The Study And Realization Of Spread Spectrum Digital Microwave Communication System For Multi-route E1

In the wired communication network, we can use the wireless technology to expand the network to some remote location and in the occasion for temporary use. Even in the mobile communication field, we can use the wireless relay system to replace the wired transmission network. Spread spectrum technology has been a very important communication method in the physical layer of wireless communication.In order to realize the telecom access in some remote location of the village, the Information Industry Ministry started up the "Village Telecom Access Project" in 2004, the spread spectrum digital microwave technology can play an important role in the project. In the remote area of poor communication establishment while lacks of fund, the usage of spread spectrum digital microwave equipment is an ideal solution to exchange data signal such as El, which has the advantage of low cost, great mobility and flexibility. Under this background, we have had this research in the spread spectrum digital microwave communication system for multi-route El.The system adopts the Direct Sequence Spread Spectrum (DSSS) and Complementary Code Keying (CCK) modulation technology, works on Frequency Division Dual (FDD) mode and uses the 2.4~2.7835GHz ISM frequency. It can relay the 5×E1 multiplexed signal. The paper designs and implements the baseband processing module, the spread spectrum processing module, the IF modulation and demodulation, AGC, synchronization, equalization, etc. The system uses the FPGA and Verilog Hardware Description Language to process the baseband data signal, included transforming the speed between the baseband data stream and the spread spectrum data stream, recovering the clock of the baseband data stream, 5 XE1 multiplex, etc. The study has realized the hardware, programmed the software and done the debugging. We use the QSZ24 2Mbit/s digital transmit integrate test instrument to test the BER, in the laboratory condition, the BER is equal to zero after a long time testing. The result shows that the system works in a good state and the design scheme is correct and feasible.The system supplies a good choice for the relay of data signal in the circumstance of inconveniently wire lay down, the temporary use, and some special occasion. It can also be used in the "Village Telecom Access Project". So it has a good value for engineering design and a great social significance.