QSLAC Rx Loss and Tx Gain Adjustment
The Rx (receive) Loss and Tx (transmit)
Gain discussed in this document are the loss and gain from the DSP (the signal
from the digital circuit, not the analog circuit), instead of the unit. Thus,
the Rx Loss (from the DSP) is actually the transmit loss of the unit and the Tx
gain (from the DSP) is the receive gain of the unit.
The purpose of this adjustment is to
increase the voice volume on the analog phone ports.
Use following command to adjust the
values. User has to save a reset the unit after the changes.
set qslac rxloss <phone port <digital dB>> <analog dB>
set qslac txgain <phone port> <digital dB> <analog dB>
save profile 1
reset
Use the following command to display the
current value:
get qslac <phone port>
In above commands:
phone port -- 1 to max phone port (2 or 4)
analog dB -- 0 or 6 (notice, it is 0 or 6, not 0 to 6)
digital dB -- 0 to 12 (this one is 0 to 12, incremented by 1)
by default all values are 0 (no
amplification or decrease of signal)
Increasing the Rx Loss (Receive Loss)
values will lower the volume on the unit. Default is 0, so user doesn't need to
increase the Rx Loss values if they are experiencing voice low problem.
Increasing the Tx Gain will increase the
Voice Volume of the unit. User may first only increase the "digital db
" value till 6 to see the effect. After 6, user may change the "analog
db" to 6 and start to increase the "digital db" from 1 to 12
again, since the effect is a result of the combination value of analog db and
digital db.
Increasing the analog db will amplify the undesired noise.
Increasing the digital db will introduce saturation and the result will be distorted voice.
User should try to find a set of values that provides satisfactory voice volume and acceptable noise level and distortion in the meanwhile.
User may use the following command to experiment with different value until find a set of satisfactory values and then use the "set" commands to change the values permanently. The values in the following command will take effect immediately without saving and resetting. However, the values will not longer work after a reset or shutdown of the unit.
test qslac rxloss <phone port> <digital dB> <analog dB>
test qslac txgain <phone port> <digital dB> <analog dB>
It is considered that adjusting the voice volume using these QSLAC gain and loss are better than adjusting the phone port Tx and Rx gains. QSLAC adjustment can be considered that the voice source itself is being amplified and adjusting the phone port analog gains can be considered as amplifying the analog output of the voice.
Like the Phone port Tx and Rx gain adjustment, increasing the QSLAC Tx gain too high (like 6, which means amplifying the signal by 2) will cause the unit not to accept (iGATE doesn’t recognize the tone anymore, due to the amplification) the DTMF tone dialed from the PSTN or a handset directly connected to the unit FXS port.
Normally, FXS volume should be OK and we recommend keep the default values. Adjust the values when experiencing lower voice volume when the call is routed to/from the PSTN through a FXO port.