Config: Rx) Fec (Fec Type) - Comtech EF Data CDM-570 Installation And Operation Manual

CDM-570/570L Satellite Modem with Optional IP Module
Front Panel Operation
Selection Sect.
Descram 5.2.2.1.4.7
Buf 5.2.2.1.4.8
Inv 5.2.2.1.4.9
EbNo 5.2.2.1.4.10
VERY
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:
FEC type (Highest) ► Demodulation type ► Code Rate ► Data Rate (Lowest)
If a parameter is changed 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 you have selected Viterbi + Reed-Solomon, QPSK, Rate 1/2.
Now, the you change 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/).

5.2.2.1.4.1 (CONFIG: Rx) FEC (FEC Type)

Rx FEC: Viterbi Vit+RS
TCM+RS TPC Uncoded
IMPORTANT NOTE: All available choices are presented at all times. If an
option is not installed (Hardware or FAST) or valid, the ◄ ► arrow keys will
force the cursor to skip past the unavailable choice.
CASE
Viterbi
Vit+RS
(Viterbi +Concatenated Reed-
Solomon)
TCM+RS
(Trellis Coded Modulation +
Concatenated Reed-Solomon)
TPC
(Turbo Product Codec)
Uncoded
Description
(Descrambler) Used to select whether or not data descrambling is used.
(Buffer) Used to select whether or not the Plesiochronous/Doppler buffer is
used, and if so, the size of that buffer.
(Inversion) Used to invert the sense of the received spectrum, or to invert the
sense of the received baseband data.
E /N
( Alarm threshold) Used to determine the
b 0
IMPORTANT NOTE:
RULES
Always valid
If the RS codec is installed
If the RS codec is installed
AND 8-PSK FAST is enabled
If the TPC codec is installed
Always valid - BPSK, QPSK and
OQPSK only.
5–21
E /N
alarm threshold.
b 0
The FEC type takes
COMMENT
Fixed at 8-PSK and Rate 2/3
Forces Code Rate to 1:1 (uncoded)
Revision 12
MN/CDM570L.IOM
the highest