Teledyne-lecroy AORM - Advanced Optical Recording Measurements Manual de usuario descargar pdf (Pagina 33)

AORM Software Package

923133 Rev A ISSUED: June 2013 31

Pit or Space Identification

This is determined uniquely by the threshold, hysteresis, and edge polarity of threshold crossings.

A positive threshold crossing indicates the start of a positive polarity pit and the end of a negative

polarity space. A positive threshold crossing followed by a negative threshold crossing fully

delineates a pit. A negative crossing followed by a positive crossing fully delineates a space, as

illustrated in the following figure.

In order to prevent false pit and space identifications, hysteresis is provided. Hysteresis adds an

additional condition that must be met before a threshold crossing is recognized as a pit/space

edge. It requires that the waveform make an excursion of a certain distance from the threshold

before the next threshold crossing is recognized.

The next figure shows a threshold crossing that would result in incorrect pit identification without

hysteresis.

Voltage

Threshold

Space

Pit

False

Pit

Level

Threshold

1 2 ... 28 29 30 31 32 33 34 35 36 37 38 ... 124 125

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Teledyne-lecroy AORM - Advanced Optical Recording Measurements Manual de usuario Pagina 33