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Author Topic: Spikes again....  (Read 13032 times)

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radarspotter10

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Re: Spikes again....
« Reply #15 on: January 21, 2010, 02:13:53 PM »
I'm hoping that when the 3D software is finally passed for shipping that Airnav will get down to going through the bug reports and start dealing with the remaining irritating but non-fatal bugs in 3.13, but when that will happen I don't know.

hi fenris.
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from pat

eggplant

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Re: Spikes again....
« Reply #16 on: January 22, 2010, 10:47:38 PM »
Thanks for the info Dave.  I've attached a screenshot of my Mylog data for the aircraft.  Do you think this is due to my db being out of date ? - or is this the bug to which you referred ?

Eitherway, I guess other users such as me , i.e  with an out of date db could be experiencing spikes due to this ??

No, there's no connection between the RadarBox bug and your or AirNav's database being out-of-date.

For a more detailed discussion of the issue re some ATPs showing spurious positions on RadarBox see www.airnavsystems.com/forum/index.php?topic=3763.msg36963#msg36963

Dave,

I have read through the thread, and noted your comments. The aircraft in question (modes 400A92) appears on mylog as ADSB equipped and giving positional data which marries precisely with my spikes.  Although my database is clearly out of date I think I am correct in understanding from you, and believing that the out of date database has no link with this. Again, If I understood you correctly, the reports I receive are not due to a bug. You also say this aircraft never gives out positional data ?  Thus do you have any idea how/why this aircraft may appear to give positional data that matches my spikes ?

I don't mean to be a pain in the proverbial, would just like to understand what is happening here.

Thanks
 
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DaveReid

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Re: Spikes again....
« Reply #17 on: January 22, 2010, 11:11:42 PM »
Again, If I understood you correctly, the reports I receive are not due to a bug. You also say this aircraft never gives out positional data ?  Thus do you have any idea how/why this aircraft may appear to give positional data that matches my spikes ?

The positional data matches your spikes because they are both derived from the same source, so no surprises there.

However the source is invalid.  The ATP in question is not equipped with either 1090 Extended Squitter or ADS-B. 

However it is ELS-equipped and will send 112-bit packets (Comm-B Capability, Flight ID, TCAS RA, etc) in response to a ground station interrogation.  RadarBox appears to be misinterpreting some or all of these responses as 1090ES Airborne Position Squitters (which are also 112 bits).

This phenomenon appears to be confined to RadarBox - I have SBS logs featuring said ATP going back to 2006 with no indication of any ADS-B capability.

I hope that makes sense, feel free to ask if you need any more background.  Likewise AirNav, if you plan on doing anything about this bug I'm happy to provide as much information as I can.
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eggplant

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Re: Spikes again....
« Reply #18 on: January 22, 2010, 11:55:43 PM »
Thanks very much for the info Dave - though the tech stuff goes a bit above my head I can understand the principles behind what you're saying.

Much appreciated.
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bratters

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Re: Spikes again....
« Reply #19 on: January 23, 2010, 06:33:45 AM »
Eggplant - you have stolen what I thought to be my personal spike. Identical.

g0seg

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Re: Spikes again....
« Reply #20 on: January 23, 2010, 07:34:33 AM »
Morning all. For Bratters. Looks as though you`ve proved your point about the spikes being long range intermittent strikes. Had three turn up in quick succession yesterday whilst i was watching. I`ve been keeping my eye on the French Radarvirtuel site and sure enough, they plotted the aircraft on the spike locations just out of normal range for here. makes you wonder how they get such good coverage unless they have spies planted all over the place - some site to say the least! Bi now and thanks, Roger

bratters

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Re: Spikes again....
« Reply #21 on: January 23, 2010, 08:24:19 AM »
g0seg

Reading Dave Reid's post above, it looks as though our distant aircraft are phantoms and the result of "misinterpreted" signals, all of which which is a bit of a shame.

At ranges of 260nm and 280nm for my two, it didn't seem outlandish for real highflyers, but I bow to superior technical knowledge.


eggplant

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Re: Spikes again....
« Reply #22 on: January 23, 2010, 08:53:37 AM »
Eggplant - you have stolen what I thought to be my personal spike. Identical.

Bratters - I think we have all been cheated. I too thought they were mine and mine alone. Sniff.
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DaveReid

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Re: Spikes again....
« Reply #23 on: January 23, 2010, 08:55:57 AM »
Reading Dave Reid's post above, it looks as though our distant aircraft are phantoms and the result of "misinterpreted" signals, all of which which is a bit of a shame.

At ranges of 260nm and 280nm for my two, it didn't seem outlandish for real highflyers, but I bow to superior technical knowledge.

I agree, 260nm wouldn't be out of the question for a high-flyer given a bit of ducting - although I would hesitate to describe the ATP as a "high-flyer" :-)

But bear in mind that, as well as those position reports showing N48.0 E0.0, Eggplant's log/screenshot showed other reports from N24.0 E0.0 and even N12.0 E0.0.

Apart from those coordinates being suspiciously rounded, AirNav don't need me to tell them that the last pair of lat/lons would put the aircraft in Burkina Faso - a distance of around 2400nm, which would certainly qualify as "outlandish" in my book !
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bratters

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Re: Spikes again....
« Reply #24 on: January 23, 2010, 09:29:32 AM »
Thanks Dave - no doubt a glitch that Airnav will clear up in the fullness of time.

After which in our new spike-free world,  we can indulge in a little competition to record the most distant signal.

PS & OT  Burkina Faso eh? Not many of us got that one in our passports.

eggplant

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Re: Spikes again....
« Reply #25 on: January 23, 2010, 11:59:30 PM »
I'm pleased the spikes matter has now been understood, thanks to Dave.  During the posts on this thread I have learnt that the aircraft 400A92 was incorrectly detailed on my database. I've corrected it now - but am wondering how many other inaccuracies I have in my database, and more importantly how to correct them. Going through each modes code one by one and checking it against www.airframes.org really is impractical - Does anyone know if there is a better way ?

Thanks
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