Author Topic: I can see other traffic but my the Vector chart shows no broadcasts - resolved  (Read 10931 times)

exfirepro

Hi Neil,

Just checked - Overfarm is definitely active again!

We have P3i reports from your flight yesterday from Cheltenham, Kemble, Nympsfield, Overfarm and Aston Down. Maximum range reported on P3i was Kemble at 26Km. Also lots of ADSB reports from multiple sites at varying ranges.

Looking at the Groundstation Replay (link below, but you need to set the correct date, time and search period), however, I'd have to say your tracks look pretty sketchy with lots of significant gaps. I have to go out shortly (childminding) but will take another look at it when I get home this evening.


https://playback.pilotaware.com/playback/groundstations/?ICAO=407F92&RxType=PAW

Best Regards

Peter

FlyingPastor

Hi Peter,

Thank you for looking at that, my uninformed eye would read that as I still have a problem. The aerial was replaced in September, but given I'm flying around Over Farm for most of it even the dodgiest aerial in the world wouldn't have those many gaps surely?

Hope the child minding went well ...

n

exfirepro

Hi Neil,

As promised, I have had another look at the database, track replay via groundstations and coverage via the Vector Tool. All 3 indicate excellent ADSB coverage, but poor / very intermittent P3i coverage - at least using your 'official' 407F92 Hex ID.

Unless your unit has somehow reverted to the 'default' MAC-based Hex ID again, it appears that there is still an issue with your P3i transmissions. Unfortunately I don't have access to the relevant part of the database to ascertain the MAC of your PAW myself (so I can't check for reports under that Hex ID), and I obviously can't phone Ash at this time of night to get it. I will however speak to him in the morning and see if we can get to the bottom of what is going on.

In the meantime a few thoughts / questions. EDIT: Having just re-read the full thread I see that some of these questions were answered back on page 1, sorry  :-[ .  For the sake of clarity, I have added your earlier replies here.

Is your DeltaJet fibreglass or carbon fibre? A: fibreglass

I am assuming you are using an externally mounted 1/4 wave monopole antenna on a suitable ground plane. Is this correct? A: Yes - PAW External aerials

If so, where on the aircraft is it mounted? A: antennas are below the aircraft with sticky sheet metal backplane

I still need the following...

Have you checked for electrical continuity between the outer of the P3i antenna cable at the PAW and the metal ground plane? (If the ground plane isn't working properly there will be a significant impedance mismatch which could account for lack of transmitted signal).

Where is the PAW itself fitted? (of lesser significance with extenal antennas, but still relevant in relation to the next question)

What are you using to provide the GPS data - plugged-in GPS dongle or remote GPS 'mouse'? And if the latter, where is the mouse positioned?

How are you powering the PilotAware? - if directly from the aircraft, how is it wired and what make/type of 12 volt to USB reducer are you using?

Do you have any photos of the installation available?

Depending on the above, I may also ask you to power up the unit and take and provide screen grabs from the PAW 'in situ' and running. If so I will get in touch and explain exactly what I need you to provide.

Best Regards Meantime
Peter
« Last Edit: January 10, 2025, 09:26:38 am by exfirepro »

exfirepro

Postscript: Friday 10/01 at 10:45am

Hi Neil,

I have just spoken to Ash, who confirmed that your PAW Classic performed perfectly to spec on the test rig, and I now have your 'default' Mac-Based Hex ID (F596F1).

I re-ran my checks on your 8th January flight  on that (default) ID - nothing showing on any of the analysis tools - which proves that you did change the Hex ID to 407F92 prior to your flights on 8th January.

More worryingly :(, your flight from 4th January - with the default MAC ID - shows excellent P3i transmission on all 3 analysis tools, with groundstation replay from multiple stations concurrently throughout the flight and excellent all-round Vector coverage. This proves without doubt that your PAW was definitely transmitting P3i during both flights on 4th January - which is of course good  :D. Unfortunately, it doesn't help explain why it wasn't working on the 8th.

So what changed between the two flights on 4th January and the ones on 8th January (apart from resetting your HexID to the correct ICAO one)? Did you have the unit out of the aircraft, or did you just change the Hex ID via your tablet/phone?

Thinking about recent UK weather conditions, one possibility is that there might be a build up of snow or ice (or even damp mud) around the short insulating sleeve which separates the active transmitting element of the antenna from the ground (mount) under the aircraft, which could be causing a short circuit between them.

The only other thing I can think of at the moment is that something has come loose, so please check all power lead and antenna connections - including the connection between the antenna mount and the ground plane.

Let me know what you find.

Best Regards

Peter

 
« Last Edit: January 10, 2025, 11:11:21 am by exfirepro »

FlyingPastor

Hi Peter,

Absolutely nothing changed apart from changing the Hex-ID. It takes 40 minutes to get the aircraft apart and back together again to access the unit so I tend to leave it well alone. Everything is cable tied down, the PilotAware unit itself velcro on the aircraft and doesn't move. I will clean the aerial and see what happens, I have a lesson in just over an hour.

I must confess I find the whole failure utterly bizarre. SkyDemon would suggest it is working perfectly as far as GPS and power are concerned (it is my GPS source for SkyDemon). The SkyDemon logs are bang on and no gaps. When I've had GPS gaps in the past SkyDemon has complained, there were no complaints in respect of the logs ...

n

FlyingPastor

Hi Peter,

I flew today, Friday 10th January, from about 13:10 to 14:10. Does it look any better?

n

exfirepro

Hi Neil,

That's MUCH Better!

The groundstation playback of P3i shows pretty much a solid altitude profile and ground track, with concurrent reports from multiple ground stations throughout the flight. Vector shows pretty much 360 degree coverage at varying ranges up to around 50Km. (At this stage the 'Range' reported by Vector is dependent on where you actually flew in relation to those ATOM stations which saw you. The density of the diagram should improve with additional flight reports.)

So did you find something specific which has caused this change?

Best Regards

Peter
« Last Edit: January 10, 2025, 05:49:32 pm by exfirepro »

FlyingPastor

Hi Peter,

So I cleaned the outside of the aerial as you suggested, the only other difference was I wasn't running SkyDemon.

The flight was up to the south-east of the Malverns, then back to just west of Huntley, then returning to Over with quite a bit of manoeuvring between 1800' and 2700' in that triangle.

I notice there are gaps in the trace you sent, but not many. Is that usual or might it point to a continuing problem?

As ever thank you for your continued help.

n

exfirepro

Morning Neil,

Thanks for the feedback.

Not running SkyDemon shouldn't have had any influence either way on your P3i transmissions. I was easily able to follow your track on the playback tool. As nothing else physically changed between your flights on 4th and 8th January, wet or frozen mud contamination causing a short circuit around the base of the antenna could have been the problem as I suggested. I have certainly had that once before myself. We will just need to keep an eye on it and see how your PAW performs from now on.

Odd small gaps in your 'groundstation' playback aren't unusual, as reception can be affected by obscuration due to things like aircraft framing or undercarriage or ground terrain between you and the ground stations. Obviously less significant if you are flying over flat ground where there is a good density of ground stations. Are you aware that you can also download your own track files directly from your PAW (onto your phone or tablet for example), then play them back using the 'Track' playback tool at https://playback.pilotaware.com/playback/ . That option also shows any received traffic and (with a bit of work) you can analyse things like GPS reporting - though this takes a fair bit of time to get your head round if you have to do it manually.

Please keep me informed of any further issues.

Best Regards

Peter