1. Electrostatic diagnostic apparatus for distinctly correlating different events occurring in an operating gas turbine engine, comprising: elecgrostatic signal means, including a probe to be disposed in the gas stream of an engine, for providing, when said probe is disposed in the gas stream of an operating engine, a probe signal having a waveshape defined by amplitude variations thereof across a time interval of a given duration in response to electrostatic charge flowing in the gas stream in the vicinity of said probe; an analog to digital converter connected for response to said electrostatic signal means; and signal processing means connected to said analog to digital converter (a) for causing said analog to digital converter to sample the probe signal provided by said electrostatic signal means in a manner to provide a record of digital signals indicative of the amplitude variations of said probe signal defining the waveshape thereof, (b) for storing, in response to the amplitude of one of said digital signals being in excess of a threshold magnitude, a record comprising a contiguous sequence of said digital signals sufficient to define the waveshape of said probe signal, repetiively, to provide a first classification group consisting of a given number, M, of records, and (c) for selectively providing for each of said records, a particular engine event identifying signal selected, in response to variations in amplitude of the digital signals in said record, from among a plurality of identifying signals in dependence upon the waveshape of signals represented by each of said records having characteristics correlated to an engine event corresponding to said particular identifying signal.