Dialogic Support Helpweb
Dialogic® DM3 & JCT Media Boards
Alternate Impedance and Gain settings for the DMV160LP and D/41JCT Boards
Problem Description:If you are installing and configuring an Dialogic DMV160LP or D/41JCT Analog Telephony board, be aware that the default settings are set to 600 ohms, which is sufficient for most PBX/Analog configurations. Check with your PBX administrator or Carrier supplier prior to configuring an analog board, to ensure it matches the 600 ohm setting avoiding an impedance mismatch. An impedance mismatch could produce symptoms such as excessive line echo, false interpretations of voice responses by an ASR speech engine, and 'self barge-in' by the system prompts
Solution Summary:
If you find you need to adjust the impedance settings for the DMV160LP or D/41JCT board, alternate settings are provided below for 900 ohm switches, using different Transmit and Receive gain values.
Technical Discussion:
DMV160LP Settings
- If you are using default configuration settings in your current .fcd file, select one of the alternate impedance choices below, choose the corresponding .fcd file in the attached .zip file, and place it in the Dialogic\Data directory. In the Dialogic Configuration Manager (DCM), double click on the board, highlight 'FCDFileName' in the 'Misc' Tab, enter the name of the new file in the 'Value' field, and then restart the board. The new values should take effect when the board drivers have been successfully started. The .config files are provided for informational purposes only.
- If you have previously modified the default .config file, it is recommended to add those previous changes to the selected .config file below, run fcdgen.exe to create a new .fcd file, and then place it in the Dialogic\Data directory. In the Dialogic Configuration Manager (DCM), double click on the board, highlight 'FCDFileName' in the 'Misc' Tab, enter the name of the new file in the 'Value' field, and then restart the board. The new values should take effect when the board drivers have been successfully started. In this case, the .config files are used to create a new .fcd file containing the new impedance settings along with your original changes.
DMV160LP alternate impedance choices
- DMV160LP_900a - 900 ohms resistive coefficient, Default Tx gain = +3db, Rx gain +3db
- DMV160LP_900b - 900 ohms resistive coefficient, Tx gain = +2db, Rx gain -1db
- DMV160LP_900c - 900 ohms resistive coefficient, Tx gain = 0db, Rx gain 0db
- DMV160LP_900d - 900 ohms resistive coefficient, Tx gain = -3db, Rx gain -3db
- DMV160LP_904 - 900 ohms resistive + 2uf coefficient, Default Tx gain = +3db, Rx gain +3db
- DMV160LP_904a - 900 ohms resistive + 2uf coefficient, Tx gain = +0db, Rx gain +0db
Select either impedance choice below, and place the corresponding .prm file in the Dialogic\Data directory. In the Dialogic Configuration Manager (DCM), double click on the board, highlight 'ParameterFile' in the 'Misc' Tab, and enter the name of the new file in the 'Value' field. To modify the Receive Gain, highlight 'ReceiveGain' in the Country Tab and choose from the following seven gain settings –
- RXGAIN_0 (no change in default gain)
- RXGAIN_N1 (decrease gain by 1 dB)
- RXGAIN_N2 (decrease gain by 2 dB)
- RXGAIN_N3 (decrease gain by 3 dB)
- RXGAIN_P1 (increase gain by 1 dB)
- RXGAIN_P2 (increase gain by 2 dB)
- RXGAIN_P3 (increase gain by 3 dB)
The impedance and gain settings will take effect when the board drivers have been successfully started.
D/41JCT alternate impedance choices
- ms_900.prm – 900 ohms resistive coefficient
- ms_cplex.prm – 900 ohms resistive +2uf coefficient
Impedence.zip
First Published:
04/30/04
Last Updated:
04/30/0
