HF Software Receiver Arrays (HFSRA)

Period of Performance: 09/29/2007 - 09/29/2008


Phase 1 STTR

Recipient Firm

Atmospheric & Space Technology Research
5777 Central Avenue, Suite 221
Boulder, CO 80301
Principal Investigator

Research Institution

Southwest Research Institute
6220 Culebra Road, P.O. Drawer 28510
San Antonio, TX 78238
Institution POC


Accurate real-time knowledge of the bottomside ionosphere is necessary for covert HF communications, near vertical incidence sounding, and geolocation of HF transmitters. Sky-wave TDOA geolocation is the "holy grail" of HF geolocation techniques due to its passive nature, low cost, and easy deployment. To achieve sky-wave TDOA it is necessary to know the dominant mode of propagation, which requires accurate knowledge of the bottomside ionosphere over a wide geographical region. The bottomside ionosphere is not well characterized, because existing instrumentation is expensive, sparse, and usually views only a local region. Thus, a requirement exists for low-cost sensors that can provide information over an extended region. To address this problem we propose a feasibility/design study involving two types of HF instrument: (1) a receive-only sensor, that collects data from all known HF "transmitters of opportunity"; (2) a transmit/receive sensor that cycles over a range of frequencies. We will also study the feasibility of combining multiple instruments into a network, whose data can be ingested into appropriate ionospheric specification algorithms. This system will provide the capability to determine the dominant propagation mode for HF geolocation, a solution to the long-standing problem of HF geolocation, and improved security for the USA.