[Elecraft] Multiple Ghost Image CW Decodes While Using CW Skimmer & a K3

[Guy Olinger K2AV]

3 X the sound frequency sounds like sound card over-drive, or simply
exceeding the actual linear range of the sound card.  On-board sound chips
and cheep Chinese sound cards are particularly vulnerable to showing
odd-order effects if you look way down.  Those can sometimes be
significantly improved by managing the range of input sound and line-in
levels.

If you want to see a clean 100 dB range in audio devices, you will have to
get a high-end audio card.  The cheep stuff just doesn't go there.

73, Guy.

On Mon, Feb 28, 2011 at 1:53 PM, kk7uq <discobay at waypt.com> wrote:

> Hi Tom
>
> SNIP
> -----------------------
> Been toying around with CW Skimmer, kinda an interesting program.
>
>  Anyway, I'm receiving multiple "ghost image" CW decodes from the same
> station while running Skimmer. They are 1 Kc or so apart from another.
> Better stated, the same stations signal is being shown on the horizontal
> waterfall numerous times. I have tried narrowing the K3's filters, reducing
> sound card audio into Skimmer & toyed around with every other parameter
> with
> no success.
> ------------------------
>
> I have seen the same thing on strong signals displayed on CW Skimmer.  On
> DX
> Skimmer, I can see the same signal at 3x the pitch frequency.  I can not
> see
> it on the waterfall view of the spectrum from MixW which is running at the
> same time.  This particular signal was running 50 dB above noise level and
> harmonics were not visible in either the MixW spectrum or waterfall
> display.
>
> If I increase the audio output level from the interface to the point where
> there is clipping in the audio coming from the interface, I can see the
> signal at 2x, 3x and more on the skimmer waterfall, but can only see the 3x
> signal on the MixW waterfall.
>
> Try reducing your audio drive into the soundcard input to be sure a strong
> signal is not clipping there, and then see if the multiple copies go away.
> CW Skimmer does it's own AGC so it can operate well with reduced audio
> levels.
>
> 73, Clint KK7UQ
>
>
> --
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> Sent from the Elecraft mailing list archive at Nabble.com.
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