retrieving RSSI values in software

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BSJR
Posts: 9
Joined: Wed Nov 01, 2017 6:43 pm

retrieving RSSI values in software

Post by BSJR » Wed Nov 01, 2017 7:08 pm

Hello I am new to the SDR-LTR community and was hoping to find some answers here. I'm not at all a DIY in the electronic field, yet I am majoring in it. So bear with me if I will mention some idiotic things :? :? :?

I was wondering what would be the best way to fetch the RSSI values of signals acquired during measurements. I would like to come up with some kind of classification algorithm of protocols based on RSSI values. I am planning on buying the SDR-LTR (USB) and know that it is compatible with SDR#. Is it possible to get the RSSI values in the software in an easy way or can I only reach them on hardware level.

KG,

Kris

rtlsdrblog
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Joined: Mon Nov 19, 2012 11:54 pm

Re: retrieving RSSI values in software

Post by rtlsdrblog » Thu Nov 02, 2017 6:22 am

All RTL-SDRs are not calibrated, so only SNR measures would be valid. The RSSI wouldn't be accurate unless you create a calibration table with a known frequency source.

If you get the IQ data from the dongle then you have all the signal info there which can be processed on any way you see fit.

I'm not sure why you're trying to classify signals by their RSSI though?

BSJR
Posts: 9
Joined: Wed Nov 01, 2017 6:43 pm

Re: retrieving RSSI values in software

Post by BSJR » Mon Nov 06, 2017 1:42 pm

Thanks for the reply. The I/Q data is indeed what we need. What would be the easiest way to retrieve these from the dongle?
I assume software like SDR# uses this data for its calculations, so they must be stored somewhere right?

Thanks,

Kris

rtlsdrblog
Site Admin
Posts: 2421
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Re: retrieving RSSI values in software

Post by rtlsdrblog » Tue Nov 07, 2017 3:43 am

You'll probably want to take a look at the code of a simple program like rtl_fm, or rtl_tcp.

With rtl_tcp you can get the IQ data via a TCP connection which makes it pretty easy to acquire and work with.

BSJR
Posts: 9
Joined: Wed Nov 01, 2017 6:43 pm

Re: retrieving RSSI values in software

Post by BSJR » Tue Nov 07, 2017 2:20 pm

thanks!

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