## [Qucs-help] noise root mean square with logarithmic AC-analysis?

 [Qucs-help] noise root mean square with logarithmic AC-analysis? From: chloros - 2013-09-17 13:17:44 ```Hi qucs community, i was wondering if there is an easy way to calculate the root mean square noise value from the spectral density if the simulation step is non linear (logarithmic)? for linear scale it should be sth like this: urms=sqrt(integral(abs(Unoise)^2)) which (if i am correct) could be implemented as: urms=sqrt((max(acfrequency)-min(acfrequency))*avg(abs(Unoise.vn)^2)) however that does not hold for logarithmic scaled AC-simulations (i.e. acfrequency logarithmic). anybody an idea for an easy solution or do we have to fiddle with the logarithmic derivatives? Best regards! ```

 [Qucs-help] noise root mean square with logarithmic AC-analysis? From: chloros - 2013-09-17 13:17:44 ```Hi qucs community, i was wondering if there is an easy way to calculate the root mean square noise value from the spectral density if the simulation step is non linear (logarithmic)? for linear scale it should be sth like this: urms=sqrt(integral(abs(Unoise)^2)) which (if i am correct) could be implemented as: urms=sqrt((max(acfrequency)-min(acfrequency))*avg(abs(Unoise.vn)^2)) however that does not hold for logarithmic scaled AC-simulations (i.e. acfrequency logarithmic). anybody an idea for an easy solution or do we have to fiddle with the logarithmic derivatives? Best regards! ```
 Re: [Qucs-help] noise root mean square with logarithmic AC-analysis? From: Stefan Jahn - 2013-09-17 14:45:04 ```Hello, are you asking for noise in a bandwidth, right? For this purpose we have a receiver() equation, see english help on math functions... BR, Stefan. On Tue, September 17, 2013 3:17 pm, chloros wrote: > Hi qucs community, > > i was wondering if there is an easy way to calculate the root mean > square noise value from the spectral density if the simulation step is > non linear (logarithmic)? > > for linear scale it should be sth like this: > urms=sqrt(integral(abs(Unoise)^2)) > which (if i am correct) could be implemented as: > urms=sqrt((max(acfrequency)-min(acfrequency))*avg(abs(Unoise.vn)^2)) > > however that does not hold for logarithmic scaled AC-simulations (i.e. > acfrequency logarithmic). anybody an idea for an easy solution or do we > have to fiddle with the logarithmic derivatives? > > Best regards! > > > > ------------------------------------------------------------------------------ > LIMITED TIME SALE - Full Year of Microsoft Training For Just \$49.99! > 1,500+ hours of tutorials including VisualStudio 2012, Windows 8, > SharePoint > 2013, SQL 2012, MVC 4, more. BEST VALUE: New Multi-Library Power Pack > includes > Mobile, Cloud, Java, and UX Design. Lowest price ever! Ends 9/20/13. > http://pubads.g.doubleclick.net/gampad/clk?id=58041151&iu=/4140/ostg.clktrk > _______________________________________________ > Qucs-help mailing list > Qucs-help@... > https://lists.sourceforge.net/lists/listinfo/qucs-help > ```