SI2493-C-GT Silicon Laboratories Inc, SI2493-C-GT Datasheet - Page 190

• Manufacturer Part Number: SI2493-C-GT
• Description: IC ISOMODEM SYSTEM-SIDE 24TSSOP
• Manufacturer: Silicon Laboratories Inc

Specifications of SI2493-C-GT

• Mfg Application Notes: SI2493/57/34/15/04, Appl Note AN93
• Data Format: V.21, V.22, V.23, V.29, V.32, V.34, V.90, V.92, Bell 103, Bell 212A
• Baud Rates: 56k
• Interface: Parallel
• Voltage - Supply: 3 V ~ 3.6 V
• Mounting Type: Surface Mount
• Package / Case: 24-TSSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AN93
When to Use Audio Recording
This technique is best used when the modem appears
to connect normally against some servers but does not
connect well when calling a specific server or modem.
This implies the hardware is functional and the issues
most likely involve the negotiations between the
modems during connect and retrain.
One way to rule out the possibility of a hardware issue is
to call the server or modem where the connect issue is
found using the Silabs EVB module.
Times When Audio Recording May Not
Help
Some signals are exceptions and cannot be monitored
in this way due to the limits of the bandwidth examined.
Examples are the dc voltage and currents that exist
during both on- and off-hook conditions, precise details
of the pulse dialing waveforms, and most EMI signals.
These EMI signals, which are not visible during the
recordings, may produce in-band demodulated and
190
The larger of the
two jacks (3.5 mm)
carries audio to
the PC
Figure 52. Hardware Setup
Rev. 0.9
cross product signals in the modem.
Some in-band signals cannot be easily monitored this
way because they are common mode signals. While
they may be less visible to the recording apparatus,
they can be received by the modems in some cases. An
example of this is a strong common mode 50 or 60 Hz
hum with its harmonics (a 50 or 60 Hz buzz).
Hardware Setup
The Radio Shack Catalog No. 43-228A "Recorder
Control" contains a transformer that bridges the phone
line with a dc blocking capacitor, as well a voice-
operated switch output that starts and stops a recording
device. We only use one of the output connectors since
we are not interested in the VOX mechanism. Connect
the Audio output connector (a 3.5 mm O.D. connector)
to the microphone input socket at the back of the PC.
The RJ11 connector from the "Recorder Control" should
be connected to the tip and ring of the phone line being
monitored.
Connect the R11
jack “in parallel”
with Tip/Ring of
modem