Comtech EF Data CDM-625 - Manual (Page 123)

CDM-625 Advanced Satellite Modem Revision 15
Front Panel Operation MN-CDM625
5–23
TPC/LDPC Codec is installed.
3. The VFEC and ULL encoding selections display only when the optional
VersaFEC Codec is installed.
On the bottom line – When Reed-Solomon is selectable, use the ▲▼ arrow keys to select On or
Off, and then press ENTER.
CONFIG: Rx  FEC  Reed-Solomon On
Reed-Solomon Decoding =IESS-310(219/201)
(Standard(126/110),IESS-310(219/201)) ()
Use the ▲▼ arrow keys to select an available parameter, and then press ENTER. Depending on
the Framing mode, possible selections are as follows:
► IESS-310, open or closed network 219/201
► IBS or D&I 126/112
► EDMAC or EDMAC2, closed network 200/180
► IDR, open network
225/205, 219/201 or 194/178
► ESC++ or D&I++, closed network 126/112
► Unframed closed network:
○ Comtech standard 220/200
○ Legacy EF Data 225/205, with V.35 scrambling
Otherwise, when Diff Encoder is selectable, use the ▲▼ arrow keys to select On or Off, and
then press ENTER.
CONFIG: Rx  FEC  Diff Encoder On
When selecting Differential Decoding as OFF, there is no way for the modem to
resolve the phase ambiguities associated with PSK modulations. For BPSK there is a
1 in 2 chance that the polarity of the data will be correct. In QPSK there is a 1 in 4
chance that the data will be correct.
Enc=None (None,Vit,Seq,TCM,TPC,LDPC,VFEC)
Diff Encoder=On (Off,On) ()