| 摘要 |
<P>PROBLEM TO BE SOLVED: To suitably extract required Doppler information in technology for extracting Doppler information from a target position utilizing continuous waves. Ž<P>SOLUTION: FM continuous waves outputted from an FM modulator 20 are delayed in a delay circuit 25, the delayed FM continuous waves are directly supplied to a mixer 32, and on the other hand, the delayed FM continuous waves are supplied to a mixer 34 through a π/2 shift circuit 26. In the delay circuit 25, the phase of a receive signal from an intended depth and the phase of a reference wave are made to match each other, whereby a demodulation signal from the intended depth can be selectively extracted. Further, the Doppler information analysis part 44 extracts a direct current component as a Doppler signal based on the electric power of a spectrum from a direct current component and an unnecessary wave component included in a frequency spectrum of the demodulation signal corresponding to the intended depth. Ž<P>COPYRIGHT: (C)2010,JPO&INPIT Ž
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