Anritsu MS9740B - Page 177

5.5 Measuring WDM (Wavelength Division Multiplexed) Signals
5-27
5
Measurement Functions
5th POLY: Fifth-order polynomial equation for noise linear
data
f (λ) = aλ
5
+ bλ
4
+ cλ
3
+ dλ
2
+ eλ + f
Fitting Curve Display:
Fitting curve display setting
Off: Does not display fitting curve on screen
On: Displays fitting curve on screen
Area Type: Area setting method for calculating fitting curve
Channel: Both sides of each Signal wavelength
User Specify: User specified range
Channel: Area setting when Noise Area is Channel
Fitting Span: Wavelength range for calculating fitting curve
Masked Span: Wavelength range excluded from fitting curve
calculation
User Specify: Area setting when Noise Area is User Specify
Noise Position: Wavelength difference between screen center
wavelength and area center wavelength
Span: Area wavelength range
Figure 5.5.3-4 Noise Level Measurement Range Set at Area Type
Note:
When the wavelength range set at Channel or User Specify cannot
be accommodated within the measured wavelength range, the
fitting curve is calculated using only the measured wavelength
range data.
When the wavelength range set at Channel or User Specify is
outside the measured wavelength range, SNR is displayed as ***
and no fitting curve is displayed.
Wavelength (nm)
Level (dBm)
(a) Channel
Signal Wl
(b) User Specify
Wavelength (nm)
Level (dBm)
Noise
Position
(left)
Noise
Position
(right)
Center
Wavelength
Span
Span
Fitting
Span
Masked
Span