Research And Implementation Of Receiving Key Technology Based On The Short Burst Low Spectral Density Signal

With rapid progress of communication technology, the requirement of the performance of communication system in anti-interference and anti-interception becomes higher. Especially in military communications, this demand is more urgent. This thesis, firstly, discusses the relative theories of anti-interference and anti-interception. A communication scheme based on short burst, spread spectrum technology and LDPC code is designed, and realizes a communication system which has superior properties of anti-interference and anti-interception.In order to improve the communication system's performance of anti-interception, the sub-band division and sub-band merge modules being embedded. Signal spectrum is divided into a plurality of sub-bands, and thus even after the enemy intercepted the sending signals it is difficult to recover the original signal.The main contents and works are as follows:1. This thesis makes thorough study of the key theoretical knowledge of the system, including matched filtering, synchronization acquisition, spread spectrum and dispread spectrum and LDPC decoding method. In addition, the PMF-FFT method used in the design is derived in detail.2. The communication system and its key modules have been simulated by Matlab. The simulation results show that the algorithm can satisfy the system requirements. An improved synchronization acquisition scheme is presented when discusses synchronization acquisition theory, and simulation analysis of the improved scheme.3. During FPGA implementation, a real-time capture scheme suitable for spread spectrum communication system is presented. This scheme can save chip resources by using time multiplexing technology to synchronization acquisition module.4. The modules of FPGA are designed based on the Matlab program, and the functional simulation has done. Meanwhile, this thesis introduces the design idea and implementing process of each module. Finally, debugging on board is finished via Signal Tap II.5. The united test scheme is analyzed, and then provides the system structure diagram. Finally, debugging on board of the united program is finished via Signal Tap II.