| 摘要 |
<P>PROBLEM TO BE SOLVED: To prevent an effect of noise as much as possible even if a level of reception signal is reduced, and to reduce the occurrence of erroneous reproduction of reception data. <P>SOLUTION: An I signal and a Q signal are generated from a modulated reception signal and local signal, and the local signal obtained by shifting a phase at 90 degrees, and DC components of the I signal and Q signal are removed by capacitors 37, 38. Further, higher frequency components than frequencies of the I signal and Q signal are removed by lowpass filters 35, 36. The I signal passing through the lowpass filter is squared by an I signal square part 43, the Q signal is squared by a Q signal square part 44, and further the squared I signal and Q signal are added to each other by an adder 45. A level of an added signal S1 is compared with a threshold T1 by a comparator 18 to obtain a signal S2, and further a data generator 48 of a digital signal processor 12 reverses a signal level every rising timing of the signal S2 to demodulate reception data. <P>COPYRIGHT: (C)2007,JPO&INPIT |
