From osmocom at gustad.com Thu Dec 18 15:59:53 2014 From: osmocom at gustad.com (Petter Gustad) Date: Thu, 18 Dec 2014 16:59:53 +0100 (CET) Subject: rtl_sdr for Yocto? Message-ID: <20141218.165953.1533849118079364360.petter@gustad.com> Is there a meta layer or other method to include rtl_sdr in Yocto? Thanks! //Petter From andreas.hornig at aerospaceresearch.net Thu Dec 25 10:14:24 2014 From: andreas.hornig at aerospaceresearch.net (Andreas Hornig) Date: Thu, 25 Dec 2014 10:14:24 -0000 Subject: How to cross-correlate two I/Q streams of same radio-station? Message-ID: Hi everyone and merry Christmas! :) I want to find the same snippet of I/Q data of a radio station in another I/Q recording of the same station but recorded with another dongle. Of course both with rtl-sdr dongles. I did this here http://filebin.net/8nevid3yk3 and played around with a python script and numpy math-lib to find this "needle" in the "haystack" and the timeshift. But it didn't work. That's why I am here to ask you how to do that. First of all, I would like to ask you if you could somehow check if both streams are actually containing the "same" I/Q data. Perhaps you can do that with one other software if you can find it. What I did was to use the numpy correlate function and added there some lines to have it normalized to have the results between -1 and 1 as explained here http://en.wikipedia.org/wiki/Cross-correlation#Normalized_cross-correlation But it couldn't find a needle sequence of 1000 samples that could be refound in the haystack (about 2000000 samples) when the starting of the needle samples were shifted a bit with some new 1000 samples. I guess that the analogue radio channel on this carrier and thus the I/Q doesn't form the I/Q enough to use each sample on that 2MHz sample rate, but much less in the KHz range. But I am not fully sure if this is true. This is why I am also here to ask about the influences on a cross correlation and how to set it up. So, any answer is very welcome. I hope it will work out in the end :). Best regards, Andreas -------------- next part -------------- An HTML attachment was scrubbed... URL: