PilotAware
British Forum => Technical Support => Topic started by: Steve6443 on July 29, 2018, 07:21:05 pm
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Up until about 3 months ago, my Pilotaware was running fine, however just recently (since updating to the latest version from May) it has started to show a ghost target 100 feet above me, no direction. Occasionally it will show as level. It doesn't show an ID, I'm pretty sure it's a ghost but what can have changed since the update?
My settings are correct, anyone got any hints what to test next? I've not moved anything around, It's all fitted as previously..... Cheers!
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Hi Steve
I think I know the issue, I will have an enhancement in next release
Would you like to test out an engineering release ?
It would be good to get feedback
Thx
Lee
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Hi Lee,
I would like to receive an engineering release please as my PAW is currently unusable due to ghost warnings.
Thanks,
Roger
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I would like to receive an engineering release please as my PAW is currently unusable due to ghost warnings.
Roger,
This should not make it unusable, if it is unusable, then there is another problem.
As a minimum you should be able to operate without Mode-C support, which will continue to provide
Mode-S, ADS-B, P3I, OGN-R.
Please confirm the issue you are seeing is only Mode-C returns for false-positives.
(BTW, is your transponder Mode-C or Mode-S, can you provide a model reference ?)
I can provide a link to an engineering release, but please ensure you are using a second MicroSD card so that you have a backup
I think the root problem here, is that ModeC is only accurate to within 100ft, with no indication of rounding (up, down or to nearest)
Thx
Lee
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You are entirely correct Lee.
I will use a different card.
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It’s an old Bendix mode c with ameriking encoder.
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It’s an old Bendix mode c with ameriking encoder.
Hi Roger
I dug out the specs here :-
http://contrails.free.fr/temp/9.1.23.pdf
Quite surprised to read on page 14 (of the PDF) that the correspondence error is +/-125ft
I wonder if that is why we are seeing this issue with your setup ?
IIRC you provided me with a track file, and what I could see is that it was being reported just outside the 100ft limits for each warning.
Thx
Lee
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Hi Lee,
my transponder is a GTX330ES, non ADS-B out and if you have a new release to test, please let me know, I'd love to trial it.
Thanks.
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I seem to be getting the same "ghost" reports. These indicated C-045F and C031E (twice) whilst flying along south coast. All three were +100ft. This was my first proper flight with SkyDemon and other contacts were displaying correctly. There were still, of course, visual contacts which did not display but they probably had no transponder (or were just careless). I have screen prints of the "contacts" if this is any help?
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I have been having the exact same issue since upgrading to the latest software. My transponder is a Mode S Garmin GTX 330.
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Hi all
Can I get track files in order to verify ?
Thx
Lee
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I'm also getting ghost reports 100 feet above and below since upgrading the firmware. Becker Mode S and Ameriking encoder, non ADS-B out.
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Ok, tracks please, and does this happen in a climb/descend by any chance ?
Interesting the same encoder which has +/-125ft accuracy
Thx
Lee
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Hi all
Can I get track files in order to verify ?
Thx
Lee
Wilco.... hope to get them this evening and will send to you....
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I was wrong on the brand, Garmin GTX 320.
But right on encoder, Ameriking AK-350.
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Any eta for the software download please Lee?
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Wilco.... hope to get them this evening and will send to you....
Hi Steve
had a brief look at your tracks, can you please confirm, are you selecting :-
Mode-CS, or
Mode-CS+Filter
Your tracks would indicate the Filter is not enabled.
Thx
Lee
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Wilco.... hope to get them this evening and will send to you....
Hi Steve
had a brief look at your tracks, can you please confirm, are you selecting :-
Mode-CS, or
Mode-CS+Filter
Your tracks would indicate the Filter is not enabled.
Thx
Lee
Hi Lee,
previously it was enabled, now it was just set on Mode-CS. Have set it to Mode-CS+Filter. Thanks.
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Hi Lee,
previously it was enabled, now it was just set on Mode-CS. Have set it to Mode-CS+Filter. Thanks.
Well, you may not be pleased about that, but I am!
That makes me feel much better, looking at your track I was seeing a very powerful transponder (which is your own) which should have been filtered using the Machine Learning detector. The fact that I saw it repeating, indicated that the Machine Learning algorithm was either a bit ill-educated or not enabled !
Thanks for clarifying
Lee
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I had a very similar issue when flying in a friends aircraft last week. I changed the hex code and stuff but throughout the flight I had the ghost image but with different C- codes.
I've checked as as far as I can see I was using the Mode CS + filter in the profile. Otherwise, the published HexCode on G-INFO was wrong.
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I had a very similar issue when flying in a friends aircraft last week. I changed the hex code and stuff but throughout the flight I had the ghost image but with different C- codes.
I've checked as as far as I can see I was using the Mode CS + filter in the profile. Otherwise, the published HexCode on G-INFO was wrong.
If you can provide the track files we can investigate what could be happening.
Hex Codes are irrelevant as far as Mode C is concerned I am afraid
thx
Lee
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..Interesting the same encoder which has +/-125ft accuracy
I recall that this is a left-over of parallel altitude encoders for early Mode-C transponders. They used octal encoding (just like the xprd codes themselves) and this allowed for a good trade-off between bits required and accuracy. A single octal digit (3 bits) is enough to encode 1000ft. Flight levels are divided up in 500ft increments (East/West, IFR/VFR), so having 125ft steps are plenty to have error margin and still keep things safe.
The fact that we now have cheap sensors that can do +/-10cm for penny's wasn't so obvious when the Mode-C standard was cooked up.
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Flew for 5 hours today with the engineering software release & have sent you the track files for analysis.
Best regards,
Roger
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Can anyone please advise how to send a track file. When I tried it said there was a512kb limit.
Peter
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There are two ways to do it.
Put in an online store like Dropbox, make it public and send the link to Lee.
Or
Email the file to Lee.
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Cheers
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I've also suffered fairly frequent Mode C alerts although I've started to learn to ignore them due to the callsign format (e.g. C-0A60) and the fact they appear instantly as a red ring and fairly quickly disappear again. They are random in nature and I'm unsure what triggers them. On a trip to Newquay yesterday I had several. See a screen grab of SKD and the track file.
Example extracts from the Track file below. I'm assuming these are ghost targets. I've a GTX330 Mode S.
https://www.dropbox.com/s/pptipmxkgt7i4ii/2018-08-17_11-56.trk?dl=0
$PFLAA,3,1500,,-33,1,FF0A60!C-0A60,,,,0.0,8*04
AlarmLevel = 3
Rel North = 1500
Rel East =
Rel Vertical = -33
ID Type = 1
ID = FF0A60!C-0A60
Track =
Turn Rate =
GroundSpeed =
ClimbRate = 0.0
Aircraft Type = 8*04
$PFLAA,3,1500,,-37,1,FF0A60!C-0A60,,,,0.0,8*00
AlarmLevel = 3
Rel North = 1500
Rel East =
Rel Vertical = -37
ID Type = 1
ID = FF0A60!C-0A60
Track =
Turn Rate =
GroundSpeed =
ClimbRate = 0.0
Aircraft Type = 8*00
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Hi davidbu99
Can You please confirm your Mode C/S settings selections (or post your configure page)
thx
Lee
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Lee, sorry for the delay, attached.
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Hi David
This is great data, I am sure this is you, and it has (just) bypassed the filter !
Basically your transponder encoder is disagreeing with the PilotAware alt encoder, here is the first message
$PFLAA,3,1500,,-31,1,FF0A60!C-0A60,,,,0.0,8*06
31 metres below, this equates to 101.7ft, the accuracy of a ModeC encoder is rounded to 100ft increments (PilotAware is 3ft increments) so this is just outside the scope of the filter - AARRGHGHH!
I have seen this a couple of times now, and I think we need to counter for the fact of this rounding issue in the ModeC Encoder. Interestingly, I can find nowhere where the Altitude encoder rounding mode is defined, it could be
- round up
- round down
- round to nearest
but not defined anywhere I have seen.
I think we can address this.
Other observation, previously I have seen this in ascent or descent, whereas in your case it looks like level flight. I wonder if there was suddenly a drop in external air pressure compared to internal air pressure perhaps ?
Thx
Lee
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Lee,
Almost all of my logs (the last 8 at least) contain these PFLAA sentences. To confirm your theory not a single sentence shows a relative vertical distance of less than 100 feet. If its of interest I noted a lot of the PFLAA alarm level 3 messages seem clustered around a relative vertical distance of 59m to 62m. Or is this a function of sensitivity setting? Some of the alerts are seen when descending or climbing.
I concur these are most likely my own target. I've a new bridge now as I've upgraded to Rosetta but haven't flown with this yet.
Not sure I opened the door during flight or dangled my PAW unit out of the window so unsure there was any sudden change of air pressure :)
If you want any more track files let me know. I'll retest with Rosetta shortly and advise if I am seeing the same ghost targets.
Thanks for the email btw.
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Hi David
We have some additional ideas we will be implementing to help ignore your own mode C responses
Are you interested in trying out beta code ?
The beta code will generate lots of diagnostics we can analyse offline
Thx
Lee
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Lee, yes, happy to do some beta code testing. I’ve got a few flights coming up so good timing, thanks, David
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I've also suffered fairly frequent Mode C alerts although I've started to learn to ignore them due to the callsign format (e.g. C-0A60) and the fact they appear instantly as a red ring and fairly quickly disappear again. They are random in nature and I'm unsure what triggers them. Usually 100ft below.
We have the same problem. I'm learning to ignore them, but it frightens the passenger.
We have a Garmin GRX327 Mode C.
If there is a fix/Beta available I'd like to try it.
Thanks...
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Over the past 2-3 months this has started happening to me too. I have checked and mode CS+filter is selected. Is there going to be an update soon to tackle this please? At present I'm disconnecting the audio to cut out the continuous warnings.
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Over the past 2-3 months this has started happening to me too. I have checked and mode CS+filter is selected. Is there going to be an update soon to tackle this please? At present I'm disconnecting the audio to cut out the continuous warnings.
Hi stillstanding
What version are you running ?
Can you take a screenshot of your home page & the configure page
Also can you provide the track file for the flight which has reported your own transponder.
There is an upcoming improvement I am hoping to release soon
Thx
Lee
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Thanks. Version is 20180520. Files attached plus link for log. https://www.dropbox.com/s/yjvkmxc8yebxpiz/2019-01-15_14-35.trk?dl=0
Mike
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Lots of data in the track log that Lee is best placed to comment on. A significant number of mode C audio alerts particularly in climb and decent, all less than 100ft below.
There also seem to be some issues on the Home page, perhaps because it had only been running for a few minutes? Can you do a new screenshot after it has been running for more than 15 minutes in view of the open sky?
Cheers
Ian
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Sorry, should have said I captured the Home page with the PA indoors, it was raining hard, it all lights up green.
Yes the audio alerts start in the climb, don’t know about descent as audio muted at about 500 feet!
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It is the "Command Not Registered" that interested me.
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Thanks Ian. Its stopped raining so I've tested the unit, rebooted 3 times and left it on as you suggested. Screen shots attached.
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Can you give me full details of your power supply and USB cable that feeds the power?
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It is the "Command Not Registered" that interested me.
Ian,
I’m pretty sure Lee said elsewhere that that’s just because the unit is running an older Kernel, so it isn’t able to respond to the ‘Throttling Display Command’. Not something to worry about.
Peter
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A fully charged Anker 20100 with JuiceBitz cable.
Can you give me full details of your power supply and USB cable that feeds the power?
It is the "Command Not Registered" that interested me.
Ian,
I’m pretty sure Lee said elsewhere that that’s just because the unit is running an older Kernel, so it isn’t able to respond to the ‘Throttling Display Command’. Not something to worry about.
Peter
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Thanks. Version is 20180520. Files attached plus link for log. https://www.dropbox.com/s/yjvkmxc8yebxpiz/2019-01-15_14-35.trk?dl=0
Mike
Hi Mike,
I have looked at the track file, and it appears to be representative of the case which I have a fix in the pipeline.
So please hold fire till the release and see if this fixes the issue you are seeing.
If it does not, there is also more logging that is put into the track file to indicate why you are seeing these false-positives
Thx
Lee
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Thanks Lee, appreciated.