App-24
IM AQ6370D-01EN
Appendix 4  Detailed Explanations of WDM Analysis Function
When the number of WDM channels “n” is 1
Internally obtain the measurement resolution of SNi calculation trace and the value of 
the noise measurement point NOISE AREA in accordance with the resolution, and then 
obtain the values from the following equations.
  NA_Ri = λi + NOISE AREA
  NA_Li = λi − NOISE AREA
 When the number of WDM channels “n” is 2 or more
  λN1 = (3λ
1
 − λ
2
)/2
i=2,3,…,n
  λNi = (λ
i
 − λ
i-1
)/2
  λNn+1 = (3λ
n
 − λ
n-1
)/2
If the above values are calculated, the following results will be generated.
i=1,2,…,n
  NA_Li = λNi
  NA_Ri = λNi+1
Fitting Algorithm
While the setting to AUTO-CTR, LINEAR is used for the fitting algorithm, which is 
calculated as follow.
•  Obtain ELi and ERi as the level (LOG) of each position of the noise areas NA_Li and 
NA_Ri.
•  Use the data of the straight line connecting the two points of ELi and ERi to fill the 
inside of the fitting range. 
•  Set the level of λi of the data generated in the fitting to the noise level LNi.
Note
Due to being set to LINEAR, it is not possible to set the mask areas.
PIT
Noise Algorithm
Obtain the noise areas for measured waveform to the minimum level position of a before 
the next channel in each channel. 
When inside noise areas obtain at the left and right noise areas of each channel. outside 
noise areas is applied.
When the number of WDM channels “n” is 1
Internally obtain the measurement resolution of SNi calculation trace and the value of 
the noise measurement point NOISE AREA in accordance with the resolution, and then 
obtain the values from the following equations.
  NA_Ri = λi + NOISE AREA
  NA_Li = λi − NOISE AREA
When the number of WDM channels “n” is 2 or more
 i=1
  NA_Li = λi − (λNi − λi)
  NA_Ri =λNi
  i=2,3,…,n−1
  NA_Li = λN(i − 1)
  NA_Ri =λNi
 i=n
  NA_Li = λN(i − 1)
  NA_Ri =λi + (λi − λN(i −1))