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Operation
V.13 Synchronous Mode
The \M1 command selects the Synchronous V.13 Protocol. V.13 mode is a simulated controlled
carrier mode designed for polling applications. It uses the ITU-T V.13 RTS/DCD signaling method
to control the remote modem's DCD lead via the local modem's RTS lead.
The RTS/DCD signaling can be configured for either bi-directional or unidirectional control by the
&E command. The following DTE data rates are available (\Tn command) when the modem
operates in V.13 synchronous mode:
28,800 bps
16,800 bps
4800 bps
Synchronous Compression Mode
The \M2 command selects the Synchronous Compression Protocol. The modem can compress
synchronous DTE data framed in HDLC/SDLC format, with a maximum frame length of 2048
bytes. Synchronous compression supports the following DTE data rates (\Tn command):
128,000 bps
72,000 bps
38,400 bps
21,600 bps
Two techniques for modem-to-DTE hardware flow control are available for use with synchronous
compression. Both require that the modem be configured for internal timing (see below). Flow
control for synchronous compression can be accomplished by:
•
Clock Stopping (\Q5) in which the modem prevents buffer overflow by sharply reducing the
frequency of the transmit clock signal it outputs to the DTE.
•
Clock Throttling (\Q6) in which the modem prevents buffer overflow by varying the rate at
which it outputs the transmit clock signal to the DTE
Note
Synchronous Compression is an optional feature that is not included in all modems. To check the presence
of the feature in your modem, use AT command
dem. Sync Compression On/Off is included in that list.
Note
Synchronous compression mode will not be available in modems configured for AES Encryption.
060R122-000
Issue 15
26,400 bps
24,000 bps
14,400 bps
12,000 bps
2400 bps
1200 bps
115,200 bps
112,000 bps
64,000 bps
57,600 bps
32,000 bps
28,800 bps
19,200 bps
I4
SpectraComm Dual V.34 Modem
Installation and Operation
Synchronous Operation
21,600 bps
9600 bps
96,000 bps
56,000 bps
26,400 bps
to display a list of information concerning the mo-
19,200 bps
7200 bps
76,800s
48,000 bps
24,000 bps
3-33
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