| 摘要 |
PROBLEM TO BE SOLVED: To prevent the mingling of an unnecessary virtual image into Doppler information by making a filter process with a minimum-maximum value filter. SOLUTION: Image clutter is removed from a Doppler signal by a flash suppressing processor for each large frame in a display signal. When the Doppler signal of the new frame Fn is received, it is compared with the value of the previous frame Fn-1 , and the minimum value MIN1 is selected by a minimum value selector 630. It is compared with the previously selected minimum value MIN2 stored in an image buffer A by a maximum value selector 636 to select the maximum value MAX. The minimum-maximum value is subtracted from the Doppler signal value of the frame Fn-1 at that time by a subtractor 638, it is compared with the signal displacement threshold value by a comparator 640. If it is the threshold value or above, the minimum-maximum value is set as the Doppler signal value of the present frame. If it is the threshold value or below, the frame value Fn-1 is set as the Doppler signal value of the present frame. A virtual image can be then removed. |
