Comtech EF Data CDM-600/600L - Manual (Page 163)

CDM-600/600L Open Network Satellite Modem Revision 3
Clocking Modes and Drop and Insert (D&I) MN/CDM600L.IOM
8–9
8.8 Drop and Insert (D&I) Clocking
Figure 8-4 illustrates the general arrangement for Drop and Insert clocking in the CDM-600/600L.
Figure 8-4. Drop and Insert Clocking
Note that there are two inputs and two outputs shown for Drop and Insert Operation:
• Drop Data In (DDI)
• Drop Data Out (DDO)
• Insert Data In (IDI)
• Insert Data Out (IDO)
This arrangement permits the user to choose between fully independent operation of the incoming
and outgoing E1/T1 signal, or to use the same T1/E1 signal for both Dropping and Inserting (looped
mode). If ‘Loop’ has been selected under the Drop and Insert configuration menu, the Drop Data
Out (DDO) signal is automatically looped internally, to become the Insert Data In (IDI).
In this mode, timeslots are dropped from an incoming E1/T1 signal for transmission over the
satellite, and the same E1/T1 signal has time slots re-inserted into it that will over-write data in
existing timeslots.