The Proper Use of the Spectrum Analyzer

We all know that the spectrum analyzer can be applied in many areas and plays a important part. We need to know more about it such as how to use it properly.
RBW represent the lowest difference of frequency width of two signal with different frequency that can be told apart. If the frequency width of two different frequency signal is lower than the spectrum analyzer RBW, the two signal will overlap. So the proper PBW width is the important concept for the proper using of the spectrum analyzer.