Fatshaft Posted August 6, 2015 Report Share Posted August 6, 2015 I'm having a strange issue and was wondering what happened to my "Long Term average graph" The red graph I wanted to check a 40HZ test tone but the average graph (RED) is on the 20HZ !!! Does anyone know why that is? Pic here Link to comment Share on other sites More sharing options...
Shredhead Posted August 6, 2015 Report Share Posted August 6, 2015 Nope, I never noticed that one before. Try re-loading your settings file and re-check. Link to comment Share on other sites More sharing options...
Fatshaft Posted August 7, 2015 Author Report Share Posted August 7, 2015 Shred, sorry I didn't respond sooner...I fugured it out...Don't fuk with the fft tab. Thanks Link to comment Share on other sites More sharing options...
andycatblack Posted August 8, 2015 Report Share Posted August 8, 2015 Could be a ghosting phantom. I'm trying to remember the term used on the CB radio 35 years ago? Remember spectrum lab was designed for "Ham radio" use. I recall if I was transmit on one mode and band on the CB frequencies away form most others while chatting modulating with another breaker my transmission might be picked up on another band/mode. Say I'm on Low band AM channel 24. My transmission might be picked up by someone else not too far from me on High band FM channel 35. Its strange thing it was as I used to pick up same kind of ghosting or phantom transmissions? Another possibility is your level is far too high so don't compete with others for how many sub bass speakers you want at 250db to deafen you, TURN THE LEVELS down and see if the level of your 40Hz doesn't show a phantom 20Hz ghosting a few Hz below? Link to comment Share on other sites More sharing options...
openglcg Posted October 10, 2015 Report Share Posted October 10, 2015 a 40 hz wave could look like a 20hz if the sample points used by the test were not exactly synced at a power of 2 ratio to 40hz. So if you looked at the sample point it would be slightly different each time as it rolled across the 40hz wave and looking only at those samples you would see a slight oscillation maybe going between a higher average over the first 40 hz wave and a lower average on the second 40 hz wave and since you are dealing with a pure 40 hz tone this could repeat enough to register. or something like that Link to comment Share on other sites More sharing options...
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