Forum: GNU Radio Receiving Spread Spectrum signals in Gnuradio

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Mir M. Ali (Guest)
on 2009-05-24 11:52
(Received via mailing list)
I have a few questions regarding receiving Direct Sequence Spread
signals using USRP and gnuradio. I am transmitting a signal that is
using gold codes at 2.4GHz. The USRPs that I have show a frequency
offset of
about 8kHz. In order to receive the signal so as to be able to de-spread
demodulate them I must implement a signal acquisition and tracking
Can someone suggest me ideas to do this. I came across a few things that
gave me an idea of accomplishing this.

"Fundamentals of Global Positioning System Receivers - A software
was once suggested to me on this list. The acquisition scheme suggested
this book is FFT based and the tracking scheme consists of
Correlation scheme for code tracking and Costas loop for carrier

1. Is there any such acquisition scheme already present in Gnuradio? I
looked at usrp_spectrum_sense and I have an idea of what to do. I want a
system that should work in real time with simultaneous transmissions
different Tx.
2. If I know the offset then by tuning my usrp to a frequency such that
offset is negated will I be able to skip the acquisition part?
3. What other things should I be looking into or taking care of in order
implement a DSSS system.

I have just started working on my "Communication Systems" knowledge so
please bear with me.

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