Multi-hop Processing for OTHR Range Extension M191-011-0105

Extending the range of High Frequency (3MHz-30MHz) Over The Horizon Radars (HF-OTHR) to multi-hop range will provide a significant capability enhancement to neutralize anti-access/area denial (A2/AD) capabilities developed by US adversaries. To provide target detection for OTHR at multi-hop ranges we will develop the Radar Environment Response Function (RERF) solution that employs a comprehensive processing system of ionospheric propagation characterization to determine target matched filters. \n\n The RERF solution compares OTHR clutter returns to an ensemble generated using a comprehensive set of ionospheric states to select the one that most closely matches the current conditions. Once the ionospheric state is selected, then matched filter responses can be generated for potential targets as a function of target position, velocity and Radar Cross Section. These matched filters can be applied to Doppler processed data to optimize the target detection process, particularly at multi-hop ranges. The RERF solution combines existing state-of-the art HF radar ray propagation, ionosphere, and surface terrain models with proven detector response matrix and data inversion techniques that have been applied successfully in gamma-ray astrophysics for decades. In order to demonstrate the practicality of implementing the RERF algorithm, we will we will stand up a side car supporting the RERF algorithm and databases connected to an operational OTHR data processing string. This will allow us to demonstrate the RERF algorithm with  actual radar data in real time.