INITIAL SYNCHRONIZATION LOOP IN SPREAD-SPECTRUM RECEIVER

摘要

a first signal mixer for mixing a reference frequency of a local oscillator and a PN code; a second signal mixer for mixing the shifted reference frequency by 90≰and the PN code; a first analog matching filter for mixing the output signal of the first signal mixer and a received input signal and for integrating the mixed signal; a second analog matching filter for mixing the output signal of the second signal mixer and the received input signal and for integrating the mixed signal; first and second multipliers for obtaining absolute values of the output signals from the first and second matching filters; an adder for adding the output signals from the first and second multipliers; a comparator for comparing the added signal of the adder with an auto-correlation threshold value of the PN code to output the compared result; and a PN code generator for producing the PN code corresponding to the output of the comparator to supply the PN code to the first and second signal mixers.