It seems odd that, if a 24-bit address is being incorrectly decoded, it always happens to match that of another aircraft that's being picked up at the same time - I would have thought that data corruption would produce random address errors.
I still think Edgy31's theory is the most plausible explanation I've heard so far - at least the parts that I understand. That affects the SBS-1 receiver as well, and is described over on the SBS-1 support forum at http://www.kinetic-avionics.co.uk/forums/viewtopic.php?f=5&t=5691&p=42860&hilit=parity#p42860
My own theory is that this is a generic problem affecting any ModeS receiver that is not able to receive the transmissions from the ground station requesting the aircraft data in the first place, and so not able to check parity on all message types.
Our Professional customers (which we have quite a few Airlines, ATC and Agencies) do use the RadarBox but do not use the .rbl files or the 30003 port data. They use a different interface altogether and we haven't had issues with them regarding this.
$PTA,400620,NPT521P,,,,,,,,,,17In this example, it appears to be getting a negative altitude (-1200) from DF17 messages. The altitude from DF4 and DF20 looks okay.
$PTA,400620,,,,,,,,,,,11
$PTA,400620,,16000,,,,,,,A,,4
$PTA,400620,,-1200,,,,,12.0127,0,A,,17
$PTA,400620,,,,,,,,,A,6005,21
$PTA,400620,,-1200,,,,,12.0127,0,A,,17
$PTA,400620,,16000,,,,,,,A,,20
$PTA,400620,,16000,,,,,,,A,,20
$PTA,400620,,,,,,,,,A,6005,21
$PTA,400620,,-1200,,,,,12.0127,0,A,,17
$PTA,400620,,,,,,,,,,,11
$PTA,400620,,-1200,,,,,12,0,A,,17
$PTA,400620,,16000,,,,,,,A,,0
$PTA,400620,,-1200,,,,,12,0,A,,17
$PTA,400620,,,,,,,,,,,11
$PTA,400620,,-1200,,,,,12,0,A,,17
$PTA,400620,,16000,,,,,,,A,,20
$PTA,400620,,16000,,,,,,,A,,20
$PTA,400620,,16000,,,,,,,A,,20
$PTA,400620,,-1200,,,,,12,0,A,,17
$PTA,400620,,,,,,,,,,,11
$PTA,400620,,16000,,,,,,,A,,0
$PTA,400620,,-1200,,,,,12,0,A,,17
$PTA,400620,,16000,,,,,,,A,,4
$PTA,400620,,16000,,,,,,,A,,4
$PTA,400620,,-1200,,,,,12,0,A,,17
Hmmm, I'm not sure that's the same problem, bearing in mind what we know about the ADS-B fit on ATPs - unless you're suggesting that there's a submarine close to you with a similar hex code :-)
In your testing, do you know if it was particular DF messages that were causing the anomolies?
Tarbat, Silly question from someone who hasnt a clue, is this the fault of radarbox or duff info coming from the aircraft?.
Got an entry in my log today for G-JAKF an R44 with start altitude of 01700 ft and an end altitude of 18800 ft.
This might be related: on the 2010/05/16 I remember this plane alternating between flight ID 353 and TSO354 it might even be in the RBL i sent.
Dave, checked my log and the 3 aircraft you mentioned are not on it.
I have several Robinson R44 helicopters logged around 36 to 37000 feet. Although I'm no expert I think that is beyond their known ceiling. Perhaps the owners/operators had installed nitrous oxide systems or such like :-)
I have several Robinson R44 helicopters logged around 36 to 37000 feet. Although I'm no expert I think that is beyond their known ceiling. Perhaps the owners/operators had installed nitrous oxide systems or such like :-)
Safe limit is to 14,000 feet for the R44, so obviously JATO versions ;-)
Slightly OT, but an interesting snippet from the R44 Type Certificate says that, although the Density Altitude Limit is 14,000ft, the aircraft isn't allowed to fly more than 9,000' AGL "to allow landing within 5 minutes in case of fire ".
Does the FAA know something about Robinsons that we don't ? :-)
Our Professional customers (which we have quite a few Airlines, ATC and Agencies) do use the RadarBox but do not use the .rbl files or the 30003 port data. They use a different interface altogether and we haven't had issues with them regarding this.
That's good news.
If you are saying that there is an alternative way of getting data out of RadarBox that's reliable then I would welcome details and, if satisfied, will happily put RadarBox back onto the shortlist for use in developing professional solutions.
Email sent re evaluation of the Professional version.
Not sure if this is the same problem that you experience? From todays log
400EBE GBYWB G-BYWI G115 Vt Aerospace Ltd 2010/05/20 09:05:07
400EBE GBYWG G-BYWI G115 Vt Aerospace Ltd 2010/05/20 13:52:29
400EBE GBYWI G-BYWI G115 Vt Aerospace Ltd 2010/05/20 13:12:36
also
400EEE GBYUJ G-BYVR G115 Vt Aerospace Ltd 2010/05/20 14:03:18
400EEE GBYVR G-BYVR G115 Vt Aerospace Ltd 2010/05/20 08:17:51
Thanks for that, it was just in the back of my mind that this issue has been around for some time.