How to display the "infinity" data?

[happybird]

Hellow!
I am using labview 7.0 to read waveform from TDS 420A osilloscope to do a frequency response measurement,i need to get the Amplitude-excitation frequency curve,but when the resonance happens,the amplitude become " Infinity" in osilloscope ,then the amplitude at resonance frequency in Amplitude-frequency curve become approximately 0. so i guess labview did not get amplitude value at the resonance frequency point,so are there any one can tell me how to convert the "infinity" to a meaningful number so that the Amplitude-excitation frequency curve will be meaningful. thanks!

[happybird]

Attached is a description,why the amplitude-exciation frequency curve is like that?

[Conseils]

Looks like the scope has simply reached the limit of resolution when taking a measurement for the selected range.

Have you checked the resolution for the seleted range or is it dynamically ranging when taking the measurements.

If it is fixed on one range you could try changing the measurement range on the equipment, after all its only the resonant point that you are interested in.

If you calculate what frequency error you can tolerate you will be able to determine your required system resolution.

Could be that you just have to threshold the data as the instrument may not be capable of the required resolution. But with your calculation you will then understand the measurement limits of your system.

Hope this helps.