Echo from C20

[Luke Sykes]

Good Afternoon

I have a customer who is having an issue with their c20 installation.

For some reason the codec keeps ramping up the gain on the microphone until the audio begins to echo, then when the customer talks directly into the microphone the gain goes down, but once again is starts ramping up the gain.

Perhaps the codec doesnt close the microphone at the end of a sentence when speaking at a normal level as you would in a videoconference.

The codecs firmware version is TC5.1.3

Is there a bug in this firmware version that causes this?

They have two microphones connected to the codec. We have tested the system with just one microphone connected and this does not resolve the problem.

There is an airconditioning system in the room but this is not directly above where the microphone sits, and the problem persists whether the A/C system is switched on of off anyway.

Is there anything else I can try?

Many thanks

Luke

[david.sharp]

Hi

just to expand on this as I worked with Luke on this issue.

The problem appears to be that the AEC built into the codec doesn't appear to be working very well, what we noticed whilst testing is that the audio could be heard back very muffled but there was certainly echo there.

We have checked the screen settings to ensure that there are no audio processing functions which could cause a delay in the audio playback but noticed the following.

when the room is quiet there is a quite hum from an air conditioning unit, that persons in the room can hear, this hum would not be disruptive to a meeting but is certainly noticeable when listened for.

when the person at the far side (the room where the C20 is) remained quite the pickup on the microphones appeared to ramp right up as if the microphones was attempting to listen to the aircon and transmit this to the far side.

Whilst the person was quiet in the room we could hear the constant hum from the background noise, but when the person spoke directly into the microphone which I expect would have caused the gain to drop (and it appeared to do so) the audio then sounded ok, I was not hearing myself echo back, then spend a few moments completely silent again and the gain on the microphones appeared to ramp up very quickly at which point I could hear myself echo back muffled again.

what I would normally do, if using a digital mixer or an integrator codec at this stage would be to disabled AGC and manually adjust the level of the microphones to a suitable level.

whilst I don't think this is an issue strictly with audio leveling I suspect that when the gain ramps up the AEC isn't performing as effectively as it can do so.

so the question is, what can we do with this C20, without looking at environmental changes.

Cheers

Dave

Think with Portals

[mubakhta]

Hi David & Luke,

I have created a document for checking all the necessary things for Echo Issues. Can you go through the document and let us know what all things have been performed so far.

Here's the link to the document:

https://supportforums.cisco.com/docs/DOC-24155

Please share the results of the operation.

Regards,

Mubashshir Akhtar

[david.sharp]

Hi Mubashshir

thanks for pointing us in the right direction, when I was looking at the audio settings I was looking for the very same as mentioned in the document about disabling any advanced video processing which could cause a delay to the audio.

we are planning on taking a look at this on Friday 14/09/2012 shall let you know the results, hopefully adjusting the ECreferencedelay or disabling any audio processing on the screen will have the desired effect.

Cheers

Dave

Think with Portals

[mubakhta]

Hi Dave,

It is possible that you do not get any positive results after following the two steps that you have mentioned. Those two steps are applicable for codecs that have Echo Cancellation Engine. That particular engine is not available on C20. Hence, checking Audio processing or increasing the delay might not provide you the desired behavior. I recommend checking these things:

Check if the customer is using external speakers as well as speakers on the display. If he is using speakers on the display, turn them OFF :

xConfiguration Audio Output HDMI 1 Mode: Off

 Check the customer’s room setup and microphones being used. Unidirectional microphones take input from one direction however, Omnidirectional take input from all directions:

Unidirectional Microphone

Omnidirectional Microphone

 Try to swap the microphone ports to see if that changes the situation.

 At this point, swap the codec with any spare codec to see if that fixes the issue; if yes then proceed with the RMA for the faulty codec.

 Often the echo issue does not get resolved by replacing the codec. If any of the above steps do not work, then convince the customer to have sound absorbing objects in the conference room (plants, curtains) and avoid having glass objects which would reflect the sound waves within the room.

Regards,

Mubashshir Akhtar

[david.sharp]

Hi Mubashshir

In response to your points above.

Check if the customer is using external speakers as well as speakers on the display. If he is using speakers on the display, turn them OFF :

xConfiguration Audio Output HDMI 1 Mode: Off

 Check the customer’s room setup and microphones being used. Unidirectional microphones take input from one direction however, Omnidirectional take input from all directions:

Unidirectional Microphone

Omnidirectional Microphone

 Try to swap the microphone ports to see if that changes the situation.

 At this point, swap the codec with any spare codec to see if that fixes the issue; if yes then proceed with the RMA for the faulty codec.

 Often the echo issue does not get resolved by replacing the codec. If any of the above steps do not work, then convince the customer to have sound absorbing objects in the conference room (plants, curtains) and avoid having glass objects which would reflect the sound waves within the room.

Either ways we shall keep you posted on the results and thank you very much for providing this information, very useful

Regards

Dave

Think with Portals

[jcromwell]

We've had this same issue with a SX20 Quickset on 5.1.3.  We downgraded the firmware to 5.1.2 and echoing was gone.  Upgraded back to 5.1.3 and it was back.  LoL.  Hope this helps!

[Luke Sykes]

Thank you all for this info.

I will be speaking to the customer on Friday so I will go through these steps with her and hopefully come to a resolution.

Many Thanks

Luke

[Luke Sykes]

Echo from C20

Thank you all for this info.

I will be speaking to the customer on Friday so I will go through these steps with her and hopefully come to a resolution.

Many Thanks

Luke

[david.sharp]

Hi All

thanks for your response, i have had an issue with another C20 in a different site and had the opportunity to attempt some different firmware versions.

i have attempted with firmware version 5.1.2 and 5.1.4, in neither firmware version the AEC function did not appears to be performing very well.

this is another codec which is connected to a Samsung screen same model as already described in this post.

We have run through the screen configuration with a fine toothed comb and removed all configuration options which may impact the timeliness of the audio playback, however these screens do not have a "game" mode, so that is an option we are unable to select.

whilst performing the downgrade to firmware version 5.1.2 and tweaking the screen has provided for a solution that i suspect would be acceptable to the customer (potentially not notice the echo) i found that if i was to produce a short sharp sound such as the click of a keyboard or mouse the audio would echo back very clearly, if i was to continue to speak for a period of time the AEC would appear to function correctly as i do not hear the entiry of my words feeding back to myself, however for short words and at the beginning of the sentence there is an echo that can be heard which is a little disconcerting.

i get the feeling that echo cancelation on the C20 doesn't appear to be working so well.

we also have a similar issue with the C40 on the latest firmware, we are attempting to downgrade these systems to 5.1.2 as suggested above to see if this has any impact but we are currently suffering network performance issues which is preventing this, the C40's audio is being played back via an amplified which connects to ceiling mounted speakers, so i would expect any delay in audio playback to be minimul.

i'm startnig to run out of idea's other than to balance the audio between the output speakers and the gain on the microphones as i would if i was levelling a sound re-enforcement system, however this doesn't prove practical in the context of a VC system when the issue is with far end echo.

Cheers

Dave

Think with Portals

[Martin Koch]

Two other things I had seen which caused audio trouble:

* TV Style monitor with "Video/audio enhancements", try to disable this featrue, if you do not find an option,

disable the hdmi sound output and test an simpel external amplifier or active speakers to see if this removes the issue

* attempt to connect 3rd party microphones or a microphone system

with the c20 only use the original silver square mics.

[david.sharp]

Hi Martin

thanks for the suggestion, i have just spoken to the senior site engineer who has confirmed that we have tried a basic amplifier and speakers, and turned the audio right down on the HDMI, it didn't appear possible to disbale the audio.

and apparently we are still getting the far end echo.

i can't believe that we would be the only people suffering with this, we are seeing this on multiple codec's using the originally supplied microphone and with boundary microphones installed instead of.

i wonder if the gating function isn't kicking in fast enough which is allowing a certain amount of audio to feedback, i wonder if this could be adjusted in the backend somehow.

Cheers

Dave

Think with Portals

[david.sharp]

Hi All

I have just found some interesting information which is as follows.

i have a C20 setup with the C20 microphone and playing HDMI via a screen, I adjusted the setting on the screen to enable functions such as SRT, etc... which made the problem worse, I then reset the screen to what it was previously, with no video processing and no audio processing outside of what the screen stated was standard (no game mode option in this instance) and we still had the far end echo.

I upgraded the codec to firmware version 5.1.4 which didn't affect the echo issue, although the echo wasn't great it was still noticeable.

at this point I thought if the system isn't handing the AEC correctly then maybe a factory reset could help, I performed a factory reset and the system appears to be working much better, the echo is not noticeable so I think we shall have a look at completing this onsite, fingers crossed this will cure the issue.

Regards

Dave

Think with Portals

[david.sharp]

Hi

Just to put this particular thread to a close.

we discovered that we had to adjust the echo reference deley and the setup of the microphones in the room to best find a solution which meant that there was no far end echo feeding back.

what we discovered is that the air conditioning in the room was causing a constant audible pickup on the microphone which meant that it took the AEC a fraction of a second to initiate even with the echo reference delay adjusted, to be frank when i heard the background noise i was surprised that the echo canceller was working at all.

so an adjustment to the microphones physical location and pickup pattern has reduced the background noise, and along with the echo reference delay adjustment this has cured the problem.

Regards

Dave

Think with Portals