Underwater Tactical Data Lin

There is a requirement for a reliable tactical underwater data link to link under- water and surface Navy assets. In this Phase I effort, we propose to evaluate 3 alternative techniques which are potential solutions to meeting the requirement, as well as recommend the one which is the most feasible. The 3 techniques include 2 long range, relatively low data rate (100-500 and 1200 bits/sec) configurations, and a short range, relatively high data rate, (10 kbit/sec) configuration. The 2 long range configurations are a multiple convergence zone acoustic data telemetry system that uses Quadrature Phase Shift Keying (QPSK) or Digital Coded Phase Modulation (DCPM) at data rates of 100-500 bits/sec, and a system that employs a surface RF buoy to relay acoustic data telemetry from a subsea source that uses Frequency Shift Keying (MF$K) modulation at a data rate of 1200 bits/sec. The 3rd, high data rate technique, is intended for short range, low power, Low Probability of Intercept (LPI) applications and uses the QPSK technique at a data rate of 10 kbits/sec. Our evaluation effort will encompass open water tests using existing 1200 bits/sec acoustic modems modified to implement the various modulation schemes and allow us to evaluate various performance factors such as power efficiency, reliability, data accuracy, and transducer design. The deployed system will also allow us to analyze performance under different environmental conditions.