Patent ID: 7076380

Claim:
Method for analysing the frequency in real-time of a non-stationary signal, characterised in that said method includes the following operations: A) the signal is sampled at a frequency (fe) at least equal to twice the highest expected frequency and the samples obtained are digitised, B) the sampled and digitised signal is broken up into sub-bands by applying the samples to a bank of digital filters with adjacent pass bands, C) the signal is modelled in each sub-band by an auto-regressive filter, the transfer function of which is 1/A(z), where A(z) is a polynomial of the complex variable z=exp(j2Ï€f/fe) by implementing an adaptive method that is recursive in time and in order, all the polynomials A(z) with a degree between 1 and a maximum value selected in advance are calculated, D) the order of the model is estimated and of all the calculated polynomials the one retained is the one having said order, E) using a recursive algorithm, at least some complex roots of the polynomial selected are calculated, F) from the phase of the roots obtained, the corresponding frequencies are determined, and from the frequencies, the square of the distance separating a current point corresponding to a component at one sampling instant from the points obtained at the previous sampling instant, the previous point which minimises said square is made to correspond to the current point and the different points are connected by minimising a weighted function of said square and the amplitudes are sought for the sinusoidal components that have said frequencies and which minimise the quadratic error between the sum of said components and the signal for analysis, the sinusoidal components are monitored by calculating, in a frequency-amplitude plane.