JPH05243896

PURPOSE: To reduce interference by multiplex reflection by moving a part of surface reflectors to positions corresponding to the half of desired travel time by random values. CONSTITUTION: A high frequency signal is inputted to an input/output cross finger-type converter 10 provided on a piezoelectric substrate 1 and it is converted into an acoustic surface wave. It is transmitted on the substrate 1 and is reflected on the surface wave reflectors 11-N. Then, individual reflection components are inversely converted into pulse electric signals. The surface wave reflectors 11-N are moved from the positions corresponding to the prescribed travel time of surface waves between the converter 10 and the reflectors by the numerically random values, by ±λ/4 or ±λ/8, for example. The occurrence of multiplex reflection at the same phase is suppressed and interference for reducing it is generated and the total amplitude of multiplex reflection is reduced.