Find bandwidth of signal vs frequency data

I have some data taken while analyzing a filter - it is in the form of two vectors, frequency and output magnitude. The plots all have a single peak. I'm looking for the bandwidth of this filter (gain drop of 3dB).

It looks like I want the bandwidth function, but I don't know how to create a system model from my data to pass into the bandwidth function.

I appreciate the help, Istvan.

Answer 1

[Star Strider]

The 3 dB down value is the half-magnitude value. All you need to do is find the values that are half the peak, and determine the frequencies at those points. The interp1 function will probably make your problem considerably easier, although you will have to use it once for each frequency.