Different numbers of aircraft in apps all fed by VRS

Are you having trouble getting Virtual Radar Server installed and running? If so then this is the place to ask about it.
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sonicgoose
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Location: Ontario, Canada
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Different numbers of aircraft in apps all fed by VRS

Post by sonicgoose » Tue Jan 08, 2013 12:14 am

This is driving me nuts. I have a RTLSDR dongle that is controlled by RTL1090. VRS is connected to port 31001 to get the Beast feed from RTL1090. VRS then rebroadcasts this data over three different ports: one is pass-through, one is BaseStation, and one is AVR. I have used the VRS built-in web server to plot planes, and I've used ADSBScope, BaseStation and PlanePlotter as well. And all four show different numbers of aircraft being tracked! VRS is tracking 87 aircraft; ADSBScope sees 103 aircraft; PlanePlotter sees 105; and BaseStation sees just 27. Why is the number in BaseStation so much lower? I have Show All turned on, and I'm not clipping based on elevation (in fact I set the elevation range from 0 to 500000 to make sure it got everything.) I'm stumped why four apps being fed from one dongle through one server are producing four different results. Anyone else seeing this?

Rob
Web: http://www.sonicgoose.com
Twitter: @blindedbtflash

agw
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Re: Different numbers of aircraft in apps all fed by VRS

Post by agw » Tue Jan 08, 2013 8:39 am

It's probably because each program is using different timeouts. By default VRS takes aircraft off the display 30 seconds after their last transmission but others will wait for a minute or two. If you configure them all to be on the same timeout then I imagine the results will get a lot closer.

I've no idea why BaseStation is so low. It doesn't do any filtering and the default timeout isn't very aggressive. I would take a look at the aircraft that are missing from BaseStation and see if you can spot a pattern amongst them.

sonicgoose
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Joined: Tue Jan 08, 2013 12:03 am
Location: Ontario, Canada
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Re: Different numbers of aircraft in apps all fed by VRS

Post by sonicgoose » Tue Jan 08, 2013 11:22 am

I had changed all of the apps to have the same30 second timeout. It just doesn't make sense. I'll have a look at the missing ones, though, to try and spot a pattern.
Web: http://www.sonicgoose.com
Twitter: @blindedbtflash

agw
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Joined: Fri Feb 17, 2012 3:20 am

Re: Different numbers of aircraft in apps all fed by VRS

Post by agw » Wed Jan 09, 2013 12:13 am

VRS won't start tracking an aircraft until it sees an all-call reply or an extended squitter for it, it could be that PP and ADSBScope are taking a different approach there. I'll take a look at the weekend, or earlier if I get the time, and see if I can see what's happening.

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