Maxim Integrated Teridian V.22 bis Linux Softmodem for 73M1822/73M1922 MicroDAA - Manual (Page 55)

UG_1x22_043 V.22 bis Linux Softmodem for 73M1x22 MicroDAA User Guide
Rev. 1.5 55
Resetting the TSC Softmodem
A reset of the TSC Softmodem can be performed three different ways:
• A power-on reset
• Reset Button (similar to power on reset)
• Start the soft modem from Linux prompt
Call Progress Detection
The TSC Softmodem has expanded call progress detection capabilities. In addition to the
capability of detecting some precise tones (see S19), the TSC Softmodem implements
some imprecise call progress capabilities (wide frequency bandwidth filters). Each call
progress tone can be monitored and validated according to the following parameters:
• Frequency
• Level
• Cadence
The TSC Softmodem has 4 preset frequency filters. At least one range of frequencies will
meet the requirements for call progress detection worldwide. The selection of the filter that
will apply during either the pre-dial phase (dial tone) or during the post-dial phase (busy
tone) is made through the Imprecise filter template register, S88.
The detection bandwidth of the preset filters are:
• 280Hz √ 680Hz
• 370Hz √ 500Hz
• 240Hz √ 580Hz
• 200Hz √ 650Hz
In addition, it is possible for a user defined frequency filter. Contact your local TERIDIAN
representative for further details on that function.
Once the frequency filter has been chosen, the threshold of detection needs to be set
through registers S75 and S76. Due to the variety of requirements for different countries,
there is the provision to select a different threshold for both the pre dial and post dial
phase. The range of detection thresholds allowed are from –25dBm down to –60dBm.
Please note that level detection results may vary due to different line interface
implementations.
After the frequency ranges have been selected, the last step is to select the proper
cadence of the call progress tones we are about to detect. The TSC Softmodem features
an expanded support for cadence detection in order to meet requirements worldwide.
There are four different types of cadences defined in the TSC Softmodem. Each parameter
for those cadences can be selected by the user to modify the detection criteria.