| 摘要 |
PROBLEM TO BE SOLVED: To reduce a memory use amount, decrease a device scale, and shorten a frequency spectrum analyzing process time period in a frequency spectrum analyzer after the device scale is reduced in correspondence to a plurality of communication systems. SOLUTION: Each radio frequency of a plurality of communication systems is converted into each digital signal by a single digital converting means, and the one digital signal is inputted into a high-speed Fourier conversion part 16 as it is to make a frequency spectrum analysis. The other digital signal is composed in frequency with a local frequency L02 via a transfer switch by a testing signal conversion part 13, and the frequency-composed testing signal S13 is filtered to be converted into a testing signal S14 in which a necessary signal is left behind. The filtered testing signal S14 is decimated, and the decimated testing signal S15 is subjected to a frequency spectrum analysis by the high-speed Fourier conversion part 16.
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