RC56D, RC336D, and RC144D Modem Device Sets Designer’s Guide
1-6
Conexant
1154
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.
Summary of Contents for RC144D
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