# Advanced Eye DI (δ-δ)

The Advanced Eye *Deterministic Interference* (DI) is a measure of the amount of vertical interference on a signal that is due to deterministic causes. The corresponding jitter measurement is Deterministic Jitter (DJ). The DI 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. Deterministic Interference is displayed in the current vertical channel units or **Unit Amplitude**. Make these selections in the Amplitude Measurements tab of the Configure Jitter Measurements dialog.

DI is measured using the following steps:

- The instrument measures Random Noise (RN), Periodic Interference (PI), and Inter-Symbol Interference (ISI).
- The ISI histogram for the one level is convolved with the histogram of the one level RN and PI data, and the same is done for the zero level data. These histograms are referred to as the Total Interference (TI) histograms.
- Using the measured value of RN, a dual-dirac model is fit to the TI histogram. The model is fit at a probability of 10E-3 divided by the pattern length.

## 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

`:MEASure:EYE:DI`