KEYWORDS: Signal to noise ratio, Estimation theory, Error analysis, Statistical analysis, Interference (communication), Signal processing, Electronic filtering, Monte Carlo methods, Information security, Receivers
A blind parameters estimation algorithm based on forward difference of power spectral density is presented to solve the problems in co-channel multiple signals processing. The proposed algorithm can fast and accurately estimate such parameters as number of signals, center frequency, signal power, noise power and signal to noise ratio of the mixed signals. Both theoretical analysis and simulation results show that the algorithm is effective.
In the paper, an on-line detecting system for ships in lock is presented. The system has three functions: (1) judging whether there are ships in lock in time; (2) detecting whether ships cross the forbidden lines in lock; (3) observing whether there are ships out of lock. First, a Gaussian probability distribution model (probability field) is generated from the gray-level histogram to diminish the affection of shades of buildings and white speckles by bright light. Second a fundamental optical flow method based on spatio-temporal intensity derivatives is used to calculate normal velocity field of image sequences. Third, a probability velocity field is defined and generated by combining the velocity field with probability field. Two calculating methods about probability velocity field are presented, one method is multiplying probability value with magnitude of velocity field, and the other is using probability field to compute the velocity field. Finally, a movement block detection method is designed according to probability velocity field. And the method not only detects the size and position of movement blocks, but also obtains the direction of movement blocks. These methods have been tested and installed successfully in the temporary ship lock of the Three Gorges Project (TGP).
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