technique in the OSA’s WDMapplication. This technique, asshown in Figure 3, takes twosweeps and determines the OSNRfrom the composite results. Thefirst sweep is taken at a userspecified wide resolution bandwidth filter (e.g. 0.2 nm) toensure accurate signal amplitudemeasurements. The secondsweep is taken at a user-specifiednarrow resolution bandwidthfilter (e.g. 0.06 nm) to ensureaccurate noise power spectraldensity measurements. With thefast sweep speed of the AgilentOSA, the result is a quick andaccurate OSNR measurement.Automated analysis of WDM spectraUsing the WDM application’sAUTOSCAN feature, the OSAimplements the dual sweep methodto measure channel wavelength,signal amplitude and OSNR. Eachchannel is individually markedand numbered for a quick verification of channel count. Thecenter wavelength is reportedwith industry leading wavelength accuracy throughout CBand and L-Band. Additionally,the application automaticallyanalyzes the results and reports:■ span tilt* in dB/nm andnormalized to dB■ peak-to-peak deviation■ minimum and maximumchannel power■ minimum and maximum OSNR3Figures 4 and 5. Graphical and tabular results.Easy access to resultsThe results are available in either a graphical or tabular display. Thetable can be configured to display the results in either units of frequency(THz) or wavelength (nm).The graph and table can be printed to either the internal OSA printeror an external printer. The table can be saved to a floppy in .CSVformat. The WDM application is fully GPIB-controllable, making it theperfect solution for fast-paced manufacturing environments.* Span tilt is defined as the slope of the line that is the best fit to the channel powersin dB/nm.