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Conexant
MD211
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.
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.
Voice/TAM Mode
Voice/TAM Mode features include enhanced ADPCM
compression/decompression, tone detection/generation
and call discrimination, concurrent DTMF detection, and
8-bit monophonic audio data encoding.
Voice/TAM Mode is supported by three submodes:
1. Online Voice Command Mode supports connection to
the telephone line or, for SP and SVD models, a
handset.
2. Voice Receive Mode supports recording voice or
audio data input at the RIN pin, typically from the
telephone line or, for SP and SVD models, a
microphone/handset.
3. Voice Transmit Mode supports playback of voice or
audio data to the TXA1/TXA2 output, typically to the
telephone line or, for SP and SVD models, a
speaker/handset.
Telephony Extension Operation
Extension pickup/remote hangup detection and line-in-use
detection are supported.
Speakerphone Mode (SP and SVD Models)
The speakerphone mode features an advanced
proprietary speakerphone algorithm which supports full-
duplex voice conversation with both acoustic and line
echo cancellation. Parameters are constantly adjusted to
maintain stability with automatic fallback from full-duplex
to pseudo-duplex operation. The speakerphone algorithm
allows position independent placement of microphone and
speaker.
The speakerphone mode provides hands-free full-duplex
telephone operation under host control. The host can
separately control volume, muting, and AGC in
microphone and speaker channels.
AudioSpan Mode (SP and SVD Models)
AudioSpan provides full-duplex analog simultaneous
audio/voice and data over a telephone line at a data rate
of 4800 bps with audio using V.61 modulation. AudioSpan
can send any type of audio waveform, including music.
Data can be sent with or without error correction. The
audio/voice interface can be in the form of a headset,
handset, or a microphone and speaker. Handset echo
cancellation is provided.
DSVD Mode using RCDSVD SCP Device (SVD Models)
On-board DSVD operation requires installation of the
optional RCDSVD SCP (R6715-14).
DSVD provides full-duplex digital simultaneous voice and
data over a single telephone line. DSVD uses codecs in
the RCDSVD SCP to code (compress) analog speech
signal on the RCDSVD LINEIN pin or MICIN pin for
passing to the modem controller in digitized form, and to
decode (decompress) coded speech received from the
modem controller for routing to the RCDSVD LINEOUT
pin or SPKP/SPKN pins in analog form.
DSVD operates in accordance with ITU-T interoperable
G.729 and G.729 Annex A with interoperable G.729
Annex B. Voice activity detection supports speech coding
at average bit rate significantly lower than 8.0 kbps.
DSVD decoder timing recovery algorithm compensates for
clock skew, asynchronous host-to-decoder data transfer
delay, intervening variable length data block transmission
delay, and loss of encoded speech data.
The voice interface can be in the form of a headset,
handset or a microphone and speaker (half-duplex
speakerphone). Handset echo cancellation supports
handset use through a hybrid.
In Handset Mode, the RCDSVD SCP interfaces to the
telephone interface circuit using the Line Input (LINEIN)
and Line Out (LINEOUT) lines. In Headset or
Speakerphone Mode, the RCDSVD SCP interfaces to the
audio interface circuit using the Microphone Input (MICIN)
and Speaker out (SPKR) lines.
Host-Based DSVD
All modem models support host-based ITU-T V.70 DSVD.
The RCDSVD SCP (R6715) is not required. V.70 software
drivers for Windows 95 are provided which support a
speech/audio bit rate of significantly less than 8.0 kbps by
implementing interoperable G.729 and G.729 Annex A
with interoperable G.729 Annex B. The minimum PC
performance recommended for host-based DSVD is 150
MHz Pentium or equivalent. The V.70 software drivers
require about 10% of the MIPS available in a Pentium 150
MHz class PC. The host PC must supply full-duplex
sound support, typically to a microphone/speaker, such as
provided by Conexant WaveArtist devices or a sound
card. The modem is configured for host-based V.70 via
AT commands, and, when using a TAPI-compliant
communication application, the V.70 software drivers will
automatically run upon a successful V.70 connection.
Sleep Mode
Sleep Mode is supported in the modem device set and the
RCDSVD SCP device.
Modem Data Pump (MDP)
The data/fax/voice/optional speakerphone modem data
pump (MDP) is a Conexant R6764 packaged in a 100-pin
PQFP. The input clock frequency is 28.224 MHz and can
be supplied by the MCU. An internal phase locked loop
(PLL) circuit supports 56.448 MHz internal operation. The
operating voltage is +3.3V, which can be supplied by the
MCU, with +5V tolerant inputs. The MDP su5V
analog signal interface.
