Now, this post is not strictly speaking only about wanpipemon, in fact, most of the commands shown in this posts are executed using the companion tool “wan_ec_client”. It is important to note that “wan_ec_client” is a lower level tool than wanpipemon in the sense that it is meant to interact “directly” with the echo canceller.

The echo canceller can be set into 3 states:

* Powered Off

* Powered On – Normal Mode

* Powered On – Speech Recognition Mode

Powered Off means the actual hardware EC chip will be set in power off mode and therefore won’t be processing any audio at all.

Powered On is the normal status of the echo canceller if your wanpipe configuration contains the setting “HWEC_OPERATION_MODE   = OCT_NORMAL” (this is the default when using wancfg_dahdi or wancfg_fs to configure your environment).

This is how you can check the status of the echo canceller:

# wan_ec_client wanpipe1 stats

This should display the status of the echo canceller in all channels in span 1 (w1g1).

root@sigchld ~
# wan_ec_client wanpipe1 stats

wanpipe1: Running Get stats command to Echo Canceller device...	Done!

****** Echo Canceller Chip Get Stats wanpipe1 ******
  wanpipe1: Number of channels currently open			31
  wanpipe1: Number of conference bridges currently open		0
  wanpipe1: Number of playout buffers currently loaded		0
  wanpipe1: Number of framing error on H.100 bus		0
  wanpipe1: Number of errors on H.100 clock CT_C8_A		0
  wanpipe1: Number of errors on H.100 frame CT_FRAME_A		0
  wanpipe1: Number of errors on H.100 clock CT_C8_B		0
  wanpipe1: Number of internal read timeout errors		0
  wanpipe1: Number of SDRAM refresh too late errors		0
  wanpipe1: Number of PLL jitter errors				0
  wanpipe1: Number of HW tone event buffer has overflowed	0
  wanpipe1: Number of SW tone event buffer has overflowed	0
  wanpipe1: Number of SW Playout event buffer has overflowed	0

If you want statistics for a particular channel you can execute the ‘stats_full’ version

root@sigchld ~
# wan_ec_client wanpipe1 stats_full 1

wanpipe1: Running Get stats command to Echo Canceller device...	Done!

  wanpipe1: 1: Echo Channel Operation Mode			: POWER DOWN
  wanpipe1: 1: Enable Tone Disabler					: TRUE
  wanpipe1: 1: Mute Ports					: NONE
  wanpipe1: 1: Enable Extended Tone Detection				: FALSE
  wanpipe1: 1: Current Echo Return Loss				: Invalid
  wanpipe1: 1: Current Echo Return Loss Enhancement		: Invalid
  wanpipe1: 1: Maximum value of the ERL				: Invalid
  wanpipe1: 1: Maximum value of the ERLE			: Invalid
  wanpipe1: 1: Number of Echo Path changes			: 0
  wanpipe1: 1: Current Echo Delay				: Invalid
  wanpipe1: 1: Maximum Echo Delay				: Invalid
  wanpipe1: 1: Tone Disabler Status				: Enabled
  wanpipe1: 1: Voice activity is detected on SIN port		: TRUE
  wanpipe1: 1: Echo canceller has detected and converged	: TRUE
  wanpipe1: 1: Average power of signal level on RIN		: -69 dBm0
  wanpipe1: 1: Average power of signal level on SIN		: -207 dBm0
  wanpipe1: 1: Current gain applied to signal level on RIN	: 0 dB
  wanpipe1: 1: Current gain applied to signal level on SOUT	: 0 dB
  wanpipe1: 1: Average power of the comfort noise injected	: -207 dBm0
  wanpipe1: 1: (TDM) PCM Law type on SIN			: ALAW
  wanpipe1: 1: (TDM) TDM timeslot on SIN port			: 0
  wanpipe1: 1: (TDM) TDM stream on SIN port			: 6
  wanpipe1: 1: (TDM) PCM Law type on RIN			: ALAW
  wanpipe1: 1: (TDM) TDM timeslot on RIN port			: 0
  wanpipe1: 1: (TDM) TDM stream on RIN port			: 4
  wanpipe1: 1: (TDM) PCM Law type on SOUT			: ALAW
  wanpipe1: 1: (TDM) TDM timeslot on SOUT port			: 0
  wanpipe1: 1: (TDM) TDM stream on SOUT port			: 7
  wanpipe1: 1: (TDM) PCM Law type on ROUT			: ALAW
  wanpipe1: 1: (TDM) TDM timeslot on ROUT port			: 0
  wanpipe1: 1: (TDM) TDM stream on ROUT port			: 5
  wanpipe1: 1: (VQE) NLP status					: TRUE
  wanpipe1: 1: (VQE) Enable Tail Displacement			: FALSE
  wanpipe1: 1: (VQE) Offset of the Echo Cancellation window (ms)	: 0
  wanpipe1: 1: (VQE) Maximum tail length			: 128 ms
  wanpipe1: 1: (VQE) Rin Level control mode			: TRUE
  wanpipe1: 1: (VQE) Rin Control Signal gain			: 0 dB
  wanpipe1: 1: (VQE) Sout Level control mode			: TRUE
  wanpipe1: 1: (VQE) Sout Control Signal gain			: 0 dB
  wanpipe1: 1: (VQE) RIN Automatic Level Control		: FALSE
  wanpipe1: 1: (VQE) RIN Target Level Control			: -20 dBm0
  wanpipe1: 1: (VQE) SOUT Automatic Level Control		: FALSE
  wanpipe1: 1: (VQE) SOUT Target Level Control			: -20 dBm0
  wanpipe1: 1: (VQE) Comfort noise mode				: NORMAL
  wanpipe1: 1: (VQE) Remove any DTMF tone detection on SIN port	: FALSE
  wanpipe1: 1: (VQE) Acoustic Echo				: FALSE
  wanpipe1: 1: (VQE) Non Linearity Behavior A			: 1
  wanpipe1: 1: (VQE) Non Linearity Behavior B			: 0
  wanpipe1: 1: (VQE) Double Talk algorithm			: NORMAL
  wanpipe1: 1: (VQE) Default ERL (not converged)		: -6 dB
  wanpipe1: 1: (VQE) Acoustic Echo Cancellation default ERL	: 0 dB
  wanpipe1: 1: (VQE) Maximum Acoustic Echo tail length		: 128 ms
  wanpipe1: 1: (VQE) Attenuation Level applied to the noise signal	: -18 dB
  wanpipe1: 1: (VQE) Silence period before the re-activation of VQE features	: 1836 ms
  wanpipe1: 1: (CODEC) Encoder channel port			: SOUT
  wanpipe1: 1: (CODEC) Encoder rate				: G.711 64 kBps
  wanpipe1: 1: (CODEC) Decoder channel port			: RIN
  wanpipe1: 1: (CODEC) Decoder rate				: G.711 64 kBps

You can completely shut down the EC operation on a given channel (you most likely don’t want to do this unless you know what you’re doing)

wan_ec_client wanpipe1 mpd 1

This puts the channel 1 echo canceller in “power down” mode (mpd as in ‘Mode Power Down’)

As you guessed probably already, the other modes are ‘mn’ for  and ‘msr ‘ for ‘Mode Normal’ and ‘Mode Speech Recognition’ respectively.

wan_ec_client wanpipe1 mn 1

wan_ec_client wanpipe1 msr 1

Instead of disabling the echo canceller you can enable/disable the bypass functionality. Confusingly, “bypass enable” means that audio goes through the echo canceller, whereas “bypass disable” means audio skips the echo canceller path (but the EC is still turned on). This is due to historical reasons and due to giving low-level programmers too much freedom naming commands

The bypass commands are actually working at the FPGA level. When the bypass is enabled, the FPGA bridges the audio through the echo canceller first before sending it to the driver. When the bypass is disabled the audio is not bridged through the echo canceller. Simple hu?

root@sigchld ~
# wan_ec_client wanpipe1 bd all
wanpipe1: Running Disable bypass command to Echo Canceller device...    Done!

You can verify with wanpipemon that the EC is “disabled” (bypass disabled).

root@sigchld ~
# wanpipemon -i w1g1 -c ehw
Sangoma HW Echo Canceller is disabled for all channels!

Now enable the bypass back.

root@sigchld ~
# wan_ec_client wanpipe1 be all
wanpipe1: Running Enable bypass command to Echo Canceller device...     Done!

root@sigchld ~
# wanpipemon -i w1g1 -c ehw

Sangoma HW Echo Canceller is enabled for channel 0
Sangoma HW Echo Canceller is enabled for channel 1
Sangoma HW Echo Canceller is enabled for channel 2
Sangoma HW Echo Canceller is enabled for channel 3
Sangoma HW Echo Canceller is enabled for channel 4
Sangoma HW Echo Canceller is enabled for channel 5
Sangoma HW Echo Canceller is enabled for channel 6
Sangoma HW Echo Canceller is enabled for channel 7
Sangoma HW Echo Canceller is enabled for channel 8
Sangoma HW Echo Canceller is enabled for channel 9
Sangoma HW Echo Canceller is enabled for channel 10
Sangoma HW Echo Canceller is enabled for channel 11
Sangoma HW Echo Canceller is enabled for channel 12
Sangoma HW Echo Canceller is enabled for channel 13
Sangoma HW Echo Canceller is enabled for channel 14
Sangoma HW Echo Canceller is enabled for channel 15
Sangoma HW Echo Canceller is enabled for channel 16
Sangoma HW Echo Canceller is enabled for channel 17
Sangoma HW Echo Canceller is enabled for channel 18
Sangoma HW Echo Canceller is enabled for channel 19
Sangoma HW Echo Canceller is enabled for channel 20
Sangoma HW Echo Canceller is enabled for channel 21
Sangoma HW Echo Canceller is enabled for channel 22
Sangoma HW Echo Canceller is enabled for channel 23
Sangoma HW Echo Canceller is enabled for channel 24
Sangoma HW Echo Canceller is enabled for channel 25
Sangoma HW Echo Canceller is enabled for channel 26
Sangoma HW Echo Canceller is enabled for channel 27
Sangoma HW Echo Canceller is enabled for channel 28
Sangoma HW Echo Canceller is enabled for channel 29
Sangoma HW Echo Canceller is enabled for channel 30
Sangoma HW Echo Canceller is enabled for channel 31

That’s it for today folks, next time you want to debug echo issues, noise on the lines, distortion etc, it’s a good idea to rule out the echo canceller using the commands described in this post.

It is sometimes required to analyze protocol messages in a given link in order to troubleshoot call problems. Wanpipemon makes possible to create a pcap file with all D-channel data which can then be examined using Wireshark.

What makes it so convenient is that this method is independent from the application you’re using (Asterisk, FreeSWITCH or whatever). You basically have the capability to tap into the D-channel, pretty much like using tcpdump to monitor TCP/IP traffic.

wanpipemon -i w1g1 -pcap -pcap_file isdn.pcap -prot ISDN -full -systime -c trd

You can refer to the Sangoma Wiki for other details (and SS7 tracing commands too): http://wiki.sangoma.com/wanpipe-wireshark-pcap-pri-bri-wan-t1-e1-tracing

Next time your D-channel link does not come up, fire up wanpipemon and take a look in Wireshark to what’s going on!

This time I’ll show you how to check whether an FXO line is plugged into the the card via the command line. You can also check if the FXO is OnHook (http://en.wikipedia.org/wiki/On-hook) or OffHook (http://en.wikipedia.org/wiki/Off-hook)

In order to check the analog status for a given analog channel in a Sangoma card you can do the following:

# wanpipemon -i w1g1 -c astats -m 1

The -i option is used in most commands to specify the wanpipe interface in which will be run. You can find your wanpipe interfaces using ifconfig, normally they are named in the form “wXg1”.

The -c option is used to specify the command to run in the given interface.

The -m is used to specify the analog channel.

Typical output for an FXO channel not connected will be:

root@sigchld:/home/moy # wanpipemon -i w1g1 -c astats -m 4

        ------- Voltage Status  (FXO,port 3) -------

VOLTAGE : 1 Volts

        ------- Line Status  (FXO,port 3) -------

Line    : disconnected

The voltage comes handy if you want to check if the line is OnHook or OffHook. The typical voltage when the line is connected and OnHook is around 53, 53 volts. When the line is OffHook and the circuit is closed, the voltage drops to 8, 9 volts.

Even when the output of the command tells you if the line is connected or not, you can also appreciate that the voltage is very low when the line is not connected (1 volt is reported in this case).