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SDM-300L3 Satellite Modem
Modem Types
5.5.1
AUPC Operation (with Reed-Solomon)
AUPC only operation between two modems, with No ASYNC, is available with the AUPC
option with Reed-Solomon cards installed. This eliminates the need for the Overhead card in
applications where Closed Network operation in not required and when the ASYNC channel is
not required. Setup is similar to the operation of Section 5.5, except, ASYNC parameters are not
available.
5.6
Closed Network Operation (Comtech EF Data)
The modem does not require any additional hardware installed to operate in EFD Closed Network
configuration. The basic modem configuration, which includes the 25-pin D Data I/O connector,
supports V.35, EIA-422, and EIA-232 data with no overhead. The EFData closed network
configuration allows the SDM-300A to be compatible with any EFData closed network
application.
The modem can be compatible with other closed network applications by selecting different
modulator and demodulator types. Fairchild and Comstream compatible closed network systems
can be supported with the modem. When selecting these modulator and demodulator types, the
modem becomes compatible with Fairchild or Comstream closed network modems that may be at
the distant end of the link.
The modem can also support SDM-51 receive-only Remote Space Link Controlled (SLRC)
modems. These receive-only modems are used in closed network applications where a small
amount of overhead is used for monitor and control functions by the transmitting modem. The
modem would become a transmit-only modem when the SDM-51 compatible modulator type has
been selected.
To operate the modem in the SDM-51 compatible configuration, the modem does not require any
additional hardware installed. The 25-pin D Data I/O connector supports either EIA-422 or EIA-
232 data that is used in the SDM-51, SDM-52, or SDR-54 receive-only modems. Refer to Table
5-7 for EFD Closed Network parameter settings.
5–6
Revision 1
MN/SDM300L3.IOM
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