“…To further improve the accuracy of the estimator, Turajlic [31] and Khmag [32] use the SVD domain to obtain the initial estimate and build a quadratic adjustment based on the original estimate. To improve the adaptability of the algorithm, Prasetyo uses particle swarm optimization [33] and symbiotic search techniques [34] respectively to optimize the scaling factor between the mean value of tail singular values and the noise STD. Liu [35] proposes a robust estimation algorithm for multilevel analysis of noise STDs in small regions.…”