HIGH ALPHABET FLIGHT TERMINATION SYSTEM

Abstract

This paper proposes a modification of the high alphabet method of data transmission over an RF carrier. The system maps eleven characters into three tones. The three tones are Frequency Modulated onto an RF carrier. The 165 unique characters can be utilized for data transmission. The advantages of this system are: 1. Longer duration data words which have narrow bandwidth yielding a high signal to noise ratio. 2. Digital Signal Processing can be utilized to reconstruct characters from the tri-tone encoding. 3. The system will be less susceptible to external interference than normal Frequency Shift Keying system. The majority of the three tone burst would have to masked in order to loose a data word.