Single-Source Multiple Modems - Comtech EF Data CDM-625 Installation And Operation Manual

CDM-625 Advanced Satellite Modem
Clock Modes and Drop and Insert (D&I)
detects no activity at IDI input, or cannot detect the expected frame format, Buffer Clock = Rx
Satellite will be chosen as a fall-back.
If 'Insert' is not the selected buffer clock reference, the clock and data from the IDI port is
ignored, and a new E1/T1 frame is generated. The time slots coming from the satellite are then re-
inserted into the selected timeslots of this new blank frame, and output on the IDO port.

9.10 Single-Source Multiple Modems

Two ways to connect a single T1 or E1 stream to several modems are by looming or daisy-chaining
modems. Looming method is illustrated in Figure 10-5, and Figure 10-6 illustrates the daisy-chain
method; each requires the RX Buffer Clock = Insert setting.
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•
Figure 9-5. Single-Source Multiple Modems (Looming)
MODEM
DDI
DDO
Terrestrial Trunk
Figure 9-6. Single-Source Multiple Modems (Daisy-chain)
Assign all timeslots to not overlap.
Assign modems to number of TX/RX channels as required.
IDI
IDI
IDO
Multiple Modem Drop & Insert Application: This application shows how the loop is extended
to one or more additional modems.
DDO- IDI connection may be made internally using Loop = Y under D&I menu.
MN-0000036 (Ref MN/CDM625.IOM)
MODEM
9–9
Revision 1
MODEM