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DSOX3024 FFT Strange Behavior

Question asked by Willco788 on May 2, 2012
Latest reply on Jun 14, 2012 by swperk
This has nothing to do with the ASV but it's something I discovered while fiddling with channel impedance.   When I first turn-on the scope, the FFT that was configured previously, launches automatically.  When I change the channel impedance from 50 ohm to 1 MegOhm, the Max measurement changes from dbm to dbv.  It stays that way when I toggle the impedance back to 50 Ohms.  When I go the the FFT/More FFT/Vertical Units, the default is Decibels.   When I toggle the menu to V RMS and back to Decibles, then Max measurements is locked to dbm.  

After fiddling with  FFT/More FFT/Vertical Units again, It's in a mode where when I select V RMS, the FFT dissapears and the Max Measurement shows 0dbm.  When I launch  FFT/More Auto Setup, the measurement is back to 0dbm but when I select V RMS the the measurement is 223mv, the noise floor and the level drops. Back to Decibles and the measurement is correct.

Things aren't consistant and it appears the the measurements are all out of wack.  There's no clear way to correct the problem and by changing other settings, the FFT can shut down.

Edited by: Willco788 on Jun 9, 2012 6:25 AM