Research On The Key Techniques Of HF Wideband Signal Monitoring

The short-wave communication plays an important role in the military and civilian fields, and faces many new problems with the development of microelectronics, the improvement of communication technology and the application of the new system. Delves into these problems, this paper studies the problems of signal preprocessing and searching, burst signal detection and frequency-hopping detection and extraction under the condition of wideband signal detection in the real short-wave channel, realizes the related algorithms based on a common signal processing platform, and constructs a short-wave wideband signal detection system. The main contents in this thesis can be summarized as follows:1. The preconditioning techniques and signal search algorithms in the environment of short-wave channel is studied in this paper. With the analysis of short-wave channel characteristic and mathematic morphology theory, the binarization method for short-wave spectrogram is presented. With regards to the practical problem of short-wave signal detection, this paper summarizes the commonly used methods of preconditioning, and investigates a signal searching algorithm based on the morphology preconditioning for the short-wave channel. The experimental result shows the algorithm is effective, which helps to improve the detection rate of weak signals.2. This paper discusses the correlation technique of burst signal detection. It obtains the occupied time rate using the method of morphology skeletonization algorithm and selects its frequency range for the duration characteristic of burst signal. It analyzes the advantage of Goertzel algorithm and achieves rapid detection of burst signal with Power-Law detector. It also improves the conventional double sliding window algorithm and reduces the difficulty in estimating the begin-end time of burst signal. In the end, an effective scheme of burst signal processing is proposed.3. The blind detection and extraction of frequency-hopping signal are analyzed in the paper. It discusses the operational principle and main parameters of frequency-hopping system, summaries the common time-frequency analysis methods and chooses the method for short-wave burst signal blind detection in consideration of the advantage and disadvantage of the methods and the actual needs of the post-processing. It presents a blind detection method using morphology matching algorithm which base on the analysis of frequency-hopping signal spectrogram. Lastly, the simulation performance proves a good recognition and extraction performance of the frequency-hopping signals in the target frequency band, as well as the effective separation of different frequency-hopping signals.4. On the basis of the research achievements, a short-wave wideband signal detection system based on digital receiver is constructed, which realizes the basic function of normal signal searching, burst signal detection and capture, as well as frequency-hopping signal detection and extraction.