes the demodulation type from QPSK to 16-QAM. In this case, Rate
1/2 is no longer a valid code rate, and so it will be automatically changed to the nearest
valid code rate (Rate 3/4).
Each of the configuration sub-branches will now be described in detail.
(Config
%
Rx
%
FEC) – RX FEC TYPE
Rx FEC: Vit Vit+RS TCM+RS
TPC ( ◄ ► ENT)
All possible choices are presented at all times. If an option is not
installed (either Hardware, or FAST) or valid, the
◄ ► arrow keys will
force the cursor to skip past the unavailable choice.
IMPORTANT
CASE RULES COMMENT
Vit (Viterbi) Always valid
Vit+R-S (VConcatenated
Reed-Solomon) Always valid
TCM+R-S (Trellis Coded
Modu Concatenated
Reed-Solomon) If 8-PSK FAST is enabled Fixed at 8-PSK and Rate
2/3
TPC (Turbo) If the TPC codec is installed
If
Vit+RS
or
TCM+RS
displays the following submenu:
Rx Rs (n/k): ( ◄ ► , ENT)
IESS-310 network (219/201)
5–22