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From: | Wang Kang |
Subject: | Re: [Discuss-gnuradio] GPS Signals recorded IQ samples file |
Date: | Sat, 22 Aug 2015 09:47:34 +0800 (HKT) |
User-agent: | Alpine 2.20 (DEB 67 2015-01-07) |
On Fri, 21 Aug 2015, Francisco Albani wrote:
Wang: Sounds good! Thanks! Did you try it?
Yeah. It works like a charm, in both HackRF and BladeRF.
Jean: many many thanks for sharing all the scripts! Your paper has caught my attention. I will print it and read it. Marcus: I was not expecting to "see" the signal because I already knew it was under noise floor. My conclusion of "signal absence" was after my GPS receiver was not able to decode it when I replayed it with an USRP. However, due to my little knowledge of GPS, it did not occur to me any other way of searching, so I thank you for your suggestion. I nearly killed my pc with a naive approach. :P I need a wiser one. Sylvain: interesting. I will try that too. Thanks! 2015-08-21 9:07 GMT-03:00 Sylvain Munaut <address@hidden>:Hi,are you sure you did not see GPS? The problem is that GPS is often belowthethermal noise floor and only detectable by the virtue of processing gain. I'd try and take a whole lot of samples (like: 2s worth of samples), and calculate the autocorrelation[1]. You should see peaks at multiples of 1ms,because that's the spreading code's period.You can also square the signal, then decimate it a bit and FFT it and you'll see peaks at whatever doppler the sat currently has. (so you'll see different peaks for different sats). Cheers, Sylvain _______________________________________________ Discuss-gnuradio mailing list address@hidden https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
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