Introduction
Rapidly advancing computing and RF technology is making available communications techniques that were not previously possible. I have long been interested in communications both in my professional experience and as a hobby. Within the hobby domain, I look for ways to exploit the latest technology using design and construction techniques that could be executed in a poorly equiped home shop. This site is dedicated to the distribution of the results of my efforts in this area, particularly with respect to low cost hardware for software-defined and software-controlled radios.
SDR hardware is only part of the problem. For software we exploit the excellent efforts of a number of projects openly available through the web. Most of our efforts have focused on the GNU radio software. By building a software block (GNU radio terminology) that links this hardware into the GNU radio framework, we immediately take advantage of a large collection of reconfigurable signal processing functions designed specifically for communications systems. Eventually we plan to build interfaces to other packages (e.g., Dttsp, Linrad).
This project was intended to be a "do it yourself" effort. The SDR Module board, even with surface mount and fine pitch parts, was designed using open source tools and constructed in a home shop using creative construction techniques that have recently emerged (e.g., Low Cost Stencils and Skillet Reflow). The Digilent Nexys2 board, the core of this system, with a 1.2M gate FPGA costs $119 and the SDR Module can be built for about $80 per board (parts in single/small quantity from Mouser/Digikey) resulting in a receive-only SDR testbed for less than $200. As can be see in the figure, a second channel can be added and other connectors are available for future expansion.
This project is a learning exercise for me and constructive comments and discussion are invited. (See "Add comment" at the bottom of each page for registered users)