Specifications

Chapter 2 21
Measuring Multiple Signals
Resolving Small Signals Hidden by Large Signals
Measuring Multiple Signals
Figure 2-9 Signal Resolution with a 30 kHz RBW (ESA left, PSA right)
Step 5. Reduce the resolution bandwidth filter to view the smaller hidden
signal. Place a delta marker on the smaller signal:
Press
BW/Avg, 1, kHz.
Press
Peak Search, Marker, 50, kHz.
NOTE The ESA 1 kHz filter shape factor of 15:1 (PSA is 4.1:1) has a
bandwidth of 15 kHz at the 60 dB point (PSA has a BW of 4.1 kHz). The
half-bandwidth (7.5 kHz for ESA and 2.05 kHz for PSA) is narrower
than 50 kHz, so the input signals can be resolved.
Figure 2-10 Signal Resolution with a 1 kHz RBW (ESA left, PSA right)
NOTE To determine the resolution capability for intermediate amplitude
differences, assume the filter skirts between the 3 dB and 60 dB points
are parabolic, like an ideal Gaussian filter. The resolution capability is
approximately:
where ∆f is the separation between the signals.
12.04 dB
∆f
RBW
-------------


•
2