3-11
IM AQ1200-01EN
Optical Pulse Measurement and
Analysis Conditions
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Index
App
Approximation Method
When the AQ1200 calculates splice loss, it extrapolates straight lines. These straight lines are known
as approximated lines.
There are the following two kinds of approximated lines.
• Least squares approximation (written as LSA below)
• Two point approximation (written as TPA below)
LSA
The AQ1200 calculates the loss between two points by using the least squares method on all the
data between the two points.
This method has the following characteristics.
Merits: Because all the data between the two points is used, errors in the calculated value
are small.
Fluctuations in the calculated values are reduced, and highly reproducible values can
be obtained.
Demerit: If a large reflection or splice loss is present in the section whose loss is being
calculated, those values are also included in the calculation, so large errors result.
If no reflection and splice loss events are present in the section being calculated, the LSA provides
a value that has a smaller degree of error than the TPA.
1
2
Approximated line
calculation range
TPA
The AQ1200 uses the difference between the levels of the two specified points to calculate the loss.
The level of fluctuation and reproducibility in the calculated value may vary greatly. If reflection and
splice loss events are present in the section being calculated, the TPA provides a value that has a
smaller degree of error than the LSA.
1
2
Approximated line
calculation points
3.6 Setting Analysis Conditions
