Setting Proper Parameters - ADInstruments AD5000 Manual

4.6
At the fist time using OTDR, if user choose some testing parameter which is
not suitable to the real condition may cause the bad result. User should take
Testing range,pulse width and wavelength into consideration.
Setting proper testing range
Testing range means maximum display range.This parameter will indicate
how long will OTDR display on its screen.this range must longer than testing
fiber,Usually we choose range which is 20% longer than testing fiber.Take
note that testing range should not has large difference with testing
fiber,Otherwise it will affect the effective resolution and overlarge testing range
will result in the generation of huge and useless data(see Figure 1).
Setting proper pulse width
Pulse width and blind area, dynamic range are directly related to the
maximum length ,in below picture, use ten different pulse width to test one
testing fiber.the smallest pulse width result in the smallest blind area and the
most terrible noise. The longest pulse width result in the smoothest curve and
almost 1km blind area(see Figure 2).

Setting Proper Parameters

164km test range is too long to the fiber
of 7.6km
Figure 1
Figure 2
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