| 摘要 |
PROBLEM TO BE SOLVED: To correctly restore an original transmission signal while preventing the influence of level variation of a pilot signal, in a transmission/reception system in which a transmission signal and the pilot signal are upconverted and transmitted and a receiver side corrects the frequency of a downconverted reception signal using the pilot signal. SOLUTION: In the transmission/reception system in which a transmitter upconverts a terrestrial digital IF signal and the pilot signal (PILOT) and transmits them by radio, a receiver 50 downconverts the reception signal to separate it into the IF signal and PILOT, generates a correction signal by performing frequency conversion for PILOT with a correction reference signal, and corrects the frequency of the IF signal with the correction signal, thereby restoring the original terrestrial digital IF signal. In order to perform the restoring operation highly accurately, two level control circuits consisting of variable attenuators 62, 92 and detection circuits 68, 98 etc. control the reception signal and PILOT at a target level. COPYRIGHT: (C)2007,JPO&INPIT
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