Re: [Discuss-gnuradio] How to use USRP to detect and collect weak satellite signals

[Carles Fernandez]

Hi there,

for those folks interested in GPS (and Galileo) signal processing with USRP+DBSRX and GNU Radio related stuff, please take a look at the publications available at http://gnss-sdr.org/documentation/publications 

We use three VOLK-based correlators for GPS L1 and five for Galileo. An active antenna is also desirable, but any cheap ($20) commercial part should work well.

Best regards,

Carles

On Fri, Sep 6, 2013 at 9:38 PM, Marcus D. Leech <address@hidden> wrote:

On 09/06/2013 03:33 PM, Ian Buckley wrote:

Filters will all to some degree attenuate your signal of interest, but by how much varies dramatically depending on the type and design of the filter, it could be 0.5dB or 20dB, but the point is that it attenuates potential interferers and noise by a great amount. An LNA cascaded into a bandpass filter as close as possible to the antenna is generally an ideal setup for this type of weak signal work.

LNA into filter is the line-up we use in radio astronomy, which might be described as the "limiting case" of weak-signal work.

A circular-waveguide feedhorn designed for the band of interest will act as a high-pass filter with a "knee" at the design frequency of the feedhorn.  This,
  combined with directionality of a dish is often enough to eliminate the worst of the interferers *before* the LNA, and then apply a filter after the LNA.

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