The Author – John Petrich (W7FU)

This site is intended to promote interest in the GNU Radio Open Source Digital Signal Processing (DSP) application and practical amateur radio oriented SDR applications.  DSP is a modern iteration of radio communications technology.  GNU Radio is an approachable “ham friendly” DSP graphical programming application that is freely available to any interested party.  This powerful software tool lends itself to interesting and exciting SDR applications.

A lifetime interest in amateur radio has brought me to this place.  I became licensed as an amateur radio operator after learning the Morse code and I have remained continuously active since October 1955; first as KN6OJV, then W7HQJ, and most recently as W7FU.  My amateur radio career is not an unexpected mirroring of the evolution of over 100 years of radio technology.  I began studying radio as a child by building a homemade galena crystal detector receiver and listening to AM broadcast radio.  The elementary crystal detector was followed by a single tube regenerative detector that allowed reception of short wave broadcast signals.  With my license ham radio communications activity started out with QRP as a novice.  The rig was a crystal controlled 6V6 tube transmitter built on a wooden chassis and a 3 tube super heterodyne receiver.  As time went by, my equipment collection moved on through modified surplus and home designed receivers and transmitters.  Each step of new equipment utilized increasingly sophisticated analog components for increased radio performance. These last 30 years, my activity has spanned AO6, AO7, and AO8 satellites as well as the HF bands. At the present I am quite active building and operating microwave equipment with the local group.  Building strictly analog rigs stopped about 20 years ago but radio building continued with radio systems that utilized computer interfaces.

Having embraced digital technology, I now operate an experimenter’s station built around Software Defined Radio (SDR): HF to Microwave SDR Station. My first SDR rigs were open source QSD style SDR transceiver platforms modified for multi-band operation. In essence versions of the classic Flex 1000 transceiver, itself is a landmark design. My current station consists of second generation SDRs that reflect the transition from the QSD SDR architecture to the more advanced direct sampling SDR transceiver architecture of digital down conversion (DDC) and digital up conversion (DUC).  At present I am building radio systems starting from the Ettus N200 for HF, and the Ettus B210 for VHF through Microwave:  These SDRs utilize software DSPs that have been authored using GNU Radio; GNU Radio


John (W7FU)

Email: petrich (at) UW (dot) edu