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3.18
EBEM Framing Unit
The DMD1050TS EBEM framing Unit provides the ability to multiplex both Serial (MIL-STD-188-
114A or High Speed Serial Interface (HSSI)) with Bridged Ethernet payload, overhead and
embedded channel data within the over-the-air transport stream.
3.18.1
EBEM Mode Set Up on the DMD1050TS
When in EBEM Network Spec mode, the Ethernet interface is always active. Therefore, you
cannot select it as the interface type when in EBEM mode. EBEM mode always runs two
interfaces simultaneously: the Ethernet interface and one of the serial interfaces (HSSI or
MIL-188-114A).
First, make sure one of the serial interfaces (HSSI or MIL-188-114A) is set as the interface type.
After you enable EBEM as the Network Spec, both the serial interface and the Ethernet interface
will be active. However, only the serial interface shows for the interface menus. The Ethernet
interface does not show for the interface menus.
When in EBEM mode, the Modulator and Demodulator DATA menus show the ETH RATE. This
is where you set the Ethernet data rate.
There is also a DATA RATE, which is where you set the serial interface data rate.
•
Run only Ethernet by setting an ETH RATE and then setting DATA RATE to 0.
•
Run only serial by setting a serial rate for DATA RATE and then setting ETH RATE to 0.
•
Run Ethernet and serial simultaneously by setting both the serial rate for DATA RATE
and the Ethernet rate for ETH RATE.
The combined Ethernet and serial rates must be within the data rate limits for the configuration in
use (Modulation type, FEC etc.). Chapter 7, Technical Specifications, shows the data rate limits
for the various Mod Cods.
3.18.1.1 Exit EBEM Mode
To change from EBEM mode to another mode, such as closed network mode, you must first have
a serial rate set for DATA RATE. For example, if you were running in EBEM mode but using only
the Ethernet interface (ETH RATE is set but the DATA RATE set to 0), the modem will not let you
exit the EBEM mode until you enter a valid rate for DATA RATE.
3.18.2
DMD1050TS Information Throughput Adpatation (ITA)
Refer to Appendix I for additional information.
3.18.3
Embedded Channel
The embedded channel is used for exchanging messages between DMD1050TS units. ITA,
AUPC and TRANSEC traffic encryption/decryption key negotiation are typical examples of
messages sent through the DMD1050TS embedded channel. The nominal rate of the embedded
channel is 4 kbps.
Theory of Operation
DMD1050TS Satellite Modem Board
3–37
Revision 1
MN-DMD1050TS
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