| 摘要 |
A window-passage detection system has a ground system comprising: a first course generator (3) for generating a horizontal DDM (Differential Depth of Modulation) pattern for defining a horizontal width (25) of a virtual window frame by emitting a first carrier signal and a first side-band signal from a pair of first transmission antennae (6a and 6b), a second course generator (4) for generating a vertical DDM pattern for defining a vertical width (26) of the virtual window frame by emitting a second carrier signal and a second side-band signal from a pair of second transmission antennae (7a and 7b), and a third course generator (5) for generating a longitudinal DDM pattern for defining a longitudinal position (27) of the virtual window frame by emitting a third carrier signal and a third side-band signal from a pair of third transmission antenna (8a and 8b). Pairs of the first to the third transmission antennae (6a to 8b) generate three orthogonal polarization planes. With each pair of antenna, each carrier signal is emitted with the same phase and each side-band signal is emitted with inverted phase. Each carrier signal is amplitude-modulated with addition of a first and a second modulation signal, and each side-band signal is balanced-modulated with differential of the first and the second modulation signal.
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