Detector circuits
AssigneeData Recording Instrument Company Limited
InventorKeith Francis Walker
Life of this patent
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Abstract
A waveform-level detector circuit is described for use in conjunction with waveforms showing positive and negative excursions about a neutral axis, the waveform trace crossing the axis between positive and negative peaks. Ideally, each axis crossing has significance, but the presence of noise produces spurious crossings and the circuit is arranged to accept as significant only an axis crossing which occurs in a single transition of the waveform trace between reference levels on either side of the axis. However, in detecting such a crossing, its actual timing is not accurately registered, so the apparatus also produces a timing response accurately related to all crossings, significant or not, and then combines this response with accepted crossing signals to derive a final output.
Claims5
A waveform-level detector useable in conjunction with an applied waveform having positive and negative excursions relative to a neutral axis to produce an output indicative of significant excursions of the applied waveform across the axis, and a zone lying between a pair of reference levels one on each side of the axis, the detector including;
- means responsive to changes in polarity of the waveform to produce a stylised waveform output first signals for all the axis crossings;
- first pulse forming means responsive to the stylised output to produce a first pulse train output in which each axis crossing of the applied waveform is represented by a different pulse, the relative timings of the pulses in the first train corresponding to the relative timings of the axis crossings;
- means for delaying the first pulse train to enable the pulses each to occur a predetermined time interval after that axis crossing to which it corresponds;
- means for deriving second signals from the applied waveform in respect of each transition of the applied waveform across each zone laying between the pair of reference levels;
- and
- means for combining the delayed final pulse train and the second signals thereby to produce delayed signal outputs only in respect of significant axis crossings.
Dependencies are inferred from the claim text.