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GRF-1300 User Manual and Teaching Materials
Signal under test
RBW
Results
RBW1
RBW2
Figure B-4. The effect of different RBWs (1)
After passing the narrower RBW1 filter, the components of the two tone
signal are clearly distinguished from each other as a result. But in the wider
RBW2 filter, the result is not as clear as RBW1. We can predict that if the
resolution bandwidth of RBW2 is wider, we could even misinterpret the
result as only one signal. This will also happen if these two signals are even
closer together in frequency.
Another case is when the amplitude of one signal is much higher than the
other; the smaller signal can still be detected using RBW1, but it is obscured if
RBW2 is used. Figure B-5 illustrates this difference. This is why these filters
are known as resolution bandwidth filters.
Signal under test
RBW
Results
RBW1
Figure B-5. The effect of different RBWs (2)
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RBW2