| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a pulse compression ultrasonic detection device that has a frequency sweep width enlargement circuit for a receiving signal included in a receiver thereof, and suppresses a side-lobe level to such an extent as if a frequency modulation sweep width of a transmission pulse were enlarged, though the frequency modulation sweep width is not enlarged.SOLUTION: A sine-wave receiving signal that is an input signal is squared by a square calculator 1 in order to obtain a sine-wave signal of a double frequency containing a direct-current (dc) component. After the dc component is removed by a dc component cutout unit 2, the resultant signal is passed through a square root calculator 4 in order to return an amplitude characteristic from a square characteristic of an input amplitude to a linear characteristic. An unnecessary harmonic component resulting from processing of the sine-wave signal performed by the square root calculator 4 is filtered by a harmonic cutout filter 5 and then outputted. Thus, the frequency is doubled. Accordingly, a frequency sweep width of f→fon an input state is doubled to be 2f→2f=2(f→f) on an output state. By laying the present invention n times, the frequency sweep width gets 2times larger.</p> |
