Hello all, I read from many books that the power reflection is :
Pr/Pi=Rf, which Pr = Power Reflected, Pi = Power Incident, and Rf = Reflection Coefficient.
And Rf=((n1-n2)/(n1+n2))^2, which n1 = IoR medium 1 and n2 = IoR medium 2.
And I'm using this formula to calculate the power that OTDR detect for the Fresnel Reflection caused by using a connector (refractive index difference between the air and connector)? Is it right to use this formula?
I've tested this formula and after I get the reflected power in mW, I then do the logarithmic calculation, 10 log (Pr), and I got a negative value for either dB or dBm. (Because, as I know that OTDR display is either dBm or dB).
How can the OTDR convert this negative value to a positive one (spike at the OTDR)?
Thanks.
This is my calculation :
I've got the power before reflected is -11,25 dBm so after I do the anti-log, I got 0,075 mW (power incident).
Then I multiply it with the reflection coefficient (0,035), so I get the power reflected is 2,625.10^-3 mW.
Then I do the log to the power reflected, and I got -25,809 dBm as the result.
The truth is that the OTDR showing as 25,809 dBm.
How can that be happen? Or is there any mistakes in my calculation?
- Badges
- Science topic
- Similar topics
- Mathematical Sciences
- Graphs