On 10/06/2015 17:14, Joe Taylor wrote:
> Hi Bill and all,
Hi Joe,
>
> FYI:  While echo-testing with his 10 GHz EME setup, Charlie (G3WDG)
> discovered that reducing power by 3 dB using our "Pwr" slider actually
> reduced his power by 6 dB.
>
> We are, of course, adjusting voltage rather than power, so line #149 in
> soundout.cpp should read
>
>     m_volume = qPow(10.0, -a/20.0);
>
> rather than the previous expression with "-a/10.0".  I have committed
> the correction.
Agreed but it will not be consistent everywhere I'm afraid. On Linux the 
calibration of the volume setting seems to be sound card specific rather 
than any well defined scale.

There have been a couple of requests to decrease the range of the 
slider, as some find it too coarse. It used to be 10dB (so probably 20dB 
on Windows) before I changed it to the level before this change. 
Personally I use it on minimum regularly for testing with two WSJT-X 
instances back to back, the minimum as it was was just right i.e. just 
decodable and not audible. I suspect that on air the minimum before this 
was reducing the modulation to the same level as any transmitter close 
in spurii. What should be the maximum attenuation? Is the "true" 30dB as 
a result of this change better then the previous 60dB?
>
>       -- Joe
73
Bill
G4WJS.

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