Filter Analysis. The Filter Analysis Function. a PDF file by Sam Wetterlin.
In this window, the user can turn filter analysis on or off, indicate what marker is to mark the peak, and also indicate the dB points to mark. Here we have marked that we want the points that are 3 dB down, and “-20” dB down. The dialog allows the dB values to be positive or negative, but always interprets them as being below the reference marker.
When OK is clicked, the MSA will place markers at the appropriate points on the graph.
this case, markers 2 and 3 are placed at the -3dB points, and
markers 4 and 5 are placed at the -20 dB points. If the scan continues,
position of the markers will be adjusted at the end of each scan. The
data is displayed below the graph, and some additional data is
describing the filter characteristics: the bandwidth at -3 dB and -20
the shape factor (the ratio of the -20 dB and -3 dB bandwidths), and
ripple. The ripple is measured between the -3 dB points, and with such
rounded peak it is zero.