[asterisk-users] digium HW echocancellation - fax tone detection

[Tim Nelson]

----- "Johann Steinwendtner" <steinwendtner at gmx.net> wrote:
> Hello !
> 
> I 'm using a TE405P with a HW echocanceller module attached on it.
> dahdi version is dahdi-linux-complete-2.2.0.2+2.2.0.
> 
> As far as I know, the fax tone detection is done on the FW board.
> How can I verify that the echo canceller has been turned off ?
> 
> When I do a cat /proc/dahdi/1 for span 1 I see still the VPM450 entry
> near the channel although this was a fax call with CED tone.
> 
> 	   1 TE4/0/1/1 Clear (In use) (EC: VPM450M)
> 
> Greping through the source, i see only a CED tone detection
> entry in:
> 
> static const struct dahdi_echocan_features vpm450m_ec_features = {
>          .NLP_automatic = 1,
>          .CED_tx_detect = 1,
>          .CED_rx_detect = 1,
> };
> 
> Does it mean that CNG tone is not going to be detected ?
> Does the CED tone detection routine also detect ANSam tone for Super
> G3 fax ?
> 

Check your '/var/log/messages' or run 'dmesg'. It should say something like this if the tone is detected and appropriate action taken:

dahdi: Disabled echo canceller NLP because of CED rx detected on channel 97

--Tim