The Research Of Spread Spectrum Code Rapid Acquistion

Compared with other regular communication systems, Spread Spectrum(SS) technology has the advantages of low probability to intercepting, a high immunity to interference ,hiding the useful information and multiple-access communication ability,At present, this system not only extensive application used in military communication, also used in civil communication.At present, more and more attentions are paid to Spread Spectrum (SS) communication because of its numerous features. However, technical problems of Spread Spectrum (SS) communication have much more complicated than those of common communication, which leads to some obstacles to the development of Spread Spectrum (SS) communication. For example, acquisition and synchronization of expand frequently code is communication-specific. Only if the codes of receiver parts are identical with the transmitter part, information modulated by codes could be de-spread or demodulated right. Keep the send part and receiver parts Synchronism is an important and challenging technique in SS communication, This is the starting point that this paper is studied too, Generally speaking, It expand frequently divide yard in step for ,which can be achieved by two steps: acquisition and tracking. What this text studied is acquisition step。This paper investigates functions of SS communication and generation and correlation of pseudo code. Comparative study of conducted among Single integral sliding acquisition method and Multiple integral sliding catch France acquisition method and matched filter acquisition method, and N integrators slipping acquisition system, Analysis and comparison of a single integral sliding acquisition method was found to capture a longer time, Multiple integral sliding hardware circuitry needed to capture the more complex method, Digital matched filter capture method used by the hardware circuitry more complex and generally suitable for short-spread-spectrum code acquisition, in order to reduce the spread-spectrum code acquisition time, this method of sliding catch a certain amount of improvement, sliding mode from one-way sliding improved to bi-directional sliding, a new acquisition technique, bidirectional-slipping-acquisition-method is put forward in this paper. This paper analyses bidirectional-slipping-acquisition-method from Acquisition time, false alarm probability, and detection probability are the key technical indicators that measure acquisition performance of pseudo code, which are analyzed and calculated in this paper. By analyzing the results of that, after a two-way sliding catch improved method can effectively shorten the average capture time, capture time is about half of the before。...