| 摘要 |
PURPOSE: A synchronous obtaining device in a communication system is provided to quickly obtain a reliable synchronization by not performing a multiplying calculation and integral calculation about PN code phase, widely searches a phase interval in an integrator having a short integral period, and then precisely searches a phase interval in an integrator having a long integral period. CONSTITUTION: A received PN code signal is multiplied by a reference phase PN code, is multiplied by 1/2 chip-delayed rate PN code centering around the PN code, and is multiplied by 1/2 chip rapid early PN code. The signal wherein the PN code signal and the rate/early PN code are multiplied is integral-calculated during a predetermined short time, thereby calculating a rate correlation value and early correlation value. If the rate correlation value is higher than the early correlation value, a clock of PN code generator(20) is generated by 1/4 chip until the rate correlation value is smaller than the early correlation value. If the rate correlation value is smaller than the early correlation value, the clock of PN code generator(20) returns to a previous clock, thereby activating a comparator. The comparator(24) compares a calculated correlation value with a threshold value. If the correlation value is smaller than the threshold value, the clock of PN code generator is delayed by 1/8 chip until the correlation value is higher than the threshold value. If the correlation value is higher than the threshold value, PN code phase having the correlation value at that time, thereby adjusting a synchronization of the PN code. Thereby, a rapid synchronization detection time is made, and a reliable synchronization is obtained. |
