Tektronix CSA8000B - Manual (Page 290)

Appendix B: Automatic Measurements Reference
B- 28 CSA8000B & TDS8000B User Manual
Table B- 4: RZ Measurements - Amplitude (cont.)
Name Definition
RZ Suppression Ratio
(dB) The ratio of the average power level of the logic High to the Suppressed level measured
between two consecutive RZ pulses, with the result expressed in decibels. The RZ pulse is
sampled within the Eye Aperture where the High is determined as the mean of the histogram of
the data distribution in the upper half of the pulse. The same region is sampled to record the
data distribution in the lower half of the pulse, data corresponding to the logical level 0.
Similarly, data is sampled in an equivalent sized region placed at one-half bit interval offset from
the Eye Aperture. The mean of the histogram of the data distribution between the peaks
adjusted by subtracting the zero level histogram yields the Suppressed level.
Where:
H High and Low are the logical 1 and 0 levels
H Suppress is the mean of the histogram of the data within an Eye Aperture in the
suppressed region
The Eye Aperture is adjustable and defaults to 5% of the RZ pulse width. See RZ Eye Aperture
Parameters on B--62.
If enabled, measurement gates constrain the measurement region to the area between the Start
Gate (G1) and Stop Gate (G2). The region used for sampling the suppressed region is equal to
the Eye Aperture and has no independent control. See To Localize a Measurement on
page 3--83.
This measurement requires the use of a waveform database. When this measurement is turned
on, it will automatically set the measurement system to use a waveform database if available.
See Use a Waveform Database on page B--70.
For best measurement results:
H Perform a Dark Level compensation before taking this measurement. See To Perform
Dark-Level and User Wavelength Gain Compensations on page 3--98.
H Optimize the vertical resolution before taking this measurement. See How to Optimize the
Vertical Resolution on page B--70.
RZ Suppression Ratio [dB]
= 10 × log
Ꮛ
High
(Suppress
− Low)
Ꮠ