2-3
IM AQ7280-01EN
Optical Pulse Measurement (OTDR)
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Index
Setting Analysis Conditions in Simple Mode
Press the
Analysis Setup
soft key to display the following screen.
Set the approximation
method (LSA, TPA).
Approximation Method
When the AQ7280 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 (LSA)
• Two point approximation (TPA)
• LSA
The AQ7280 calculates the loss between two points by using the least squares method on all the
data between the two points (between 1 and 2).
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 events such as reflections and splice losses 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
2.1 Setting the Measurement and Analysis Conditions
