1090mhz ADS-B / noise cancelling Headset noise.

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Rich
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Re: 1090mhz ADS-B / noise cancelling Headset noise.

Post by Rich »

This isn't the same thing, but I've had occasion for the squelch for the copilot side needing to be adjusted when it was hooked up and there was no head in the headset :D
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Rick
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Re: 1090mhz ADS-B / noise cancelling Headset noise.

Post by Rick »

Rich wrote:
Sat Apr 25, 2020 11:04 pm
This isn't the same thing, but I've had occasion for the squelch for the copilot side needing to be adjusted when it was hooked up and there was no head in the headset :D
I've seen that too - when I hang it on the back of the co-pilot seat and the vent is blowing at it!
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soarer20
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Re: 1090mhz ADS-B / noise cancelling Headset noise.

Post by soarer20 »

Colin wrote:
Tue Apr 21, 2020 11:49 pm
I believe that is your transponder transmitting when it is interrogated.
This is what I've experienced.

I've got the once per few second click coming from my transponder/ GDL-82. The avionics shop that installed the ADS-B told me everyone is dealing with the noise. The noise is more noticeable if I'm using noise cancelling.

Has anyone been able to eliminate the click?
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Steve
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Re: 1090mhz ADS-B / noise cancelling Headset noise.

Post by Steve »

So, to update everyone about my ferrite installation...

It slightly reduced the noise, but didn't eliminate it completely. In my case the noise is a very brief (0.02 sec), low level repetitive hiss at about once every 1-2 seconds. I have tracked it down to the Copilot's mic breaking squelch (only when the transponder/ADS-B is on, and only when the headset is not being used). I tried cleaning all of the plugs and using Deoxit first, without any noticeable effect. If I unplug the Copilot's mic plug, it stops entirely, and if the headset is on a Copilot's head, with the mic positioned properly, it is reduced about 95%. I suspect that it is something weird in my intercom squelch circuit is allowing the squelch to trigger under ambient noise conditions.

I have a PMA-7000BT audio panel, and it does not have any manual squelch adjustments. It instead uses a microprocessor that analyzes the noise levels at each mic and triggers the squelch accordingly. Apparently, the ADS-B pulse messes with it somehow. It isn't tremendously bothersome - I can only hear it flying solo, when there is no radio chatter or music playing. Under those circumstances, I pull the Copilot's mic plug...

Steve
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Re: 1090mhz ADS-B / noise cancelling Headset noise.

Post by Charles »

Not sure a Faraday cage around the headset box would make a difference because I get the noise in my Zulus even when they’re unplugged. As someone said above, the noise goes away completely if I put the Zulu control unit on my lap.

I like the idea of adding ferrite chokes to the wires. Would be interested on results from Steve.
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