Tektronix TekRanger 2 TFS3031, Руководство по обслуживанию

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Performance Check – TekRanger (serial nos. below B052000)
3–8
TFS3031 TekRanger/TekRanger 2 Service Manual
Scatter plots are constructed showing loss vs. distance data points for each event.
If 40 instruments are used, and each instrument is allowed to scan the fiber five
times, the total number of data points is 200.
Figure 4–8 is an example scatter plot for a 50 m event.
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Loss (dB)
Distance (m)
Figure 3–2: Scatter Plot for 50 m Event
Once the data points are gathered, a confidence area can be drawn so that 95
percent of all subsequent data will fall within the area. The suggested area
corresponds to the
1.96-
σ
limits of a Gaussian distribution.
The confidence of the location of each event can then be determined by using
this formula:
Location Confidence = X 2
σ
Where: X = sample mean for all tests.
σ
= sample standard deviation for all tests.
Example: X = 48.045,
σ
= 0.0045.
Location confidence: = 48.045 1.96
δ
= 48.045 1.96 X 0.0045
= 48.045 0.00882
Or,
48.045 – 0.00882 = 48.03618 (lower confidence limit)