METHOD AND APPARATUS FOR PN CODE ACQUISITION SCHEME USING MATCHED FILTERS IN CDMA SYSTEM

摘要

PURPOSE: A method for initially synchronizing in CDMA(Code Division Multiple Access) receiving system using a matching filter and arrangement thereof are provided to solve a problem related to time and prevent a hardware to be complicated by constructing an adder in tree type and allow I and Q elements in one correlator to be shared. CONSTITUTION: A DATA ARM divides an input analog signal, and stores IAO, QAO in m-chip interval in each tap. A PN(Pseudo Noise) sequence generator and sequence SIPO(Serial Input Parallel Output) register stores PN code corresponding to 256-chip interval in PN sequence generated from the PN sequence generator in SIPO. A correlator computes correlations of I ARM and Q ARM in the DATA ARM. An adder tree adds 256 correlations. An energy calculation block calculates the first energy form a sum of correlations of 256 taps and calculates the second energy n verification mode. A search controller is comprised of a state machine, an index counter, and the second window counter. A lock interrupt mask/clear block allow CPU to clear a lock interrupt generated in the second window. A clock generator generates chipx2 clock and chipx1 clock form chipx4 clock. A threshold comparator determines whether the energy calculated by the energy calculation block exceeds a certain energy level, and whether synchronization is suitable.