A proposal of a precise distance measuring system which counts the number of phase cycles of a radio wave transmitted by an airplane employed for flight test. The objective of the study is to analyze the accuracy of the measurement of the distance between the ground station and the plane which usually flies quite closely to the station and at low altitude.
The system employs two crystal oscillators having a stability of about 10-10 per hour, one at the station, the other in a plane and they are synchronized each other. Therefore, the distance is measured by counting phase cycle of the radio wave, purely sinusoidal one in 30MHz band.
Since the multipath phenomenon is the most important factor for the range determination accuracy, the influence is studied and evaluated.
The received signal is cross correlated with the synchronized signal, the output of synchronized oscillator.
The study indicates an error less than 0.1% can be expected for the system even in the worst circumference.
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