VHF/UHF Hybrid Modulation Signal Detection And Parameter Estimation

The hybrid modulation signal of VHF/UHF channel is used in many fields. It is also a kind of importent signal for electromagnetic spectrum monitoring. The paper mainly researchs automatic recognition and parameter estimation of hybrid modulation signal, signal reconnaissance and detection in VHF/UHF channel. The studied relevant algorithm has also been realized on a general signal processing platform. The main work can be summarized as follows:1. With obscure definition of hybrid modulation signal in reality, the paper sums up three kinds of hybrid modulation signals, disscusses their characteristics of the spectrum and compares their difference of hybrid type.2. For the recognition of hybrid modulation and non-hybrid modulation signal, the paper studies the spectrum difference of instantaneous frequence and amplitude. One new characteristic which shows the number of subcarrier signal is proposed to acheive the classification of hybrid modulation and non-hybrid modulation signal. For the classification of hybrid AM and hybrid FM, the paper discusses the unitary variance of instantaneous amplitude of signals. For the recognition between the hybrid modulation signals, the paper improves the algorithm of nonlinear transformed spetctrum feature and statistic histogram. The improved algorithm extracts the subcarrier signal feature and realizes the classification of hybrid modulation signal. Finally, a classification scheme is designed to fit for the task which is given using the classical decision tree structure, and it gets an optimal classifying result.3. A carrier estimation algorithm of non-hybrid modulation signal is improved for practical hybrid signal, by suming up the algorithm of nonlinear transformed spetctrum feature for estimation of subcarrier frequence. For the symbol rate estimation for hybrid modulation signal, two methods are proposed in the paper; one method is based on Hilbert-nonlinear transform, the other is based on Hilbert-wavalet transform. The result shows the performance of method based on Hilbert-wavalet transform is better efficient4. The paper studies the normal method of signal reconnaissance. With the problem of level seting from channel color noise in signal reconnaissance, a new signal reconnaissance method based on channel color noise suppressing is proposed in the paper. The algorithm improves the pragmatic performance of signal reconnaissance in VHF/UHF channel.5. .A system for monitoring hybrid modulation signal is implemented, and its functions are introduced in the last chapter. The experiment shows the system is pragmatic and efficient.