An HF Software-Defined Radar to Study the Ionosphere

In this paper, a novel design and implementation of a software-defined high frequency ionospheric radar, the Penn State Ionospheric Radar Imager (PIRI), is described. Furthermore, preliminary results produced by the system (located at 40.71 ? ? N, 77.97 W) are presented. PIRI is designed to be a modest and low-cost radar system which is composed mostly of commercial-off-the-shelf products and utilizing open-source software to perform pulse generation, pulse coding, downconversion, data acquisition, and signal processing. It is designed to be mobile as it can easily be deployed at temporary locations to study local ionospheric disturbances. For the results presented herein, the radar operating frequency was 5.125 MHz. However, as the system is software-defined and short active receive antennas are used, only the transmit antenna needs to be changed to operate over the entire HF band. The two orthogonal receive antennas enable both linear and circular polarization measurements. Peak transmit power of the system is 500 W. PIRI is designed to be a modest and cost-effective alternative to the current standard HF ionospheric sounding systems and can be readily replicated.