Wireless interference...

  • 3 October 2011
  • 4 replies

Userlevel 2
Hi folks,

I stumbled on another thread that showed the network matrix ... cool info, even though I'm not 100% sure what I'm looking at.

First, I want to state the problem is not directly with the Sonos, although it might be causing some issues. Virtually all my devices are wired, but as I've added a ton of devices I'm having problems with some devices like an Soundcast Outcast, and my wireless range for laptops/etc doesn't seem as good, but I've had to move a few devices a bit.

Even though the playback on the Sonos is fine, I was hoping to use it to help me figure out where I might have issues. I figure I can use it when I make changes to the environment and hunt down potential issues.

I'm uploading an image of it here, removing the MAC addresses:


My first assumption after looking at it is that the 2 wireless devices seem to be fine.

I'm not quite sure what the left y-axis colors refer to, but the colors in the grid I'm assuming are signal strength.

Anyway, like I said, just playing around hoping that the Sonos mesh can help me figure out wireless issues.

Any suggestions/tips? Thanks!

4 replies

The signal strengths to the wireless nodes are fine but the level of local RF noise experienced by a number of the units is evidently considerable -- dire in the case of the Master Bedroom Play:3. It would be interesting to see the contents of the /proc/ath_rincon/phyerr branch of /support/review for that node.

Which version of Sonos software are you running? As of v3.5.2 OFDM Weak Signal Level 5 and OFDM ANI Level 0 represent the good end of the scale. ANI Level 9 looks horrific -- what's located in the vicinity of the Master Bedroom player?

A few possibilities spring to mind:

- The Soundcast Outcast could be using a spread-spectrum technique across the entire 2.4GHz band. Turn it off and refresh the matrix to see if things change.

- Some other wireless appliances in the house could be butting in, such as a baby alarm, video sender, cordless phone, etc.

- Check your WiFi is set to channel 1, 6 or 11 -- one which Sonos isn't occupying -- and that 40MHz/wide channels are not in use. You can also scan for neighbours with a tool such as inSSIDer.
Userlevel 2
Thanks ratty!

I checked this morning and the master bed play:3 is ANI 6, so a little improvement. (Tested before I posted and it's 5.) Here's the pasting of the data you mentioned (not sure what it represents):

contents of /proc/ath_rincon/phyerr 10 100 1000 5000 10000 10001+
1975754 0 0 121 0 0 0
1975815 0 0 121 0 0 0
1975875 0 0 121 0 0 0
1975936 0 0 121 0 0 0
1975996 0 0 121 0 0 0
1976057 0 0 121 0 0 0
1976117 0 0 121 0 0 0
1976178 0 0 121 0 0 0
1976238 0 0 121 0 0 0
1976299 0 0 121 0 0 0
1976359 0 0 121 0 0 0
1976420 0 0 121 0 0 0
1976480 0 0 121 0 0 0
1976541 0 0 121 0 0 0
1976601 0 0 121 0 0 0
1976662 0 0 121 0 0 0
1976722 0 0 121 0 0 0
1976783 0 0 121 0 0 0
1976843 0 0 121 0 0 0
1976904 0 0 77 0 0 0

Ironically, there is _nothing_ in the vecinity of the Play:3. I can switch it to hardwire if need be (although it plays fine). The only thing on the table is an alarm clock, otherwise, that's it. Even adjoining rooms are fairly empty. If I had to guess the quietest spot in the house for RF, this would be it (no TV, etc.).

So ... the color on the left y-axis is amount of interference?

The outcast wasn't on, but I turned off the transmitter just to see. Can't tell if there's a difference yet, since across the board things seem a little better this morning.
Here's the pasting of the data you mentioned (not sure what it represents)
It's a history of physical level errors seen over the last 20 mins, one line per minute of sampling with the most recent at the bottom. The left column is a timestamp, the other numbers represent increasing intensity from left to right. The figures in fact all look good.

Bear in mind that errors occur all the time and Forward Error Correction plus higher level protocols are designed to deal with this, albeit with a gradual reduction in usable bandwidth. When interference constricts bandwidth to such a degree that the player is starved of data the music drops out.

So ... the color on the left y-axis is amount of interference?
I understand it's related to the ambient noise seen by the radio receiver ('Noise floor' figures are the -X dB figure relative to some reference or other), but I confess I haven't delved into the detail of OFDM ANI etc so I've no idea why yours might appear so poor and whether it could be connected with the degradation you've observed in WiFi performance.

Unless someone else here can shed further light on things, you could always submit a diagnostic and throw a query at Sonos Support. Bear in mind though that you'd be asking questions about an unsupported diagnostic where your system appears to be performing satisfactorily, so you may not get too far. Let us know if you make progress. It would be interesting to know what's causing the amber/red squares in the matrix left column.

In spite of the high ANI, your phyerr rates are very low and similar to mine -- and we have a similar level of wireless devices. I don't recall seeing any lower phyerr error rates. I assume that this is the "background" level when more than one SONOS device is in the area.

Where is your WiFi access point located? You may be able to find a better location. Sometimes moving a few inches results in a dramatic change in performance.

It would be interesting to move that bedroom unit to another area and check the ANI.

I find that wireless performance varies wildly for laptops. The newer units are much more potent. I have a recent premium laptop that continues to amaze. In familiar areas where my older laptop with PC card WiFi and a few other laptops with built-in WiFi struggled, the new machine shines.


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