XPost: rec.audio.pro, comp.dsp   
   From: MrT@home   
      
   "Dick Pierce"  wrote in message   
   news:icbbek$km8$1@speranza.aioe.org...   
   > glen herrmannsfeldt wrote:   
   > > In comp.dsp Dick Pierce  wrote:   
   > >   
   > > (snip, I wrote)   
   > >   
   > >   
   > >>>In EE, RMS can mean different things.   
   > >   
   > >>Not in any "EE" I ever encountered. It means one thing:   
   > >   
   > >>   sqrt(sum(X1^2 + X2^2 ... +Xn^2) / n)   
   > >   
   > > It used to be, for DVMs, that was called True RMS.  When   
   > > they figured out how to actually do that electrically.   
   > >   
   > > Maybe they all do now, so it isn't a problem anymore,   
   > > but it didn't used by be that way.  Also, it isn't   
   > > for the peak-to-peak reading VTVM, normally calibrated   
   > > with an RMS (assuming sine) scale.   
   >   
   >   Sorry, wrong. RMS, or "root-mean-square," is a term   
   > that predates voltmeters and DVMs and VTVMs. It is a   
   > mathemateical, yea, a statistical mathematics defintion.   
   >   
   > That is has been misused, misappropriated, improperly   
   > implemented, misunderstood or whatever does NOT change   
   > the fact that it has a precise, well understood and   
   > universally agreed-upon mathematical definition.   
   >   
   > That you can cite one or more examples of a piece of   
   > instrumentation that claims "RMS" merely points out   
   > that there are different claims, some valid, some not,   
   > of implementations. It does NOT siggest that there are   
   > different meanings to the term.   
      
      
   He's wrong in any case, ANY meter which was average responding and   
   calibrated in RMS, ALWAYS assumed a SINE wave input and was corrected for   
   it. That's why True RMS meters were necessary for anything other than pure   
   sine waves.   
      
   MrT.   
      
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