AL2094S Designers Guide
Doc. No. DG_2094E
Altec Electronic AG
Seite 7 / 30
1.3 TECHNICAL
OVERVIEW
1.3.1 General Description
Modem operation, including dialing, call progress, telephone line interface, telephone
handset interface, and host DTE interface functions are supported and controlled through the
V.250, V.251, and V.253-compatible command set.
1.3.2 MCU Firmware
MCU firmware performs processing of general modem control, command sets, data modem,
error correction and data compression (ECC), fax class 1, fax class 1.0, voice/audio/TAM,
worldwide, V.80, and serial DTE host interface functions according to modem models (Table
1-1).
1.3.3 Operating Modes
In V.90 data modem mode (V.92 models), the modem can receive data from a digital source
using a V.92-compatible central site modem at line speeds up to 56 kbps. Asymmetrical data
transmission supports sending data at line speeds up to V.34 rates. This mode can fallback
to full-duplex V.34 mode and to lower rates as dictated by line conditions.
The following modes are also supported in V.92 models:
•
QuickConnect which allows quicker subsequent connection to a server using stored line
parameters obtained during the initial connection. The server must support quick connect
profiles.
•
Modem-on-Hold which allows detection and reporting of incoming phone calls on the
PSTN with enabled Call Waiting. If the incoming call is accepted by the user, the user has
a pre-defined amount of time of holding the data connection for a brief conversation. The
data connection resumes upon incoming call termination. The server must support
Modem-on-Hold functionality.
In V.34 data modem mode (V.90+ and V.34 models), the modem can operate in 2-wire, full-
duplex, asynchronous modes at line rates up to 33.6 kbps. Data modem modes perform
complete handshake and data rate negotiations. Using V.34 modulation to optimize modem
configuration for line conditions, the modem can connect at the highest data rate that the
channel can support from 33600 bps down to 2400 bps with automatic fallback. Automode
operation in V.34 is provided in accordance with PN3320 and in V.32 bis in accordance with
PN2330. All tone and pattern detection functions required by
the applicable ITU or Bell standards are supported.
In V.32 bis data modem mode, the modem can operate at line speeds up to 14.4 kbps.
In V.22 bis fast connect data mode, the modem can connect at 2400 bps with a very short
training time, which is very efficient for small data transfers.
1.3.4 V.44 Data Compression
V.44 provides more efficient data compression than V.42 bis that significantly decreases the
download time for the types of files associated with Internet use. This significant
improvement is most noticeable when browsing and searching the web since HTML text files
are highly compressible. (The improved performance amount varies both with the actual
format and with the content of individual pages and files.)
