Fluke DSP-FTA420 User Manual page 56

DSP-FTA420/30/40
Users Manual
dBm
A unit of power (in decibels), assuming a reference of 1 mW (1/1000 of a
watt).
The dBm unit expresses loss or gain as a ratio of output power to the reference
power, as follows:
Full-duplex
Simultaneous transmission of data in two directions.
Headroom
The smallest margin in a set of loss margins.
Index of refraction (n)
The ratio of the velocity of light in a vacuum to the velocity of light in a fiber.
Light travels more slowly through a fiber than through a vacuum, so n values
are always greater than or equal to one.
Insertion loss
Loss of optical power caused by adding a connector, adapter, splice, or other
optical component to a fiber path.
Launch cable
A fiber patch cord used to couple an optical source to a fiber.
Macrobending losses
Light losses due to large-radius bends in a fiber, such as bends made during
installation.
48

output
 
dBm = 10 log


power
 

1 mW