Hi All - I hope somebody can clarify for me what exactly fxotune does, and how it is related to gain settings. I've been reading what appears to be conflicting information from various sources. I've got a box with an AEX800 with 6 lines (from Qwest) running asterisk and zaptel versions 1.4.20.1 and 1.4.11 respectively. We've been experiencing some echo/quality issues on certain calls which seem to happen on all 6 of the lines. I manually calibrated the rxgain/txgain using ztmonitor and a milliwatt test line to the somewhat improbable levels of +10.0/-2.0 (about the same for all 6 lines). These settings yield acceptable call volumes, but echo and noise are problems. If I run fxotune, it gives me the following numbers: 1=10,0,0,0,0,0,0,0,0 2=12,0,0,0,0,0,0,0,0 3=12,0,0,0,0,0,0,0,0 4=10,0,0,0,0,0,0,0,0 5=10,0,0,0,0,0,0,0,0 6=10,0,0,0,0,0,0,0,0 Two questions here: 1) What do these numbers mean? Are they in any way related to either rxgain or txgain? 2) Am I supposed to set rxgain and txgain back to 0 if I use fxotune -s? If I do use these fxotune settings and set rxgain and txgain to zero, the volume on incoming zap calls is almost too low to be heard, but echo issues seem to be solved. Do I have to choose between 1) acceptable call volume with echo or 2) super-quiet call volume without echo? Should I petition Qwest to install a repeater? Thanks, Noah
In short, fxotune adjusts line impedance, where as adjusting gains I believe is essentially adjusting the amplification / deamplification of the signal. http://www.voip-info.org/wiki/view/Asterisk+fxotune -- Matt Watson http://www.mattgwatson.ca On June 6, 2008 12:43:51 am Noah Miller wrote:> Hi All - > > I hope somebody can clarify for me what exactly fxotune does, and how > it is related to gain settings. I've been reading what appears to be > conflicting information from various sources. > > I've got a box with an AEX800 with 6 lines (from Qwest) running > asterisk and zaptel versions 1.4.20.1 and 1.4.11 respectively. We've > been experiencing some echo/quality issues on certain calls which seem > to happen on all 6 of the lines. I manually calibrated the > rxgain/txgain using ztmonitor and a milliwatt test line to the > somewhat improbable levels of +10.0/-2.0 (about the same for all 6 > lines). These settings yield acceptable call volumes, but echo and > noise are problems. > > If I run fxotune, it gives me the following numbers: > > 1=10,0,0,0,0,0,0,0,0 > 2=12,0,0,0,0,0,0,0,0 > 3=12,0,0,0,0,0,0,0,0 > 4=10,0,0,0,0,0,0,0,0 > 5=10,0,0,0,0,0,0,0,0 > 6=10,0,0,0,0,0,0,0,0 > > Two questions here: > > 1) What do these numbers mean? Are they in any way related to either > rxgain or txgain? > 2) Am I supposed to set rxgain and txgain back to 0 if I use fxotune -s? > > If I do use these fxotune settings and set rxgain and txgain to zero, > the volume on incoming zap calls is almost too low to be heard, but > echo issues seem to be solved. > > Do I have to choose between 1) acceptable call volume with echo or 2) > super-quiet call volume without echo? Should I petition Qwest to > install a repeater? > > > Thanks, > Noah > > _______________________________________________ > -- Bandwidth and Colocation Provided by http://www.api-digital.com -- > > asterisk-users mailing list > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users
Hi Matt -> In short, fxotune adjusts line impedance, where as adjusting gains I believe > is essentially adjusting the amplification / deamplification of the signal. > > http://www.voip-info.org/wiki/view/Asterisk+fxotuneWell, that clears it up a little. I think where I get confused is that sometimes using fxotune is called balancing the hybrid and some times using ztmonitor and adjusting the txgain/rgain settings is called balancing the hybrid. Perhaps they both try to achieve the same goal, but through different means? This leads me to my other question - Are these two techniques mutually exclusive? In some posts from Matthew Frederickson, it seems that they are, and that if you use fxotune, you should set your gains back to zero. Some other people seem to suggest using both fxotune and adjusting gain levels. I note that Stephen Bosch asked just this question some time back, and nobody was able to answer him. Does anybody know? Thanks, Noah
Noah Miller wrote:> Well, that clears it up a little. I think where I get confused is > that sometimes using fxotune is called balancing the hybrid and some > times using ztmonitor and adjusting the txgain/rgain settings is > called balancing the hybrid. Perhaps they both try to achieve the > same goal, but through different means?Not quite. Gain adjustment affects volume levels of the respective direction you are adjusting (echo and all). Balancing the hybrid via fxotune attempts to balance the hybrid in a manner so that the hybrid will remove as much of the echo as possible.> This leads me to my other question - Are these two techniques mutually > exclusive? In some posts from Matthew Frederickson, it seems that > they are, and that if you use fxotune, you should set your gains back > to zero. Some other people seem to suggest using both fxotune and > adjusting gain levels. I note that Stephen Bosch asked just this > question some time back, and nobody was able to answer him.These techniques are not mutually exclusive, I usually want people to use gain modification as the last step in trying to eliminate echo (after balancing the hybrid and making sure you are using a good echo canceller). In the case of running fxotune, your zapata.conf software gain levels should not affect its operation. If you are using any of the hardware gain settings (wctdm24xxp module parameters) you should normalize those to 0 beforehand so that they do not interfere with the calibration process. -- Matthew Fredrickson Software/Firmware Engineer Digium, Inc.