I have N9000A set up to measure radiated EMI against EN 60945 in a shielded room.
I do a background scan (peak) in the Maritime VHF band (156-165 MHz), and everything is well below limit (~ 15 dB or so below 24dBuV/m).
I add a random frequency (eg. 159 MHz) to list via marker and perform "(Re)Measure All Signals".
QP result is just around limit, typically 3 dB above, so I am failing to perform final measurement on the background noise, when I can do a full scan that shows that the background noise is well below limit.
I am pretty confident that the final measurement is incorrect and that I am getting the results of a noise floor.
Why might it be that the final "(Re)Measure" QP measurement is higher than the peak prescan?