Teledyne LeCroy AORM - Advanced Optical Recording Measurements - Manual (Page 52)

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ISSUED: June 2013 923133 Rev A
DP2CS DELTA PIT TO CLOCK SIGMA
Description
Dp2cs provides a measurement of the mean, normalized standard deviation of the Delta Pit-to-
Clock measurements (see Dp2c). When a single n is specified, or in ‘nT Table’ Show mode, the
value calculated for the n
th index is calculated using the following equation for standard deviation:
( )
( )
∆ ∆
∆
∆
∆
P CS P C
P CS
P C
P C
N
N
n n
n
n
n
n
n
2 2
2
2
2
1
2
2
=
=
−
−
∑
∑
σ
Delta Pit-to-Clock Sigma cannot be calculated for a given index n unless there are at least two Delta
Pit-to-Clock values calculated for that n index.
When Delta Pit-to-Clock is configured as a custom parameter with a range of n, the value calculated is
the standard deviation of the distribution that results by normalizing each independent distribution
categorized by nT. Distributions are normalized by subtracting the mean of the distribution from all of
the elements in the distribution. This results in the following equation for overall Delta Pit-to-Clock
Sigma resulting from the individually categorized Delta Pit-to-Clock Sigma values:
( ) ( )
∆
∆
P CS
P CS N
N
overall
n n
n
2
2 1
1
2
=
⋅ −
−
∑
∑
Note: The value calculated by DP2CS will generally not be the same as the sigma of DP2C measurement displayed on
the parameter line when a range of n is used and statistics is on. This is because the two measurements are not the
same. DP2CS measurement normalizes the results for each n by subtracting the mean DP2C from each DP2C in the n
th
distribution. This results in a superposition of mean centered distributions, not a superposition of 0 centered distributions
contributing to DP2C measurements. DP2CS will always be less than or equal to the standard deviation of DP2C
measurements.