Axis Cameras And Echo Cancellation

Goal (aka what the tree house should look like in the end): To have successful video and two-way (duplex) audio between a central location and 20 rooms utilizing Axis P3364 cameras. And to keep things consistent, let’s say I’m just connecting to each room as needed with an IE web browser.

Current state of the tree house: I have 20 rooms (approximately 14’x20’), each with an existing Axis P3364 camera, and one spare/unused PoE network drop.

Things I’ve tested: Installed a Louroe AOP-SP-CF. It’s basically a ceiling mount speaker microphone with a built in amplifier.

http://www.louroe.com/product/aop-sp-cf/

The speaker/mic is powered by a Louroe IF-PX (single zone PoE extractor with a variable gain adjustment and audio I/Os which connect to the camera).

http://www.louroe.com/product/if-px/

Everything works great doing a push-to-talk solution, but when implementing a duplex setting on the camera, I get the dreaded echo in my ear piece when speaking from the web browser to the camera/room. Note: I’m using a headset on my PC to listen and to send my voice.

My next thought is the disconnect the microphone on the speaker/mic unit and install a separate mic 10 feet away from the speaker, but I haven’t done that yet. I have a feeling it will be the same result though. I also have a feeling that the responses will include comments that the Axis P3364 doesn’t have echo cancellation, and that I’m up a creek….but you never know unless you ask.

Looking for any thoughts or recommendations….or other products <you pick> to finish my tree house. Adding the Louroe gear mentioned above would be about $700 / room, but at this point functionality without echo may trump overall price.


Hi Louroe guy here.

Is your audio setting on the camera set to half duplex? 9 times out of 10 that will fix the issue you're describing.

When the camera is in half duplex mode the two way audio works fine, but when we change to full duplex, then we have the echo. Ideally, we would like to have a full duplex solution.

At full duplex settings the camera is engaging the mic and speaker simultaneously. If full duplex is a must you'll need to isolate the mic from the speaker. In a room that size you may not be able to completely eliminate the echo/feedback.

How do speakerphones handle it?

Our units have a muting circuit designed to prevent feedback and echo so that when the mic is active the speaker isn't and when the speaker is active the mic isn't. Hence the need for using half duplex settings on the camera. Full duplex will have both the mic and the speaker active at the same time, which on account of that muting circuit isn't what this product is designed to do.

So would everything from Louroe be for a half duplex solution or do you have anything ideal for full duplex? Just curious. I really do appreciate the feedback. It's all about using a product the way it was designed/intended to be used.

I've used Polycom equipment for video conferencing 5+ years ago that let everyone in the room be heard as well as hear everyone from the remotes at the same time. Don't know if they offer something standalone.

Yes, our units are half duplex solutions. We've found it to be appropriate for just about all applications where this unit is used (your tree house notwithstanding). When you get in to teleconferencing as UD1 brings up, it's a different need for full duplex than what we see in security.

I really do appreciate the feedback.

Yes and no. :)

I will simply add to the already good comments. AEC is the only way to really do full duplex unless, as Cameron stated, you isolate the microphone from the loudspeaker. What is the need for full duplex anyways? AEC is expensive and many audio processors are available today that do it really well but the main use is teleconference. The big problem is that many of the microphones for surveillance are omni-directional so they are the most prone too feed back. Your acoustic space has a lot to do with echo as well if there are a lot of hard surfaces where the loudspeaker hits the surface and immediately bounces back.

On a side note regarding the power of processing. I did a live demo with a rep trying to keep people from two separate rooms from hearing each other's conversations while still successfully recording each room's audio. The rooms were poorly isolated to begin with but that would have required more money than this would if it worked. We used an audio processor and a sound masking system. The sound masking system helped to provide the isolation between the rooms while the audio processor's AEC was used and set to capture the white noise and cancel it out so the microphone could still clearly hear potential whispers in each respective room. I was surprised at how well it worked. This was a few years back and now it's amazing how many phones use similar technology.

Isolating the mic mechanically isn't enough. If you can't mute the mic while someone is speaking perhaps the M3037 or A8004-VE is a better choice as they are designed to handle this out of the box.