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Author Topic: Double\Incorrect callsigns  (Read 3587 times)

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Jordan

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Double\Incorrect callsigns
« on: November 14, 2011, 05:43:34 PM »
Lately Ive been having a problem with the RB, sometimes when there's 2 different aircraft. different Reg. but same company\Country, it would show same callsign.
For example, lets say I'm receiving  F-GKXP and F-GKXM, one of them is AFR570, the other 1621. The RB shows it as if their both 1621, when on one they show the TLV-CDG route, while on the other one it shows the CDG-AMM-DAM route.
Sometimes it happens with aircraft who arent even around, and thats when it gets really annoying.
Does it happen to anyone else? knows how to fix it? it seriously just came out of nowhere.
And also, it keeps the incorrect flights in the log, and when i come back to check on a certain reg i cant tell if it really is the actual flight it performed.

ACW367

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Re: Double\Incorrect callsigns
« Reply #1 on: November 14, 2011, 11:53:33 PM »
This is a known system limitation which will in high density areas, affect circa 1% of the records in MyLog and Reporter.  (roughly 10 out of every 1000 recorded callsigns in your reporter).
See this for a full explaination of the phenomena
http://www.airnavsystems.com/forum/index.php?topic=5957.0

Airnav's explaination is here
http://www.airnavsystems.com/forum/index.php?topic=5957.msg62468#msg62468

You are correct, that for that small percentage of recorded hits, you cannot tell if it is from the aircraft shown by RB or another aircraft completely, which RB has been unable to properly decode, as described by Airnav. 
« Last Edit: November 14, 2011, 11:57:19 PM by ACW367 »

Hawkeye

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Re: Double\Incorrect callsigns
« Reply #2 on: November 16, 2011, 02:15:15 PM »
The explanations given by AN when I raised the subject in March and reiterated by ACW367 above, seem to suggest that this anomaly only happens, or is more likely to happen, in high density areas with high message counts and long timeout settings in RB.
I regularly get it happening here in a by no means high density area, (bearing in mind I only use the supplied antenna and don't subscribe to the network).
As a for instance, I've attached a snip showing an occurence this morning. At the time I only had 27 flights showing in MyFlights, messages/sec was varying between 101 and 122  and I had a 30/60 timeout setting.
I accept AN's explanation that this anomaly is not limited to just RB, but from personal experience, examples are certainly far more prevalent than the 1% stated

Syd

Runway 31

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Re: Double\Incorrect callsigns
« Reply #3 on: November 16, 2011, 03:35:38 PM »
It can also happen as in your case when the hex codes received are so close together and has been discussed on the forum previously.

Alan

Jordan

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Re: Double\Incorrect callsigns
« Reply #4 on: November 16, 2011, 04:10:01 PM »
Ok thanks everyone. Im in the same boat with Hawkeye, this is a very low density area, at the moment I have only 11 flights, 35msg count, And yet, I just had  that again.
Runway31, The weird thing is it never happend untill last few weeks, In that case what triggered it?
« Last Edit: November 16, 2011, 04:16:22 PM by Jordan »

tarbat

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Re: Double\Incorrect callsigns
« Reply #5 on: November 16, 2011, 04:39:55 PM »
The weird thing is it never happend untill last few weeks, In that case what triggered it?

It can be something as simple as a corrupted ModeS message.  For example, a one-bit error in the Hex Code in the message can then assign that Flight ID to the wrong aircraft.  For most ModeS messages there is no parity checking available, so it's impossible for Radarbox to know that the hex code has been corrupted.

See http://www.airnavsystems.com/forum/index.php?topic=5957.msg63016#msg63016 for some thoughts in reducing timeouts to minimise the effect of corrupted messages.
« Last Edit: November 16, 2011, 04:52:47 PM by tarbat »