PURPOSE: To allow quick measurement of a plurality of distances by a phase difference method under transponder system.
CONSTITUTION: First and second distance measuring means 1100, 1200 on the master station side transmit microwave transmission signals B, B' having frequencies increasing/decreasing with a shift exceeding an oscillation signal P. Phase differences G, G' between signals F, F', obtained by separating the oscillation signal P from receiving signals E, E', and reference oscillation signals Q, Q' are sampled. The phase differences G, G', where the frequency of one of transmission signal B, B' increases and the frequency of the other signal decreases, are excluded and the distance to a slave station 200 is determined depending on the variation rate thereof and the like. This constitution allows parallel measurement of distance.
SAKAMOTO YUKIO
TANAKA YASUO
