Sensornet ORYX DTS, Руководство пользователя

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Page 72 Oryx DTS User Manual v4
Figure 51 - Setting the fibre end point
Once this is done, the reverse raw data signals will start and end at exactly the
same positions on the length scale – see Figure 52. The combined (red)
temperature trace should show a sensible reading, although some deviation from
the single-ended calculation (white trace) will be apparent especially if there are
fibre connectors, splices etc. in-line or there are different types of fibre connected
together.
NOTE: An easy way to begin the alignment is to adjust the ‘fibre end point’ value
until the forward and reverse raw signals line up at the start and end of the traces.
(Figure 52)
In the case of a fibre loop formed from two fibres in one cable (‘U’ installation), the
combined temperature trace will be symmetrical about the cable centre point, as
shown diagrammatically in 0. Due to the splice or bend at the end of such a cable, it
is also usual to observe a small spike (either up or down) at the centre point. This
feature can be used to accurately align the forward and reverse traces. The ‘fibre
end point’ value should be adjusted to make the spike feature as narrow as possible
(this may not be the smallest amplitude however).