Not receiving known PilotAware and ADS-B equipped aircraft

[Mat]

Rather odd behaviour with PilotAware today. Flew to Blois with G-CJAK and C-SLNT this weekend (and others, but those were in our return formation today). All three aircraft including mine (G-XLAM) are ADS-B transponder equipped and have PilotAware devices connected to SKyDemon.

I have not been able to see G-SLNT all weekend in SkyDemon. Initially put this down to reception problems due to him being directly behind me and my device being sat on the dash. No problem with others. No difference with him in front. Something's up.

I had time to do a bit of digging during our hours of flying today:
* G-CJAK visible in SkyDemon and verbally in PilotAware audio output.
* G-SLNT not visible in SkyDemon (maybe I saw him once but not long enough to screenshot and shown as a hex [ICAO?] code which I assume was his due to location), very occasionally verbalised by PilotAware audio output.

Traffic display appears to show lack of CSA in mode column for G-SLNT (presume those are Mode-C, Mode-S and ADS-B?)



Radar display appears to show G-SLNT ahead of me (and G-CJAK) behind. Why does it appear here yet not in SkyDemon? I've never managed to get SkyDemon to filter traffic even though I know it's supposed to be able to. With hindsight should have checked with my phone too.



Logs appear to show CRC errors. Is this normal, or related?



Have pulled device from the plane, so can extract logs if I know what I'm looking for.

[exfirepro]

Hi Mat,

This is clearly an issue with G-SLNT as both yourself and G-CJAK were seeing each other reliably throughout the trip.

As you know I was at Sywell yesterday evening, having stayed on after working at the LAA Rally to meet up with Allan on your return, so I was tracking your group back from France from just after you crossed the Channel (on FR24 as the temporary Sywell OGN-R Ground Stations had been dismantled by that time). I can confirm that, like yourself and Allan, G-SLNT was showing on FR24, but unlike G-CJAK and G-XLAM which were both rock solid, G-SLNT was jumping about all over the place like a mad thing - often racing ahead and off to the side of track at supersonic speed, then suddenly jumping back to the ‘group’ - so his position signal is at best ‘intermittent’ and that’s me being ‘polite’ about it. Unfortunately, I didn’t think at the time to check if G-SLNT’s FR24 track source was showing as ADSB or MLAT as I wasn’t aware at the time that you guys were also having a problem tracking him, and just took a mental note to suggest he check his GPS feed and antennas.

I understand from our brief post-landing discussion that the GPS source for G-SLNT’s Mode-S/ES (ADSB) is NOT PilotAware (I think he said it was from his EFIS ?) In any case, his setup definitely needs checking as he isn’t showing as Mode CS in your Traffic Table either.

Looking again at your table this morning, G-SLNT is showing as PilotAware Only (—-P-) with a Sig(nal) Strength of ‘0’ which is extremely unusual. I would suspect from this that he also has a problem with his PAW antenna or Bridge.

It’s almost certainly not the case here as you were seeing the others in your group, but remember that appearing on PAW RADAR but not on SkyDemon can simply be to do with your filter settings as your PAW Radar Screen is fed with RAW received data, whereas the data used to drive SkyDemon is subject to any filtering set in PilotAware AND any additional filtering set in SkyDemon. In this case however, you must have had ‘Mode CS’ selected in PilotAware (hopefully ‘+ Filter as you are transponder equipped) as the others are all showing as CSA. Out of interest - what Mode CS ‘Range’ and Vertical Display Range were you running? Same question for SkyDemon - Did you have ‘Show Bearingless Targets’ turned ‘On’ in SD - It’s now ‘Off’ by default and might have defaulted to this on your last SD update so worth checking. What did you have ‘Show Within Vertically’ in SD set to? As I say, almost certainly nothing to do with why G-SLNT wasn’t showing though.

You should be able to replay your track files using James Rose’s excellent replay tool at https://aircrew.co.uk/playback/ though I can’t remember if it differentiates between source systems.

You can also download your track files from the ‘Tracks’ Tab either directly or onto a USB stick and you can send them to Lee (Admin) for analysis if he thinks this is appropriate.

Please let us know what you find.

Best Regards

Peter

[Admin]

Hi All

Let me clarify a few things

Looking again at your table this morning, G-SLNT is showing as PilotAware Only (—-P-) with a Sig(nal) Strength of ‘0’ which is extremely unusual. I would suspect from this that he also has a problem with his PAW antenna or Bridge.

The signal strength is only measured for a transponder, PilotAware does not provide signal signal strength, and is therefore always 0

I suspect this is coming from Mode-S (MLAT), take a look here, altitude all over the place, and lots missing
https://flight-data.adsbexchange.com/map?icao=401292&date=2019-09-01
compared to CJAK
https://flight-data.adsbexchange.com/map?icao=407016&date=2019-09-01

the strange thing is not being visible in SD but it is in PAW-RADAR
If I can get a track file for this, it may give some clues.
I doubt it is SkyDemon settings, as it would have also ignored CJAK

What 3rd party connection method is used in SkyDemon ?

thx
Lee

[Mat]

This is clearly an issue with G-SLNT as both yourself and G-CJAK were seeing each other reliably throughout the trip.

What I failed to mention was that Alan in G-CJAK could see G-SLNT certainly on the first trip and I think on the second trip. So that adds a bit of more confusion.Not sure if he's got any relevant screenshots/tracklog.

In diagnosing this Alan also spotted another aircraft with a different ICAO between PilotAware and transponder. He's going to let him know (looks like a typo between 0 and 9). Surprisingly it didn't seem to cause any problems to us, although I suppose both were overlaid on the display.

[...] unlike G-CJAK and G-XLAM which were both rock solid, G-SLNT was jumping about all over the place like a mad thing - often racing ahead and off to the side of track at supersonic speed, then suddenly jumping back to the ‘group’ - so his position signal is at best ‘intermittent’ and that’s me being ‘polite’ about it.

That's just Kev's flying I had a bit of jumping about between me and G-CJAK earlier in the trip - noticed because I was jumping behind and ahead of him on screen but only close behind in reality. Didn't have spare brain capacity at the time to figure out whether it was him or me jumping about, but it was probably a somewhat smaller jump.

It’s almost certainly not the case here as you were seeing the others in your group, but remember that appearing on PAW RADAR but not on SkyDemon can simply be to do with your filter settings as your PAW Radar Screen is fed with RAW received data, whereas the data used to drive SkyDemon is subject to any filtering set in PilotAware AND any additional filtering set in SkyDemon. In this case however, you must have had ‘Mode CS’ selected in PilotAware (hopefully ‘+ Filter as you are transponder equipped) as the others are all showing as CSA. Out of interest - what Mode CS ‘Range’ and Vertical Display Range were you running? Same question for SkyDemon - Did you have ‘Show Bearingless Targets’ turned ‘On’ in SD - It’s now ‘Off’ by default and might have defaulted to this on your last SD update so worth checking. What did you have ‘Show Within Vertically’ in SD set to? As I say, almost certainly nothing to do with why G-SLNT wasn’t showing though.

I did wonder whether there was any filtering going on, but I'm not aware of any other than the vertical and horizontal extents. I thought I'd read there was a way to filter traffic (i.e. those you're flying all the way with) on the SkyDemon radar view, but I've never been able to get it to do anything other than show the corner bigger. Interesting that the radar display is RAW but the feed is further filtered in PilotAware before going to SkyDemon.

All settings you mention seem fine:



I assume automatic decluttering doesn't affect aircraft targets?

I was getting some bearingless targets, but presume these were other unsighted aircraft rather than a corruption of G-SLNT (e.g. one had what appeared to be a valid French registration).

You should be able to replay your track files using James Rose’s excellent replay tool at https://aircrew.co.uk/playback/ though I can’t remember if it differentiates between source systems.

I have a few tracklogs due to PilotAware drop-outs that I separately need to resolve, but I've put a large 20MB one on there (https://aircrew.co.uk/playback/2de11d) and a smaller 642KB one (https://aircrew.co.uk/playback/afc2f1). This seems to confirm G-SLNT is only received as PilotAware and no transponder, but doesn't explain why the PilotAware position was not shown on my SkyDemon (yet was on the radar).

the strange thing is not being visible in SD but it is in PAW-RADAR
If I can get a track file for this, it may give some clues.

2019-09-01_09-34.trk (20MB)
2019-09-01_12-09.trk (642KB)

What 3rd party connection method is used in SkyDemon ?

PilotAware.

[Admin]

Hi Mat,

From the track file G-SLNT is definitely in there, and would have been sent to SD, here are some records

$PALOG,20190901,093434,PAWRT,401292,0,A,0,C,0,S,0,ES,1,P,0,F,0,U,0,M,00,valid,00,vers,00,nacp,00,nica,00,sil,00,sils,*78
$PFLAA,3,-3,9,-7,1,401292!G-SLNT,0,0.0,0,0.0,8*33
$PFLAA,3,-5,9,-7,1,401292!G-SLNT,0,0.0,0,0.0,8*35
$PFLAA,3,-5,9,-8,1,401292!G-SLNT,0,0.0,0,0.0,8*3A
$PFLAA,3,-5,9,-8,1,401292!G-SLNT,0,0.0,0,0.0,8*3A

The first line is critical, it says we received PilotAware - but no transponder
now, we have seen that when very close together, there can be saturation of the RF - this is a possibility

*edit*, no I doubt this, I see you were upto 5km apart at times.

are all the transponders involved of the same type ?

thx
Lee

[Mat]

Yeah, my Sky Ranger Classic sometimes struggles to keep up with a CTSW, so he can be some way away.

G-XLAM and G-CJAK both run Trig transponders, I think G-SLNT has a Funke. That being said, we did have the amusement of another Funke transponder (sans PilotAware) flying sideways/backwards to France due ADS-B lacking correct heading info.

Further, G-XLAM's transponder is fed from a separate GPS mouse, not PilotAware. Not sure about the other two, but I'll direct them here.

[Kevin W]

Evening All

Sorry Peter I didn't know it was yourself at Sywell last night!

Focusing on my ADSB out for a second, there could be something wrong, but fr24 can see me near perfectly.

As we briefly said last night, my Transponder GPS feed comes from my MGL IEFIS box.  The MGL never complains about lost GPS issues.

FR24 has solid tracks for me coming back from LFAT last night, and the CSV data from them is perfect, apart from the Speed which has always jumped about all over the place.  Looks like Velocity is being calculated, but nothing else?

Timestamp   UTC   Callsign   Position   Altitude   Speed   Direction
1567352673   2019-09-01T15:44:33Z   GSLNT   50.551819,1.596581   1950   83   338
1567352679   2019-09-01T15:44:39Z   GSLNT   50.554367,1.594969   2025   84   340
1567352686   2019-09-01T15:44:46Z   GSLNT   50.556564,1.59374   2150   335   341
1567352697   2019-09-01T15:44:57Z   GSLNT   50.561222,1.591385   2325   123   343
1567352705   2019-09-01T15:45:05Z   GSLNT   50.563797,1.590199   2450   67   345
1567352711   2019-09-01T15:45:11Z   GSLNT   50.566437,1.589083   2500   87   346
1567352718   2019-09-01T15:45:18Z   GSLNT   50.568344,1.588341   2600   84   349
1567352726   2019-09-01T15:45:26Z   GSLNT   50.571304,1.587308   2675   105   348
1567352735   2019-09-01T15:45:35Z   GSLNT   50.575333,1.586151   2900   81   352
1567352742   2019-09-01T15:45:42Z   GSLNT   50.577236,1.58552   2950   70   349
1567352750   2019-09-01T15:45:50Z   GSLNT   50.580322,1.584489   3025   129   349
1567352761   2019-09-01T15:46:01Z   GSLNT   50.585106,1.582996   3175   220   350
1567352768   2019-09-01T15:46:08Z   GSLNT   50.587463,1.582103   3225   131   347
1567352782   2019-09-01T15:46:22Z   GSLNT   50.592957,1.579863   3425   144   345

Cheers
Kev

[Admin]

Hi Kev
I will email you today or tomorrow to follow up
Do you know what FW your funke has ?
Thx
Lee

[Mat]

Sorry Peter I didn't know it was yourself at Sywell last night!

We were all pretty knackered after five hours flying diagnosing tracking issues. 

[Kevin W]

Hi Lee,

I can't verify in person, but the upgrade email says it went to SW 5.2.B in May 2017.

HW 3.0, and hence can't be upgraded to v5.3 or beyond I am told.

Thanks
Kev

Hi Kev
I will email you today or tomorrow to follow up
Do you know what FW your funke has ?
Thx
Lee

[PaulSS]

Seems to me these Funke transponders have a lot to answer for as far as extended squatters are concerned. These problems appear far too regularly to be coincidence.

[tnowak]

There is an issue with some Funke transponders regarding the varying speeds as seen on FR24.
I think you need to upgrade to the latest firmware and software version to fix this problem but Funke want around EUR 500 for the upgrade.
My friend, also experiencing that groundspeed issue, decided it wasn't worth it and has now got a Trig TT21 and their certified GPS source.
Tony