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Echo Canceller
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AudioSpan Mode (SP Models)
AudioSpan provides full-duplex analog simultaneous
audio/voice and data over a single telephone line at a
data rate with audio of 4800 bps 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 (half-
duplex speakerphone). Handset echo cancellation is
provided.
Data Formats
Serial Synchronous Data
Data rate:
300-56000 bps (RP56), 300-33600 bps
(RP56 and RP336), or 300-14400 bps,
±0.01%.
A data echo canceller with near-end and far-end echo
cancellation is included for 2-wire full-duplex
V.34/V.32 bis/V.32 operation. The combined echo span of
near and far cancellers can be up to 40 ms. The
proportion allotted to each end is automatically
determined by the MDP. The delay between near-end and
far-end echoes can be up to 1.2 seconds.
V.90 and K56flex echo cancellation is also provided.
ADPCM Voice Mode
The Adaptive Differential Pulse Code Modulation
(ADPCM) voice coder and decoder (codec) compresses
and decompresses voice signals for efficient digital
storage of voice messages. The codec operates at 28.8k,
21.6k, or 14.4k bps (4-bit, 3-bit, or 2-bit quantization,
respectively) with a 7.2 kHz or 8.0 kHz sample rate.
Transmit Voice.
16-bit compressed transmit voice can be
sent to the MDP ADPCM codec for decompression then to
the digital-to-analog converter (DAC) by the host.
Receive Voice.
16-bit received voice samples from the
MDP analog-to-digital converter (ADC) can be sent to the
ADPCM codec for compression, and then be read by the
host.
Voice Pass-Through Mode
Voice pass-through mode allows the host to transmit and
receive uncompressed voice samples in 16-bit linear form
at 7.2 kHz, 8.0 kHz, or 11.025 kHz sample rate, or in 8-bit
A-Law/µ-Law PCM form at 8.0 kHz sample rate.
Transmit Voice.
Transmit voice samples can be sent to
the MDP DAC from the host.
Receive Voice.
Received voice samples from the MDP
ADC can be read by the host.
Speakerphone Voice/Audio Paths (SP Models)
The MDP incorporates a dual integrated analog interface.
The voice/audio transmit and receive signals can be
routed through several paths. The voice/audio paths are
available in the speakerphone mode configuration and are
selected through DSP RAM.
The voice/audio input can be taken from one of four
different sources: telephone line input (RIN), handset
(TELIN), microphone (MICM or MICV).
The speaker output (SPK) can originate from one of five
different sources: RIN, TELIN, MICM or MICV or from the
MDP’s internal voice playback mode.
The voice/audio output may be routed to the telephone
line output (TXA1 and TXA2) or handset (TELOUT).
The voice paths can be switched to allow an audio input
to be routed to the telephone line output through a
variable gain for applications such as music-on-hold.
The “room monitor” mode allows the MDP to receive
audio from its surroundings and concurrently transmit the
audio to a remote site.
Selectable clock: Internal, external, or slave.
Serial Asynchronous Data
Data rate:
300-56000 bps (RP56), 300-33600 bps
(RP56 and RP336), or 300-14400 bps,
+1% (or +2.3%), -2.5%;
0-300 bps (V.21 and Bell 103);
1200/75 bps (V.23).
Bits per character: 7, 8, 9, 10, or 11.
Parallel Synchronous Data
Normal sync: 8-bit data for transmit and receive
Data rate:
300-56000 bps (RP56), 300-33600 bps
(RP56 and RP336), or 300-14400 bps,
±0.01%.
SDLC/HDLC support:
Transmitter: Flag generation, 0 bit stuffing,
CRC-16 or CRC-32 generation.
Receiver:
Flag detection, 0 bit deletion,
CRC-16 or CRC-32 checking.
Parallel Asynchronous Data
Data rate:
300-56000 bps (RP56), 300-33600 bps
(RP56 and RP336), or 300-14400 bps,
+1% (or 2.3%), -2.5%;
1200, 300, or 75 bps (FSK).
Data bits per character: 5, 6, 7, or 8.
Parity generation/checking: Odd, even, or 9th data bit.
Async/Sync and Sync/Async Conversion
An asynchronous-to-synchronous converter is provided in
the transmitter and a synchronous-to-asynchronous
converter is provided in the receiver. The converters
operate in both serial and parallel modes. The
asynchronous character format is 1 start bit, 5 to 8 data
bits, an optional parity bit, and 1 or 2 stop bits. Valid
character size, including all bits, is 7, 8, 9, 10, or 11 bits
per character. Two ranges of signaling rates are provided:
•
Basic range: +1% to –2.5%
•
Extended overspeed range: +2.3% to –2.5%
0'
CONEXANT [ CONEXANT SYSTEMS, INC ]
