XPost: rec.audio.pro, comp.dsp   
   From: spope33@speedymail.org   
      
   Don Pearce  wrote:   
      
   >On Sat, 20 Nov 2010 08:03:14 +0000 (UTC), spope33@speedymail.org   
      
   >>I woulda said that a 0 dBFS signal has the RMS level of a sine wave   
   >>that just barely doesn't clip  a converter (or, a hardlimited channel;   
   >>it does not need to be a converter).   
   >>   
   >>(This is an important concept, of sorts, in that is shows that   
   >>an N bit converter has a full-scale-signal to quantization noise   
   >>ratio of 6*N + 2 dB, not the 6*N + 5 dB that some texts claim.)   
   >>   
   >>One can debate these things.  Most outcomes of such debates are   
   >>equivalent within a factor of two.   
      
   >Here's how the maths works.   
   >   
   >Lets call the clipping point 0dB.   
   >The biggest sine wave it can hold is -3dB RMS. (peaks just clip).   
   >The lowest bit level is - 16 * 20log(2), or -96.3dB   
   >   
   >Because the converter is perfect, the noise is TPD, which has an RMS   
   >value 4.8dB below the 1 bit peak. So the noise level is -101.1dB   
      
   >So the dynamic range is 101.1dB -3dB +4.8 or 98.1dB. That is the range   
   >from a just-clipping sine wave, to a signal equal in RMS amplitude to   
   >the noise.   
      
   I agree with the result, but what is "TPD"?  (I'm thinking "triangular"   
   something...)   
      
      
      
   S.   
      
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