The Design Of Synchronous Time Service Unit Of D-SCDMA System

As the Third generation of Mobile Communication Standard (abbreviated to 3G) put forward and IPRs predominantly own by China, TD-SCDMA has become a world wide accepted and approved international wireless communication standard. With the rapid commercialization development of TD-SCDMA system, the demand for the stability, reliability and precision of its synchronous time service unit and cost reduction is higher and higher. And therefore, it is of great significance to design a GPS time service unit which can meet the synchronization demand of TD-SCDMA system in functionality and performance and the market requirement in cost and practicability.The main research contents of this thesis is that by the analysis of theory and application of the TD-SCDMA system time synchronization and by the use of demodulation process of the GPS module, we transform the GPS signal to timing signal 1PPS, TOD information and position information of absolute time and so on, which are provided to the system clock module at base station to achieve system synchronization.The implementation methods are analysis of the theory of GPS time service unit; comtrast and lectotype from the kinds of GPS module in the market; according to the time service unit performance requirement of TD-SCDMA system and the work condition influence to the module, ensuring the product quality and performance by a detailed EMC, ESD and design for reliability; designing test cases and test methods according to actual service condition, and doing relevant experiments; and testing and verifying the time service system functionality and performance by the time service module test software.The GPS time service unit we design uses a mature GPS receiving module to be its platform, which plays an important role in TD-SCDMA system. And therefore, besides considering the achievement of its performance, it is more important to pay close attention to the reliability and stability of the unit and design relevant reliability experiment to test its performance. For the circuit includes radio-frequency circuit, digit circuit and steering circuit, wiring should be separately considered. And considering to the service condition of the unit and its importance in the system, the demand of integrated circuit card EMC, ESD, and design for reliability, which will influence the reception sensitivity of the receiver and the 1PPS signal quality, is rather high.