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No Map, not much else

Posted: Wed Dec 12, 2012 1:45 am
by W9ran
I just started using VRS today, using DVB-T dongle and ADSB software to stream messages in AVR/Beast mode. I'm seeing at least three big problems:

1. I've configured the web server properly I think because I can access it from another PC on my LAN, and the main VRS screen shows that messages are coming in, and other activity. But despite have left it run all afternoon with a total of over 9 million messages total shown on the VRS main screen, there are only "4 aircraft tracked". Can this be right?

2. Moreover, the map is not displaying at all, and not updating. When I bring up the webpage from another PC it will display the outline of the screen, including the fields above "Powered by Virtual Radar Server" on the right, so I know there's an http connection -- but the area where the Google Map is supposed to be is just blank - grey. Reloading the page updates the page but still no map.

3. When an aircraft number is displayed on the right-hand area that I can see, and I click on it - it does bring up a Google map that is centered on the initial coordinates I put in, but also just a "registration invalid" error.

I'd appreciate any suggestions as to what I may be missing, and confirmation that this is not normal behavior. Thanks.


Re: No Map, not much else

Posted: Wed Dec 12, 2012 3:09 am
by agw
It does sound like you're not having much luck :) Going through the points:

1) The message count is just a count of what's coming out of the receiver, it's hard to say whether 4 aircraft currently tracked from 9 million messages since startup is reasonable without knowing how long VRS has been running for. It's possible that you're either getting a lot of corrupt messages or the aircraft flying around are transmitting a lot of Mode-A/C but not a lot of the right flavour of Mode-S. VRS doesn't start tracking an aircraft until it receives a message that unambiguously identifies it, which many messages don't do. Whereabouts in the world are you? If you're in the Americas then you'll see less traffic than you would, say, in Western Europe.

VRS doesn't provide a breakdown of corrupt messages or message types, but thinking about it it sounds like something that would be useful - I'll add it to the list of things to do. In the meantime if you like I can PM you the instructions for a program that can record the network stream from the receiver, you can send me the file and I'll take a look at what you're seeing and what kind of proportion of the messages are corrupt / ambiguous / unusable. Or if you're handy with setting up port forwarding you could put the receiver onto the Internet (if it's connected via serial then VRS can rebroadcast it onto the Internet - I can give you instructions on setting that up if that's the case) and I can look at it directly from here.

2 & 3) Which browser are you using? (2) sounds like javascript is disabled in the browser, but if that were the case then you wouldn't see a Google Map in 3) either. Are the Google Map controls showing? If so then do they show you as being zoomed all the way in? Depending on what you're zoomed in on you can end up with a fully grey (or blue, green etc.) map if you do that.

I've just done a search on the source and I don't have the message "Registration invalid" anywhere. The closest is "Registration not found" when you enter an invalid registration in the report criteria for an aircraft. Does your router support UPnP, and are you using Windows? If you put VRS onto the Internet and PM me the address it reports for "Show Internet address" (bottom-ish left on the main screen) then I can take a look at it from here and maybe get a clearer picture of what you're seeing.

But the short answer is no, that's not normal behaviour :)

Re: No Map, not much else

Posted: Wed Dec 12, 2012 6:16 am
by W9ran
AGW - thanks much for your response. Since I don't have enough posts to be able to PM I'll reply here, briefly.

I should have tried other browsers before I posted, now that I've done soe and can see the Google Map in IE and Chrome, it seems there's an issue with Java in Firefox, my usual browser. Even better, while I had Chrome up, I did see one plane pop up and was correctly identified - so basically, it's working.

I have no idea as to the validity of the frames that are scrolling by in a blur, but if you'd like to send me the info on how to capture the data stream from the receiver I'll be happy to do that. In the meantime if I get it set up through my router I can let you take a look at it that way. Incidentally, I'm using the new ADSB software from ... ng-rtl-sdr Now that this is working I can do some improvements to optimize the antenna.

I think having a way to see the number/% of valid vs. corrupt frames would be a good idea, but I always prefer having tools and not needing them than the opposite!

I'll see what's up with Java and work on improving the RF end to be sure I'm getting good data. I'm 100 miles west of Chicago and according to what I see on PlaneTracker and FlightRadar24, there should be a fair amount of activity within range. Thanks again,


Re: No Map, not much else

Posted: Wed Dec 12, 2012 6:05 pm
by W9ran
following up on the Java issue in Firefox:

I found several old versions and removed them. I've updated to the latest version of Java, according to the Java website:
Java(TM) Platform SE 7 U9
Next Generation Java Plug-in 10.9.2 for Mozilla browsers

Still, the frame of the page will display but nothing I can do makes the Google Map appear in Firefox. I've cleared the browser cache, made sure Javascript is enabled, used Firefox's plugin updater to make sure it's happy, reloaded the page endless times, and restarted Firefox slightly fewer times, yet the problem persists. I can't remember running into Java-related issues with any other web page and I use Firefox extensively. The map works in IE and Chrome. but I'm kinda out of ideas to try with Firefox - open for suggestions.


Re: No Map, not much else

Posted: Wed Dec 12, 2012 6:59 pm
by agw
VRS doesn't use Java, it only uses javascript and HTTP - despite the names Java and javascript are entirely unrelated, you don't need Java installed to run VRS. Javascript is handled entirely by the browser without the need for plugins. Do you have any extensions loaded that could be blocking javascript, such as Noscript? They usually allow you to add exceptions, you'll need to add one for the IP address of the machine running VRS (or if Firefox is running on the same PC as VRS).

Re: No Map, not much else

Posted: Thu Dec 13, 2012 12:15 am
by W9ran
Thanks for your assistance, Andrew. While the Java issue remains in Firefox, I'm able to see the realtime map display with Chrome, and that works for me for now.

The main problem I reported yesterday - lots of messages but not much tracking - was resolved by improvements I made today on the antenna system. I built an 8 element collinear antenna for 1090 Mhz and wow! What a difference it made! As soon as I connected it the screen filled with over 50 aircraft being tracked, whereas previously I might have had enough signal for one or two of the nearest ones. I've also confirmed with the author of the DVB-T software I'm using that they pass along all interesting frames (DF17), but that subsequent CRC checks are made in the plotting software. So, it's not unusual to see a lot of raw frame traffic and relatively little usable messages, if the system has a poor signal to noise ratio.

I'm located west of Chicago under one of the busier approach corridors so I think I'll have plenty of action to observe!

Thanks again and 73,


Re: No Map, not much else

Posted: Thu Dec 13, 2012 1:14 am
by agw
Java*script* issue ;) VRS doesn't use Java.

Good news about the antenna - VRS will use more than just DF17, if the DVB-T software can be made to pass everything through to VRS then you should get a bit more information out of it. I think I was sent a link to the software you're using over the weekend, if it's the same thing then I think he publishes his source code. I'll take a look at it and see if it's straight-forward to remove the filtering.

EDIT: Just taken a look at the source, he's already passing through more than just DF17. There is a filter on the frame types that get passed through but it's not going to take out anything important.

Re: No Map, not much else

Posted: Sun Dec 30, 2012 4:39 pm
by steflp

I thing I have the same problem ( my ADSB# program decode but bad ;-( ) so I thing is the antenna ..
I built an 8 element collinear antenna for 1090 Mhz and wow
Have you got a link to make an antenna for band 1090 MHZ .

Thanks a lot

Best Regards ...

Re: No Map, not much else

Posted: Tue Jan 01, 2013 8:11 pm
by W9ran

This is the one I made, essentially: I found the tape in between more trouble than it was worth, so with sections pushed within 5mm or so of each other just wrapped tape over the outside and installed in PVC pipe housing. I'm seeing planes to 100 nmi with this antenna fed with 50ft of RG/6U.

73, Bob W9RAN