Pcsu1000 measuring voltage with spectrum analyzer

Instruments PC Oscilloscopes and Recorders
1

I was using the PCSU1000 to measure harmonics of 60 Hz being induced into railroad signal equipment by a power line. I recorded the pictures of the spectrums which show the voltage per unit of 0.1 volt and range of 300 Hz. The highest harmonic doesn’t seem to have any relationship to the unit scale in volts or db. Is there any way to determine what voltage the highest harmonic was at when I took the picture?

When I connect the unit to an audio oscillator, the peak voltage shown on the spectrum analyzer display doesn’t seem to have any relationship to the input voltage. If I change scale from .2 v per division to .1 v per division, the height of the peak voltage changes very little, but the height of the harmonics increase. Is this all in db even though the scales are in volts?

I wish the instructions were more detailed for those of us who have never used a spectrum analyzer before.

2

If I change scale from .2 v per division to .1 v per division, the height of the peak voltage changes very little, but the height of the harmonics increase. This may indicate the waveform is not fit to the oscilloscope screen but is the top and/or the bottom of the waveform is “clipping” on the oscilloscope screen. Please make sure not to use too high V/Div sensitivity.

[quote]Is this all in db even though the scales are in volts?[/quote] Yes, the spectrum analyzer scale is always dB.
You may use the markers to measure the signal amplitude in dBV.

You can use the File menu option Save FFT Data to save the FFT data in text form.
The data can be imported to Excel for further analysis:

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