OTDR Setting UP - Pulse Width

All OTDRs regardless of brand have four basic setup requirement i.e. the OTDR user is required to key in these four basic data parameters into OTDR in order to get good and accurate fiber trace analysis.

The required data parameters are :-

1. Testing Range 
2. Pulse Width
3. Index of Refraction 
4. Averaging Time 

What is Pulse Width?

• OTDR pulse width determines length of fiber that can be measured before OTDR traces become noise.
• Larger pulse width provides larger dynamic range 
• Narrow pulse width provides reduced dynamic range. 
• Dynamice range is associated with pulse width and in turn describes length of fiber that can be measured by OTDRs.

• Always start testing with a shorter pulse width. 
• The shorter pulse width is useful for locating any faults that may otherwise be hidden in longer pulse width.
• A gradual increase in pulse width is necessary to prevent two or more faults from overlapping.

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Rule of Thumb Long pulse width for longer fiber distance. Short pulse width for shorter fiber distance. Always start with shorter pulse width and gradually increase the pulse width to detect all possible fault traces.