| 摘要 |
PURPOSE: An LMDS(Local Multipoint Distribution Service) system having a bidirectional converter is provided to integrate a down converter and an up converter into one board, and to share a local oscillator, so as to reduce a producing cost. CONSTITUTION: A bidirectional converter operates as follows. A duplexer(5G) separates signals transceived through an outdoor antenna(1). A common local oscillator(5D) forms a down converter and an up converter into one board, and supplies IF signals to the up and the down converter. Multipliers(5i,5j) generate required local oscillating frequencies between each mixer(5c,5C) of the up and the down converter. An outdoor network interface unit(8) changes the IF signals into band signals, and converts the band signals into digital signals. A subscriber controlling set top box(9) is for watching an image of a required channel on TV.
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