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Function Reference
OSNR Marker
N o t e
For Agilent 86146B only, if filter mode is enabled, the noise marker, marker BW, delta marker, and
OSNR marker are disabled.
= noise marker symbols
N = interpolated noise
N
P = peak
P
P
Center amplitude = P
OSNR = Center amplitude / N
Interpolating Noise
To accurately measure noise, the noise level must be determined at the signal wavelength. The
measurement cannot be directly performed because the signal power level masks the noise. To
estimate the noise at the signal wavelength, the OSA measures the noise power above and
below the channel wavelength at the predetermined offset or pits (depending on the Noise
Method selected in the Marker Setup panel). Next, the values are linearly interpolated to deter-
mine the noise value at the channel wavelength.
3-46
= interpolated noise amplitude
a
= peak amplitude
a
= center wavelength
w
-N
a
a
(normalized)
a
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