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 <246...@gmail.com>:
Hi,
are you sure you did not see GPS? The problem is that GPS is often below
the
thermal 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 1
ms,
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
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