Abstract: A method of characterising tremor stability in a subject is described for a subject having an involuntary tremor symptomatic of a neurological disorder. The method comprising: identifying a series of tremor cycles from measured tremor data of the subject, said tremor cycles measuring periodic variation in movement of the subject due to the tremor; determining an instantaneous frequency for each tremor cycle and collating the instantaneous frequencies; determining an instantaneous variation between the instantaneous frequencies of each pair of adjacent tremor cycles within the series; comparing the instantaneous variation to the collation of determined instantaneous frequencies to determine a distribution of instantaneous variations; and determining an index value of the distribution of the instantaneous variations, said index value defining the stability of the tremor.

Abstract: A method and apparatus for estimating the frequency of a dominant periodic component in an input signal by modelling the input signal using auto-regressive models of several different orders to generate candidate frequencies for the periodic component, generating synthetic sinusoidal signals of each of the candidate frequencies, and calculating the cross-correlation of the synthetic signals with the original signal. The frequency of whichever of the synthetic signals has the highest cross-correlation with the original signal is taken as the estimate of the frequency for the dominant periodic component of the input signal. The method may be applied to any noisy signal which has a suspected periodic component, for example physiological signals such as photoplethysmogram signals, and in the estimation of heart rate and breathing rate from such physiological signals.

Abstract: A method of characterising tremor stability in a subject is described for a subject having an involuntary tremor symptomatic of a neurological disorder. The method comprising: identifying a series of tremor cycles from measured tremor data of the subject, said tremor cycles measuring periodic variation in movement of the subject due to the tremor; determining an instantaneous frequency for each tremor cycle and collating the instantaneous frequencies; determining an instantaneous variation between the instantaneous frequencies of each pair of adjacent tremor cycles within the series; comparing the instantaneous variation to the collation of determined instantaneous frequencies to determine a distribution of instantaneous variations; and determining an index value of the distribution of the instantaneous variations, said index value defining the stability of the tremor.

Abstract: A method and apparatus for estimating the frequency of a dominant periodic component in an input signal by modelling the input signal using auto-regressive models of several different orders to generate candidate frequencies for the periodic component, generating synthetic sinusoidal signals of each of the candidate frequencies, and calculating the cross-correlation of the synthetic signals with the original signal. The frequency of whichever of the synthetic signals has the highest cross-correlation with the original signal is taken as the estimate of the frequency for the dominant periodic component of the input signal. The method may be applied to any noisy signal which has a suspected periodic component, for example physiological signals such as photoplethysmogram signals, and in the estimation of heart rate and breathing rate from such physiological signals.