Echo issue on Plcm V-series system

[StianS]

Anyone having echo issues on their V-series system (running rel 8) when turning the volume on the codec above 30?
We are currently having echo problems when the volume exeeds 30 on the codec even if the loudspeakers are muted.....

Stian

[tom9933]

I’ve not seen this problem, but I can do some testing to try to reproduce it. What concerns me though is that you say you get echo even when the loudspeakers are muted. It almost sounds like something isn’t wired correctly. Are you coming directly out of the Polycom into the speakers or is there a mixer in the middle?

[StianS]

No mixer or other sound processing devices, the audio is connected directly to the speakers.

[trapehzoid]

If the audio is distorted.. you will get echo as well (the echo canceller can't compare what it knows went out compared to what it got back from the mic).

If it only happens when you turn the volume up, my assumption is you have poorly matched gains between the vsx's output and your speaker input or the speakers themselves are turned up too loud.

Why not describe your actual setup, what gear, hooked where, and trying to provide audio for what environment.

[StianS]

...echo appear even when the loudpseakers are muted (no audio from far end at all...)

Stian

[trapehzoid]

...echo appear even when the loudpseakers are muted (no audio from far end at all...)

Stian

That really makes no sense at all unless you have external equipment hooked up to the unit incorrectly.

When you say 'muted' are you talking about turning off the loudspeakers but not muting via the video system? Sounds like you have a loop in your audio setup.

Your PA system should not change volume around, that will cause the echo canceller to have to keep adjusting. You should set the volume of the PA and leave it fixed, then adjust the volume via the video unit, including trying to mute the remote site by muting in the video unit.

The echo canceller can only do so much, if there is too much volume or too much distortion it can not compensate.

If you truely want help on this, you're going to have to describe your configuration and setup, with specifics, not just trying to point fingers at the video unit.

[Gary Miyakawa]

I hate to ask late questions but....

Are you "hearing" echo (meaning it's coming from the far end) or are people hearing echo from you ? (at the far end) .


Are there any VCRs/DVD/DVR devices connected to either systems ? It's pretty easy to get an audio loop thru these devices if not configured correctly.

Gary Miyakawa

[hhmmb]

I think I can anwer this one (I am the "owner" of the VSX sytems StianS talks about)
We have a mix of FX4000's and some VSX8000/7000 and many V500's. The echo problem seems to only exist on the VSX series (all models/sw versions). It is very noticable in a dayly Multipoint MGC-50 conferece we have with up to 8 VC participants. It is also the same in point to point (not when two FX's are involved)
We have done careful tests, and came to this conclution:

In this example Site A is any VSX with codec volume set to over 30-35 and without external echo cancelling. Site B is FX or VSX or whatever.

When site B speaks the problem often appear the first seconds when site A starts to talk (becomes "Active speaker") If the users are very diciplined and dont talk at the same time it is better, but the phenomen can accure even if Sit A allready are talking. The sound is not really normal echo, more like a distorted "wobbeling" sound like in a sewer pipe or something. After some time site A's echo canseller seems to cath up and it is OK until next "Active speaker switch". It is site B that hear those annoying souds from A.
If Site A turns the volume down to ca. 25 and if needed compensates by adjusting speaker volume up it normaly solves the problem.
We dont seem to have the problem on 8000's with external echo canceling. And as Stian said, it is the same on V500 with LDC 20", VSX7000's with inbuilt speakers etc.

We have many users complaining about this (asking them to throw the P'com remote in the garbage bin is not an option) . Half of our units are on offshore rigs, the rooms are not always perfect for VC and this dont exactly make the problem easyer since there seems to be a narrow balance between room properties, codec/speaker volum settings to get a axeptable result. Turning the codec volume to low often generate a "normal" acustic echo. The problem also appears on "perfect" rooms from a audio perspecive.

We have raised a support case to Polycom on the issue, but wanted to check if this is a known problem.

[trapehzoid]

what are you using for speakers? Aren't you hooking it up to the TV? What are you doing for volume settings there?

What you describe is expected behavior when the echo canceller can't cope.. because the other side is too 'hot' or because it can't deal with the local room. Typically you'll hear clipping, 'wobbling', or other distortion when people speak. The issue here is the EC is being driven harder then it can cope either by too much gain or distortion. As most other people don't seem to have this issue, I again ask for the 3rd time.. how is the audio hooked up in the rooms. Be specific.

[StianS]

The audio is connected from the V500 directly to the LCD monitor audio input.
If you in site A turn the volume above 30 on the codec and at the same time mute the volume on the monitor so there is no audio heard in the room, a kind of echo (wobbling) is heard at site B when speaking at the same time in a conference. When the volume on the codec at site A is below 30, this echo (wobbling) disapear. The monitor volume is still muted, site B has no changes in volume at all during this two scenarios.

Stian

[trapehzoid]

you should never mute the monitor, only the codec. Don't do that.

you should set the monitor volume in the middle of its range.

I bet you have the monitor volume up high causing distortion or overdriving the echo canceller.

Set your TV volume in the middle, and then throw away the remote control. Do not use the TV volume for anything, use the codec volume for all audio control.

[StianS]

If you have a V-series system I suggest you try it yourself to see the problem. It's not releated to distorted audio or that the audio in the room is to high for the echo canceller.
When i increase the volume on the codec I also decrease the volume on the monitor to keep the same level of audio in the room.
And even if I mute the audio completly on the monitor the problem is still to be heard especially when site A and B speaking at the same time.

Stian

[trapehzoid]

how many times do I have to say it? DON'T USE THE SPEAKER VOLUME

Honestly, why do people come here to ask questions if they don't listen to the answers?

[hhmmb]

trapehzoid,
Some of those rooms have integrated solutions. The users use a Crestron panel, and VC is only a part of the Collaboration rooms. They have to be able to adjust volume for PC's, DVD/VCR and other sorces too. And even on some of the the simple V500/TV monitor solution we can not throw away the TV remote. Some of them have TV antennas, DVD players etc. connected, and have to be able to adjust speaker volume.
We have tried to explain you that our problem occures when the POLYCOM VSX CODEC volume is too loud, over 30 on a scale to 50. The remote site hears distorted "wobbeling" sound. The speaker volume seems to have limited influence as StianS have tried to communicate, since the remote part hear distorted audio even if the speakers is turned off. In general I am shure you are absolutly correct, but this seems to be a VSX echo canceler problem in general.

[trapehzoid]

trapehzoid,
Some of those rooms have integrated solutions. The users use a Crestron panel, and VC is only a part of the Collaboration rooms. They have to be able to adjust volume for PC's, DVD/VCR and other sorces too.

In those solutions, a properly designed system would either

1 - feed those audio inputs through the VC system so they can be used both locally and remotely.. and therefore the echo canceller is aware of the gain control
2 - use an external echo canceller and feed all the audio inputs through that, and setup your mix-minus with that (like a Getner, etc)

If you are simply using the TV for multiple things, and not using the DVD/etc along with the VTC system.. well you are reaping what you sowed. You have to train people to setup the gear correctly when they switch it around.

The warbling you are experiencing is exactly what happens when the Echo caneller can not cope. It will clip or distort.

Your options are to setup your audio correctly or move the microphones further away (and that will only minimize it a bit, not fix it).

Its possible the aucoustic environment is too challenging for the built-in echo canceller, which might be improved with a more robust external echo canceller, but given you are using VS500s.. I doubt putting more money into it is an option. I don't even know if a VS500 can be setup properly with an external echo canceller.

Your solution is to use the gear correctly, and train your people to setup the systems in the proper fashion after they have changed them around.

You can't goto the doctor and say 'hey, when I jump off my roof, my leg hurts.. stop it from hurting when I jump'. He'll tell you stop jumping off your roof, your legs aren't built for that. Same applies here.

The speaker volume seems to have limited influence as StianS have tried to communicate, since the remote part hear distorted audio even if the speakers is turned off.

Simply put.. that is an invalid test. Especially with VSX systems that have their own speakers in addition to your external speakers.. which would REALLY screw with the EC. Turning off the TV speakers proves nothing except for you like to abuse yourself.

In general I am shure you are absolutly correct, but this seems to be a VSX echo canceler problem in general.

Any full duplex echo canceller can not cope when deployed incorrectly.

[StianS]

how many times do I have to say it? DON'T USE THE SPEAKER VOLUME

Honestly, why do people come here to ask questions if they don't listen to the answers?

How hard is it to understand????? I DON'T use the speaker volume, it's fixed under normal conditions. I just used this to explain you that this is not a "normal" problem when acustic echo appear! (As when the audio level in the room is to high)!

It seems like I'm not able to explain you the problem so I suggest that you try this yourself if you are able to...

It's not easy to instruct hundres of users to not exceed 30 in volume on the codec, if they feel that the audio is to low they increase it so long it is possible.

Stian

[StianS]

I hate to ask late questions but....

Are you "hearing" echo (meaning it's coming from the far end) or are people hearing echo from you ? (at the far end) .


Are there any VCRs/DVD/DVR devices connected to either systems ? It's pretty easy to get an audio loop thru these devices if not configured correctly.

Gary Miyakawa

Echo is heard from the site which exceed 30 on the volume scale on the V-series system. No VCRs/DVD/DVR devices is attached.

[trapehzoid]

How hard is it to understand????? I DON'T use the speaker volume, it's fixed under normal conditions. I just used this to explain you that this is not a "normal" problem when acustic echo appear! (As when the audio level in the room is to high)!

That isn't what your user (or owner, whatever) said. Just look two posts up. They said they do use the TV volume. Plus, you insist on pointing out the echo is there when the TV is muted reagardless of how I explain that test is pointless.

It seems like I'm not able to explain you the problem so I suggest that you try this yourself if you are able to...

I have, and the system performs fine as long as the overall volume is not too high. The volume control on the VSXs goes quite high (too high). Try using the audio meter at those high volumes and you realize just how loud the system is.. too loud.

Basically if the speakers are adjusted properly, the system should be able to get more loud then anyone should need. If not, I suggest you look into a better speaker system that will give you increased volume with less distortion. You can't endlessly turn up the speaker and vsx volume and expect the system to perform. TV Speakers stink.

Feel free to call tech support and complain.. you aren't going to get anywhere. Try solving your audio problems rather then focusing in on why a full duplex echo canceller has limits.. they all do.

It's not easy to instruct hundres of users to not exceed 30 in volume on the codec, if they feel that the audio is to low they increase it so long it is possible.

If they feel they have to turn it up that loud.. you have other issues to address. You should not have to have your systems cranked that loud so that everything is distorting to be heard.

[hhmmb]

I am glad U2 gentlemen understood eacother at last.... I apreciate your thoughts trapehzoid. We dont expect to mutch out of the Polycom support case, but I still think there is something wrong with the VSX echo cancelling/codec volume. At least now we know more of what is causing the audio problem. We have to just adjust things as good as we can, and train the users for now.

[Skylark]

Two basic questions:

Is the V500 on top of the monitor? and if so have you tried laying it beside the monitor incase there are any vibrations interfearing with the built in mike.

the audio output on the V-series can both be used for recording confrences and audio (recording = mixed) Is it possible that your uints outputs are set for VCR?

[hhmmb]

yes they are on a plastic shelf on the top of the TV, but this has little or no impact on our problem. As we have said, this is not "normal"acustic echo, it seems to be a weaknes in the V-series echo canseler.

[trapehzoid]

different echo cancellers behave differently when they are past their limits.. some echo.. some will clip.. some will distort.

You guys are so hung up on this ia problem with the echo canceller... come back to reality and recognize **ALL** echo cancellers have their limits. Your comment about 'normal' acoustic echo is kinda funny. Each EC will behave differently..

[StianS]

Just for your information:
Polycom has acknowled that this is a issue and will come up with a fix shortly.

Stian

[thestoic22]

I think you two should fight. When you are finished rolling around in the dirt maybe we can get back to trying to troubleshoot.

I had this type of problem with a Polycom Media Center cart with an FX on the top. After driving myself crazy about it, I found the little jumper (looks like an RJ11) that goes into the subwoofer. Once I plugged in this jumper, the system worked beautifully and has ever since. I guess the question would be, could his system need something such as this even though everything seems to be external to the codec? Just a thought......

[buchu70]

I ran into this issue while setting up two rooms at Ft Detrick using VSX 8000's with Samsung LCD monitors. Turns out there was enough delay created by the Samsung monitors, in placing the audio thru to the audio out port that it caused an "echo" effect. Upon placing audio to external speakers the issue went away.

Another thing that we had tried was padding down the audio transmit level on the polycom but in order to get rid of the "echo" the transmit level needed to be dropped so low, the rooms audio out was in turn very low. We did this using the (audiotransmitlevel set X, where X is the level you want to set), through a telnet session.

[hhmmb]

Here is an update of our problem:
We had Polycom experts joining a conference via ISDN on my V500 unit. He was logged on remote via telnet on the unit. He recogniced the echo/distorted sound in his end. Escpessialy the first minutes of the conference, when I had the V500 volum level set too high. As a "primitive/temporary" fix we have gotten a hotfix sw for the V-series where the volume can not be gained more than ca. 35 (on the scale to 50) allthough for the users it looks like it can be gained to max. We have not had ANY complaints from the users (ca. 100 units) after this update. So ofcause we can say this is the users fault, they should not turn the volume to high ! But you know, if you cant beat them, join them ! Just let them think they play it load.....