FM336 V.34/Group 3 High Performance Fax Modem Family
4Conexant 100086B
Technical Specif ications
The single device modem provides the processing
core for a complete facsimile modem design.
Configurations and Rates
The selectable modem configurations, signaling rates,
and data rates are listed in Table 2.
Automatic Mode Selection (-D / -D90)
When Automatic Mode Selection (AMS) is enabled, the
modem configures itself to the highest compatible data
rate supported by the remote modem. Automode
operation is supported in V.90 (-D90 only), V.34,
V.32 bis, V.32, V.22 bis, V.22, V.21, V.23, Bell 212A,
and Bell 103 modes.
Automatic Rate Adaptation
In V.34 duplex, V.34 half-duplex, and V.32 bis modes,
Automatic Rate Adaptation (ARA) can be enabled to
select the optimal highest acceptable data rate based
on the Eye Quality Monitor (EQM). This selection
occurs during startup.
Two ARA modes are available. ARA in ROM is an
adaptive selection made by the modem based upon a
fixed ROM table. ARA in RAM is based on the host
programmable RAM table and can be changed by the
user.
Data Encodi ng (-D / -D90)
The data encoding conforms to ITU-T
recommendations V.90 (-D90 only), V.34, V.32 bis,
V.32, V.17, V.29, V.27 ter, V.22 bis, V.22, V.23, or
V.21, and is compatible with Bell 208, 212A, or 103,
depending on the configuration.
Tone Generation and Supervisory Tone Detection
The modem can generate single or dual voice-band
tones from 0 Hz to 3600 Hz with a resolution of
0.15 Hz and an accuracy of ± 0.01%. Tones over
3000 Hz are attenuated. DTMF tone generation allows
the modem to operate as a programmable DTMF
dialer.
Three parallel tone detectors (A, B, and C) are
provided for supervisory tone detection. The signal
path to these detectors is separate from the main
received signal path.
Each tone detector consists of two cascaded second
order IIR biquad filters. The coefficients are host
programmable. Each fourth order filter is followed by a
level detector which has host programmable turn-on
and turn-off thresholds allowing hysteresis. A pre-filter
and squarer precede tone detector C. This circuit is
useful for detecting a tone with a frequency equal to
the difference between two tones that may be
simultaneously present on the line. The squarer may
be disabled by the SQDIS bit causing tone detector C
to be an eight-order filter. The tone detectors are
disabled in data mode.
The tone detection sample rate is 9600 Hz in V.8 and
V.34 modes and is 7200 Hz in non-V.34 modes. The
default call progress filter coefficients are based on a
7200 Hz sampling rate and apply to non-V.34 modes
only. The maximum detection bandwidth is equal to
one-half the sample rate.
Auto-Dialing and Auto-Answering Control
Features are provided to allow the host to perform
auto-dialing and auto-answering. These functions
include DTMF or pulse dialing, ring detection, and a
comprehensive supervisory tone detection scheme.
The major control parameters are host programmable.
Transmitted Data Spectrum
The transmitter spectrum is shaped by raised cosine
filter functions, either the square root of 12.5% (V.34,
V.32 bis, V.32), 20% (V.17 and V.29), 50% (V.27 ter,
Bell 208), or 75% (V.22 bis, Bell 212A).
Transmit Level
The transmitter output level is selectable from 0 dBm
to –15 dBm in 1-dB steps and is accurate to ±0.5 dB
when used with an external hybrid. The output level
can also be tuned by changing a gain constant in the
modem DSP RAM. The maximum V.34 transmit level
for acceptable receive performance should not exceed
–9 dBm.
Answer Tone (-D / -D90)
When the NV25 bit is a zero, the modem generates a
2100 Hz answer tone at the beginning of the answer
handshake for 5.0 seconds (V.8) or 3.6 seconds (V.32
bis, V.32, V.22 bis, V.22, V.23, and V.21). The answer
tone has 180° phase reversals every 0.45 seconds to
disable network echo cancellers (V.8, V.32 bis, V.32).
Receive Level
The modem satisfies performance requirements for
received line signal levels from 0 dBm to –43 dBm
measured at the receiver analog (TIP and RING) input
in V.17, V.29, V.27 ter, and DTMF modes. In V.90,
V.34, V.32 bis, V.32, V.22 bis, V.22, and V.23 modes,
the receive level range is from –9 dBm
(–15 dBm at RIN) to –43 dBm.