IMPROVED CLUTTER ELIMINATION

摘要

Signal processing apparatus and methods for elimination of undesirable clutter signals from desirable signals. This is performed without the use of filters by subtracting orthonormal basis functions from signal samples until the appropriate degree of clutter removal is achieved. Estimates of frequency information such as Doppler shifts due to fluid flow may thus be achieved with superior discrimination of true flow signals from sources of clutter or artifact, greater sensitivity to low flow rates, minimal computational effort and with fewer samples than the prior art. Apparatus and methods for clutter elimination from signals are also provided for iteratively subtracting from each of the samples of the signals, and the difference is stored in an i difference signal until i + 1 difference signal is less than a threshold. In various embodiments, the threshold may be an absolute noise floor (R) preset by a manufacturer or a user. In other embodiments, the threshold may be based upon an absolute or relative predictor error of the signal once the basis function (filter) has been removed. The i difference signal may then be used for performing a frequency estimate of the signal.