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AirNav RadarBox and RadarBox24.com => AirNav RadarBox and RadarBox24.com Discussion => Topic started by: Falcon on March 10, 2009, 11:04:30 PM

Title: What Did I Pickup 280nm Out?
Post by: Falcon on March 10, 2009, 11:04:30 PM
Hi,

I wasn't recording but my polar diagram which has been building for a couple of days picked something up from 280nm out in each direction travelling in a east - west or west - east direction. It obviously exceeds the mode s max range rings. Its an even 280.2nm in each direction. I always lose aircraft out to the west pretty much consistently in the same place as you can see.

Could some sort of glitch somewhere cause this.

Any ideas?

Thanks
Title: Re: What Did I Pickup 280nm Out?
Post by: kdt1 on March 11, 2009, 03:12:35 AM
Hay Falcon

I have noticed at times some ADS-B equipped planes
send out faulty positional data. So one second there in Florida
and the next there in Africa or in your case 280+nm on either
side of you. That’s my thought anyways.

Cheers
Title: Re: What Did I Pickup 280nm Out?
Post by: viking9 on March 11, 2009, 11:12:23 AM
It's a spurious signal of some sort. I get one running approx north/south every few days.

Tom
Title: Re: What Did I Pickup 280nm Out?
Post by: AirNav Support on March 11, 2009, 12:06:21 PM
Aircraft such as gulfstreams are sometimes quite common in doing this. Some people are suggesting its to mask there positions.
Title: Re: What Did I Pickup 280nm Out?
Post by: viking9 on March 11, 2009, 01:42:37 PM
Quote from: AirNav Support on March 11, 2009, 12:06:21 PM
Aircraft such as gulfstreams are sometimes quite common in doing this. Some people are suggesting its to mask there positions.

Not so. It only happens on AirNav. When it happens I check on PP and find that I can track the aircraft perfectly, SBS users have told me that they have not seen this problem.
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 11, 2009, 03:01:54 PM
I agree - I think that suggesting aircraft are transmitting incorrect coordinates to conceal their position is disingenuous.

There are/were a very small number of aircraft with bugs resulting in incorrect coordinates being generated via ADS-B.  One was B733 EC-JTV, which was flying for Hola until a few months ago. Another, also a B733, was OM-HLB and ditto B735 LZ-BOY.

I've never picked up a Gulfstream transmitting obviously incorrect coordinates, although I recall in the early days of SBS a bug in the Kinetic decoding algorithm produced spurious coordinates for some Challenger aircraft.

Not that I'm suggesting that RadarBox has a similar bug affecting Gulfstreams, of course.
Title: Re: What Did I Pickup 280nm Out?
Post by: AirNav Support on March 11, 2009, 03:05:24 PM
Its hard for us to confirm this either way unless someone wants to lease us there Gulfstream for a nice test run?
Title: Re: What Did I Pickup 280nm Out?
Post by: Keith L on March 11, 2009, 03:09:02 PM
I just had a Grob Tutor indicating 40000' for a short while before reverting to a more believable 4570'.  Just noticed another Grob Tutor at 12,000 which is unlikely given that it isn't pressurised.
Title: Re: What Did I Pickup 280nm Out?
Post by: Fenris on March 14, 2009, 09:49:09 AM
Quote from: AirNav Support on March 11, 2009, 03:05:24 PM
Its hard for us to confirm this either way unless someone wants to lease us there Gulfstream for a nice test run?

Surely someone who sees the problem frequently could be provided with a version that captures internal RB processing data so you could see what is happening?
Title: Re: What Did I Pickup 280nm Out?
Post by: AirNav Support on March 14, 2009, 03:19:41 PM
At the moment we don't believe this to be a RB fault as the position data fault would mean all aircraft are affected as they send the same type and format of data (ADS-B) which is not the case.

We do believe this effect is down to specific aircraft spoofing there position deliberately or a faulty transponder.
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 14, 2009, 04:09:20 PM
Quote from: AirNav Support on March 14, 2009, 03:19:41 PM
At the moment we don't believe this to be a RB fault as the position data fault would mean all aircraft are affected as they send the same type and format of data (ADS-B) which is not the case.

We do believe this effect is down to specific aircraft spoofing there position deliberately or a faulty transponder.

That's what Kinetic told users in relation to the Challenger position bug.  Coincidentally, the bug disappeared when they brought out an SBS firmware upgrade.

Either that or they sent a team around the world fixing faulty aircraft transponders ...
Title: Re: What Did I Pickup 280nm Out?
Post by: AirNav Support on March 14, 2009, 04:16:32 PM
There are still reports from SBS users with aircraft jumping and changing heading etc.. but we won't discuss what bugs or issues they have.

Some of these position movements only happen over land or at certain times. This would not present a bug in decoding as it would mean it should affect all aircraft virtually all the time. If you think you know why, then were happy for you to contact us and show us the light? :)
Title: Re: What Did I Pickup 280nm Out?
Post by: jgrloit on March 14, 2009, 04:26:04 PM
For the cockpit aware amongst the users -
Do Gulfstreams have more than 1 transponder?
If so then it sems as though one of them may be picking up, and forwarding incorrect data - possibly 1 using radio altimeter and the other an airtube based one - possibly giving different heights.
Could the positional be from GPS for one and inertial guidance system for the other, or is the second one giving ground accuracy, by mistake and fooling the systems.   ground positions being repeated every 98Nm?
The transponder theory being prompted by a comment on an Airframe comment on a particular aircraft giving different ModeS Id-s on different transponders on The Commercial aircraft in the Database.
Title: Re: What Did I Pickup 280nm Out?
Post by: viking9 on March 14, 2009, 04:33:53 PM
I don't think rad alts are used above 2,500 ft.
Title: Re: What Did I Pickup 280nm Out?
Post by: jgrloit on March 14, 2009, 04:56:23 PM
I was just trying to consider alternate information sources, that could be fed into different Transponders - to explain a monitored, alternating height senario as recently seen on my system!!!
Title: Re: What Did I Pickup 280nm Out?
Post by: Falcon on March 14, 2009, 05:47:02 PM
Hi,

Here is another diagram I built up over a day or so. I did manage to match up the logs for the larger of those two spikes you see. I couldn't find anything on the narrower one. I am still not sure whether to believe there could be reception over 290nm out given my overall reception to the west but the information is in the log. It even extends well past any coverage I normally get to the east.

Regards,
Darryl
Title: Re: What Did I Pickup 280nm Out?
Post by: Johnn on March 14, 2009, 07:39:02 PM
Quote from: Falcon on March 14, 2009, 05:47:02 PM
Hi,

Here is another diagram I built up over a day or so. I did manage to match up the logs for the larger of those two spikes you see. I am couldn't find anything on the narrower one. I am still not sure whether to believe there could be reception over 290nm out given my overall reception to the west but the information is in the log. It even extends well past any coverage I normally get to the east.

Regards,
Darryl

Hi Falcon, Was That Polar Diagram Taken With A Standard Antenna Or External?
Thanks John
Title: Re: What Did I Pickup 280nm Out?
Post by: Falcon on March 14, 2009, 08:13:52 PM
Quote from: Johnn on March 14, 2009, 07:39:02 PM
Hi Falcon, Was That Polar Diagram Taken With A Standard Antenna Or External?
Thanks John

Hi John,

It was with the antenna included with Radarbox on the ENE side of my house. I get regular contact between 100nm and 150nm out towards the east. The polar diagram I posted was not complete as it was only over a short period of time. It's usually spikey vs a spikey circle which I see from others living elsewhere where there is flatter terrain. The aircraft are generally coming in on the arrival routes over mountainous terrain which start quite a ways out. I am actually quite impressed with the reception given the hilly and mountainous terrain I live near. I will get drop outs depending on the aircraft altitude and it's location in relation to the local hills or mountains around me. So far today I have logged 286 aircraft at 20:12 UTC, which are mostly large and medium size aircraft. I probably don't get anywhere near what some in the UK or parts of Europe may see but its quite good for around here.

Regards,
Darryl
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 14, 2009, 10:45:37 PM
Picked up today from Derby UK N52.3 W01.5

AE087F 01-0029 GLF5 USAF. Mylog has me picking it up over antarctica?
Previous contact is somewhere over the arctic.

Polar Diagram gif and mylog gif attatched. The spike to the south has happened 4 times in the same place I'll see if I can find what produced it.

Cheers John

[attachment deleted by admin]
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 14, 2009, 11:18:17 PM
Its not just Gulfstreams giving out spurious position data I have ATP's doing same G-OAAF,G-BTPE and G-BUUP

[attachment deleted by admin]
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 15, 2009, 07:50:43 AM
Quote from: EGNXR on March 14, 2009, 11:18:17 PM
Its not just Gulfstreams giving out spurious position data I have ATP's doing same G-OAAF,G-BTPE and G-BUUP

That's very strange.  None of those aircraft has ADS-B, so you shouldn't be seeing coordinates at all for them.

My money is still on a decoding bug.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 15, 2009, 10:02:14 AM
If none of these are ADS-B why is rb saying they are? I've seen them tracking across the screen in and out of EGNX most evenings.

It appears as that its one of these aircraft that has created my spike to the south.

see gif below the coordinates match the tip of the spike in my previous polar diagram

[attachment deleted by admin]
Title: Re: What Did I Pickup 280nm Out?
Post by: tarbat on March 15, 2009, 10:08:00 AM
Interesting.  I've got G-BTPE in my log, but only with start/end positions of N12 00.0 E000 00.0.  And G-BUUP only has start/end positions of N12 00.0 E000 00.0 and N24 11.3 E000 00.0.

These are obviously spurious numbers, but are they being transmitted by the aircraft, or misintepreted by the RB software?  Given that it's the same spurious value for 2 different aircraft, my guess is that RB is misintepreting the data.

Can others search through their logs for obvious spurious lats/longs.
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 15, 2009, 10:57:10 AM
Quote from: EGNXR on March 15, 2009, 10:02:14 AM
If none of these are ADS-B why is rb saying they are? I've seen them tracking across the screen in and out of EGNX most evenings.

Well I'm prepared to be convinced by a radar screenshot  :-)

Are you sure you aren't confusing those aircraft with some of the other ATPs like G-MANH and the former G-MANP, which do have ADS-B ?
Title: Re: What Did I Pickup 280nm Out?
Post by: tarbat on March 15, 2009, 11:08:07 AM
Okay, an analysis of my logs show only the following aircraft with spurious lat/long:
G-BTPA   N12 00.0 E000 00.0   N12 00.0 E000 00.0
G-BTPA   N12 00.0 E000 00.0   N53 57.7 E000 00.0
G-BTPA   N78 00.0 E000 00.0   N66 00.0 E000 00.0
G-BTPE   N12 00.0 E000 00.0   N12 00.0 E000 00.0
G-BTPE   N12 00.8 E000 00.0   N12 00.0 E000 00.0
G-BTPF   N12 00.0 E000 00.0   N12 00.0 E000 00.0
G-BTPF   N54 00.0 E000 00.0   N12 00.0 E000 00.0
G-BTPF   N78 00.0 E000 00.0   N12 00.0 E000 00.0
G-BTPF   S42 00.0 E000 00.0   N12 00.0 E000 00.0
G-BUUP   N12 00.0 E000 00.0   N24 11.3 E000 00.0
G-BUUP   N12 00.0 E000 00.0   N54 00.0 E000 00.0
G-BUUR   N12 00.0 E000 00.0   N24 11.3 E000 00.0
G-BUUR   N12 00.0 E000 00.0   N54 00.0 E000 00.0
G-BUUR   N12 00.0 E000 00.0   N54 00.0 E000 00.0
All British Aerospace ATPs, so maybe it's an aircraft problem rather than a RB problem.  Unless other aircraft types are also showing the same problem?
Title: Re: What Did I Pickup 280nm Out?
Post by: besty on March 15, 2009, 11:08:56 AM
Hi all I've got 10 ATP aircraft showing as ADSB of these 9 are showing same as Tarbat, only one is showing what looks like correct data, that is

400749  G-MANH   ATP   Atlantic Airlines
(http://farm4.static.flickr.com/3120/3356302948_e724a2a165.jpg)
http://farm4.static.flickr.com/3120/3356302948_e724a2a165_b.jpg

400FEB G-BUUR  ATP  Atlantic Airlines
(http://farm4.static.flickr.com/3537/3355484335_7a4e3053fe.jpg)

http://farm4.static.flickr.com/3537/3355484335_7a4e3053fe.jpg
Title: Re: What Did I Pickup 280nm Out?
Post by: jgrloit on March 15, 2009, 11:19:35 AM
ATP data seen here.

G-BUUP - invalid positions
G-MANH - Valid Positions
G-BTPE - invalid positions, but value varies by date
G-BTPA - invalid positions, vary by date - fixed within date
G-BTPF - as BTPA
G-BUUR - invalid positions
G-BTPH - ADSB  not seen, short isit to box Less than 1 minute.

Values look similar to those from Tarbat.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 15, 2009, 11:31:07 AM
Quote from: DaveReid on March 15, 2009, 10:57:10 AM
Quote from: EGNXR on March 15, 2009, 10:02:14 AM
If none of these are ADS-B why is rb saying they are? I've seen them tracking across the screen in and out of EGNX most evenings.

Well I'm prepared to be convinced by a radar screenshot  :-)

Are you sure you aren't confusing those aircraft with some of the other ATPs like G-MANH and the former G-MANP, which do have ADS-B ?

Looks like I'm on ATP watch this week then:-)

Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 15, 2009, 01:13:57 PM
I have been through Mylog and these are all aircraft with position data outside of my maximum polar range. By type.

ATP LX-WAL,SE-MAP + those already quoted
C650 D-CMPI
CL60 HB-IVS,XA-JVL
H25B VP-CLU below is a gif as this has spurious height info also
GLF5 00-0128,00-0129,01-0076,97-0401,99-0402,N522EE,N508P,N526EE,N531AF,N596GA,
N673P,N740SS,VP-BNL,VP-CES
FA10 F-GPGL

Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 15, 2009, 09:00:59 PM
JAL B744 purple rain off the network thats another type to add to the list:-(
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 16, 2009, 11:42:44 AM
Quote from: EGNXR on March 15, 2009, 01:13:57 PM
I have been through Mylog and these are all aircraft with position data outside of my maximum polar range. By type.

ATP LX-WAL,SE-MAP + those already quoted
C650 D-CMPI
CL60 HB-IVS,XA-JVL
H25B VP-CLU below is a gif as this has spurious height info also
GLF5 00-0128,00-0129,01-0076,97-0401,99-0402,N522EE,N508P,N526EE,N531AF,N596GA,
N673P,N740SS,VP-BNL,VP-CES
FA10 F-GPGL

If it's any help, I've just run a quick-and-dirty analysis of these aircraft over the last 3 years (except XA-JVL, which I can't trace).

Out of 568 log reports, other than a handful of examples of the SBS/Challenger decoding bug, the maximum range I've had is 212nm.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 16, 2009, 05:16:16 PM
Hello Dave, XA-JVL was a typo should be (0D0134 XA-JZL).
I must admit I was wrong about Watching ATP's the ones I saw last night certainly did not show up. I know I've seen G-MANH the rest must be a case of what I thought I saw:-)

I have seen others appearing in random places briefly ie over the North pole. I will endevour to get a screenshot next time I see it.

ALso witnessed GLF5 N225EE it was displaying route EGLF-EGPE although it was making the return journey. It was bouncing between Ontario and UK as it tracked down over Manchester to Oxford. Strange thing was as it began to decend its track became stable. If it was trying to mask its position why display valid route information? The other thing is the position data in mylog is correct for where I picked him up and lost him. I have a screen shot of him over wolverhampton.
Title: Re: What Did I Pickup 280nm Out?
Post by: kdt1 on March 16, 2009, 06:07:24 PM
Quote from: AirNav Support on March 11, 2009, 03:05:24 PM
Its hard for us to confirm this either way unless someone wants to lease us there Gulfstream for a nice test run?

Are you prepared for that bill?

I have experienced gulfs transmitting the wrong positions in my area with the SBS, haven’t seen it yet with the RB as I think they have fix them. I do think it would be very dangerous not to mention illegal to transmit false positions.

Title: Re: What Did I Pickup 280nm Out?
Post by: CoastGuardJon on March 16, 2009, 08:36:53 PM
Quote from: kdt1 on March 16, 2009, 06:07:24 PM
I have experienced gulfs transmitting the wrong positions in my area with the SBS, haven’t seen it yet with the RB as I think they have fix them. I do think it would be very dangerous not to mention illegal to transmit false positions.

Virtually all UK Government authorities fall back on "Crown Indemnity", I am employed by 2 of the less "iffy" Agencies and see this used quite often to get around or create loopholes in the law! Doubtless, the US are probably even more liberal with their interpretation..................
Title: Re: What Did I Pickup 280nm Out?
Post by: jgrloit on March 16, 2009, 09:04:29 PM
Having just looked through the rules on the NATS site - I find no mention of Positional requirements on the transmission under the required modes.

Nats Docs require Mode A or C with Altitude details from the pressure sensors.
Even Mode S excludes Positional requirements  _
ENR 1.6.2 gives details along with current Squawk codes.
So if position is NOT required is an invalid position illegal??
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 16, 2009, 09:25:54 PM
Quote from: jgrloit on March 16, 2009, 09:04:29 PM
So if position is NOT required is an invalid position illegal??

We have no evidence that any aircraft are intentionally transmitting invalid positional data, in fact the only aircraft that consistently come up with spurious coordinates on both RadarBox and SBS are a handful of older 737s, and clearly the authorities couldn't care less about those.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 16, 2009, 10:06:06 PM
G-BTPH on Network now over Burkina Faso? And in Formation with SE-MAP

There are several ATP'S on Network now 22:03pm
Title: Re: What Did I Pickup 280nm Out?
Post by: DaveReid on March 16, 2009, 10:37:15 PM
Quote from: EGNXR on March 16, 2009, 10:06:06 PM
G-BTPH on Network now over Burkina Faso? And in Formation with SE-MAP

Hmmm, same issue as noted previously - both those ATPs are definitely non-ADS-B and shouldn't be plotting at all ...
Title: Re: What Did I Pickup 280nm Out?
Post by: jgrloit on March 16, 2009, 10:54:58 PM
Seems strange that these ATP's are always at either N12:00:00 by 0:00:00   or N24:00:00 by 00:00:00
Now 12 is 1100
   24 is 11000  in binary     could this indicate anything?
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 16, 2009, 11:07:40 PM
Thing is I've not been able to see them on my flights just Network. I spotted the first two at Gardermoen ENGM Norway SE-MAF and SE-MAH both are tracking normaly. Some one has a RB quite close to the airfield.
Title: Re: What Did I Pickup 280nm Out?
Post by: AirNav Support on March 16, 2009, 11:14:14 PM
Interesting, certainly a few ATPs are plotting correctly so its not an aircraft issue. Surprising though if the ones with weird positions if they are not ADS-B are plotting with position data.

Common sense would say if these aircraft of the same type are doing this that its a aircraft issue as if it was decoding issue it should in theory affect all aircraft.

The more information we get (this topic is helping),  we can try and get a more technical answer or fix if required.
Title: Re: What Did I Pickup 280nm Out?
Post by: tarbat on March 16, 2009, 11:15:48 PM
Quote from: jgrloit on March 16, 2009, 09:04:29 PM
So if position is NOT required is an invalid position illegal??
Yes it is, for example, when flying above the North Sea within the Amsterdam flight information region.  From the end of this month, all aircraft flying below 3,000ft must provide accurate position information.

"To ensure the quality of the onboard position-information, especially in offshore applications where the navigational ground infrastructure is limited, the position-information must be based on input from a GNSS receiver certified against ETSO C129A (class C), ETSO C145 or ETSO C146. It is recommended to have a direct interface between the onboard GNSS receiver and the mode S transponder in order to minimise onboard data latencies."
Title: Re: What Did I Pickup 280nm Out?
Post by: Canonjohns40D on March 17, 2009, 08:39:54 PM
Hi anyone noticed this one Alafia Jet TYSAM000 BAE125 showing over SE Ireland but purple rain running down to South Atlantic area? Possibly heading NW still showing over southern Ireland.

John
Update still over Southern Ireland purple rain showing out to Artic Ocean now.

Further update now several lines into USA still showing over Southern Ireland on Map

Presently 20.49 showing east of Enniskillen Northern Ireland.
Now 20.57 approaching Portrush Northern ireland just outside my area of coverage.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 17, 2009, 11:06:29 PM
Tonights unstable tracks on network
CL60 N300TW,C-GQBQ,N453GS,N800YB,C-GCNR
GLF5 N405LM,N85V,99-0402
FA50 N411GC

N800YB and N405LM Tracked normaly then started bouncing then went stable again.
Title: Re: What Did I Pickup 280nm Out?
Post by: EGNXR on March 18, 2009, 08:46:59 PM
Another Purple rain offender EC-KPP Falcon 100

So is it an airnav problem?
A mode-S - GPS problem?
or a deliberate act?

We have several ATP'S that are not supposed to be ADS-B but show as being in Mylog
A rogue B747 in the middle of the ocean
Several GLF5's
Several Challengers
2 x Falcon 10
1 x Falcon 50
3 x H25B all giving purple rain this week
Title: Re: What Did I Pickup 280nm Out?
Post by: Canonjohns40D on March 18, 2009, 09:27:38 PM
Ref reply #42 above.
The purple Rain offender last night, 0942AB TY-SAM BAE125-700B of Alafia Jet is in my log this afternoon. 14.05pm position start N55.02.7 W006.59.4 Fl16025 position end N54.17.8 W005.19.1 FL25575.

Not sure if it helps but thought I should update.

John