Anritsu MS9740B - Page 194

Chapter 5 Measurement Functions
5-44
9. The noise measurement position and range are determined in
accordance with the Noise Parameter Detection Type and Noise
Position settings.
Table 5.6.3-1 Noise Measuring Point
Noise Parameter
Detection Type
Noise
Position
Noise
Parameter
Area Type
Position
or
Area
Point
Off
–
Figure 5.6.2-3 (a)
On
–
Figure 5.6.2-3 (b)
Area
–
Channel
Figure 5.6.2-4 (a)
–
User Specify
Figure 5.6.2-4 (b)
10. When the Noise Parameter Detection Type is Point, the level at the
position set at Noise Position is measured.
When the Noise Parameter Detection Type is Area, the fitting curve
specified at Fitting Curve is calculated. The level at the fitting curve
WDM signal wavelength is measured.
11. SNR (signal to noise ratio) is calculated by the following formula.
SNR (Res ***nm) is calculated by the following formula.








=
)(
log10
,
sig
LinS
N
L
SNR
l
(dB)
When the Noise Parameter Detection Type is set to Point,
)()(
, sigsigLinS
NPL
ll −=
(W)
P(λsig): level at detected optical signal wavelength
N(λsig): noise level at optical signal wavelength
When the Noise Parameter Detection Type is set to
Σ
Power,
)(
*
1
*)}()({
1
,
iesActRSampl
Span
NiPL
n
i
sigLinS
a
l
−
−=
∑
=
n: Data count in the range of Signal Span
Span: Span (nm)
Sampl: Sampling point
P (i): ith data level (W)
ActRes (i): ith data Actual Resolution
α: Equipment dependent power correction coefficient
N (λ
sig
): Linear value (W) of noise level at optical signal
wavelength