Tektronix WFM6100 Opt. MB, Service Manual

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General Maintenance
WFM6100, WFM7000, and WFM7100 With Option FP Service Manual
4- 21
Eye Pattern or Jitter Waveform Display Problems. Jitter waveform display is only
available with Option PHY. The Eye Pattern and Jitter Waveform displays are
formed from data sampled from the input signal and the recovered clock sine
wave. Eye display bandwidth, rise and fall time, and transient response
aberrations are controlled by circuits contained on the Eye board.
Cable Loss, Approx Cable, and Source Level Readout Problems.
These measure-
ments are made by a “cable meter” circuit. This circuit is located on the EYE
board, but is largely independent from the Eye and Jitter display and measure-
ment functions. If other EYE/PHY functions operate correctly, then a “cable
meter” circuit problem is indicated. Replace the EYE/PHY board.
Jitter Readout and Jitter Meter Problems.
These measurements are derived from
sampled recovered clock sine wave data. Operation is unlikely to fail if the basic
Eye pattern display works correctly. Measurement accuracy is not adjustable, but
jitter noise floor depends on adjustment of Eye HD CDR calibration items.
Eye Amplitude, Eye Risetime, Eye Falltime, and Eye Rise- Fall (difference) Readout
Problems.
These readouts are only available with Option PHY. These readouts
are derived from the Eye pattern display. Measurement accuracy depends on the
Eye Gain calibration items, and on front--end bandwidth and transient response,
which are not adjustable. Operation is unlikely to fail if the basic Eye pattern
display works correctly.
It is normal for these measurements to stop or become intermittent if there is
excessive waveform noise, aberrations, jitter, or cable loss.