| 摘要 |
PURPOSE: To provide a radio unit and a communication system which is provided with an automatic intermediate frequency filter correction mechanism, improves the overall sensitivity and selectivity of the radio unit and also can cope with a temperature change. CONSTITUTION: A communication system 10 is provided with a base station 12 for controlling a control channel signal 16 and plural traffic channels and a communication device 17 which responds the control channel signal 16 and also receives plural traffic channels. The communication device 17 is provided with a tuning filter 48 which has adjustable characteristics to substantially filter all of the traffic channels excluding a selected one among the plural traffic channels and with a tuning circuit for controlling the filter characteristics. The tuning circuit uses the control signal 16 as an accurate center frequency Fo for the pass band of the filter 48 and also adjusts the filter characteristics to the minimum insertion loss at the accurate center frequency Fo . |
