Low-Probability-of-Intercept/Low-Probability-of-Detection (LPI/LPD) Data Link Navy SBIR FY2005.1 Sol No.: Navy SBIR FY2005.1 Topic No.: N05-029 Topic Title: Low-Probability-of-Intercept/Low-Probability-of-Detection (LPI/LPD) Data Link Proposal No.: N051-029-1371 Firm: Time Domain Corporation 7057 Old Madison Pike, Suite 250 Huntsville, Alabama 35806 Contact: William Beeler Phone: (256) 428-6403 Web Site: www.timedomain.com Abstract: Time Domain Corporation (TDC) proposes using an Ultra-wideband (UWB) communication system to provide a reliable 30 km RF link between an unmanned aerial vehicle and a ground station. Pseudo random flipped and time hopped codes provide a whitened pulse train with very low power spectral density (PSD). The PSD looks like Gaussian distributed noise to most narrowband low noise detection systems and would be very difficult to detect with wideband systems. The intended UWB receiver uses coherent integration to pull the signals out of the noise and to reconstruct and decode the information symbols. TDC has demonstrated several long range line of sight ground-to-ground links (approximately 15 km) using a high gain directional receive antenna, and shorter range LOS ground-to-UAV links (approximately 1 km) using very small omni-directional antennas and radiated effective isotropic power (E.I.R.P.) of 9.5 dBm = 9 mW. In Phase I, TDC will define requirements, build a demonstration platform, perform link budget analysis, conduct LPI/LPD analysis, and plan the prototype design. The program will determine feasibility of meeting size, weight, and power consumption requirements with UWB radios that provide sufficient data rate over a 30 km link. Benefits: Designing a highly reliable, 99% = 3 sigma, 30 km (18.7 mile), lightweight, low power, LPI/LPD communication link that can downlink audio, data, and video from a small UAV (Pioneer or smaller class), and uplink command and control functions to the UAV from the ground, would be very useful to the UAV community. The solution requires consideration of several technical approaches. These approaches include using small lightweight antenna arrays, high gain small directional antennas such as circular disc monopoles (5.7 dBi gain each antenna, 2 to 12 GHz bandwidth) or cavity backed wideband dipoles, wide bandwidth low PSD signals, short acquisition times, and receivers capable of coherent integration and multiple simultaneous high speed correlator/sampler channels. The required robustness of the up/down links necessitates sufficient margin to account for normal impacts to the propagation channel as well as hostile attempts to disable or degrade the performance of the UAV mission. UWB signaling schemes, along with the advent of fast low power silicon, enable many theoretical communication concepts to be implemented into baseband processing that allows covert, robust, jam resistant, low power, small footprint, expendable communication systems to be designed, built, and deployed at ever decreasing costs. TDC expects that completion of this phase of the project will prepare the way for a Phase II demonstration of a UWB radio link that meets the objectives of this SBIR project. Return