Echo Issues

Hello all,

I’m having some echo problems that I’d like to get rid of. So far the staff is being patient with me but I don’t expect that to last forever.

I have a TDM2400P with the hardware echo cancellation card. The connections to the CO lines are 4 foot runs from the 66 block into the 24 port patch panel sold by digium.

I have individualy set the tx/rx gain on each channel to balance them out and run fxotune, but I’m still getting some really obnoxious echo on random lines. The echo is usually most prevalent at the start of a call but can start in the middle of a conversation and typically lasts about 15 seconds but has been reported to last for several minutes on a couple of occasions.

After a reboot of the box I typically login, stop Asterisk, and then run fxotune -s and then restart Asterisk.

I have the following at the top of the [channels] section of chan_dahdi.conf:

echocancel=yes
echotraining=yes
echocancelwhenbridged=yes

My questions are:

  1. Should I include the ‘echocancel’ directives on each channel?

  2. Are there any other directives I can/should include?

  3. How do I automate the fxotune -s command to run if the box has to be rebooted? (CentOS 5.2)

Any nuggets of wisdom would be appreciated.

Howdy,

What version of the DAHDI software are you using?

We’ve recently introduced a new firmware load for the VPMADT032 module that provides substantial improvements to the echo cancellation in many situations. This firmware load, and the associated changes required to use it, are a part of DAHDI 2.2.1.

Cheers.

Look at oslec
rowetel.com/ucasterisk/oslec.html

I have the same problem.
At the beginning of a call (and sometimes during the call) i can hear an echo.

I’m using TDM400P board(port 1- fxo, port 2,3,4 - fxs), i have echocancel=yes option in /etc/asterisk/chan_dahdi.conf file.
I have the vpmadt032 hardware cancellation module.

I enabled echotraining (but i discovered that is not useful for hardware echo cancellation module).

I tried using dahdi_monitor tool, calling a 1004 Hz tone generated with Milliwatt() (and also Playtones(1004/1000) ) applications and tuning the 14844 value with rx and tx gain.

I tried using fxotune.

I tried the 2.2.1 dahdi driver.

I continue hearing the echo…

Does oslec works with the vpmadt032 hardware module?

Any other suggestion?

Hello giorgio80,

Please open a case with our technical support group if you have not already done so. If the VPMADT032 is enabled, configured properly, not functioning abnormally otherwise, and using the latest DAHDI 2.2.1 drivers, we’d like to get audio captures of the echo that you’re experiencing.

Our support group may be contacted via the links here:

digium.com/support

Cheers.

Hi malcolmd, thanks for your tip.

Now I’m triing using lower tx volume (txgain -9.0 in chan_dahdi.conf), without according with the dahdi_monitor 14880 suggested values.
So i have less echo.
Now I’m testing the system.
If the called party can hear me fine I hope I solved.
If it isn’t I’ll contact the digium support.

I just opened another post about dahdi_test accuracy results… could echo problems be related to bad accuracy?

Howdy,

What does the kernel dmesg output say about the latency for which your card is programmed while it’s operating? The 128 setting is a maximum setting and the card should bump itself by 1ms increments if it finds other devices are hogging interrupt time.

I think latency is 64.

This is the dmesg output about dahdi driver, there isn’t indications about latency.

dahdi: Telephony Interface Registered on major 196
dahdi: Version: 2.2.1
Port 1: Installed – AUTO FXO (FCC mode)
Port 2: Installed – AUTO FXS/DPO
Port 3: Installed – AUTO FXS/DPO
Port 4: Installed – AUTO FXS/DPO
VPM100: Not Present
dahdi_vpmadt032_loader: module license ‘Digium Commercial’ taints kernel.
wctdm24xxp 0000:01:08.0: Booting VPMADT032
VPMADT032: Present and operational (Firmware version 120)
Found a Wildcard TDM: Wildcard TDM410P (4 modules)
dahdi: Registered tone zone 0 (United States / North America)
dahdi: Registered tone zone 11 (Italy)
– Setting echo registers:
– Set echo registers successfully

This is the lspci -v output about digium card, is here the latency value?

01:08.0 Ethernet controller: Digium, Inc. TDM400P (rev 11)
Subsystem: Digium, Inc. TDM400P
Flags: bus master, medium devsel, latency 64, IRQ 10
I/O ports at a000 [size=256]
Memory at ed000000 (32-bit, non-prefetchable) [size=1K]
[virtual] Expansion ROM at 88000000 [disabled] [size=128K]
Capabilities: [c0] Power Management version 2

Hi

Looking at your tonezone you are not in the US but italy

Your card is set for US impedance and line

you need to set the opermode to what ever the Italian setting is.

Ian

Malcolmd,

I apologize for the long delay in the response.

I upgraded to the 2.2.1 version of DAHDI and it didn’t seem to help. Even after an fxotune -i? to train all of the lines and running fxotune -s after DAHDO loads but before asterisk.

Below is an extract from dmsg on the last load:

dahdi: Telephony Interface Registered on major 196 dahdi: Version: 2.2.1 ACPI: PCI Interrupt 0000:04:02.0[A] -> GSI 18 (level, low) -> IRQ 233 Port 1: Installed -- AUTO FXO (FCC mode) Port 2: Installed -- AUTO FXO (FCC mode) Port 3: Installed -- AUTO FXO (FCC mode) Port 4: Installed -- AUTO FXO (FCC mode) Port 5: Installed -- AUTO FXO (FCC mode) Port 6: Installed -- AUTO FXO (FCC mode) Port 7: Installed -- AUTO FXO (FCC mode) Port 8: Installed -- AUTO FXO (FCC mode) Port 9: Installed -- AUTO FXO (FCC mode) Port 10: Installed -- AUTO FXO (FCC mode) Port 11: Installed -- AUTO FXO (FCC mode) Port 12: Installed -- AUTO FXO (FCC mode) Port 13: Installed -- AUTO FXO (FCC mode) Port 14: Installed -- AUTO FXO (FCC mode) Port 15: Installed -- AUTO FXO (FCC mode) Port 16: Installed -- AUTO FXO (FCC mode) Port 17: Installed -- AUTO FXO (FCC mode) Port 18: Installed -- AUTO FXO (FCC mode) Port 19: Installed -- AUTO FXO (FCC mode) Port 20: Installed -- AUTO FXO (FCC mode) Port 21: Installed -- AUTO FXS/DPO Port 22: Installed -- AUTO FXS/DPO Port 23: Installed -- AUTO FXS/DPO Port 24: Installed -- AUTO FXS/DPO VPM100: Not Present dahdi_vpmadt032_loader: module license 'Digium Commercial' taints kernel. wctdm24xxp 0000:04:02.0: Booting VPMADT032 VPMADT032: Present and operational (Firmware version 120) Found a Wildcard TDM: Wildcard TDM2400P (24 modules) dahdi: Registered tone zone 0 (United States / North America) -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully -- Setting echo registers: -- Set echo registers successfully

I enabled the MG2 software echo canceller which has helped a lot but we’ve now started experiencing DTMF detection issues.

Are there any special configuration directives I need to put in either system.conf or chan_dahdi.conf for the hardware echo canceller?

Thanks for your help,


Michael Sheldon

Howdy,

Please contact our support team using the links at:

digium.com/support

Cheers.

Hi,

If you are unable to resolve the echo using Asterisk’s built-in AEC, you can always resolve it via a commercial
solution. For example, you can try the PBXMate product.

Hope this helps,
Valer