SNR calculations (was Re: setup.exe missing from FTP site)

[Linda Walsh]

Dave Korn wrote:
> On 23 May 2007 13:19, Eric Blake wrote:
> 
>>  [ ... ]   8:1 ratio in bytes of fluff to content 
> 
> 
>   I prefer to express that as an SNR of -18dB :-)
---
     Could you please show your work!

     I arrived at -9dB. Work:
         For each doubling/halving of power one adjusts by ~(+/-)3dB.
             (note: "3" is approximation of 10*log(2) or,
                    to 7 decimal places, 3.010900)
		so 1 unit / 2 units of signal would be -3dB,
		   1 unit / 4 units: -6dB,
		   1 unit / 8 units: -9dB

     From my limited understanding, -18dB would be a reduction of 6 factors of
2, or a 1:64 signal/noise ratio.

"Humbly" :-),
    Linda Walsh