Study And Implement Of The Related Algorithm In The Radio Monitoring And Direction Finding

The rapid development of the software radio techniques drives to the transformation of the radio monitoring technology. Currently the monitoring systems based on the software radio architecture are moving towards digital, network-oriented direction. However, with the rapid development of communication technology, the wireless environment became increasingly complicated. For instance, the coexistence of a variety of different modulation schemes and signals intensity distribution within a fixed bandwidth and so on, which poses enormous challenges to the diversity of modulation recognition、the accuracy and real-time performance of the direction finding algorithms in the existing monitoring systems.This thesis is based on the background of the electromagnetic environment monitoring, the main contents include the recognition of the single-carrier signals and multi-carrier signals and the recognition of the QAM signals in the task of signals monitoring,and the relevant interference finding algorithm of signals finding:1. For the recognition problem of the single-carrier signals and multi-carrier signals, the thesis applies Kurtosis coefficient of the power spectrum of the signals after bandwidth normalization and power normalization. And the result of the simulation proves that the characteristic parameters has good robustness in various conditions and the correct identification rate under SNR=0dB is more than 95%.2. For the problem that the presence of timing error and frequency offset will cause the decline in the recognition performance of the QAM signal, the thesis proposes a recognition scheme to improve recognition performance: Firstly, before recognition, the O&M timing synchronization and differential processing are applied to the received QAM signal. Simulation result shows the proposed scheme is robust to timing error and frequency offset, when SNR ?12d B, the successful classification rate reach 98%.3. Focus on the problems of the accuracy and the poor real-time performance of the traditional correlation interference direction-finding algorithms, the thesis suggest that apply the interpolation algorithm to measurement angle to improve the accuracy of the algorithm. Additionally the thesis also present the improvement structure of the traditional correlation direction-finding : Introduce the spatial angle and use one-dimensional information instead of the two-dimensional spatial information. Only as for the amount of computation, the improved algorithm reduces 73% and improves the real-time performance.4. At last, the thesis described the operating mode、the sample database and the design of the program of dual-channel the correlation interference direction-finding in detailed based on the hardware platform of FPGA + DSP. Finally analysis the speed and the accuracy of the single-frequency signal direction-finding processing, and the results show that both of them meet direction indicator.