[Elecraft] Audio artifacts in DATA A mode with KX3

[Wayne Burdick]

This is on the KX3 firmware list. I'll move it up a notch.

Wayne
N6KR


On Jan 3, 2017, at 12:16 AM, David Anderson via Elecraft <elecraft at mailman.qth.net> wrote:

> Nick,
> 
> Thank you for bringing this up.
> 
> I never did get a satisfactory explanation, I contacted support too but that didn't get me anywhere either, I don't think they understood my question, which is quite simple really, why can't we get the same bandwidth in Data mode as in SSB mode? I think it's a simple oversight, but nobody seemed interested in acknowledging it or fixing it.
> 
> 
> 73 from David GM4JJJ
> 
>> On 2 Jan 2017, at 23:54, Nicklas Johnson <nick at n6ol.us> wrote:
>> 
>> Jörg in the Elecraft KX3 group on Facebook had an interesting observation:
>> with WJST's waterfall, if the "flatten" mode is on, it produces some
>> unusual artifacts in the presence of sharp spectrum drop-offs, and indeed
>> if I turn off the "flatten" feature and manually set the zero point for the
>> waterfall, the artifacts go away.
>> 
>> It's still an open question as to why the data-a mode has a steep drop-off
>> at 400Hz when the PBT settings on the rig would seem to indicate otherwise,
>> and the same drop-off isn't there in USB mode.
>> 
>> I see searching on "400 Hz" that GM4JJJ had the same question here on the
>> last back in July 2015, but never really got an answer.  I basically have
>> the same question as this one:
>> https://www.mail-archive.com/elecraft@mailman.qth.net/msg183837.html
>> 
>>  Nick
>> 
>> 
>>> On 2 January 2017 at 12:06, Nicklas Johnson <nick at n6ol.us> wrote:
>>> 
>>> I'm seeing some unexpected audio artifacts when using DATA A mode with the
>>> latest production firmware on my KX3, on all bands.  This is something I
>>> observe when the PBT BW is set all the way wide (4KHz) and FC is centered.
>>> 
>>> In DATA mode, there's an audio drop-off between 200 and 325 Hz, with an
>>> almost completely dead audio "hole" between 250 and 300 Hz.  Then there's
>>> some additional noise between 350 and 500 Hz.
>>> 
>>> If I switch to USB mode (with no EQ or audio effects applied, naturally),
>>> all of these artifacts go away, and it's perfectly smooth across the
>>> spectrum.  No drop-off, no noise.
>>> 
>>> Pictures of the waterfalls for comparison here: http://imgur.com/a/AjHu4
>>> 
>>> Am I doing something wrong, or is there something I should check?  I've
>>> taken the usual steps, but it's plausible I've missed something.
>>> 
>>> ​   Nick​
>>> 
>>> --
>>> *N6OL*
>>> Saying something doesn't make it true.  Belief in something doesn't make
>>> it real. And if you have to lie to support a position, that position is not
>>> worth supporting.
>>> 
>> 
>> 
>> 
>> -- 
>> *N6OL*
>> Saying something doesn't make it true.  Belief in something doesn't make it
>> real. And if you have to lie to support a position, that position is not
>> worth supporting.
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