The Large Step Fast Acquisition Of The PN Code And The Integration And Digitalization Of The Key Parts

Spread spectrum communication is one of the most popular topics in the communication field. With the increasing requirement for personal communication and the increasing complexity of channel condition, the advantages of spread spectrum communication in secrecy and resisting noise has been more and more important. In the spread spectrum communication system, the synchronization of receiver's Persedo-Noise (PN) code to the transmitter's PN code is such an important part that the whole system can't work at all without it. But the traditional method to capture the PN code are either too slow or too complicated to satisfy the need of today's communication system.This article works over a mathod named Large Step Fast Acquisition to capture the PN code in the receiver, which was originally put forward for the acquisition and synchronization of long PN code under the condition of low signal to noise ratio(S/N). The principle of Large Step Fast Acquisition and the circuit design of Large Step Fast Acquisition Delay Lock Loop (LSDLL) are disgussed as the emphasis. When analyzing the principle and performance of the LSDLL, circular flowgraph is used. The expression for "penalty" time and mean and variance of the acquisition time is derived from the circular flowgraph of Large Step Acquisition method. And the output components of the despread correlator under the condition of additive white gaussian noise (AWGN) are analyzed to derive the expressions for the false alarm probability and the detection probability. When discussing the digitalization and integration of the LSDLL circuit, the CPLD developing software MAXPLUSâ…¡ of ALTERA is used to program the logic circuit and simulate it's function. And the MAX7000 device of ALTERA is used to realize the logic circuit.