Teledyne-lecroy AORM - Advanced Optical Recording Measurements Uživatelský manuál stáhnout pdf (Strana 54)

52 ISSUED: June 2013 923133 Rev A

EDGSH EDGE SHIFT

Description

Edge Shift provides a measurement of the difference between the width of pits, spaces, or both,

and their ideal widths. These ideal widths are integer multiples of the clock period ‘T’. The width

of the pit or space is determined by the time between crossings of the selected voltage threshold

(see pwid).

When a single n is specified for the Edge Shift custom parameter, for each pit-width value calculated,

the Edge Shift is calculated as:

()

Tnwedgsh

iii

⋅−= when absolute time units are specified

()

Tnwedgsh

iii

%0.100

⋅⋅−=

when percent is specified,

ere n

is the n that makes the width closest to nT (i.e., n is the n category to which the width belongs).

Thus:

()

(

)

TnwTn

iii

⋅

≤

⋅

− 5.05.0

ere T is the configured period. It is very important for this parameter calculation that you enter

exactly the ideal T.

For ‘nT Table’ Show mode, or custom mode with one n specified, the value displayed for the n

index

is the average of all of the edge shift values calculated that belong to that index:

edgsh

%0.100

⋅

⎟

⎠

⎞

⎜

⎝

⎛

⋅−=

∑

ere N

is the number of pits belonging to the n

index. When edge shift is configured as a custom

parameter with a range of n, the overall edge shift is calculated and displayed as the weighted average

of the edge shift values calculated above:

(

)

∑

⋅

overall

Nedsh

edgsh

The meas

urement calculation is compliant with the definition of Edge Shift as defined by ISO/IEC

JTC1.23.14517 Section 22.4.

Display Options

ORM parameter calculations can be displayed, histogrammed, and trended in a variety of ways.

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