Tektronix CSA8000B - Manual (Page 287)

Appendix B: Automatic Measurements Reference
CSA8000B & TDS8000B User Manual B- 25
Table B- 4: RZ Measurements - Amplitude (cont.)
Name Definition
RZ RMS Noise One standard deviation of the data distribution sampled within a fixed width vertical slice located
at the center of the Eye Aperture at the High (logical 1) or Low (logical 0) levels.
RMS noise = High σ or RMS noise = Lowσ
The Eye Aperture is adjustable and defaults to 5% of the RZ pulse width. The High or Low
selection for Noise At control in the Measurement Setup dialog instructs the measurement to be
performed on the logical 1 or 0 levels. 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). 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 results with this measurement:
H Perform a Dark Level compensation before taking this measurement if the source of the
measured waveform is an optical channel. 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 Signal-to-Noise Ratio The ratio of the RZ pulse amplitude to the noise on either the High (logical 1) or Low (logical 0)
level. The data within the Eye Aperture is sampled, and the mean of the histogram yields the
High and Low levels. The noise is defined as one standard deviation of the distribution within a
fixed width vertical slice located at the center of the Eye Aperture.
Where High and Low are the logical 1 and 0 levels. See RZ Eye Aperture Parameters
on B--62.
The Eye Aperture is adjustable and defaults to 5% of the RZ pulse width. The High or Low
selection for Noise At control in the Measurement Setup dialog instructs the measurement to be
performed on the logical 1 or 0 levels.
If enabled, measurement gates constrain the measurement region to the area between the Start
Gate (G1) and Stop Gate (G2).
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.
For best results with this measurement, perform a Dark Level compensation before taking this
measurement if the source of the measured waveform is an optical channel. See To Perform
Dark-Level and User Wavelength Gain Compensations on page 3--98.
S ፒN Ratio =
(High
− Low)
High σ
or S ፒN Ratio =
(High
− Low)
Low σ