Importance

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Abstract

An oscilloscope automatically measures an interval between first and second triggering events in a repetitive input signal. The oscilloscope includes A and B sweep circuits for generating event triggered 'A' and 'B' sweep ramps, respectively. The oscilloscope also includes two comparators. One comparator generates an 'A' indicating signal when the A sweep ramp reaches the level of a first adjustable reference signal. The other comparator generates a 'B' indicating signal when the B sweep ramp reaches the level of a second adjustable reference signal. The oscilloscope initially sets both sweep circuits to repetitively trigger on the first event and sets the first reference signal to a constant level. While monitoring relative timing of the A and B indicating signals, the oscilloscope iteratively adjusts the second reference signal to a 'first pass' level for which the A and B indicating signals are repetitively generated at substantially similar times. Thereafter, the B sweep ramp is set to repetitively trigger on the second triggering event while the A sweep ramp continues to repetitively trigger on the first triggering event. The oscilloscope then iteratively adjusts the second reference signal to a 'second pass' level at which the A and B indicating signals are again generated at substantially similar times. The difference between the first and second pass levels is proportional to, and therefore a measure of, the interval between the first and second trigger events.

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First Claim