r6781-12 Conexant Systems, Inc., r6781-12 Datasheet - Page 11

• Manufacturer Part Number: r6781-12
• Description: Embedded Modem Family
• Manufacturer: Conexant Systems, Inc.

EmbeddedModem Family
1.2.3 Operation
1.2.4 Data/Fax Auto Answering
1.2.5 Data Modulation
1.2.6 Equalization
1.2.7 Scrambler/Descrambler
D224ATLVDSC
1.2.3.1 Data Modes
1.2.3.2 Fax Modes
Modem operation is controlled by AT commands, fax service class 1 commands,
and supporting S registers.
Data rate selection is determined by the speed of the originating and answering
modems, as defined in
Table 1-2. Data Rates vs. Connection Modem Rate
Fax modes are negotiated as defined in T.30 and are implemented by AT+F
commands. The AT+FCLASS=1 command causes entry into the fax mode from
the data mode. Most other fax class 1 commands, which start with the AT+F
prefix, are valid only in the fax mode. All data commands are valid in the fax
mode except A/, On, &Tn, and the escape sequence (+++). The AT+FCLASS=0
command terminates the fax mode and causes entry into the data mode.
The modem can automatically determine if the incoming call is from a data or fax
modem, make the appropriate connection, and inform the DTE of the connection
type.
The data modulation conforms to V .29, V .27 ter, V .22 bis, V .22, V .21, Bell 212A,
or Bell 103, depending on the selected configuration. Transmitter and receiver
spectrum shaping is provided in accordance with the applicable standard.
Automatic adaptive equalization and fixed compromised equalization are
provided to compensate for line distortions and to minimize the effects of
intersymbol interference.
The modem incorporates a self-synchronizing scrambler/descrambler, which
satisfies the applicable CCITT or Bell requirements.
Originate Modem Rate
(bps)
1200
2400
300
Conexant
Table
1-2.
Connect Speed Based on Answer Modem Rate (bps)
300
300
300
300
1200
1200
1200
300
1.2 Technical Specifications
2400
1200
2400
300
1-3