PilotAware
British Forum => Technical Support => Topic started by: RichJordan on April 23, 2017, 08:48:52 pm
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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
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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
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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.
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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
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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?
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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
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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
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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
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Physically connected to my ATR833, yes.
No strobes on my little plane.
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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
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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
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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
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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
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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
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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
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Great news, glad you've got your issue fixed.
I don't think distance between PAW and the radio is causing the loud white noise - mine are about 6ft apart.
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Great news Stu,
Glad you now have a fully working unit. Hopefully Lee will get to the bottom of what has been going on with your old unit, so we can learn more for the future. Pretty sure moving your unit and antennas will also have helped though.
Best Regards
Peter
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I'm just glad it's not a problem with the Funke radio. I've got one of those on my shopping list and was beginning to suspect the interoperability between it and PAW but I'm now relieved those concerns are not valid :)
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Has the issue been resolved for the original poster?
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Hi.
I'm not sure what the next step is for me to resolve the issue on my PAW?
Thanks.
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The reason I asked was because there was a lot of whooping and high fives that Stu was up and running but the OP appeared not to be. Substitution would appear to be the next step, but only the PAW team can offer that. I wonder if there are any other PAW users near you?
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Hi.
I'm not sure what the next step is for me to resolve the issue on my PAW?
Thanks.
Hi Rich
I will be taking a look at Stu's unit once returned to see if there is an issue.
I am still not totally convinced yet by one flight without interference
"one swallow does not a summer make... - Aristotle"
Rich, could you give us a full description of your installation, interconnect etc...
Thx
Lee
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Rich - where are you? If feasible I'd be happy to meet up and let you try my unit for a test flight.
Lee - my original unit was posted back to you yesterday; hopefully be with you soon, subject to the vagaries of Royal Mail. I share your concerns about the risk of the problem returning; what gives me some hope is that the transponder link worked perfectly, for the first time in perhaps 20 flights, whereas everything else in the installation remained the same - this, for me, is a more convincing hint that there was a problem with my original unit. And my interference-free flight was actually two flights ;) - perfect both there and back.
Best
Stu
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Rich - where are you? If feasible I'd be happy to meet up and let you try my unit for a test flight.
Lee - my original unit was posted back to you yesterday; hopefully be with you soon, subject to the vagaries of Royal Mail. I share your concerns about the risk of the problem returning; what gives me some hope is that the transponder link worked perfectly, for the first time in perhaps 20 flights, whereas everything else in the installation remained the same - this, for me, is a more convincing hint that there was a problem with my original unit. And my interference-free flight was actually two flights ;) - perfect both there and back.
Best
Stu
Hi Stu
2 flights is more encouraging ;)
I have also received your unit today
Many Thx
Lee
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Hi Lee,
Any update on Stu's unit? Have you managed to reproduce the issue?
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Hi Lee,
Any update on Stu's unit? Have you managed to reproduce the issue?
I ran it for 24 hours, and nothing!
Of course the differences are as follows :-
- Not connected to a transponder
although I did connect a USB/RS232 connector and configure as a transponder output, but nothing connected at the RS232 end
- Audio Connection difference
I had the audio out connected to a small amplifier - so impedences would be different
- Environmental
Clearly not in an aircraft, different power supply, not co-located to other RF sources (VHF, Transponder etc)
But no interference generated on any RF in the band from 108Mhz - 137Mhz
Thx
Lee
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was he RF testing for radiated and/or conducted emissions?
These things are always awkward to diagnose, lots of interactions between items. More often than not it boils down to some kind of grounding issue somewhere.
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was he RF testing for radiated and/or conducted emissions?
In Stu's installation he had PilotAware connected to a transponder (over USB/RS232) and connected to intercom ATR833 I think.
He was only experiencing noise on certain VHF frequencies and not at all times.
In my simple setup, I ran an SDR as a cheap spectrum analyzer.
I scanned the 108-137 Mhz range for 24 hours and picked up nothing, I did get some noise at 120mhz, but I had ran a 'control sample' without PilotAware powered up, which saw the same peak
you can see this earlier analysis here :-
http://forum.pilotaware.com/index.php/topic,873.msg10573.html#msg10573
The gain of the SDR was also pretty high at 38dB
This type of analysis is not one of my 'skillsets', and I know you have access to a pretty good spectrum analyzer Jeremy, maybe you could repeat the test ?
I think the point is that this was seen as happening infrequently at some point during the flight.
I am more inclined to believe this is a conducted issue rather than radiated.
Thx
Lee
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I can do conduced testing, and now have a TEM cell for radiated testing. The TEM cell is quite small though so may not get everything in, but it only needs to be the PAW connected to some serial devices and that would be easy enough to do.
If I get some time I'll hook up my PAW and give it a try to see what emerges.
I will be at an EMC test facility for a few days in the not too distant future, so will be comparing readings from my pre-compliance setup to theirs to give me a cross check.
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Chaps
6 flights completed with my new PAW; almost 10 hours - and zero radio interference.
New PAW has performed almost faultlessly, with the only blip being an unprompted reboot on one flight.
I'm also getting reliable ADS-B out.
Best
Stu
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Ok, where do I go from here?
Happened again tonight.
I also had some new behaviour, it would drop the data connection until rebooted. Both iPad and iPhone couldn't connect to it. Happened twice.
Gave up connecting it to my iPad after that and just used the audio alerts.
My PAW is not being the most reliable piece of kit.
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Ok, where do I go from here?
Happened again tonight.
I also had some new behaviour, it would drop the data connection until rebooted. Both iPad and iPhone couldn't connect to it. Happened twice.
Gave up connecting it to my iPad after that and just used the audio alerts.
My PAW is not being the most reliable piece of kit.
Hi Rich
I was about to ask about the power, but the fact that you use the charge 2/4 I think that rules that out as an issue. Just to confirm, you are using the power lead provided (required in order to overcome potential voltage drop)
You say
Happened again tonight.
do you mean the audio interference ?
This confuses me, because you go on to say you continued to use the audio, but not the iPad ?
I think we should arrange a Return & Swap to Dave Styles at PilotAwareHardware to investigate.
Thx
Lee
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Hi,
Yes, the white noise happened again. I pulled the power cable out and once PAW came back, didn't bother reconnecting to the iPad, just used the iPad GPS.
A swap would be great, thanks. I'll go up to the plane at the weekend and grab it. Would you want all the antennas and bits, or just the PAW unit?
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Hi,
Yes, the white noise happened again. I pulled the power cable out and once PAW came back, didn't bother reconnecting to the iPad, just used the iPad GPS.
A swap would be great, thanks. I'll go up to the plane at the weekend and grab it. Would you want all the antennas and bits, or just the PAW unit?
Hi Rich,
this is what confused me :o
How did you continue to use the audio alerts, if you had pulled the power ?
Gave up connecting it to my iPad after that and just used the audio alerts.
Sorry re-reading your post, I gather you did the following:-
1. you had white noise
2. disconnected power
3. reconnected power
4. did NOT reconnect iPad
no white noise appeared again over the audio (which was still connected)
Thx
Lee
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Hi Lee,
The recent thread regarding Maximum temperature (and issues with PAW) started by Robski mentions high levels of white noise on the audio output when the PAW unit got very hot. Is it possible that the same mechanism is occurring here?
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Hi Lee,
The recent thread regarding Maximum temperature (and issues with PAW) started by Robski mentions high levels of white noise on the audio output when the PAW unit got very hot. Is it possible that the same mechanism is occurring here?
Interesting. In case it's helpful to someone, this definitely cannot have been the cause of the white noise issue with my first PAW; it was tucked in a cool spot well out of direct sunlight. I never saw the core temp rise above the mid-40s, yet still had occasional overwhelming white noise.
Stu
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Might have been too cool. Mid -40s is pretty low 😜
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Might have been too cool. Mid -40s is pretty low 😜
2-hour flight today, decent weather (18C, sunny); core temp on landing 45C. Open cockpit cooling ;)
Multiple flights completed with my new PAW now; still yet to hear the white noise.
Stu
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Hi,
Update on this. Am still using the original PAW unit, have moved it from the tail of the aircraft to under the passenger seat. Tidied the wiring both to and from the USB charger.
Haven't had the GPS or white noise issue yet. (Admitedly I've only flown for 40 minutes in the new configuration).
Fingers crossed.
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Good news Rich. Keep us posted.
Regards
Peter
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Just to add to this thread, I am aware of at least 2 more aircraft that have had this problem, one of which I am responsible for. The noise was intermittent lasting for several seconds at a time and could not be suppressed with squelch on the Trig comm. It seemed to be frequency dependent (130.425) as changing to alternative frequency (126.4) did not show the problem. (at least in the short time I listened). Back on the ground, when I changed my power wiring to connect the PAW/Flarm to an alternative circuit breaker instead of the "avionics" circuit breaker (mainly so I could easily turn PAW off in flight), to my surprise the problem seemed to have gone away and the comm was working normally. I flew for around again for some 30 minutes with no sign of the noise. However as I remarked earlier it seemed to be frequency dependent so I cannot say that is was not on other frequencies! I have not had time to further research the effect but will try to listen on some different channels next time I'm at the airfield.
On the other aircraft reported (which I am not directly involved in) the owner tried moving the power to another CB like mine but this did not seem to cure his problem.
We are wondering if it is coming from the 12-5V regulators we are using and he is now going to try a car style USB PSU to see if it makes a difference. On the bench he reported hearing similar noise on a hand held up to 12 inches away with original PSU, but nothing with a car USB PSU. I'm waiting to hear from him if he has made any further tests.
I will add to this thread if and when we learn more but at the moment we are suspicious that it is the PSU chip radiating.
FYI the PSU we are using is a 3A block regulator from e-bay.(DC/DC Converter Regulator 12V Stepdown to 5V 3A 15W Car Power Supply Module. eBay item number:152563993051)
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It's been reported on here before that those CPT voltage converters are notoriously noisy in terms of RF interference.
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Hi Alan,
I agree with Paul, these things can be very hit or miss, which is why we recommend the Anker USB converters - which have proved more reliable than most. Personally I changed to a Charge 4 some time back, but still get white noise occasionally e.g. couldn't use the Scottish Information frequency on Saturday due to white noise when they weren't transmitting. It wasn't suppressable by turning off PAW and all my other avionics, so remained a mystery. Other radio channels I tried were all crystal clear.
Peter
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Yes I agree that these things are hit and miss.
I did take a spectrum analyser with pick up loop to it before use and didn't see anything particularly significant in the aeronautical band. However as the interference seems to come and go it may well be load dependent so not easy to see.
Yes the Anker USB units are nice but not really easy for integrating into a single box system.
Having said that I have previously de-gutted a similar unit and re packaged the electronics. Seems like this may be the way to go if my interference returns.
Shame, the format of the CPT units was ideal and easy for integrated packaging.
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Somewhere in the far reaches of the forum, someone recommended a similar unit to the CPT one, but which didn't create the RF noise.
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Here's the thread on the CPT noise issue.
http://forum.pilotaware.com/index.php/topic,838.msg10029.html (http://forum.pilotaware.com/index.php/topic,838.msg10029.html)
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I've been searching the forum and found a couple of posts that talk of this PSU (or similar). One reported seeing wide band noise but then no further information, others seemed to use with no problem, but of course if it is frequency / load dependent then it may be present, they just haven't seen it.
A couple of threads had people with access to emission testing equipment and said they might test these units, but nothing ever appeared with any results that I can find.
It would be useful to get a definitive answer as these psu modules are physically ideal for box integration.
I would have thought that an eventual natural PAW progression might be to offer a fully packaged, plug and play box for sale and that a working integrated PSU would be needed for such an item. I suspect that such a box will be needed to provoke mass appeal of PAW to "non tech" pilots.
Thanks Paul for the thread link, this was one I also had found.
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Here's another thread with RF interference issues. It has a couple of recommendations but in cigarette lighter format.
http://forum.pilotaware.com/index.php/topic,292.30.html (http://forum.pilotaware.com/index.php/topic,292.30.html)
Though I see one's not available any more, but a single USB version is. Note that it's 12V only, not suitable for 24V.
http://www.ebay.co.uk/itm/Universal-Fast-Charger-5V-2-4A-1-USB-For-Smart-Phone-Car-Adapter-GOLDEN/382072160781 (http://www.ebay.co.uk/itm/Universal-Fast-Charger-5V-2-4A-1-USB-For-Smart-Phone-Car-Adapter-GOLDEN/382072160781)
By the way, anyone reading this almost in real time, the Anker car USB thing is currently on a lightning deal for the next 2 and a half hours!
https://www.amazon.co.uk/Anker-PowerDrive-2-Port-Charger-iPhone/dp/B00VH84L5E (https://www.amazon.co.uk/Anker-PowerDrive-2-Port-Charger-iPhone/dp/B00VH84L5E)
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Aha! I found the other post about the noise on the CPT and about another recommendation.
http://forum.pilotaware.com/index.php/topic,745.msg9675.html#msg9675 (http://forum.pilotaware.com/index.php/topic,745.msg9675.html#msg9675)
The other recommendation was this:
http://www.ebay.co.uk/itm/351259407149?_trksid=p2057872.m2749.l2649&var=620423764283 (http://www.ebay.co.uk/itm/351259407149?_trksid=p2057872.m2749.l2649&var=620423764283)
But again 12V only.