si2439-a-gm Silicon Laboratories, si2439-a-gm Datasheet - Page 25

• Manufacturer Part Number: si2439-a-gm
• Description: V.92 And V.34 Isomodem With Global Daa
• Manufacturer: Silicon Laboratories

4.21. SMS/MMS Support
Short Message Service (SMS) is a service that allows text messages to be sent and received from one telephone
to another via an SMS service center. Multimedia Messaging Service (MMS) extends the core SMS capability to
send messages that include multimedia content. The Fax ISOmodem provides an interface that offers a great deal
of flexibility in handling multiple SMS standards. This flexibility is possible because most of the differences between
standards are handled by the host using the raw data itself. The Si2494/39 performs the necessary modulation/
demodulation of the data and provides two options for message packet structure (Protocol 1 and Protocol 2, as
defined in ETSI ES 201 912). The rest of the data link layer and transfer layer are defined by the host system.
The content of the message is entirely up to the host including any checksum or CRC. ETSI ES 201 912 describes
two standard data and transfer layers that are commonly used. SMS typically relies on caller identification
information to determine if the call should be answered using an SMS device or not.
See “6.4. SMS Support” in AN93 for more information on how to configure the modem for SMS support.
4.22. Codec Interface
In order to support a full range of voice and data applications, the Si2494/39 includes an optional serial interface
that connects to an external voice codec (Si3000). See AN93 for complete details.
4.23. Answering Machine Support
The TAM voice compression support includes the following formats:
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All formats use a fixed 8 kHz sampling rate. For most applications, the user wants a high-quality message format
(64 kbps) for the Outgoing Message (OGM) and is less concerned about the Incoming Message (ICM) quality.
Higher compression results in less memory use. Less compression results in higher speech quality. See AN 93 for
details. This section covers the functional operation of handset, TAM, and speakerphone modes and includes use
cases with the programming examples.
4.24. Voice Pass-Through (Speakerphone)
Voice pass-through operation employs an acoustical echo canceller (AEC), acoustical echo suppressor (AES),
double-talk detector (DTD), and line echo canceller (LEC). They provide the following performance:
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See Appendix of AN93 for details. This section covers the functional operation of handset, TAM, and
speakerphone modes and includes use cases with programming examples.
4.25. General-Purpose Tone Detectors
Two general-purpose tone detectors based on 4th-order I-quad filters are provided in addition to the other
dedicated tone detectors described in this document. These tone detectors are referred to as the Tone A detector
and the Tone B detector. They can operate independently or Tone B can receive the output of Tone A to implement
a higher-order tone detector. All filter coefficients and detector functions are controlled through U-Registers.
These tone detectors are available for use in any operational mode. Whenever an enabled tone detector output
transitions, a message will be generated. The messages follow the DLE shielded format for complex reporting.
Refer to AN93 for more details.
Signed linear 8-bit, 64 kbps
Unsigned linear 8-bit, 64 kbps
G.711 -law 8-bit, 64 kbps
G.711 A-law 8-bit, 64 kbps
G.726 ADPCM 2-bit, 16 kbps
G.726 ADPCM 4-bit, 32 kbps
Programmable echo tail filter length: up to 64 ms
Convergence speed (white noise): < 1.6 s
Single-talk echo suppression: > 48 dB
Double-talk echo suppresion: > 30 dB
Rev. 1.0
Si2494/39
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