B.3.2 Mpeg-2 Null Packet - Comtech EF Data CDM-710 Installation And Operation Manual

CDM-710/L Broadcast Satellite Modem
Appendix B
B.3.2 MPEG-2 Null Packet
When the data input to the CDI-40 is disconnected or not synchronized the
modulator sends MPEG-2 null packets in accordance with ISO/IEC DIS 13818-1
Coding Of Moving Pictures and Associated Audio.
If the interface is in Test mode with the patterns turned ON, the modulator
sends a pseudo random pattern over the link in the 187 bytes following the sync
byte, whether Tx data into the modem is present or not.
B.3.3 ASI Interface Defaults
Default settings for the interface are as follows:
CDI-40 Interface Defaults
Parameter
Mode
Active Tx Input
Data or Clock
ASI Frame Format
Loss of Data
Loop Bandwidth
B.3.4 1:1 Applications
Figure B-5 shows the typical operation of the CDM-710/L with ASI in 1:1
Redundancy (using the PL/10881-4 CDI-40 ASI Interface). This diagram applies to
CDM-710/L 1:1 operations via the CRS-180 70/140 MHZ 1:1 Redundancy Switch
(for use with the CDM-710) or the CRS-170A L-Band 1:1 Redundancy switch (for
use with the CDM-710L). For more information about 1:1 Redundant operations
with either of these switches, refer to the respective switch Installation and
Operation Manual.
Default Setting
1, ASI active
J4
Normal
188
Alarm
Wide
B–6
MN/CDM710.IOM
Revision 12