Chromaticity based monitoring methodologies have evolved from polychromatic optical fibre based sensing systems, which was first implemented during the 1980s. The evolution has led to a recognition that such a methodology is applicable to monitoring systems more widely. It is shown that the method may be regarded as the manifestation of a particular form of signal representation by Gabor transforms. Examples of generically different practical implementations of the chromatic methodology to a range of different monitoring situations are given.

A technique for interpreting acoustic signals is presented based upon the use of Gabor type devices. This interpretation technique processes the information acquired from vibration sensors and presents the information as three time-varying parameters which represent the dominant signal frequency, the nominal breadth of the frequency content of the signal and its effective energy content. The technique is an extension of the chromatic analysis used successfully in the optical domain. The information produced by this analysis proves to be more convenient for defining a signal than that yielded by the conventional Fourier transform approach. By way of an example, the Gabor transform based technique is applied to the monitoring of acoustic signals generated by a high-voltage circuit breaker (as used on power transmission networks). Results are presented which indicate that the technique is capable of quantifying trends in complicated time-varying acoustical signals.

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