HIGH FREQUENCY FREQUENCY SHIFT/PHASE SHIFT PERFORMANCE INVESTIGATION

HIGH FREQUENCY (HF) COMMUNICATION IS VERY SENSITIVE TO THE TIMEVARYING NATURE OF THE CHANNEL AND CONSEQUENTLY DATA CANNOT BE TRANSMITTED ACROSS THE CHANNEL ERROR FREE. THE CHANNEL IS INHERENTLY LIMITED IN PERFORMANCE SINCE THE CHANNEL USES THE IONOSPHERE TO REFLECT THE TRANSMITTED SIGNAL. THE QUALITY OF THE CHANNEL IS HIGHLY DEPENDENT ON THE WEATHER CONDITIONS, TIME OF DAY, AND OTHER CHANNEL VARIABLES. IN ORDER TO ESTABLISH RELIABLE COMMUNICATIONS, IT IS NECESSARY TO INCREASE THE SIGNAL-TO-NOISE (SNR) RATION AND/OR USE REDUNDANCY TECHNIQUES SUCH AS CODING. UNDER THIS EFFORT, PSI WILL INVESTIGATE POTENTIAL IMPROVEMENTS TO THE NTDS LINK 11 HF COMMUNICATION SYSTEM BY USING TRANSMISSION SIGNAL CODING. THE RELATIVE EFFICIENCY OF ERROR CONTROL CODING SCHEMES WILL BE COMPARED USING BIT ERROR RATE (BER) AS A PERFORMANCE MEASURE. THE SPECIFIC OBJECTIVE WILL BE TO ESTABLISH POSSIBLE IMPROVEMENTS IN LINK 11 PERFORMANCE WITHOUT ALTERING THE SYSTEM.