ADS-B questions (beginner)

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Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

ADS-B questions (beginner)

Post by Patrick73 » Fri Jul 05, 2019 10:02 am

Hi there,

I'm about to test ADS-B reception for the 1st time ever, using my RSPduo. Some points are not clear though ...
In Windows "Start Dump1090" menu, 4 options are available :

8 MHz mode interactive
8 MHz mode
2 MHz mode interactive
2 MHz mode

Under what circumstances should either of these options be used ?
What interactive means ? What is the "basic" mode for ?

Is it possible to display the planes on Googe Earth or Open Street Map ? If so, how to ? (step by step explanations, please !).

What about the built-in LNA ? Considering I plan to use a 130-1300 MHz log periodic + 10m only quality cable, should I enable it ? Set to which value (approx) ?

Sorry for these silly questions but these are my very first steps in the "ADS-B world" :roll:

Thanks,
Best regards

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sdrplay
Posts: 960
Joined: Wed Jan 07, 2015 7:58 am

Re: ADS-B questions (beginner)

Post by sdrplay » Fri Jul 05, 2019 2:04 pm

I would recommend looking through our user guide... https://www.sdrplay.com/docs/SDRplay_AD ... _Guide.pdf

This explains how you can get the aircraft information into Virtual Radar Server software which you can then view on a map.

The difference between interactive and non-interactive mode is that in interactive mode you will see the aircraft information updating in the terminal window. If you don't need to see that then non-interactive will take less resource.

The standard demod in dump1090 is the 2 MHz mode. We added an experimental 8 MHz demod mode. The difference should be that the 8 MHz should have a wider range, but at the cost of more CPU.

There is no gain control as such - our version of dump1090 is configured for max gain as the ADS-B signal is pretty weak.

Hope that helps.

Best regards,

SDRplay Support

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Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

Re: ADS-B questions (beginner)

Post by Patrick73 » Fri Jul 05, 2019 3:40 pm

Thanks for the prompt and detailed reply. It indeed helped :D
I had already read the ADS-B guide but I couldn't find the answers to my questions.

About the map, my request was actually : is it possible to view the planes on Google Earth or Open Street Map INSTEAD OF the Virtual Radar Server map.
There is no gain control as such - our version of dump1090 is configured for max gain as the ADS-B signal is pretty weak
OK, It means only an external LNA could be used (if necessary).

Official SDRplay distributor "Passion Radio" website mentions : "The SDRDuo is equipped with a software-adjustable LNA"
I don't find any visible LNA setting on SDRuno interface ; am I missing something ?
The standard demod in dump1090 is the 2 MHz mode. We added an experimental 8 MHz demod mode. The difference should be that the 8 MHz should have a wider range, but at the cost of more CPU.
I suppose the 8 MHz mode allows you to visualize more aircrafts ? This puzzles me a bit because I thought that only the 1090 MHz frequency was concerned by ADSB reception and not a few MHz wide range ... (8 MHz = 1086 to 1094 MHz ???).

My compliments for the quality of customer service.

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sdrplay
Posts: 960
Joined: Wed Jan 07, 2015 7:58 am

Re: ADS-B questions (beginner)

Post by sdrplay » Fri Jul 05, 2019 8:22 pm

The standard dump1090 demodulator is 2 MHz. The signal is actually only 50 kHz wide but it can be anywhere +/- 1 MHz of 1090 MHz - we added an 8 MHz demodulator as an experiment to see whether it would acquire more ADS-B data - I've not done a lot of testing, but it should be better than the 2 MHz demodulator, but as I said at the expense of CPU

The RF gain control slider in SDRuno encompasses both internal and external (to the tuner) gain steps so there is no LNA on/off any more like there used to be - it's taken care of as part of the overall RF gain control. We've already optimised dump1090 for the RSP gain control.

As well as feeding the data into Virtual Radar Server, you can actually visit the dump1090 web server directly (http://localhost:8080 if you are using a browser on the same machine as dump1090) but you will see that there are issues with this because Google changed something on their map system.

You have access to the ADS-B data directly from dump1090 in different formats (beast, etc.) so maybe google search how to get that into other map systems?

Best regards,

SDRplay Support

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Patrick73
Posts: 76
Joined: Thu May 31, 2018 9:39 am

Re: ADS-B questions (beginner)

Post by Patrick73 » Sat Jul 06, 2019 9:07 am

Clear explanations, thanks !
maybe google search how to get that into other map systems?
I will indeed launch a search for this, unless a user can explain if it is possible.

Have a nice week-end,
Patrick

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