Signal Interception And Classification In The Complex Electromagnetic Background

The basic tasks of Radio monitoring are to intercept, analyze, classify, demodulate the wireless signal. The signal interception and classification are one of great importance part. With the development of wireless technology, electromagnetic background is more complex, the signal interception and classification are more difficult .In this paper, we mainly focus on the real ultrashortwave and microwave channel, study the interception and classification in the complex electromagnetic background; realize the system to fit into the channel.Based on the work of others, the paper makes some improvement on the flow of signal search and interception in the complex electromagnetic background. By the analysis of spectrum feature of signals, the parameters estimation and modulation recognition of the communication signals are investigated. The main works can be summarized as follows:1. Based on the survey of the practical setting, the paper studies the characteristic of the complex electromagnetic background, sums up the flow of signal search and interception. The signal search algorithm in the complex electromagnetic background is brought forward.2. The intercepted signal characters are investigated. P character is put forward. These characters are used to the parameters estimation and modulation recognition of the signals. The paper studies these characters and gives the ways to get them .3. The recognition of parameters estimation of the intercepted signal is studied. The paper proposes a new method based on Chirp-Z transform and centroid of the frequency spectrum to estimate the symbol rate and carrier frequency accurately.4. A new recognition scheme is brought out, which can recognize many signals without any prior knowledge, including FM,2FSK,4FSK,8FSK,BPSK,QPSK,8PSK,OQPSK,MSK,16QAM and 64QAM.5. The realization of system is discussed. We test the function of system about signals interception and classification.