Automated Fixtures - Wireless DMX in heavily loaded Wifi band

[Peterskine]

What experience have you had using Wireless DMX in a stadium with a large Public wifi system?

Our lighting system is using 6 DMX links, mostly over very short hops to moving scenery and rotating lighting truss.
Our most critical systems are using Lumen radio CRMX Nova FX RDM - DMX/RDM/Ethernet Flex product.

The stadium has installed a 50+ access point public wifi system using all channels and 801.11n AP.

Currently our lighting works fine but what happens when we get our punters and the wifi band is loaded?

Pete Erskine

[cpf]

By "all channels" you're meaning the channels on the 2.4ghz and 5ghz bands?

[Peterskine]

they are only using all 2.4 channels.
The wireless DMX systems we have use this band.

[Chris15]

Yick.
As always, the best option just ain't going to happen - I can't see the stadium management being willing to turn off the system during the show

Being 802.11n makes it even more fun. Do you know if they are using 20 or 40 meg channels?
I guess in many ways it's moot. You've got a broadband noise floor that's not nice.

You've said your show critical links are short distance - how short are we talking and more importantly how far to the nearest APs?
Have you got access to a spectrum analyser that's 2G4 happy?

[Chris15]

Some further thoughts;

Numero uno - go install LumenRadio's management software available here: LumenRadio - CRMX SuperNova Management software and connect up via Ethernet and check your signal strengths through that.

Two - LumenRadio should be congratulated for putting actual numbers on their spec sheet here:[pdf]http://www.lumenradio.com/files/prod...tions_nova.pdf Once we can get some relative distances, it won't be too hard to work out "back of an envelope" numbers on relative signal strengths and thus safety margins.

My gut says it should work fine, but I'm also the type of guy to runs a few rough sums to ensure I don't need to see a doctor

[mbenonis]

Some further thoughts;

Numero uno - go install LumenRadio's management software available here: LumenRadio - CRMX SuperNova Management software and connect up via Ethernet and check your signal strengths through that.

Two - LumenRadio should be congratulated for putting actual numbers on their spec sheet here:[pdf]http://www.lumenradio.com/files/prod...tions_nova.pdf Once we can get some relative distances, it won't be too hard to work out "back of an envelope" numbers on relative signal strengths and thus safety margins.

My gut says it should work fine, but I'm also the type of guy to runs a few rough sums to ensure I don't need to see a doctor

Not much to add here; just work out a basic link budget to see where you stand. You can estimate the path loss here: Friis Path Loss Calculator

If I were you, try and put the wireless DMX at one edge of the band or the other and get the TX and RX as close together as possible.

[DarkCat]

After looking at the specs of the radios. It would seem that you should have a slim change of getting interference. Although the band you are using will be saturated. WIFI uses OFDM modulation, Your radios are using GFSK. As long as your radios can stay in a good range. There should be enough differences in the signal. But that is in a perfect world.