The Spectrum Power Calculations utilise Volts Squared (V^2). This can cause issues for small signals at the low millivolt (mV) or microvolt (uV) level, as the voltage is squared as part of the Power calculation - therefore signals smaller than 1V will be reduced in size.
For example 0.01V(10mV)^2 = 0.0001V - the Spectrum Channel calculation shows only up to 3 decimal places, so 0.0001V^2 would appear as 0.000V^2. The Data Pad Spectrum Power Values will show the value in scientific notation.
Note that the decimal points of the Power Channel Calculation cannot be amended. If you need to extract the numerical values, use Multiple Add to Data Pad.
For further technical assistance with this or any other issue, please contact ADInstruments Technical Support by clicking HERE.