If the Universal Software Radio Peripheral (USRP) or USRP2 is too expensive you can give the Simple Software Radio Peripheral (SSRP) a try. The primary goal of the SSRP project is to create a low-budget but still modular hardware platform for software design radio purposes (RF signal processing).
Just like the USRP1 the SSRP has a [...]

Some days ago Matt Ettus released the new USRP2 board. It’s the successor of the famous URSP/GNURadio hardware. Some of the USRP2-features:

Gigabit ethernet interface replacing the former USB2 interface
The larger FPGA (Xilinx Spartan 3-2000) containing a 32-bit RISC processor now allows you to do most processing directly within the FPGA
SD-Card for storing configuration, firmware and [...]

After the prove-of-concept of an software defined DVB-T Transmitter there is a new project concentrating on the development of an GSM basestation It’s called OpenBTS and again based on the the GNURadio / URSP hard- and software in combination with asterisk an open source PBX telephony platform. Background information on this project can [...]

William A. Sethares and Rick Johnson wrote an interesting book on a more and more hot topic in wireless technology but also security research:

Telecommunication Breakdown: Concepts of Communication Transmitted via Software-Defined Radio
There is also a PDF-version of this book available.
An brief introduction on Software-Defined Radios can be found in Michael Ossmann’s Black Hat 2008 talk [...]

This song as MP3 (local copy):
Properties of the Fourier Transform
(or, Fourier’s Song)
Integrate your function times a complex exponential
It’s really not so hard you can do it with your pencil
And when you’re done with this calculation
You’ve got a brand new function – the Fourier Transformation
What a prism does to sunlight, what the ear does to sound
Fourier [...]

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Harald recently blogged about a full-featured DVB-T transmitter using a normal PC and the GNURadio / URSP hard- and software. There is also a paper on this topic “Soft-DVB: A Fully-Software GNURadio-based ETSI DVB-T Modulator” by Vincenzo Pellegrini, Giacomo Bacci and Marco Luise presented at the WSR’08 and a additional paper on wireless protocol [...]