[Elecraft] Audio artifacts in DATA A mode with KX3

[David Anderson]

Harry,

This isn't a switch it on and off again problem I am afraid. It is simply that the KX3 Data Mode is restricted in bandwidth at the low end, unlike the SSB mode on the same radio. Bizarre but true.

73 from David GM4JJJ

> On 3 Jan 2017, at 00:00, Harry Yingst via Elecraft <elecraft at mailman.qth.net> wrote:
> 
> Back when I was playing with SDR's I would notice the same thing (Deep nulls)
> Sometimes resetting the software (or turning the rig on and off again) would cure it.
> 
> Something to try
> 
> 
> 
> 
>      From: Nicklas Johnson <nick at n6ol.us>
> To: elecraft <elecraft at mailman.qth.net> 
> Sent: Monday, January 2, 2017 6:54 PM
> Subject: Re: [Elecraft] Audio artifacts in DATA A mode with KX3
> 
> 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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