EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 302)

Managing Results
294 FTB-5240S/5240BP
Managing WDM Test Results
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Bandwidth 3.00 dB: indicates bandwidth measured by taking the
width of a signal at 50 % linear power of the peak or -3 dB from the
peak.
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Bandwidth x dB: indicates bandwidth measured by taking the width
of a signal at x dB from the peak.
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Channel number: indicates the number of the channel. Channel 1
corresponds to the first channel found.
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Channel center: indicates the channel center for the selected channel.
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Signal power calculation: indicates which calculation method to
apply for signal power value.
Integrated signal power: The integrated signal power represents the
sum of the power values included between the channel limits of this
channel, minus the estimated noise contribution between the same
boundaries. In some cases, for instance CATV signals, signals with
high-frequency modulation, or signals with an inherent line width
similar or larger than the OSA's resolution bandwidth, this calculation
becomes a better estimation of the true signal power.
Peak signal power: The peak signal power represents the maximum
power value inside the channel, but it differs a little from the peak
measurement on the spectrum due to the fact that the estimated noise
is subtracted to get the peak signal power.
Total channel power: The total channel power represents the sum of
the power values included inside the channel width (including noise).
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Channel width: indicates the limit within which the power values will
be considered in the channel.
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RBW for OSNR: indicates the resolution bandwidth for the selected
OSNR value.