Method and apparatus for measuring a waveform

摘要

A system that measures a segment of a waveform by isolating the segment by virtue of gating. A waveform anomaly may be gated. The gated waveform is supplied to a plurality of frequency information extractors, which yield information regarding the frequency content of the gated waveform at individual frequencies. Distortion introduced into the gated waveform may be measured by applying the same gating function to a reference waveform. The system may measure or gate an incoming waveform at time intervals dictated by a clock signal recovered from the incoming waveform. A segment of the waveform to be measured may be circulated through a fiber loop, with a fraction of the circulated signal split off for presentation to a measurement system with each circulation. The point in time at which the waveform crosses a threshold may be determined by straddle sampling.