Occasional Insanely Loud White Noise

[RichJordan]

Hi,

Firstly thanks for developing such a brilliant system I love flying with it, it's added a whole new level of situational awareness.

I've got a PilotAware Classic running the November firmware plugged into the aux input of my Funke ATR833 radio for audio alerts, every now again (say once every two hours of flying) I'll get INSANELY loud white noise through my headsets, loud enough that it drowns out all other noise and makes it physically uncomfortable to keep the headsets on. Pulling the power lead out of the PilotAware immediately gets rid of the noise, but also means I lose GPS for navigating.

Any ideas?

Thanks.

Rich

[Admin]

Hi Rich

Can you please describe your setup ?

PilotAware Classic / Homebuild
Power Supply (Anker 12v Aux, Anker Battery, ...)
Connectivity (Traqnsponder, Dynon ...)

We have another thread which describes an issue with white noise on particular VHF channels
http://forum.pilotaware.com/index.php/topic,858.msg10468.html#msg10468

Thx
Lee

[RichJordan]

Hi Lee,

Thanks for the reply. Power is from a Charge2 (http://www.charge4.co.uk) 2 port USB charger. I have an aukey ground loop isolator between the PilotAware and radio which has solved an issue I had with some background static, but not fixed (or caused) this loud white noise.

It's a PilotaAware classic.

I have a Funke TRT800 transponder, but it's not connected to the PilotAware.

Have just read the link to the other thread, interestingly, like the other poster it's on the SafetyCom frequency where I've had the issue, although I didn't think to try another frequency before pulling the power to the PilotAware. Will do that next time.

[sdkellner]

Have just read the link to the other thread, interestingly, like the other poster it's on the SafetyCom frequency where I've had the issue

Just for clarification, as the 'other poster', I've actually never had interference on SafetyCom - plenty of other frequencies, but not 135.475.  Like Rich, I also have the TRT800H (although mine is connected) and the Aukey ground loop isolator.

Stu

[RichJordan]

Sorry Stu, misread that bit.

So there's two of us with a similar issue. I wonder if my issue means you can discount your PAW to transponder wiring?

[sdkellner]

Hi Rich

I also have the ATR833 radio.  Not sure how feasible it is for you in flight, but it might be worthwhile trying to remove the ADS-B dongle next time the noise occurs.  I just have a hunch that this might be the cause and it would be nice to confirm or exclude.  In my open cockpit gyrocopter all I can do is kill the power; like you have experienced, there is some urgency to do this when the noise kicks in because you can't hear the radio at all.

Let's hope we get this sorted as I love what PAW is about.

Best

Stu

[Admin]

OK there is a pattern, so just to confirm
You are both using an ATR833.

Is the audio connected to your ATR833 in both of your installations ?

I want to determine is the noise fed directly, or induced over the RF

I also read on a forum, somethign about strobe LED's inducing noise over 126mhz
http://www.vansairforce.com/community/archive/index.php?t-66692.html
its a long shot, but do either/both of you have strobe LED's ?

Thx
Lee

[sdkellner]

Yes it is physically connected Lee, but even with the external input dialled down to zero I still get the noise and at the same ear-splitting level. I am almost certain it is induced.  I have non-LED strobes, but the noise continues even with them off.  I do get noise from my LED landing lights, but this is on specific frequencies and I can squelch it out; or turn them off!

Best

Stu

[RichJordan]

Physically connected to my ATR833, yes.

No strobes on my little plane.

[Admin]

As an experiment I ran an SDR as a Spectrum analyzer over the VHF band 108-137
Two scans running for a couple of hours with PAW running and with PAW turned off (background)
This probably shows that there are no significant additional RF in this band, so I am leaning toward
a conducted issue rather than RF emissions

[sdkellner]

Hi Lee

Those charts are for a correctly functioning PAW, no doubt; what if those of mine and Rich are somehow faulty?  In particular, I have a suspicion that the ADS-B dongle might be to blame.  I know it looks like the ATR833 is a common factor, but I wonder if this is a red herring?

I'm also confused as to how the noise could be conducted if my ATR833 input is dialled down to zero; this surely effectively disables the input?

Best

Stu

[Admin]

Hi Stu,

Those charts are for a correctly functioning PAW, no doubt; what if those of mine and Rich are somehow faulty?  In particular, I have a suspicion that the ADS-B dongle might be to blame.  I know it looks like the ATR833 is a common factor, but I wonder if this is a red herring?

its very possible to be a red herring, and we need to bear that in mind

I'm also confused as to how the noise could be conducted if my ATR833 input is dialled down to zero; this surely effectively disables the input?

I am reading the manual to see what it says about this.
in section 3.4 EXT – External Audio Input’s Behavior
can I ask what is your setting ?

Thx
Lee

[sdkellner]

I am reading the manual to see what it says about this.
in section 3.4 EXT – External Audio Input’s Behavior
can I ask what is your setting ?

Hi Lee

It's set to 'Auto Off'.  During my last flight I turned the Ext level down to zero, which should disable it, following the commencement of the noise; the noise continued until I cut the power to the PAW.

Best

Stu

[sdkellner]

So I went flying today with the replacement PAW supplied via Dave and Lee.

And...... EVERYTHING WORKED PERFECTLY!!  Finally, I had fully functioning traffic, ADS-B out, no radio interference... and I even had my own registration appearing loud and clear on the traffic page, every time I looked - see attached pic.

I did also move my new PAW unit so that it is now around 50 cm from my radio; I do wonder if its previous extreme closeness was part of my serious noise interference problem. 

On the balance of probabilities, it does also seem that there was a fault with my original unit.  I know I had a dodgy aerial and ADS-B dongle, but it does seem that there was also a more fundamental problem with the underlying unit as not once did it show my own registration on the traffic page when connected via my TRT800H; the new unit did so immediately and continuously.

Now to get back to enjoying the flying!

Thanks guys, and in particular Lee, Peter and Dave who have been super helpful throughout.  Dave - my old unit will be in tomorrow's return post to you.

Best

Stu

[Admin]

Hi Stu
Thats good news, can you send the unit  to me,
I am going to give it a soak test next to the spectrum analyzer, I will email my address

Thx
Lee