Improved High Frequency Communications

For decades, High Frequency (HF) communications have been an important, in some cases the only, way of providing long distance communication. For most of that time, both voice and data communications in the HF radio bands (2 30 MHz) have been restricted to channel bandwidths no wider than 3 kHz. However, recent years have seen increasing demand for higher-speed data transmission over HF links, and regulatory agencies have addressed the allocation of single HF channels wider than 3 kHz. The culmination of the regulatory efforts has resulted in the standardization of HF channels up to 24 kHz and supporting data rate of 120kbps at high signal-to-noise ratios (SNRs). Despite these recent advancements, this SBIR program is looking to identify improvements over the current state of the art in HF communications waveforms and equipment. The goal is to provide improved reliability and predictability of HF communications using either Skywave or Near-Vertical Incidence Skywave (NVIS) propagation modes at bit rates exceeding 100 kbps to overcome the shortfall in long-range tactical communications in complex terrain environments.