EXFO FTB -5240S/5240BP Optical Spectrum Analyzer for FTB 500 (NS-1434) - Manual (Page 70)

Setting Up the Instrument in WDM Mode
62 FTB-5240S/5240BP
Setting Up WDM Analysis Parameters
³
Channel width (GHz or nm): indicates the limit inside which the
power values will be considered in the channel.
For default channels, the channel width that sets the limits of the
channel, should be the same as the channel distance or smaller
(channel distance is defined while creating a channel list). If the
channel width is not compatible with the channel spacing, either a
single peak may be found for two distinct channels and two
analysis would be performed and displayed for that peak, or, it is
possible that two peaks may be found within the same channel
and be considered as one multi-peak signal. With this result, you
can use markers to find the spacing between adjacent channels or
to find the channel width.
³
OSNR distance (GHz or nm): OSNR distance is automatically set
at the channel edge, that is, at half of the channel width from the
center wavelength.
³
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).