| 摘要 |
PURPOSE:To receive PAC processed signals for echos from different depths with optimum SN ratio by receiving information about the center frequency of echo signal from a CPU, and making changing-over between the center frequency variable BPF altering the information and PLL group generating reference signals to be fed to mixers. CONSTITUTION:A CPU 20 reads the band of a probe 30 mounted. With the set sample region depth taken into consideration, the frequency of reference signal is determined, and also the center frequency of a center frequency variable BPF 23 determined. With control signals, an actual time controller 22 gives control signals for determination of the center frequency of the RPF 23 and the frequency of reference signal to the BPF 23 and switch 24 to make respective changing-over. The signal receipt echo 1 is entered into the BPF 23 to get rid of unnecessary high frequency and/or low frequency, and is emitted as an output with no damping. The output signal is entered into mixers 2, 3 and subjected to orthogonal intersecting detection with the reference signal due to orthogonal intersecting two signals at 0 deg. and 90 deg. as phase shifted by a 90 deg. phase shifter 26. As output therefrom, i-signal and q-signal of base-band detected are emitted. |
