The Receiver Development Platform (RDP) is a general-purpose tool being developed and documented here on the Receiver Development Platform Google group. The first application of RDP is an Amateur Radio Direction Finding (ARDF) project to develop dual-band receivers and transmitters for ARDF.
http://openardf.org is a new website specifically for the ARDF hardware work being done as part of RTP, and also to open ARDF projects in general: equipment, tools, and pretty much anything else that is open (as in open source), public domain, or otherwise freely available to all.