SLM-3650 Satellite Modem
Revision 3
Options
MN/SLM3650.IOM
A–91
Table A-27. Multiplexer Specifications
Multiplexer Specific Specifications
Tributary Data Interface (Synchronous Mode)
The multiplexer supports data from each tributary. The tributary interfaces use DCE
conventions with data (send data) sourced by external equipment and clock (send
timing) sourced by the multiplexer.
Tributary Clock Output (Synchronous mode)
50% duty cycle
±
10%, clock (send timing) is phase locked to aggregate clock supplied
by the modem or an external reference supplied by the user equipment. Clock stability is
based on the reference equipment.
Tributary Data Interface (Asynchronous mode)
The multiplexer supports asynchronous data interface for each tributary data interface
and uses (DCE) conventions with data (send data) sourced by external equipment. The
multiplexer samples data and passes it across the communications channel. L data
formatting and framing is preserved.
Note: CTS (Clear-to-Send) flow control is employed to prevent loss of data caused by
clock differences between the asynchronous source and the asynchronous satellite
channel.
Table A-28. Demultiplexer Specific Specifications
Demultiplexer Specific Specifications
Tributary Data Interface (Synchronous mode)
The demultiplexer supports synchronous data for each tributary. The tributary interfaces
use DCE conventions with data (send data) sourced by external equipment and clock
(send timing) sourced by the multiplexer.
Tributary Data Interface (Asynchronous mode)
The demultiplexer supports asynchronous data interface for each tributary. The tributary
data interface used (DCE) conventions with data (receive data) sourced by
demultiplexer. Asynchronous mode at the demultiplexer is really no different from
synchronous mode, because the multiplex equipment does async to sync conversion
prior to transmission over the satellite channel. The asynchronous data is passed in
virtual transparent mode and retains as the transmitting equipment. The synchronous
tributary clock remains active in this mode but is not used.
Tributary Clock Output
50% duty clock
±
10%, clock (receive timing) is phase locked to aggregate clock
recovered by the modem.
Clock Jitter
±
5% of 1/data rate, maximum (Eb/N0
>
7 dB).
Data Delay Variation
<
5% of 1/data rate, maximum unit to unit, average arrival time, including the
demodulator.
Lock Time
<
1.0 second.
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