Comtech EF Data OM20 - Manual (Page 184)

OM20 Universal Outdoor Modem Appendix E
MN-OM20– Revision 5 E–2
E.2 Drop Only
When Drop is enabled and Insert is disabled, the OM20 performs a drop-only function. Framed
E1 or T1 Data is input via the Send Data In Port, the selected timeslots are dropped into the IBS
frame structure. (Refer to Figure 3-9).
SD ( DDI )
OM 20
Modem
Terrestrial
Trunk
Figure 3-9. Drop Only
E.3 Insert Only
When Insert is enabled and Drop is disabled, the OM20 performs an insert-only function. If
framed terrestrial E1 or T1 Data is available, it should be input via the Drop Data In Port J10.
The internal looping function allows for the data stream to be internally looped with the
Terrestrial Data buffered inside the Modem. In this mode the modulator should be disabled. The
RX Baseband Processor inserts satellite data into the selected timeslots in the looped G.704
Frame and the modified terrestrial data is then output via the Insert Data Out Port J11 (refer to
Figure
3-10).
If framed terrestrial data is not available, selection of the Internal T1/E1 frame source will cause
the modem to generate the required G.704 Frame. The Satellite Data will be inserted into the
selected timeslots, and the resulting terrestrial data will be output via the Insert Data Out Port
J11. Any non-inserted timeslots in the G.704 Frame will be filled with the appropriate Idle Code
(Refer to Figure 3-11).
SD ( DDI )
DDO
IDI
RD ( IDO )
OM20
Modem
Terrestrial
Trunk
Figure 3-10. Insert Only with Eternal Frame Source