Research And Verification Of Narrowband Interference Suppression Key Technology In Portable Wireless Communication Device

Modern information war is the competition of electronic antagonism technology, and it is particularly important to develop a dedicated communication system that can suppress specific interference. By virtue of the strong anti-jamming ability and resistance to multipath fading, Direct Sequence Spread Spectrum(for short, DSSS) technology has been widely applied in military communication. But when the power of narrowband interference exceed interference margin, communication performance will deteriorate rapidly, even get malfunction. Therefore, in order to improve the reliability and validity of war communication, it is necessary to apply anti-jamming processing in DSSS system.For this reason, based on the anti-jamming research in DSSS system, an improved Code-Aided for Narrowband Interference(for short, NBI) and frequency hopping interference is designed. The NBI suppression algorithm on the FPGA hardware platform is realized, the function and performance of the algorithm are analyzed and test. In this paper, the main research work and results are as follows:Firstly, based on DSSS system, the Code-Aided technology and the Frequency Domain Notch technology is analyzed, Code-Aided technology is improved by autocorrelation matrix aid and delay branching, besides, the suppression performance of two technology for NBI and frequency hopping interference is simulated. Simulation results are as follows: Under the condition of signal to noise ratio is 10 dB and bit error rate is less than 10-5, Code-Aided technology can refrain digital modulation interference whose bandwidth is 5kHz and interference to signal ratio is 22 dB, while Frequency Domain Notch technology can refrain digital modulation interference whose bandwidth is 1kHz and interference to signal ratio is 9dB, the performance of Code-Aided technology is superior to Frequency Domain Notch technology; For frequency hopping interference whose bandwidth is 2MHz and rate is 250 hops/s, the interference to signal ratio that Code-Aided technology can suffer is 11 dB at most.Secondly, an implementation scheme of Code-Aided interference suppression technology is designed in detail. The software architecture is designed based on the portable wireless communication link. The process of key modules including automatic gain control and time synchronization is analyzed, and the scheme’s resource consumption is presented.Finally, the function and performance of NBI suppression technology are measured on the portable wireless communication device. The results show that the software can realize the function of input power control. Besides, under the condition of signal to noise ratio is 10 dB and bit error rate is less than 10-5, the performance loss of Code-aided technology is 9dB for single tone jamming and 6dB for digital modulation interference, and the performance loss is about 1.7dB for frequency hopping interference. Therefore, it can’t meet the performance requirements.In this thesis, NBI suppression technology have been applied successfully in the portable wireless communication link, which can improve communication quality to some extent. The technology is practical and portability, which provides a reference on the theoretical and application for future research.