Comtech EF Data SDM-2020 User Manual
Page 155
SDM-2020 Satellite Demodulator
Revision 4
ECL/HSSI Data Interface
MN/SDM2020D.IOM
10–3
10.1.4
Terrestrial (User) Data Interface
10.1.4.1
Terrestrial Transport Protocols
The demodulator/modulator is compatible with TM1449 transfer of MPEG-2 data signals
in the standardized transport layer format. The demodulator/modulator also supports DBS
(DBS-PS-007) no framing (187 bytes) format modes (Table 10-2). Table 10-3
summarizes the primary characteristics of each transport protocol. The demodulator was
designed to comply with these primary interface standards, however; custom interfaces
can be supported as outlined in the data transfer modes definition section of this
document
Table 10-2. Framing Format Summary
Framing Format Summary
Transport
Protocol
Transport
Package
Size (bytes)
Sync
Byte
Sync
Byte
Strobe
Data
Valid
Strobe
Comments
TM1449 (DVB)
188, 204
yes
yes
yes
SYNC active for byte time.
DBS
204
yes
yes
no
SYNC active for bit time.
Extend one bit time for error.
No
Framing 187
no
no no data
stream.