ds22-l100-041 Conexant Systems, Inc., ds22-l100-041 Datasheet - Page 21

• Manufacturer Part Number: ds22-l100-041
• Description: Cx84100-41/-23 Scxv.22bis Modem V.22bis Modem With Cx20493 Smartdaa? Line Side Device
• Manufacturer: Conexant Systems, Inc.

2.4.3
2.5
2.5.1
2.5.2
2.5.3
2.5.4
102339C
V.42 bis Data Compression
Telephony Extensions
Line In Use Detection
Extension Pickup Detection
Remote Hangup Detection
Digital Line Protection
V.42 bis data compression mode, enabled by the %Cn command or S46 register, operates
when a LAPM or MNP 2-4 connection is established.
The V.42 bis data compression employs a “string learning” algorithm in which a string of
characters from the DTE is encoded as a fixed length codeword. Two 512-byte
dictionaries are used to store the strings. These dictionaries are dynamically updated
during normal operation.
The following telephony extension features are supported that can typically be
implemented in designs for set-top box applications to enhance end-user experience:
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The Line In Use Detection feature can stop the modem from disturbing the phone line
when the line is already being used. When an automated system tries to dial using ATDT
and the phone line is in use, the modem will not go off hook and will respond with the
message “LINE IN USE”.
The Extension Pickup Detection feature (also commonly referred as PPD or Parallel
phone detection) allows the modem to detect when another telephony device (i.e., fax
machine, phone, satellite/cable box) is attempting to use the phone line.
This feature can be used to quickly drop a modem connection in the event when a user
picks up a extension phone line. For example, this feature allows set top boxes with an
integrated SCXV.22bis Modem to give normal voice users the highest priority over the
telephone line.
The Remote Hangup Detection feature will cause the modem to go back onhook during a
data connection when the remote modem is disconnected for abnormal termination
reasons (remote phone line unplugged, remote server/modem shutdown.
The Digital Line Protection (DLP) feature prevents damage to the modem if a digital
PBX telephone line is detected. This is accomplished by forcing the modem to go back
on hook if it attempts to go off hook on a digital line. This feature is enabled by default
and can be tuned via the -TTE command.
The SmartDAA qualifies the line current and power rating every time the modem goes
off hook and decides with a given threshold to qualify the presence of a digital PBX line.
CX84100-41/-23 SCXV.22bis Modem Data Sheet
Line In Use detection
Extension Pickup detection
Remote Hang-up detection
Digital Line Protection
Conexant
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