# :MEASure:JITTer:NOISe:PI?

Noise PI (δ-δ) Commands

- :MEASure:JITTer:NOISe:PI?
- :MEASure:JITTer:NOISe:PI:LEVel
- :MEASure:JITTer:NOISe:PI:STATus?
- :MEASure:JITTer:NOISe:PI:STATus:DETails?
- :MEASure:JITTer:NOISe:PI:STATus:REASon?

## Query Syntax

    :MEASure:JITTerN:NOISe:PI?

Where N identifies one of four possible jitter/noise analyses {1:4}. For example, `JITTer4`.

## Description

Returns the Periodic Interference (PI), which is a measure of the interference that is uncorrelated to the pattern, yet is periodic. Interference caused by a switching power supply is an example of periodic interference. The value is returned for the level specified by `:MEASure:JITTer:NOISe:PI:LEVel`.

Dual-Dirac PI (δ-δ) is useful when the distribution is unknown. The dual-Dirac number allows various PI measurements to be compared with one another, even when the distributions are dissimilar. It is a measure of how much the PI affects the low-probability statistics of the interference.