Research On Detection And Recognition Of Modulation Signals Under Complex Noise Background

Although with the development over several decades,the short-wave communication which is a kind of modern communication technology keeps holding full of vigor and vitality with the superiority of its mobile flexibility, the device simplicity and remote communication. However, the short-wave communication has the character of massive bad noises and many signal types, which seriously affected the staff's normal work. According to these above characters of short-wave communication, the algorithms of digital modulation signal detection and signal type recognition in short-wave communication are studied in the paper, which will improve staff's working conditions and enhance their working efficiency.In the detection of digital modulation signals, first of all, the algorithm based on the short-time standard deviation is introduced, which analyses the character of signal in the time field. Secondly, the detecting algorithm based on Fourier coefficients standard deviation and the detecting algorithm basing on AWGN parameters are introduced. Finally, all of the above algorithms are integrated. Compared to the earlier algorithms, the recent approaches have better perforrmance, and the error detection, failure detection have been better resolved in the low SNR and complex background.Based on digital modulation signal detection, the modulation signal recognition algorithm is introduced here which is different from the traditional algorithm. Because of the good result of the first detection stage, our algorithm can be researched only according to the different characteristic among digital modulation signals. The algorithm based on the twice Fourier Transformation and the algorithm based on the division are introduced and integrated. This recognition algorithm is simple and valid, which can be applied to Link11 signal, 39-Road signal, Eight Frequency Quantization, Twelve Qhases, and so on.The experimental results show that more satisfied outcome of recognition can be achieved in the complex situation of modulation signal types. Finally, the design of system software is introduced. In order to meet needs of different signal process, modulation signals processing system is divided into file module and real-time module, and the processed signals is stored well. Noise and modulation signals are stored separately as noise file and signal file. At the same time, the original signal data is backuped.