RASDR 2062: 200 Years of Receiver Evolution

D. Fields, P. Oxley, B. Vacaliuc, S. Kurtz4 and C. Lyster
Tamke-Allan Observatory
Roane State Community College
276 Patton Lane
Harriman, TN 37748

This paper has been presented at the SARA 2013 annual meeting

ABSTRACT

Decades of experimental studies led physicist James Clerk Maxwell to formulate the theoretical foundations of electromagnetic energy in 1862. Thirty years later, another physicist, Henrich Hertz, demonstrated radio transmission and reception and initiated an era of Hardware-Defined Receivers (HDR). Receivers in the span of 150 years evolved from having a design focus in hardware, to a design focus in software, as Software Defined Receivers (SDR) began a 20-y rise to dominance. The SARA development of an SDR that is optimized for Radio Astronomy, RASDR, consists of a minimalist front end and a software-driven user-defined desktop computer back end. This software-rich back end performs the signal processing required to cope with different types of modulation and to resolve/present low S/N data. RASDR is functioning in benchtop mode with multi-modulation detection capability from 0.0001 to 3.84 GHz. Current RASDR software, RASDRWin, performs some basic parameter optimizations, but the SDR software is basically static within an observing session. Current RASDR hardware consists of a benchtop developmental device (RASDR 0) and (with collaboration from the RASDR team) two versions of software-compatible commercially-produced versions, (RASDR 2). A developmental board of  the Nuand bladeRF has been received, while commercial versions of bladeRF and the Myriad DigiRed hardware are expected to be received by the RASDR team in late June, so they will be available for inspection and a possible demo.

Beyond the SDR design focus lies the Algorithm Defined Receiver (ADR) in which software will evolve based on signals detected and project goals. Project goals will eventually relate to radio astronomy research. Currently they are not now driven by scientific considerations but by military and commercial interests. Recent DARPA design challenges, cryptoanalysis applications, and multi-million dollar prizes offered by commercial interests and claimed by dedicated software groups now dominate algorithm development.

RASDR 2062 will be an ADR that copes with changing signal structures, interference from natural and other sources, and the probable detection of new forms of signal modulation that arise frequently in basic research and that may be found in SETI (Search for Extraterrestrial Intelligence). Such applications
require an ADR defined by evolving software having a flexible, purpose-driven algorithm structure.