Abstract: A system for and method of pre-filtering data to create and/or maintain data in a working memory such that the data can be more efficiently used by an expert system. In one example, event triggers are used to enable efficient management of faults that occur in an expert system, such as faults that occur in connection with the interaction between a central system and a number of remote systems controlled by the central system. The event triggers filter data that is potentially relevant to the operation of the expert system, each event trigger comprising a match portion and an action portion. A processor compares the match portion of at least one of the event triggers to the potentially relevant data, and executes the action portion of any event trigger whose match portion matches the potentially relevant data, the execution comprising modifying the working memory. The evaluation of and execution of the event triggers occurs independently of other event triggers.

Abstract: A facility is provided for measuring the signal-to-noise ratio of a transmission channel using the results obtained by transmitting over the channel a pseudorandom noise signal, in which the value of the signal-to-noise ratio may be used to determine whether the channel contains various types of pulse code modulation equipment.

Abstract: A digital signal processor is provided with the facility to range and converge on each of a plurality of echoes occurring at respective locations along a communications line. Specifically, the digital signal processor is arranged to adaptively process samples of a signal that has been transmitted to the communications line correlated with samples of a signal that have been received from the communications line. In the processing of the samples, the digital signal processor separates and measures the magnitude of each echo that it converges on, beginning with a so-called near-end echo. In addition, the digital signal processor calculates the propagation delay of each echo that it converges on using the number of sampling intervals that have been processed in order to position the processor on the dispersion of that echo.