ASYNCHRONOUS SURFACE ACOUSTIC WAVE MATCHED FILTER

摘要

PROBLEM TO BE SOLVED: To provide a SAW matched filter capable of detecting synchronizing and correlation signals in accordance with a spread spectrum communication system in which a carrier wave is asynchronous with a chip rate. SOLUTION: This filter in which an input interdigital electrode 2 and a signal tap output interdigital electrode are 3 formed on a piezoelectric substrate 1, is used for the correlation processing of a diffusion signal in which a chip rate is asynchronous with a carrier frequency. In this case, when the position of one tap output electrode 3a in the electrode 3 is made as a reference position and a carrier phase in the reference position is made to zero, the optional number of a tap output electrode 3a that is counted from the reference position is arranged at the position of a phase of a carrier, +nπ (n is an integer) or -nπ (n is an integer) in a neighborhood where the electrode 3a that is decided according to a chip rate should be located and also, the phase of the electrode 3a is set so as to coincide with the phase of a carrier which is decided by the code of a diffusion signal that should perform the correlation processing at the position of the electrode 3a.