As a radio amateur myself and also a SDR designer, I have long waited for something like Raspberry to become available, so I can design a radio "shield" for it. As Raspberry seems to do the same to high-end development range as Arduino did for basic automation for artists and students, it seems the right one to go with.
So, decided to give a little try for crowdfunding and created a project for basic SDR board what would be an inexpensive entry-level radio module for Raspberry.
The more high-end project I have, the SDR MK1.5 http://uvb-76.net/p/sdr-mk15-andrus.html
could benefit from processor upgrade as well, but the professional receiver is likely too complicated and expensive concept for successful crowdfunding, so the one I am creating is more a entry-level.
The architecture will consist of preamp, analog downconverter with programmable clock synthesizer, a good quality 24-bit ADC and some filters and glue logic, and perhaps couple of buttons and rotary encoder to make it truly standalone unit.
The feature requests are more than welcome, but pleas emid the price!
As a ham radio operator, electrical engineer, and part time amateur radio designer hack, I have been kicking around the idea of a small low frequency (30 kHz to 100ish MHz) sampling device for the front end of a software defined radio (SDR). I envision the front end being similar to the system designed by Sinisa Tasic (YU1LM out of Serbia), except built exclusively with surface mount components to minimize size, and laid out on a board the size of the Raspi. See http://yu1lm.qrpradio.com/SDR&.....-YU1LM.pdf
for a detailed description of what the RF front end would likely resemble.
I imagine that a PIC could be used to perform the analog sampling of the down-converted RF, and to convert the samples to I2C or SPI (since there is no analog capability available directly on the board. The PIC would also talk to a programmable crystal oscillator to be used for the local oscillator. A small amount of ham radio SDR software for Linux already exists, and it may be executable directly on the Raspi board. If not, some coding would have to be done, possibly making use of the onboard DSP once the DSP folks let us see behind the curtain.
This seams like a natural thing to do with a board built around a cellphone processor anyway…