Properties of a simple modulation system for multiple wireless gates

A simple transmission system developed for a 2.45 GHz wireless automatic passenger gate
^[1][2]
is discussed and its data transmission quality is measured with BER. The transmission system consists of a simple modulation/demodulation scheme for stable data transmission and a co-channel alloation system for use wih multiple gates. From the measurement results, it is proven that the realization of high quality data transmission is possible by a phase modulation system using a subcarrier. In other words, with a transmitter/receiver equipment (TRE) of 50 mW output, it is possible to get a BER of less than 1×10
^-7
at up to approximately 65 cm in distance. As for the suppression of interference signals, by providing a height difference of 30cm between the TRE and the card, and keeping the interfering TRE at a distance of more than 55 cm, a BER of less than 1×10
^-7
was obtained.