Anritsu MS9740B - Analyzing Multiple Spectrum Center Wavelength and Spectrum Width (Envelope Method)

4.5 Analyzing Waveform
4-17
4
Changing Measurement Conditions
4.5.4 Analyzing Multiple Spectrum Center Wavelength and Spectrum
Width (Envelope Method)
In the Envelope method, an envelope is drawn linking the spectrum peak
points. The center wavelength and spectrum width are analyzed from the
wavelength of the intersection between the envelope line and the cut level
part lower than the peak level as well as the spectrum width are
analyzed.
The envelope is displayed when the vertical axis is linear scale.
1. Press
f4 Envelope
.
2. Select the cut level from
f1
to
f4
or enter the value using the rotary
knob or keypad.
The cut level input range is 0.1 to 20 dB.
3. The cut level, center wavelength λc, spectrum width Δλ are
displayed.
Figure 4.5.4-1 Envelope Analysis
The center wavelength (λc) and spectrum width (Δλ) are calculated by the
following formula.
λc = (λ1 + λ2)/2
Δλ = λ2 – λ1
λ1: Shortest wavelength in all wavelengths crossing the level with the
level lowered cut level from the peak level and the envelope
λ2: Longest wavelength in all wavelengths crossing the level with the
level lowered cut level from the peak level and the envelope
Cut level
Analysis result display field
Envelope