So here's what I've done. Part of my question is should we add some check
to let people know they should adjust?
Rig Rx equalization is now -20dB
Signalink Rx at mid point (should be a reasonable analog level...I assume
it's an analog attenuator)
Xonar has no such adjustment on the device. Gotta' put on a USB sniffer
and see if the Xonar utils or other adjustsment are OS or are sent to
device.
Slider set at at mid-point
Adjusted Signalink recording level in Windows to give 30dB on slider which
it says is -19.3dB
Adjusted Xonar recording level in Windows to give 30dB on slider which it
says is -25.1dB
Max value in Siganlink WAV file with signals at -2dB on WSJT-X is 727
Max value in Xonar WAV file with same time wav file is 840
Does that all sound reasonable? I would assume adjusting the Rx level at
the Signalink is effectively the same as adjusting the level in Windows. I
don't know if the Xonar volume adjust is in the driver or actually does
something in the Xonar unit.
Wouldn't it be nice if WSJT-X told a user "You just received a -?? signal
that should be in the range of X-Y in your wav file, but your value is
Z....you need to [reduce/increase] the audio level into your sound
device." Maybe a button WAVTest.
In other words some sort of table which should be calculatable:
-30,x,y
-29,x,y
...
Or perhaps a display of the WAV's RMS noise level and what's
expected...something a bit more direct than "adjust audio to middle" and
then adjust input levels to get 30dB starting from the rig, then knobs on
sound device, the sound levels in OS.
RRR
Mike W9MDB
On Sat, Jan 23, 2016 at 8:28 PM, Bill Somerville <[email protected]>
wrote:
> On 23/01/2016 23:35, Michael Black wrote:
> > Perhaps we should consider a check of the audio level in the wav data
> > to ensure it's within some range?
> Hi Mike,
>
> you may be approaching this from the wrong side. We know that the audio
> output of a properly adjusted rig will have no more than ~60dB from the
> noise level to the loudest signals. Knowing that we can simply say that
> setting the WSJT-X thermometer meter to 30dB on a quiet band assures us
> that the audio signal from the rig will not clip at the ADC. This is
> only exactly so when the gain slider is in the middle since elsewhere
> there is a gain/attenuation factor applied to the meter.
>
> The best you can do is arrange that the audio level from a quiet band
> gives you a 30dB reading on the WSJT-X meter when the slider is in the
> middle. If you have to adjust the slider then you are compensating for
> the level presented to the ADC not being optimum, this sacrifices some
> resolution or some headroom that you may need in the presence of strong
> signals.
>
> With respect to the decoders, the WSJT-X gain setting has no bearing,
> the gain setting is just a tool to fine tune the waterfall and spectrum
> displays. To get the best performance you must get the level correct at
> the ADC and not manipulate the digital level en route to the decoder. We
> need the best possible resolution across wanted signals without
> destroying the data by overloading the ADC input.
>
> 73
> Bill
> G4WJS.
>
>
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