RC56D, RC336D, and RC144D Modem Device Sets Designer’s Guide
1-4
Conexant
1154
1.3 TECHNICAL OVERVIEW
1.3.1 General Description
The modem device set, consisting of separate microcontroller (MCU), modem data pump (MDP), optional Plug and Play
(PnP) ISA Bus Interface Device, and optional RCDSVD Speech Codec Processor (SCP) devices, provides the processing
core for a complete modem design.
For data/fax/V.80/voice/TAM/speakerphone/host-DSVD/AudioSpan operation, only the microcontroller (MCU) and modem
data pump (MDP) devices are needed. The OEM adds an MCU crystal, discrete components, and a telephone
line/telephone/voice/TAM/telephony extension interface circuit to complete the modem system. Optional on-board DSVD
operation is supported with addition of the RCDSVD Speech Codec Processor (SCP) device to an SP model (included in SVD
models). Table 1-1 shows the supported functions by product family.
Dialing, call progress, V.80, telephone line interface, voice/TAM, speakerphone, AudioSpan, and DSVD functions are
supported and controlled through the AT command set.
Connection to the host/DTE is supported by serial DTE interface (Figure 1-1) or parallel host interface (Figure 1-2) depending
on installed modem firmware.
Data/Fax Modes
In V.90/K56flex data modem mode (RC56), the modem can receive data from a digital source using a V.90- or K56flex-
compatible central site modem at line speeds up to 56 kbps. Asymmetrical data transmission supports sending data at
speeds up to V.34 rates. This mode can fallback to full-duplex V.34 mode.
In V.34 data modem mode, 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 33.6 kbps
to 300 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 standard are
supported.
In fax modem mode, the modem can operate in 2-wire, half-duplex, synchronous mode and can support Group 3 facsimile
send and receive speeds of 33600, 31200, 28800, 26400, 24000, 21600, 19200, 16800, 14400, 12000, 9600, 7200, 4800,
and 2400 bps. 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 at speeds up to 33.6 kbps with automatic rate adaption. Fax data transmission
and reception performed by the modem are controlled and monitored through the EIA/TIA-578 Fax Class 1, T.31 Fax Class
1.0, or Fax Class 2 command interface. Full HDLC formatting, zero insertion/deletion, and CRC generation/checking are
provided.
Both transmit and receive fax data are buffered within the modem. Data transfer to and from the DTE is flow controlled by
XON/XOFF and RTS/CTS.
Synchronous Access Mode (SAM)
V.80 synchronous access mode between the modem and the host/DTE is provided for host-based communication protocols,
e.g., H.324 video conferencing applications.
Voice-call-first (VCF) before switching to a videophone call is also supported.
V.80 SAM is controlled by the +ES (Enable/Disable Synchronous Access Mode), +ESA (Configure Synchronous Access
Submode), and + ITF (Select Transmit Flow Control Thresholds) AT commands.
World Class Operation
W-class functions support modem operation in multiple countries. Additional capabilities are provided in addition to the data
modem functions in areas such as for dialing, carrier transmit level, calling tone, call progress tone detection, answer tone
detection, blacklisting, relay control. Country dependent parameters are programmable by ConfigurACE II for Windows.
Summary of Contents for RC144D
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