How to Use Power Meter

Power Meter

Another measuring instrument for fiber optics and much easier to use as compare to OTDR but will not give you much details as OTDR.

So Power meter box comes with 3 major components-
1) Light Source
2) Power meter
3) Fiber of small length-Calibration cable

Most of the light source can transmit laser at 850nm,1310nm and 1550nm and depending on your system you can choose the wavelength required.

I will choose 1550nm because all the systems i worked on has Focal 903 and downlink wavelength in focal 903 is 1550nm.
Once you have selected wavelength in light source choose the same wavelength in power meter as well.

Take calibration cable and fix between light source and power meter,Switch ON both devices and note the reading in dB,I prefer it in dB because its easier for me to calculate but you can do it in dBm as well but make sure to do calculations accordingly.

Note-Techs taking reading in dBm will get readings between -2dBm  to -8dBm

You must see reading of about 65dB-75dB and if battery of any device is low you might get an error reading so be aware of this.
Note down the reading as this is our benchmark lets suppose 70dB(Benchmark reading) in this case.
Now Connect Light source at starting point in this case i am measuring total system loss by connecting light source at start of fiber in control van by disconnecting fiber at surface FO
and Power meter at the subsea end as this for illustration purpose only you can even place a particular junction box in between.

**Important Note-Do not disconnect calibration cable from the circuit while performing test

Now the reading in power meter will be suppose 60dB(Final Reading)

Total Loss in a System= Benchmark Reading - Final reading

                         10dB  =70dB - 60dB

So in this case we have loss of 10dB in whole system from Surface to subsea.
You can use this method for a particular connector as well, by placing a connector in between instead of whole system.

I hope i have explained it well on how to use power meter but if you still have any question please use the comment section.Next post i will explain how to troubleshoot FO 903