Well, it's fixed, and here's the scoop: After looking into it and fooling with it (and trying not to cuss it) I've determined that the card is a generic that's compatible with the module for the 410, but does not have the headers for the hardware echo module. It's physically laid out like a 400P.
The echo turns out to be pretty standard hybrid imbalance with a twist - since we're using Comcast Digital Voice, the hybrid is only about 20' of cable away. This gives the MG2 echo canceler fits. Also, it turns out [b]fxotune[/b] wasn't really able to calibrate, because the delay between sending a digit and the fast busy signal, in which you have silence, isn't a nice 18 seconds like with the PSTN. It's about 3.5 seconds.
I was able to find a local miliwatt test number that went to silent after 8 seconds, so I used that for [b]fxotune[/b]. That helped alot, probably cut the level of the echo in half. But there was still some echo until I switched to HPEC. Best $20 (for two channels) I've spent on this whole system.
The whole reason I'm writing this is this: If anyone else is having problems with where to put the echo cancelation commands when you're using FreePBX (the lines you'd normally put in [b]chan_dahdi.conf[/b] if you weren't using FreePBX), they have to go in [b]chan_dahdi_channels_custom.conf[/b]. When I tried to put them in [b]chan_dahdi_general_custom.conf[/b] they had no effect. I couldn't find that information anywhere. Maybe I wasn't searching well enough, or maybe I should have known that from the layout of the default Asterisk [b]chan_dahdi.conf[/b] file, but if anyone else runs into this problem, may google send them here.
It's possible that I didn't need HPEC and OSLEC would have worked, if I'd known how to turn it on in Asterisk with FreePBX. But what worked for me was to use these settings in [b]chan_dahdi_channels_custom.conf[/b] (after building, registering, and enabling HPEC, of course):
[code]echocancel=1024
echocancelwhenbridged=no
echotraining=800
rxgain=3.0
txgain=0.0[/code]
I also manually edited [b]/etc/dahdi/system.conf[/b] to reflect:
[code]# Span 1: WCTDM/0 "Wildcard TDM410P" (MASTER)
fxsks=1
echocanceller=hpec,1
fxsks=2
echocanceller=hpec,2
fxsks=3
echocanceller=kb1,3
fxsks=4
echocanceller=kb1,4[/code]
rather than having all four channels on HPEC - as it comes out of [b]dahdi_genconf[/b] - since I only purchased two HPEC channel licenses and the other two channels aren't used anyway.
And, if anyone is interested, running HPEC at 1024 taps with one active channel barely nudges a 2.8GHz Pentium D to 2% CPU usage.
Well, it’s fixed, and here’s the scoop: After looking into it and fooling with it (and trying not to cuss it) I’ve determined that the card is a generic that’s compatible with the module for the 410, but does not have the headers for the hardware echo module. It’s physically laid out like a 400P.
The echo turns out to be pretty standard hybrid imbalance with a twist - since we’re using Comcast Digital Voice, the hybrid is only about 20’ of cable away. This gives the MG2 echo canceler fits. Also, it turns out fxotune wasn’t really able to calibrate, because the delay between sending a digit and the fast busy signal, in which you have silence, isn’t a nice 18 seconds like with the PSTN. It’s about 3.5 seconds.
I was able to find a local miliwatt test number that went to silent after 8 seconds, so I used that for fxotune. That helped alot, probably cut the level of the echo in half. But there was still some echo until I switched to HPEC. Best $20 (for two channels) I’ve spent on this whole system.
The whole reason I’m writing this is this: If anyone else is having problems with where to put the echo cancelation commands when you’re using FreePBX (the lines you’d normally put in chan_dahdi.conf if you weren’t using FreePBX), they have to go in chan_dahdi_channels_custom.conf. When I tried to put them in chan_dahdi_general_custom.conf they had no effect. I couldn’t find that information anywhere. Maybe I wasn’t searching well enough, or maybe I should have known that from the layout of the default Asterisk chan_dahdi.conf file, but if anyone else runs into this problem, may google send them here.
It’s possible that I didn’t need HPEC and OSLEC would have worked, if I’d known how to turn it on in Asterisk with FreePBX. But what worked for me was to use these settings in chan_dahdi_channels_custom.conf (after building, registering, and enabling HPEC, of course):
echocancel=1024
echocancelwhenbridged=no
echotraining=800
rxgain=3.0
txgain=0.0
I also manually edited /etc/dahdi/system.conf to reflect:
# Span 1: WCTDM/0 "Wildcard TDM410P" (MASTER)
fxsks=1
echocanceller=hpec,1
fxsks=2
echocanceller=hpec,2
fxsks=3
echocanceller=kb1,3
fxsks=4
echocanceller=kb1,4
rather than having all four channels on HPEC - as it comes out of dahdi_genconf - since I only purchased two HPEC channel licenses and the other two channels aren’t used anyway.
And, if anyone is interested, running HPEC at 1024 taps with one active channel barely nudges a 2.8GHz Pentium D to 2% CPU usage.
