Tektronix WVR8200, Руководство по обслуживанию

Страница: 58 / 78

General Maintenance
Option EYE/PHY
Troubleshooting
The EYE/PHY functions depend on the EYE and Main boards, and the
interconnections between them.
Major Operational or Diagnostic Failure.
Check that the 110 pin CPCI connector
between the Eye and Main boards is correctly seated and secure.
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
measurements 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
measurement 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
fl oor 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.
4–18 WVR8200 and WVR8300 Waveform Rasterizers Service Manual