aircraft reg doesn't show any more

[sdkellner]

Ian - I thought this too, but as Peter says my understanding is that the TRT800H squits (lovely word  ) ADS-B data even when not being interrogated.  In any case, the interrogation symbol was flashing.

Peter - please do not make a specific trip on my account!  It's the Easter weekend and I'm sure you have better things to do.

As ever chaps, I really appreciate your help, and have every confidence that we'll get to the bottom of this.  In case any of this is relevant, some additional info:-

1.  I am now running PAW purely from a dedicated Anker 20100 battery pack to eliminate any possibility of spikes from the 12v socket.  I have been doing this for the past few weeks, with a fully-charged pack each flight.

2.  The nose cone of my gyrocopter is definitely GRP, not carbon fibre.  A pic is attached of the interior showing my multiple aerials, with PAW on the left wall and trimmed-to-size 1090MHz in front of the VHF radio aerial.  The plate and ground plane on which the VHF aerial sits has the transponder aerial on the underside beneath the nose cone.  I did wonder if the ground plane was perhaps shielding the 1090MHz aerial from line of sight of the transponder, but this wouldn't explain why the second, external PAW reported only PAW and not ADS-B.

3.  Both my PAW and the second external one had the default Group ID of 'PAWGRP'; might this be relevant?

4.  For the past month or so I have been getting really bad static on certain comms channels, typically between 123 and 128 MHz; it took almost maximum squelch to silence.  All radio units reported readability 5 and confirmed that the noise was not being transmitted.  I finally figured out the culprit on my last flight - my expensive, and supposedly VHF-suppressed LED landing lights, as visible in the pic.  If I turn them off the noise disappears; with them on it is very audible on certain channels.  But this only started recently, around the time I installed PAW.  I originally thought that I might be getting noise on the external input carrying the PAW audio to my ATR833 radio/intercom, so bought the ground loop isolator which improved matters for a while.  Very strange; perhaps simply down to the physical closeness of all the aerials and LEDs within a confined space.

All the best

Stu

[Paul_Sengupta]

Peter - please do not make a specific trip on my account!  It's the Easter weekend and I'm sure you have better things to do.

...than go flying?! 

[sdkellner]

I'm going to head back down to the airfield this afternoon to carry out some further tests and will report back later.

It was the testing bit that troubled me; flying is entirely acceptable

Stu

[Giver]

Hi peter
just tried my paws at the workshop and for about 10 minutes it was showing my Registration so have taken a couple of screen grabs fo my inspector,



regards
Ivor

[exfirepro]

All looks good,

Peter

[sdkellner]

Just back from a test flight which was less successful than Ivor's - at no time did my registration appear on the traffic page.

In fact I seem to have a fundamental problem with either my PAW or my installation.  After take-off the interference on certain radio channels was worse than ever; I could not understand the transmissions.  This time the interference did not go when I turned off the landing lights.  I went through a process of turning of all my electricals - iPad charging, electric fuel pump, strobes - no difference; until I unplugged the PAW, whereupon the interference disappeared immediately.  The PAW was running from an Anker 20100 power brick, as recommended.

For now, and with great disappointment, I have had to disable both the PAW and therefore my ADS-B out; the radio problems are simply too distracting.

At the moment I don't know whether I have a faulty PAW (my ADS-B dongle was definitely faulty; might this be symptomatic of a generally dud unit?), a problem with the location of my installation (although there aren't many options in an open-cockpit gyrocopter!) or perhaps a grounding problem.  The latter is not something I know much about but I will do some research.

Stu

[sdkellner]

BTW, in case it is helpful, attached is a pic of today's flight.  Note the sudden cessation, which is at exactly the point I disabled PAW and therefore the GPS input into my transponder for ADS-B out.  Once the transponder dropped to standard Mode S, I was invisible to FR24.

So I have absolutely no doubt that my ADS-B out was working fine; just unfortunate that something in my PAW installation is causing such bad RF interference.

Stu

[exfirepro]

Hi Guys,

Just back from the airfield. Lovely sunny day, but wind unfortunately 21G31KTS, so flying not an option. Powered up my PAW (in the hangar - not hanging onto the wing in that wind ) and then powered up transponder - ADSB Out reported on my PAW as normal. It is then filtered by the software to prevent it being sent to Audio Alerts or Nav System.

Got mate to power up his PAW (also in the hangar) - shows up on my traffic screen (and Nav Screen) as a danger alert with associated audio warning.

He then turned on his ADSB Out Transponder and the PAW Traffic Screen for him changed to ADSB with warnings on Nav System and Audio Alert.

So all working as expected and definitely NOT a PAW software issue. Screengrabs attached (Lack of other aircraft due to metal hangar)

Regards

Peter



 

[sdkellner]

Thanks Peter; conclusive proof that I have either a dodgy PAW or something not right in my installation.  I have never seen my Reg on the traffic page, but am 99.9% sure that my ADS-B out was working fine.

Best

Stu

[exfirepro]

Stu,

Sorry to hear about your ongoing interference problems this afternoon.

Before hearing about this, I was looking at the pics of your installation at the airfield earlier in the day with a colleague who works in data and radio transmission and we were both extremely concerned about the close proximity of your VHF and PilotAware antennas to your 1090MHz Mode S / ADSB transponder antenna. This is almost certainly the source of your problems. The transponder transmits short but very high power pulses relative to any of your other equipment (in the region of 100 Watts output at the antenna). At such close range such strong transmissions will at best significantly desensitise (deafen) PAWS 1090MHz SDR receiver and could possibly even cause it some damage. The 'short but powerful' data pulses will almost certainly also have a detrimental effect on your VHF comms receiver, again desensitising it and presenting as loud clicks, white noise or other similar interference and requiring a higher than normal squelch level to mask them - as you have reported. I appreciate that in an open cockpit aircraft antenna positioning is difficult, but I really think you need to increase the separation between your transponder antenna and the rest of your antennas.

Regards

Peter

[sdkellner]

Hi Peter

I suspect you may well be right.  The transponder and radio together with associated antennas were all installed by the aircraft manufacturer.  I had no problems with the radio before I installed PAW, so although the transponder and VHF antennas are physically closer than ideal they do seem to work as long as PAW isn't also in the mix; perhaps the significant difference between the comms frequencies and the 1090MHz transponder frequency is the reason.

I have already tried moving the antennas further away; I have the centre-fed dipole but its 10-foot cable wasn't quite long enough for the only other viable mounting option, the front of the rotor mast (accepting that this would give hardly any rearwards transmission; I was relying on my ADS-B out to cover this).  I have also cut the 1090MHZ antenna to half length but it is still too long to fit between my instrument binnacle and screen.  I will have to try a different approach, although at this point I really can't think of many alternative mounting positions.

May I suggest that the PAW manuals be updated to include guidance about ensuring separation between them and any transponder antennas;  unless I have missed it I don't think there is currently any mention of such, although there is detailed advice about situating away from people and metal!  The manuals also imply that any radio interference is almost certainly down to power supply, whereas it seems that the transponder issue may be another cause.

I just hope that we've discovered this in time before my PAW has been fried due to signal overload!

Best regards

Stu

[Admin]

Hi Stu,
Could you please try some experiments next time you get the chance.
I would like you to remove some of the dongles individually (when PilotAware is up and running) to see if they contribute to the noise, please try the following in exact order and let me know what happens

1. Remove RTL-SDR (ADS-B) dongle
(wait 20 seconds)

2. Replace RTL-SDR (ADS-B) dongle
(wait 20 seconds)

3. Remove GPS-Dongle
(wait 20 seconds)

4. Replace GPS-Dongle
(wait 20 seconds)

5. Remove USB/RS232 to Transponder
(wait 20 seconds)

6. Replace USB/RS232 to Transponder
(wait 20 seconds)

7. Remove WiFi Dongle
(wait 20 seconds)

8. Replace WiFi Dongle
(wait 20 seconds)

Remove Power
Connect Power

Please let me know what effect each of these has at each stage.
The RTL-SDR, GPS and USB/RS232 are hot-pluggable, so will recover automatically when re-inserted.
The WiFi is not hot-pluggable, and hence should be the last item to be removed in the list

Thx
Lee

[Paul_Sengupta]

Can you borrow another battery to try? It's not unknown that some examples of battery units can produce RF noise. The units use a boost converter to get the 3.2-4.2V of the lithium battery up to 5V. Usually not a problem with RF on Anker, but individual units may be slightly faulty in this regard.

[sdkellner]

Hi Lee & Paul

I will do as you suggest; I have the GPS mouse rather than the dongle; and I will use a different Anker 20100 power bank (I have two).

TBH I suspect Peter's assessment is correct, and that things are not going to improve unless and until I can find somewhere else to site my antennas.  I really don't think power is the problem;  I get the same issue whether I run from the recommended Anker power bank or 12v socket adapter.

As the problem seems to have got progressively worse, I just hope that I haven't already fried my PAW.

Best

Stu

[exfirepro]

Stu,

The (UHF) transponder will have much less effect on the (VHF) Comms Radio, than on the 1090MHz PAW SDR, though it could still desensitise it. I wouldn't be too worried about the PAW bridge as itshould be far enough off frequency not to get fried, though it might go a bit deaf during Mode S or ADSB pulses unless you can move the antenna. (You could use extension cables by the way, but try to keep them as short as possible.) You will soon know if the SDR is still working or not.

I am interested to hear the results of the tests Lee has asked you to do.

I agree with Paul's comments about battery power packs. I have experience of several non-'Anker'  packs which either won't work at all or cause PAW to generate loads of interference. Our FI also tried to power up his brand new PAW with one of the newer 'intelligent' 21,000 size Anker packs recently, which flatly refused to recognise the load and wouldn't start it, so its definitely worth trying both of your packs - other users please note!

Regards

Peter