Advanced Eye RN (rms)

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The Advanced Eye RN (rms) is noise that is uncorrelated to the pattern and follows Gaussian statistics. The corresponding jitter measurement is Random Jitter (RJ). Random noise is displayed in the current vertical channel units or Unit Amplitude as selected in the Amplitude Measurements tab of the Configure Jitter Measurements dialog. The RN measurement result is reported for both One and Zero levels. You can select the one/zero level definitions to be based on an average level or on minimum Consecutive Identical Digits (CID). Measurements based on CID minimize the effects of ISI on the levels.

RN is measured using the following steps:

  1. A particular symbol is chosen from the pattern. Each time the measurement is made, a different symbol is chosen.
  2. The instrument acquires 4096 samples at the measurement location, which is normally the center of the symbol. These samples are acquired precisely periodic in time at a rate close to the maximum instrument sample rate of 40 kHz.
  3. The power spectral density of the resulting waveform is obtained. Because the signal is under-sampled, all periodic components are aliased down below 20 kHz.
  4. The RN is calculated as the area of the power spectral density excluding any peaks in the spectrum (for example, the baseline noise of the power spectral density).
  5. The above steps are repeated, and the power spectra from acquisition to acquisition are averaged together. The data from the one levels and zero levels are not combined.

More Information

Advanced eye leverages the DCA-X's ability to measure ultra-low levels of Random Jitter (RJ). This can be used to obtain fixed RJ values.

SCPI Command