In order to solve the problem of the effect of noise on the unmixing precision and the insufficient utilization of spectral and spatial information in the actual Hyperspectral Unmixing (HU), an improved unmixing algorithm based on spectral distance clustering for group sparse nonnegative matrix factorization was proposed. Firstly, the HYperspectral Signal Identification by Minimum Error (Hysime) algorithm for the large amount of noise existing in the actual hyperspectral image was introduced, and the signal matrix and the noise matrix were estimated by calculating the eigenvalues. Then, a simple clustering algorithm based on spectral distance was proposed and used to merge and cluster the adjacent pixels generated by multiple bands, whose spectral reflectance distances are less than a certain value, to generate the spatial group structure. Finally, sparse non-negative matrix factorization was performed on the basis of the generated group structure. Experimental analysis shows that for both simulated data and actual data, the algorithm produces smaller Root-Mean-Square Error (RMSE) and Spectral Angle Distance (SAD) than traditional algorithms, and can produce better unmixing effect than other advanced algorithms.
A low complexity method was proposed for the blind recognition of BCH codes under error conditions. The existing recognition methods most come from the generic methods of linear block codes, which can't be applied when the code length is long and the bit error rate is high. This method is based on that the BCH codes come from the sub-space of Hamming codes, so the parity check matrix of the hamming codes can be used to check the BCH codes. The method contains recovering the code length, synchronization and generator polynomial. The simulations show that the algorithm runs successfully for a BCH code with length 1023, when the bit error rate is 0.5%.