Iterative time-frequency domain transform method for filtering time- varying, nonstationary wide band signals in noise

摘要

An iterative time frequency algorithm filters noisy wide band/nonstationary signals by projecting the noisy signal into the TF domain, masking the TF response, computing the inverse TF transform to extract a filtered signal, and repeating these steps until the projection lies within the mask. As a result, the TF domain properties of the extracted signal are substantially equal to the desired TF domain properties. Furthermore, the iterative approach is computationally simple because it avoids inverting matrices. The TF transform and its inverse must be selected such that the iterative algorithm is guaranteed to converge. Candidate transform pairs can be tested on known data, and if the TF transforms converge to the desired TF properties, the candidate pair can be selected. Alternately, the candidate pairs can be tested against a sufficient convergence condition, and if they satisfy the condition within an acceptable tolerance, they can be selected with confidence. Furthermore, the sufficient convergence condition can be solved directly to provide the TF transform and its inverse.