On-Line, Real-Time Recognition System on Telegraph Codes: TETAC

This paper describes studies of the TETAC system (Teaching Equipment for Telegraph Technology Aided by Computer). The system has been developed for training students at the University of Electro-Communications. TETAC is an intelligent system which recognizes Morse code sent by hand and converts it to letters by means of online and real-time processing. In addition, the system evaluates the qualities of trainees' keying operations; namely, it identifies the students' faults or tendencies. Although TETAC is now in the testing stage, we are confident of the effectiveness of the training and of TETAC's usefulness in modernizing a maritime communication system.     

Studying the Lunar Ionosphere with SELENE Radio Science Experiment

Radio occultation observations of the electron density near the lunar surface were conducted during the SELENE (Kaguya) mission using the Vstar and Rstar sub-satellites. Previous radio occultation measurements conducted in the Soviet lunar missions have indicated the existence of an ionosphere with peak densities of several hundreds of electrons per cubic centimeters above the dayside lunar surface. These densities are difficult to explain theoretically when the removal of plasma by the solar wind is considered, and thus the generation mechanism of the lunar ionosphere is a major issue, with even the validity of previous observations still under debate. The most serious error source in the measurement is the fluctuation of the terrestrial ionosphere which also exists along the ray path. To cope with this difficulty, about 400 observations were conducted using Vstar to enable statistical analysis of the weak signal of the lunar ionosphere. Another method is to utilize Vstar and Rstar with the second one being used to measure the terrestrial ionosphere contribution. The observations will establish the morphology of the lunar ionosphere and will reveal its relationship with various conditions to provide possible clues to the mechanism.