Bugs in 2.2.0

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agw
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Bugs in 2.2.0

Post by agw » Mon Sep 07, 2015 2:12 am

It's been a while coming, there's bound to be something wrong with it :)

T-EGJA1
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Re: Bugs in 2.2.0

Post by T-EGJA1 » Wed Sep 09, 2015 1:26 pm

I'm not sure if this is a bug or not ... or even if it's new, although I haven't noticed it until updating to v2.2.0 ..... anyhow, I'm seeing a discrepancy (or lag) between the number of (visible) a/c in the list and the number on the map, i.e. there are often one, two or even three more in the list (with known positions, i.e. with a value in the 'distance' column) than are shown on the map.

It's only noticeable at 'quiet' times, when there are only a dozen or less a/c being tracked, i.e. few enough to be able to easily count the ones on the map.
Terry

agw
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Re: Bugs in 2.2.0

Post by agw » Thu Sep 10, 2015 1:36 am

I had to add some stuff to the site to take aircraft off the map if they've not sent positions for longer than the display timeout, which can now happen if you're viewing a merged feed with an MLAT receiver on it.

With the display timeout now being tied to the time of the last position message from the aircraft I can imagine that you could get into a situation where an aircraft goes off the map but remains in the list for a while longer. This might happen if the aircraft goes out of range and then a few seconds later you get a non-position message come through at extreme range. The interval between the last position message and that non-position message would be the interval between it being taken off the map and it going off the list.

I could bump that timeout up a little bit, maybe by 50% or so. The issue with MLAT receivers on a merged feed was that the aircraft would freeze on the map when it goes out of range of MLAT but then remain there for ages while another receiver was picking it up - but obviously without picking up positions, as the aircraft isn't transmitting them. I don't think it'll be an issue if it remains on the map for a bit longer than the display timeout, just so long as it doesn't end up frozen on there for half an hour :)

T-EGJA1
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Re: Bugs in 2.2.0

Post by T-EGJA1 » Fri Sep 11, 2015 9:25 pm

Thanks for the explanation, Andrew.

If you can tweak the timeouts so that the the a/c on the map remain in sync with those in the list, without adversely affecting anyone's merged feed MLAT receivers, then it would be appreciated.
Terry

agw
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Re: Bugs in 2.2.0

Post by agw » Sun Sep 13, 2015 5:04 pm

I've added 60 seconds to the timeout, over and above the display timeout, which will hopefully be long enough for a position message to be picked up if the aircraft is at extreme range but short enough not to be annoying for MLAT users :) I've uploaded a preview version of VRS with the extended timeout in place to http://www.virtualradarserver.co.uk/Preview.aspx if you want to give it a try.

T-EGJA1
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Re: Bugs in 2.2.0

Post by T-EGJA1 » Mon Sep 14, 2015 10:17 am

Many thanks for this, Andrew.

I installed the updated preview version last night and since then, the number of a/c on the map has been consistent with the number of visible a/c in the list; so the extended timeout seems to have worked well :D

Thanks again,
Terry

T-EGJA1
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Re: Bugs in 2.2.0

Post by T-EGJA1 » Mon Sep 14, 2015 10:48 pm

Another issue that may or may not be a bug, but again not previously noticed .... I moved my antenna higher at the weekend and started a new range plot in VRS to get a comparison, however I've noticed that several a/c on the map are not triggering the radiating lines from my receiver position (receiver range is set to "all altitudes"); hence the range plot is not a true reflection of the actual ranges that I'm picking up a/c from.
Terry

agw
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Re: Bugs in 2.2.0

Post by agw » Tue Sep 15, 2015 12:29 am

I don't remember changing anything to do with the polar plot. However, when aircraft are first picked up they don't contribute to the plot until they've sent a few position messages, there is a sanity check that needs to see a few consistent positions before it lets it through. It might be that that you're seeing?

T-EGJA1
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Re: Bugs in 2.2.0

Post by T-EGJA1 » Tue Sep 15, 2015 1:10 am

agw wrote:... when aircraft are first picked up they don't contribute to the plot until they've sent a few position messages, there is a sanity check that needs to see a few consistent positions before it lets it through. It might be that that you're seeing?
... possibly, however if you look at the screen grab below (taken a moment ago) and look at the track of EZY63WT (top left), I would have expected it to "fill in" the areas between the red track and my receiver location ....

Image
Terry

GregoryGHarding
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Re: Bugs in 2.2.0

Post by GregoryGHarding » Tue Sep 15, 2015 7:22 am

T-EGJA1 wrote:
agw wrote:... when aircraft are first picked up they don't contribute to the plot until they've sent a few position messages, there is a sanity check that needs to see a few consistent positions before it lets it through. It might be that that you're seeing?
... possibly, however if you look at the screen grab below (taken a moment ago) and look at the track of EZY63WT (top left), I would have expected it to "fill in" the areas between the red track and my receiver location ....

Image
it would under normal feed conditions, however if your receiving sporatic positions, the sanity check will filter those from the range plot, while still adding to the track.. even if during multiple times you did not receive positions it will estimate a track

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