Hiroshi Akima

Abstract:

Modulation techniques for high frequency (HF) data transmission for the Integrated Global Ocean Station System (IGOSS) are discussed. Noncoherent frequency-shift -keying (NCFSK) and time-differential phase-shift -keying (TDPSK) systems are preliminarily selected as preferred systems. Performances of these preferred systems are discussed both in the presence of noise and/ or interfering signal and under adverse propagation conditions. A serious drawback inherent in a TDPSK system under adverse propagation conditions is pointed out. Frequency tolerance, frequency stabilization techniques, and selectivity of receivers are also discussed.

Keywords: HF; noncoherent; high frequency; data transmission; frequency stability; Integrated Global Ocean Station System (IGOSS); modulation technique; selectivity; noncoherent frequency-shift-keying (NCFSK); time-differential phase-shift-keying (TDPSK); radio frequency modulation; data transmission systems

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