HF High Data Rate/LPD Software Defined Radio

This Phase II SBIR effort will develop a LPI/LPD waveform and hardware system to transmit large data files efficiently and securely over great distances using RF signals that do not require the support of infrastructure such as cellular towers or satellites. Analysis of waveform and communication techniques will be summarized in a trade-off study and a selected waveform/communications technique will be porting into an existing hardware system.Since it is difficult to find open 10 kHz channels, we will evaluate a channel by channel spatial nulling capability to compensate for the crowded HF spectrum.The algorithm will be set to automatically form a spatial null on any signals that have durations longer than that of a symbol.The desired signals will be copied on those frequencies as long as they come from a different azimuth/elevation.Communication between transmitter and receiver will agree on a set of useable frequencies after the spatial nulls have been created.We will investigate the performance of a digital beamformers to characterize and cancel fixed frequency interference while passing short-duration signals un-attenuated.The beamformer will be implemented in a multi-channel transceiver and will allow demodulation of short duration WBMNFSK signals in a crowded HF signal environment.