An Improved Directive-Communication System

Naval UHF communication is now carried on using antennas having as nearly as possible an omnidirectional pattern in the horizontal plane. The practice permits communication to stations in any direction. However, it is believed that significant improvement in the reliability and range of uhf voice communication, data transmission, or of other types of radio links may be obtained by the use of a beamed system having automatically aligning directive antennas for transmission and reception. In military applications, the directive characteristics of such a system will reduce the possibility of enemy interception, direction finding, or jamming. A communication system with mutually aligning directive antennas has been developed at the Laboratory. The basic system has been described, and its performance during operational trials and in range runs with one terminal mobile has been indicated in a previous report. Further improvements haven been made in the basic direction indicator and AVC circuitry, and operation has been simplified by the use of guidance tones above the speech frequency range. Peak clipping of speech has been incorporated to improve the effectiveness of the system, and an automatic all-and-answer circuit has been provided to carry out the required calling or reply sequences to obtain initial directive-antenna alignment. Consideration has also been to possible specific applications of the directive system, and to the limitations of the system and the operational problems which may be introduce.