PilotAware
British Forum => Technical Support => Topic started by: bnmont on May 08, 2021, 05:48:37 pm
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I have a Funke TRT800, latest 6.3 software and hardware having taken Funke up on their substantial discount offer to upgrade from a 5.2 software transponder. At the moment I dont believe it is functioning correctly with the uncertified GPS data being sent to it. This despite assurances from Funke that all has been tested and certified.
Below is part of an email sent to Funke from which I'm awaiting a reply
Dear Michael,
Please can you ask you tech guys to explain the attached tracks as displayed on the ADSB exchange site. The first is G-CIJO my plane equipped with the latest Funke TRT and 6.3 software. NMEA data in at 9600 bd. Consistently my plane is shown as tracking North when obviously not going in that direction. Only just prior to landing does the plane show the correct orientation.
https://globe.adsbexchange.com/?icao=406cb1&lat=52.132&lon=-0.314&zoom=11.0&showTrace=2021-05-02 The Track replay of G CIJO Funke equipped Sunday 2nd May 2021
My Friend who was flying in loose formation with me whose Trig equipped is perfectly tracked on the adsb exchange site and also performs correctly when .trk files are replayed via the Aircrew website.
We have looked at the $GPRMC messages grom PilotAware to the transponder and all appears correct.
I'm awaiting a response from Funke, they were also sent the $GPRMC messages relating to the attached track.
Obviously I'm concerned how my plane is displayed via EC. How does my plane get depicted on Skydemon when its "reversing" down the track being flown?
Regards Brian
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Further attachments
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Hi Brian,
That certainly doesn’t look like a ‘fix’ to me. Sounds like Funke still have some work to do. Please keep us posted.
Regards
Peter
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Hi Peter,
Yes I'm afraid it doesnt look great.
I'm aware of one other aeroplane fitted with a Funke TRT800 and the 6.3 software. This also doesnt track correctly when on ADSB exchange.
What would be helpfull is if other such aeroplanes with GPS from uncertified source could look at how their aeroplane is reported as tracking via one of the tracking sites.
Also if anyone has a screen shot of Skydemon (others available) showing your plane clearly not following the track being flown. Obviously these will not be easily come by, needing someone PAW equipped in loose formation with both flying the same track.
What really concerns me is what is depicted when an aeroplane is "reversing " down the track being flown. Does it have a direction vector still pointing north when actually travelling South? Maybe there is no vector shown at all?
In response to a previous email I received this reply.
Dear Brian,
yesterday I had a long discussion with our tech guys. Actually they say
... well they have no explanation. We tested and certified our software
and we can say that the TRT reports only the data it gets.
The only way to find out what happens is to monitor the GPS-input and
compare it with the ADS-B-output. We have done this in extensive tests,
all works well. We can never be absolutely sure that there are no errors
in software so what we have to do is the monitoring described above.
This would require any kind of device recording the RS232-data.
Since I am not aware of the ADS-B-receivers used for your recording I
would like to note that we found some problems with ADS-B-recording
here. E.g. some receivers calculate heading and speed based on position
data rather than the data in the RMC. Especially for slow planes this
can result in erratic result.
Please do not hesitate to contact me for any further question.
Kind regards
So now Funke have the $GPRMC messages for a track bing flown and the resulting display on adsb exchange. The flight was also monitored by a friend PAW equipped, at many points my vector and the aeroplanes actual direction of travel didnt coincide with the track being flown.
I will post Funke's next response when I get it.
Regards Brian
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Image of the start up message from the new Funke. Worked fine and showed it's track fine yesterday. That was looking on FR24, haven't yet had a chance to check it with another aircraft and PAW or SE.
My old Funke transponder worked fine with a Garmin or a PAW GPS 232'd into it but I couldn't get the numbers up to get it approved as it wasn't doing what it needed to. My new one does and I may now go for the approval.
Reading the post above with interest. Regards, Clive
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I've not used the GPS Global exchange before but just had a play with it interrogating my flight last eve and I do indeed appear to be going backwards and sideways.
I then looked at my flight on FR24 and I was always going forwards, as I was when I checked the flight at the time.
I then looked at G-CIJO's flight on Flight radar from 2/5 and it was always going forwards. It looks like something to do with the functionality of the GPS Global exchange's presentation of the flight data. That doesn't show what's being presented during live flight of course but as I understand it any system will join up individual position reports and string them together so it's where you are each time your transponder transmits.
Is the heading data sent out with the position data? I don't know how it works, maybe someone that does can tell me?
Regards, Clive
P.S. how do you insert a picture in this Forum? Can't seem to figure that out...
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Hi Clive,
Thanks for the feedback. I am also not familiar with the ADSB Exchange tracking site, so unable to comment, but will take a look. What we are of course most interested in is what is showing up on our own and other ‘in aircraft’ traffic awareness systems. This is best reported from another aircraft flying with or in close proximity to you, though re-running your flight track from PilotAware through the Aircrew playback tool may also help show what is going on, see https://Aircrew.co.uk/playback .
To add photos, use the ‘Attachments and other options’ tool - below the window you are typing in, but be aware that you need to ensure that each photo (or the group of photos in an individual post) total no more than 512Kb in size. There are several photo processing apps which allow you to reduce the electronic size of photos, for example by resizing and re-saving as .jpg files where necessary. Which are available depends on the device you are using.
Hope this helps
Regards
Peter
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I've not used the GPS Global exchange before but just had a play with it interrogating my flight last eve and I do indeed appear to be going backwards and sideways.
I then looked at my flight on FR24 and I was always going forwards, as I was when I checked the flight at the time.
I then looked at G-CIJO's flight on Flight radar from 2/5 and it was always going forwards. It looks like something to do with the functionality of the GPS Global exchange's presentation of the flight data. That doesn't show what's being presented during live flight of course but as I understand it any system will join up individual position reports and string them together so it's where you are each time your transponder transmits.
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I've been flying with G-CIJO and have seen first hand on my pilot aware the incorrect funke transponder direction information showing his plane always pointing North rather than correctly showing the plane orientation. It's not constant though, sometimes his plane points in the right flight direction, sometimes it points North. I've taken screen shots of the issue for Brian to send to Funke. We've put this 'flipping' of direction to sometimes my PAW is picking up his transponder signal and sometimes it picks up his pilotaware signal, PAW correctly sends the direction track and so when receiving PAW signal the plane tracks in the right direction, when receiving the transponder it points North.
And we think this is the cause of the discrepancy between adsb exchange (which as it says is displaying ADSB information) and flight radar 24. FR24 says that it gets its track information from ADSB receivers AND glidernet (which is linked to the Atom grid network to receive PAW signals) We think its is prioritising the glidernet traffic displays over the ADSB, hence why FR24 shows the right orientation but ADSB exchange doesn't.
You make a good point that the flight replay websites could be interpreting the flight information and determining their own orientation information, not displaying what is actually received. We can't know for sure whether that is the case or not, but I can say with absolute confidence that Brian's PAW/Funke transponder combo will sometimes show the plane on the right track and sometimes it pointing North. The North orientation usually appears when we are further apart in flight and when we're not in the locality of a PAW ground station - further strengthening our view that its the transponder at fault.
Geoffrey
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I have heard back from Funke today. It appears that I didn’t attach the $GPRMC file on the email to them. So job to do.
What is interesting to me though is that any Trig equipped aeroplane always seems to track correctly on Adsb exchange and also via the PilotAware ground stations, whereas my plane often is displayed tracking incorrectly on the same sites. I’m pretty certain that the GPRMC messages going to the transponder are correct.
Regards Brian
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Further to the reports above of Funke TRT800 I did some testing today and was monitored by two EC units, my Brand new TXP is a ZTRT800 with V6.3.
I was maneuvering whilst talking to a friend monitoring my flight from his aircraft on the ground. He has SkyEcho displaying on SkyDemon and also Garmin GDL393D with it's own display. On both displays my aircraft's heading was shown pointing North and when interrogated showed 359 or zero. The positioning and movement was as would be expected.
So there is definitely something amiss in the Transponders output compared to other manufacturers.
At the time FR24 was showing it's usual jumpy but generally correct track direction.
I've just had a look at my flight on the ADSB exchange and the heading was 0.0 or very close zero throughout with the icon pointing North.
On FR24 the heading looks normal with the icon changing to match the track and the track readout changing accordingly.
What I don't know as I mentioned before is how the track is derived on any of these systems, and what is actually transmitted by the TXP within it's extended information. The GPS signal is currently from a Pilot Aware unit, I can fairly easily move this to a Garmin GPS as I have that available too.
I had a chat with Norwich Radar but their system paints in responses and they figure the track out from the movement of the contact so they couldn't help. All aspects of the TXP's transmission were OK as far as They were concerned.
I'm ready to contact with Funke but thought I'd see if there was any feedback to Brian yet?
Regards, Clive
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Hi Clive
Not much to report back yet. I had an earlier reply which basically said that the GPRMC messages being sent to the transponder had no position or speed included. And that therefore the transponder wouldn’t work correctly. Said it was a PilotAware error. When I pointed out that the aircraft was stationary at the airfield they were quick to admit they had got it wrong. I have since sent the correct GPRMC files to match the flight linked above. As far as I can see at all times when airborne PilotAware was sending all the correct info to the transponder. Funke have said it’s may be due to having a slow ground speed.
If I hear more I will post
Regards Brian
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Hi thanks for getting back with the reply.
I've been learning some more and seems the data transmitted should indeed include the heading.
I found and example of a transmitted NMEA string
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598, ,*10
RMC—Recommended Minimum Specific GPS Data
The 309.62 was the course so it certainly looks like the GPS data that the TXP is transmitting likely should include the heading.
So the question is why isn't the Funke sending out the heading information......
Seems strange that other folk's TXP manage to transmit the heading but the Funke won't. We do have examples of the PAW GPS output being used elsewhere successfully?
As I said I was flying and my friend got a screenshot of the info my TXP was transmitting and it was North all the while.
How are you reading the GPRMC messages?
Do you think it's worth me swinging mine across to the Garmin? Just to prove it's not the Pilot Aware?
Regards, Clive
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Call me Mr Pedant, but a GNSS receiver has no idea of your heading, in the aeronautical sense. All it can derive is your actual track, which is surely what you mean.
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Yes, but you knew what I meant so you are indeed a pedant!
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Hi Clive
Not much to report back yet. I had an earlier reply which basically said that the GPRMC messages being sent to the transponder had no position or speed included. And that therefore the transponder wouldn’t work correctly. Said it was a PilotAware error. When I pointed out that the aircraft was stationary at the airfield they were quick to admit they had got it wrong. I have since sent the correct GPRMC files to match the flight linked above. As far as I can see at all times when airborne PilotAware was sending all the correct info to the transponder. Funke have said it’s may be due to having a slow ground speed.
If I hear more I will post
Regards Brian
Hi Brian,
Had another read back through this entire thread and info on previous issues with Funke Transponders published elsewhere. Interestingly Funke’s comment (my bold above) seems to be reflected in my viewing of your earlier ADSBExchange track - where the only point at which your aircraft turned to face in the correct direction was when you (presumably) slowed prior to landing, though strangely not reported from the FR24 playbacks. I would also concur with your and Geoffrey’s earlier conclusions re his display reporting (correctly) from your PAW when at close range and your transponder when further apart (i.e. when your PAW signal dropped out), though I’d be surprised if this was due to FR24 prioritising PAW reports over ADSB. If they receive P3i reports at all, they will only be from those ‘non-PAW’ OGN Stations that have upgraded to run on 0.2.8ARM. This would however, certainly suggest that to discount this effect when gathering evidence, you need to be accompanied by another aircraft flying far enough apart to preferably NOT be within optimal PAW reception range.
@Clive,
Yes, two comparative test flights - ideally accompanied by the same aircraft, perhaps using a ‘non-paw’ ADSB detector, or if using PAW, keeping fairly well distanced - with the first run ‘as is’ (i.e. using the PAW GPS data to feed your Txpdr) and a second using the GPS input from your Garmin would be good, if you could manage to do that.
Best Regards
Peter
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Changing to the Garmin is a wire connection under the panel so not that easy. Given that the ADSB exchange shows the shortcomings of the Funke I'll just change it, fly and then look at the flight with that website. Will report back, Regards, Clive
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Hi Clive,
To get the GPRMC messages being sent firstly you need to download a track file from PilotAware.
This can then be opened in Excel (select all file types), in the text input wizard highlight Delimited,next, select Tab and Comma, next, select text and Finish. This should populate the spread sheet. Now you need to filter the data. Select data, filter, and tthen select only the GPRMC message type in column A.
BTW there may be a much easier way to achieve this I'm self taught and complete amateur with Excel.
Once you have the messages you can see column B time stamp , position, speed and heading, date.
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Just to quickly show the difference between the Funke and Trig transponders:-
https://globe.adsbexchange.com/?icao=405f7f&lat=52.136&lon=-0.312&zoom=11.1&showTrace=2021-05-02 This is Geoffreys Trig equipped plane . He was flying in loose formation with me. His track is displayed perfectly on the ADSB exchange site.
This is my plane flying at the same time with the latest FunkeTRT800 and software 6.3 https://globe.adsbexchange.com/?icao=406cb1&lat=52.196&lon=-0.254&zoom=11.1&showTrace=2021-05-02
Its easy to spot the difference!!
Regards Brian
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https://globe.adsbexchange.com/?icao=406cb1,406436&lat=52.712&lon=1.540&zoom=11.1&showTrace=2021-05-16
Check this out. My new Funke connected to a Garmin 396.
Comments appreciated.
Regards, Clive
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Hi Clive,
That certainly looks much better behaviour. I assume the 396 is also an un approved gps?
Does it only send the GPRMC messages? And you just used NMEA settings on the Funke?
I don’t suppose you had anyone monitoring via PilotAware and SkyDemon?
Regards Brian
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Hi Clive
Take all posted above back. It’s a mode S track only I think
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It says ADSB on the page while it plays it?
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No one monitoring, figured as the ADSB exchange showed my last flight pointing North all the while and now it shows the track like you would expect that it's a step forward?
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Apologies, you’re correct.
Don’t know what I was seeing the second time I looked at the track replay.
Brian
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can we assume there is a problem with the PAW derived GPS data?
I will try and get a friend to check it out from his equipment in the week.
Regards Clive
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Hi Clive,
I honestly dont know what to think. The garmin is uncertified I guess, I really hope it's not a problem with data from PilotAware.
Maybe Lee can comment?
Certainly my GPRMC messages from PAW to the transponder contain position and track data.
I have yet to hear anymore from Funke.
Regards Brian
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Is it possible for the RS232 converter to corrupt the signal somehow?
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Is it possible that the FTDI converter is supplying the messages at the wrong voltage?
Just a friends thought.
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I've also contacted Funke but no reply. The Garmin is an old unit but works fine and feeds my Dynon and Autopilot successfully.
Any now the Funke by the look of it. It was feeding my old TXP but I moved it to the PAW in case that was why SkyEcho's weren't picking it up. It didn't make any difference as I think the old TXP didn't have the extended Squitter working correctly.
See what Lee thinks, for sure something's changed as now my track is being transmitted and it wasn't before when it was using PAW derived data.
Regards, Clive
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Hi Both,
What a difference Clive - complete change of performance using the Garmin as your GPS source instead of your PilotAware. It appears there may be something going on here that we are not yet aware of (at least with Funke transponders).
Regards
Peter
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Hi Clive
What settings have you configured for the nmea output
You can find this under advanced settings
Brian, the 396 outputs much more than GPRMC, I wonder if funke have provided the correct info
I checked this from our ground stations too, and the DF17 has the correct data on 16/5
According to the Garmin manual
Always transmitted
GPRMC, GPGGA, GPGLL, GPBWC, GPVTG, GPXTE, GPRMB
hmm, is it really using this ....
GPVTG http://aprs.gids.nl/nmea/#vtg
Then there are optional choices
Thx
Lee
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Is it possible for the RS232 converter to corrupt the signal somehow?
It shouldn't be, despite the circuitry at its heart its just a physical connector. RS232 sends data in a serial manner with a ground and signal line into the transponder, USB is Universal Serial Bus, 4 connectors, +5v, 0v, signal and signal ground.
There's no decoding/rewriting of the data packets being done, its at the signal layer.
Worth checking that the baud, error correction bit etc are set the same and match the Funke and PAW, and maybe there's a problem with one device not being able to keep up so a different baud rate might help, but 9600 isn't exactly fast.
Geoffrey
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Hi Clive
What settings have you configured for the nmea output
You can find this under advanced settings
Just the straight NMEA at 4800 baud.
Regards, Clive
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OK, so according to the manual it will send the following
GPRMC, GPGGA, GPGLL, GPBWC, GPVTG, GPXTE, GPRMB
Thats quite a lot of messages for 4800 baud, at 4800 that is 600 characters per second
7 messages, which I think MUST be less than 80 characters, so 560 characters + '\r\n' per line=14
Brian, do you think Funke could be using these other messages ?
GPVTG is a track message
Thx
Lee
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Hi Lee,
I’m afraid I don’t know for certain. Michael at Funk’s has only mentioned the need for the GPRMC data set. Nothing else mentioned.
Would it be possible to build a beta with the GPVTG messages as well?
The Funke can do 9600bd
Regards Brian
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Had to look them up....
GPRMC, Recommended minimum specific GPS/Transit data
GPGGA, Global Positioning System Fix Data
GPGLL, Geographic position, latitude / longitude
GPBWC, Bearing and distance to waypoint, great circle
GPVTG, Track made good and ground speed
GPXTE, Cross-track error, Measured
GPRMB, Recommended minimum navigation info
OK, so according to the manual it will send the following......Whose manual?
Regards, Clive
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I think that’s from the Garmin 396 manual
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I think you are right, just been looking at it.
Doubt mine is set to anything extra but I'll go and have a look shortly.
The options to send extra data don't look like they would help with aircraft position and track which is all we need for the TXP?
Rather they are for using with other gadgets, waypoints, Routes, and to show status of the GPS and satellites.
If both can take 9600 baud maybe I'll move it up to that.
Reading the manual, whatever next.....
My GPS is connected to and works with an Dynon HSI with all the Nav stuff showing so maybe it has some extras being sent.
Heading to airfield for a look see,
CJ
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Funky with 6.3 software can do 9600 bd
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Went down the airfield and interrogated the Garmin.
It's a 196 so Black and White, I can update it so i've never thought of changing it.
It's set to 4800 and the 9600 is only available if you simplify the text it sends out so I didn't move that.
It's as Lee says so the message it's sending is as per his list which is from the manual, which obviously works.
It hasn't compromised my HSI or my autopilot so the Garmin is successfully sending to three units.
From what I've just read 232 was for a single link between two computers and as such doesn't guarantee multi drop but it obviously works in my case.
Given it seems to be doing the job for the Funke I'm going to leave it as it is.
Have also forwarded the info to Funke who replied 'we are talking to Pilot Aware'
So, looks like something needs doing with the PilotAware to supply the info that is missing (track made good), the rest seems ok?
Regards, Clive
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ADMINS: The end of this string is really about what a Funke transponder is transmitting when it gets its GPS information from the PAW unit as opposed to another GPS. As such maybe it needs to be re-titled? Or seperated?
So what happens next regarding the, what looks like, lack of track being passed over?
My tests suggest the PAW unit isn't sending the same information as a regular GPS (in my case a Garmin 196).
Is this something that can be changed within the PAW unit?
Or am I understand the functionality incorrectly?
Regards, Clive
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Hi Clive
Agree that last posts should really be moved. I have ground tested a beta software release which Lee produced. This has extra message types Including GPVTG and now appears to be performing correctly. No flights yet just a short ground run.
Funke keep saying that the transponder only needs the GPRMC data though.
Regards Brian
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Hi Clive,
Resolution of this problem is obviously at a delicate stage and as a beta test is underway it would be inappropriate for me to comment in any detail on a public forum until testing is complete.
What I will say is that if Lee’s findings are correct, the issue could well apply to GPRMC messages from other ‘regular GPS sources’ not only from PilotAware - (though it obviously doesn’t apply to your Garmin). If so, and as it is obviously not an issue for other transponder manufacturers such as Trig, the final solution may well be a further software adjustment by Funke.
In the meantime, my advice would be to continue with your Garmin feed, - though if you want to get involved in the testing, I’m sure Lee would be happy to provide you with a copy of the PilotAware Beta Software Brian is using to try out.
Best Regards
Peter
p.s. I agree it would be appropriate to split the latter part of this to a separate thread - probably from Brian’s post (Reply#18 on Page 2)
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Sounds good Peter and Brian.
I'm happy to help if I can though not keen to get under the panel again for a while. Where I have made the option to change over GPS NMEA feed easier it's not flicking a switch. I have made the change back to The Garmin semi permanent so I don't need to revisit to tidy it up.
There is one more PAW at my field but the ASDB exchange seems to be a good test tool.
I was testing Safe Skies yesterday whilst being monitored by another user on the ground, seemed pretty seamless if you have 3 or 4G, the track shows when I was turning the Funke on and off. No other aircraft about so couldn't check the collision warnings, I'm going to give that a go when I'm not the only aircraft flying in North Norfolk.
https://globe.adsbexchange.com/?icao=406436&lat=52.715&lon=1.543&zoom=11.1&showTrace=2021-05-22
Regards, Clive
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Looks like my Funke is now doing what it should. This is a Beta version first flight Funke getting its messages from PAW.
https://globe.adsbexchange.com/?icao=406cb1&lat=52.169&lon=-0.316&zoom=12.9&showTrace=2021-05-29
https://aircrew.co.uk/playback/groundstations/?ICAO=406cb1&RxType=ADB&adbVariant=*&Station=*&start=1622289600&end=1622300400
Thanks Lee
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Nice one PAW, I think I'll leave my Funke connected to my old Garmin though.
Until there's a good reason to move it back I don't fancy that trip under the panel.
Regarding Skysafe, I was away on tour darn Sarf/Cornwall over the weekend. Monitored it now and again and the phone signal soon drops out so unless low level and flying close to many masts it stops working. One thing that it shows that I've never seen before on anything is parachutes. So worth a look now and again to see who's about as discussed above.
Begs the question, could Sky Safe flying be fed into the ATOM grid for flyers who have only a mobile phone?
Regards, Clive