No relevant resource is found in the selected language.

FAQ-Optical power, what is the difference between dBm and dB unit?

Issue Description
Q：
Optical power, what is the difference between dBm and dB unit?
Alarm Information
None
Handling Process
A：
1. dBm
dBm is a value of the power absolute value, formula is: 10lgP (power value / 1mw).
[Example 1] if the transmitter power P is 1mw, converted to dBm is 0dBm.
[Example 2] for 40W power value, translated in dBm unit, value is as follows:
10lg（40W/1mw)=10lg（40000）=10lg4+10lg10000=46dBm。
2. dB
dB is the value of a characterization relative value, when consider A power compared to B power is more or less hoe many dB, calculated by the following formula: 10lg (A power / B power)
【Example 3 】A power is twice times than B power, then 10lg (A power / B power) = 10lg2 = 3dB. That is to say, the A power is 3 dB greater than B power.
[Example 4] If A power is 46dBm, B power is 40dBm, it can be said, A is larger than B.
Root Cause
None
Suggestions
Optical power is generally related to the dBm and dB two units.
dBm means 1mw relative value, can be said to be a absolute value.
dB used to measure the relative values of random two power.

END