Blog Archives

OTDR Set-UP - Pulse Width

7/16/2015

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 :-

Testing Range - Refer Article HERE
Pulse Width
Index of Refraction - Refer Article HERE
Averaging Time - Refer Article HERE

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.

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.

4 Comments

OTDR Set-Up - Testing Range

7/14/2015

2 Comments

Testing Range
Pulse Width - Refer Article HERE
Index of Refraction - Refer Article HERE
Averaging Time - Refer Article HERE

Fiber Optics Testing Range or Distance of Fiber Optics to Test

Many OTDRs have automatic length detection functions unless the end-user knows the approximate fiber distance then testing range can be set manually.
The following diagrams provide OTDR traces in accordance to OTDR testing range settings.

Too Short Testing Range

Assuming the fiber optics approximate distance is 1000 meter.
The OTDR testing range is set to 500 meter .
The OTDR image / tracse only show half of the distance thus provide inaccurate testing results.

Too Long Distance Range

Assuming the fiber optics approximate distance is 1000 meter.
The OTDR testing range is set to 5000 meter .
The OTDR image / trace shown is compressed into a scale of 1:5 thus giving smaller OTDR traces which can lead into inaccurate measured values.

Good Distance Range

Assuming the fiber optics approximate distance is 1000 meter.
The OTDR testing range is set to 1500 meter - 2000 meter .
The OTDR image / traces shown is a good OTDR chart thus measured values.

Rule of Thumb
The OTDR Testing Range must always be at least 25% greater than fiber optics under testing.

2 Comments

OTDR Set-UP - Pulse Width

OTDR Set-Up - Testing Range

Author

Archives

Categories