[EMAIL PROTECTED] wrote: > In a message dated 1/6/2008 15:01:25 Pacific Standard Time, [EMAIL PROTECTED] > > writes: > > >> 85671A package or mine, how _exactly_ are you turning the dBc/Hz values you >> get from (say) the 8561E into your ~-120 dBc/Hz numbers? Let's hear the >> step-by-step procedure on that, and the problem should reveal itself. >> > Hi John, > > by selecting a 1Hz RBW on the 8561E. The APII analyzer should have a 1Hz BW > normalization as well, although I checked in the user manual again and it > just specifies "dbm" without regards to RBW. How does one calculate RBW from > an > FFT? Is it the width of a given FFT bin? I will check this again, and try to > increase the number of samples. > > But even with say a 10Hz RBW I would expect the noisefloor to only rise > 10xlog(1/BW) or 10dB, much less error than what I am seeing. > > bye, > Said > > Said
1 Hz resolution bandwidth isnt the same as 1Hz noise bandwidth. The noise bandwidth of of a 1Hz resolution bandwidth depends on the details of the filter. For an FFT analyser, selection of a Hann, Blackman-Harris, uniform or other window function/filter changes the equivalent noise bandwidth of the filter. Bruce _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.