ATCBI-2 LINEAR SYSTEM AND ATCBI-3 LOGARITHMIC SYSTEM.
SYRACUSE UNIV RESEARCH CORP N Y DEFENSE SYSTEMS DIV
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Two methods of providing precision azimuth centermarks were built for use in the Federal Aviation Agency Beacon Navigation system. These methods utilize an amplitude monopulse beacon receiver. The receiver antenna pattern is split into sum and difference channels. The sum channnel produces a conventional maximum output with a target on boresight, while the difference channel output nulls when a target is on boresight. By comparing the relative signal strength of the sum and difference channels, the target azimuth can be determined to less than a quarter of a degree. Such an equipment must be capable of operating over an extremely wide range of signal strengths. In the ATCBI-2 linear equipment the sum and difference signals are amplified in linear IF amplifiers. The problem of varying signal strengths is solved by controlling the gain of the IF amplifiers with a sensitivity time control STC. The second method described is the ATCBI-3 logarithmic equipment. This approach to the problem of varying signal strengths was developed later and seems more satisfactory than the STC approach. Author