Qinetiq Limited

The Secretary of State for Defence in Her Britannic Majesty's Government of the United Kingdom of Great Britain and Northern Ireland

Ira James Clarke

Geoffrey Spence

John G McWhirter

A signal separation method for separation of source signals from a composite signal expresses the composite signal as a series of values of signal amplitude. The source signals have periodicities similar or equal to p. The composite signal is portioned into sections which provide respective rows of a matrix X, in which successive rows represent successive sections. A singular value decomposition of the matrix X is performed to obtain two singular vector matrices U, V and a singular value matrix &#x3bb;. An independent component analysis is performed on one of the singular vector matrices U, V to obtain an independent component matrix UR,RV and an associated component matrix R&#x3bb;V,U&#x3bb;R. One of the component matrices UR,U&#x3bb;Rcontains estimated separated signal modulation envelopes and the other component matrix R2&#x3bb;V, RV contains estimated separated cyclets.

Signal separation

A method for dynamic blind signal separation generates initialisation information by processing an immediately preceding data window. This information is input at () and used at () to initialize orthogonality of data in an immediately following window. Initialised data are decorrelated at () with small update angles using a Jacobi technique. Steps () and () are collectively a second order stage of processing in statistical terms producing orthonormal signals. The orthonormal signals are initialized at () and then undergo separation at () by ICA with small angle updates using statistics higher than second order to produce separated signals. The method may be implemented in an acquisition phase to separate signals and among them identify desired signals, and a subsequent phase in which only the desired signals are separated. It may also be implemented by obtaining first results, and subsequently iteratively updating immediately preceding results using subsequent data snapshots to produce snapshot results for combing with immediately preceding results weighted to produce exponential fading.

Dynamic blind signal separation

A method and an apparatus for distinguishing systematic artifacts from noise involves localizing functional noise in the vicinity of predicted functional peaks. The method is particularly relevant to detection and tracking of time-varying signals. An apparatus implementing such an application of the method comprises a detection system (,) which monitors each component of a multi-component periodic signal via its basis repeat unit: a cyclet, of periodicity &tgr;. The signal is digitized and clocked through the system (,) in segments. A cyclet remover (,) subtracts predicted values of previously detected cyclets from the incoming signal segment to produce a residual signal. A cyclet detector (,) uses a sliding window procedure to detect further cyclets in this residual and to measure their amplitude profiles {overscore (b)}(&tgr;) and periodicities (&tgr;). A cyclet tracker (,) uses this residual to correct errors in the predicted cyclet values ({overscore (b)}(&tgr;), &tgr;) and to predict (track) cyclet values appropriate to the next incoming signal segment. A track remover (,) monitors cyclets variations and removes sub-threshold cyclets from the tracking process.

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Malvern, United Kingdom

Ira James Clarke