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[Jens Palm Bacher]

https://www.dropbox.com/s/0qxjxll83cvglta/Video%2013-07-2017%2015.13.26.mov?dl=0

Sennheiser digital 6000, passive padle antennes, 10m lowloss coax. Venue is circus tent.

[Pete Erskine]

https://www.dropbox.com/s/0qxjxll83cvglta/Video%2013-07-2017%2015.13.26.mov?dl=0

Sennheiser digital 6000, passive padle antennes, 10m lowloss coax. Venue is circus tent.

I would suspect that the one RX antenna was near, within 6', of a TX antenna.  after that that the antenna, coax or DA was defective. 

Did you see anything on your SA.  did you look in peak mode?

What was the squelch setting?

[Tom Provenza]

Sennheiser digital 6000, passive padle antennes, 10m lowloss coax. Venue is circus tent.

Is the circus tent a key clue?

[Paul McDermott]

https://www.dropbox.com/s/0qxjxll83cvglta/Video%2013-07-2017%2015.13.26.mov?dl=0

Sennheiser digital 6000, passive padle antennes, 10m lowloss coax. Venue is circus tent.

I will take a wild guess with... Your A antenna aimed directly at the backside of a low quality LED video wall.

[Jens Palm Bacher]

https://www.dropbox.com/s/0qxjxll83cvglta/Video%2013-07-2017%2015.13.26.mov?dl=0

Sennheiser digital 6000, passive padle antennes, 10m lowloss coax. Venue is circus tent.

I was asked to investigate when they experienced low LQI (link quality) on the 6000 system, even though they had absolutely fine RF levels, and scans before and after show were clean.
They sell kids led toys outside the tent for the kids to bring in:

Apparently they come with a built in Rf noise generator, this is what caused the interference in the video. We did a test setup for the video with only one of the toys 50cm from the antenna, in real life it was 500 toys inside the tent:

[Tom Provenza]

I guess Paul wins by default.  500 of those in the seats is kinda like a low quality LED  video wall 

[Jason Glass]

They sell kids led toys outside the tent for the kids to bring in:

Apparently they come with a built in Rf noise generator, this is what caused the interference...

Hi Jens,

Out of curiosity, how did the 6k perform under these conditions? Were there audible dropouts or artfacts?

Sent from my Nexus 5 using Tapatalk

[Erik Jerde]

So how are they going to move forward?  Ditch the toys or are they looking for a tech solution?  I could see them having a lot of money tied up in the toys and being rather reluctant to stop selling them.

[Paul McDermott]

So how are they going to move forward?  Ditch the toys or are they looking for a tech solution?  I could see them having a lot of money tied up in the toys and being rather reluctant to stop selling them.

option 1: Wrap each toy in Cinifoil
option 2: Chickenwire on the downstage edge of the stage.

[Jordan Wolf]

option 1: Wrap each toy in Cinifoil
option 2: Chickenwire on the downstage edge of the stage.

Blackwrap...blackwrap EVERYWHERE, lol.

[Lyle Williams]

Try using regular antennas.

The interference may be as a result of the amps in the paddles being overdriven by a nearby toy.

[Jens Palm Bacher]

I could see them having a lot of money tied up in the toys and being rather reluctant to stop selling them.

Bingo...!
We optimised on the antenna placement and moved frequencies, so now we have a "good enough" wl performance, and they can sell the tous.

[Jens Palm Bacher]

Try using regular antennas.

The interference may be as a result of the amps in the paddles being overdriven by a nearby toy.

We are using passive paddles, no need to amplify all the noise

[Diogo Nunes Pereira]

Apparently they come with a built in Rf noise generator, this is what caused the interference in the video.

Hi Jens, do you have a scan of the noise? Wondering how it looks like... Is it wideband? Random peaks?

Enviado desde mi XT1072 mediante Tapatalk

[Jens Palm Bacher]

Hi Jens, do you have a scan of the noise? Wondering how it looks like... Is it wideband? Random peaks?

Enviado desde mi XT1072 mediante Tapatalk

It looks like this on a 9000 system, on a spectrum analyzer it looks like very fast moving peaks, so fast that they are not detected by the Rf meter on older analogue receivers.

[Jens Palm Bacher]

Hi Jens,

Out of curiosity, how did the 6k perform under these conditions? Were there audible dropouts or artfacts?

Sent from my Nexus 5 using Tapatalk

No audible artifacts, but dropouts (audio muting) with performers backstage etc. when i would have expected the system to work under normal RF conditions. They had used a ULX-D system before that performed worse, which is understandable considering the ULX-D beeing switching diversity and the 6000 true diversity.
Generally our 6000 and 9000 systems perform very good, we have just completed a large outdoor theatre play, very close to a large DVB-T broadcast transmitter without any problems.

[Lyle Williams]

The key to understanding receiver interference is to understand that many of the signals heard on a receiver (or visible on a spectrum analyser) do not actually exist "on air".

They are the result of imperfections in the receiver and pre-amps in front of it.

[Henry Cohen]

The key to understanding receiver interference is to understand that many of the signals heard on a receiver (or visible on a spectrum analyser) do not actually exist "on air".

They are the result of imperfections in the receiver and pre-amps in front of it.

When using lesser caliber equipment with low IP3 ratings. And it's not so much "imperfections" as it is saturation of the non-linear stage.

[Lyle Williams]

I struggled to find the right word.  Imperfections was not meant to mean "man, this receiver must have been built last thing on a Friday afternoon" but to indicate that things that we think of as perfectly linear are really "close enough to linear, in the absense of overload"

What we get out of a receiver is the receiver's response to the incoming signals, not the signals that were actually on air.  Under normal conditions this is close enough.

[ProSoundWeb Community]