Analysis of receiver bandwidth for viewing power line noise.

I recently discovered that in order to obtain the most accurate view of power line RFI using the audio output from my SDR receiver in AM mode to observe number of arcs per each half cycle when using my SDR receiver a very wide bandwidth is desirable. Modern SDR receivers allow us to use a much wider bandwidth than was previously possible on conventional receivers. Below are pictures in which I show the impact of 5, 10, 15, 20, 25, 50 and 100 KHz bandwidths when viewing power line noise on a standalone oscilloscope connected to my laptops audio jack as well as a software based audio oscilloscope that's running on my laptop that's also running my SDR receiver, and the results are similar even though sampling rate capability may be a limiting factor on one or the other system which I still need to investigate. I have provided the standalone oscilloscope pictures just to prove that the software based audio oscilloscope works well for this task, and I now normally just use the software based audio oscilloscope to view the audio obtained by my SDR receiver in AM mode when analyzing a signal for power line noise. Whenever possible I use at least 25 KHz of bandwidth but I often use a higher bandwidth setting (up to 100 KHz) for best reproduction of power line interference. Don Kirk (wd8dsb)

Note: the green traces below are the software based audio oscilloscope and the yellow traces are the stand alone oscilloscope, and the signal being analyzed is a power line arcing 2 times per each half of the sinewave.

5 KHz Bandwidth