FFT/distortion readings with HP 54200A

[Adam_Stouffer]

Is it possible to use an old HP 54200A digitizing scope to measure things like distortion and FFT? Is it as simple as creating an array of the output and feeding that into the distortion vi?

[Hummer1]

If the 54200A gives you the capability to capture a string of values that are samples of the waveform, and the waveform is known...then comparing the samples to the known waveform should produce distortion...

Do you have to have matching samples (time synchronous) of both the sampled signal and the created signal...?  Or can you be out of phase and just get total harmonic distortion?

Apparently, the distortion analysis express thing I looked at just calculates the "most probably" fundamental frequency and does total harmonic distortion from that...that shoul dwork.

Hummer1

[johnsold]

I have used the old Tektronix 2430A for spectral analysis.  Capture the waveform.  Extract the array of data if necessary (depends on output format of scope).  Analyze.

You may need to calculate the sample rate so that you can get the frequencies right.

Also, most oscilloscopes have only 8-bit digitizers.  This limits the amplitude resolution and dynamic range of the spectral analysis or distortion analysis.  If you can filter or suppress the fundamental before it gets to the scope, you can get much better distortion analysis. But if you had the equipment to do that, you would probably not be trying to use the scope for this.

Lynn