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Chapter 1 21
Making Basic Measurements
Resolving Small Signals Hidden by Large Signals
7. Set the resolution bandwidth to 30 kHz by pressing BW/Avg, Res BW,
30,
kHz.
When a 30 kHz filter is used, the 60 dB bandwidth could be as wide
as 450 kHz. Since the half-bandwidth (225 kHz) is wider than the
frequency separation, the signals most likely will not be resolved.
See Figure 1-12. (In this example, we used the 60 dB bandwidth
value. To determine resolution capability for intermediate values of
amplitude level differences, assume the filter skirts between the
3 dB and 60 dB points are approximately straight.)
Figure 1-12 Signal Resolution with a 30 kHz Resolution Bandwidth