[Elecraft] KDSP is done

[Phil Wheeler]

Kevin Cozens wrote:

> At 09:34 PM 05/21/2003 -0400, gwlillie wrote:
>
>> Just finished dsp and everything works fine. No problems so far and 
>> it was a perfect fit. Noise reduction is great but as you know it 
>> will affect  rec audio in the form of distortion. Its a little like 
>> having your speaker under water.
>
>
> Can you please clarify your statements about the KDSP and it causing 
> distortion in the audio. Are you speaking from experience of using the 
> KDSP in noise reduction mode or are you speculating about expected 
> distortion based on other inexpensive DSP units?
>
> I have used a JPS Communications NIR-10 DSP unit for several years. It 
> was an expensive purchase at one of my trips to Dayton. On a band like 
> 10m or 15m where band noise is fairly low, the NIR-10 in noise 
> reduction mode would almost make you think the band was dead as it 
> would take out all the background noise. When you tuned in a signal, 
> it would just pop right out at you. It was a pleasure to work stations 
> with little to no background noise and there was no audio distortion. 
> I would expect the KDSP2 would behave in a similar fashion. 


PMFJI, Kevin.  I do not yet have a KDSP (couldn't make it to Dayton, 
alas .. so I am waiting for mine to arrive in late June or so).  But I 
have used numerous commercial audio DSP units such as the JPS NIR-12, 
DSP in my TS-570DG, Timewave 599ZX (or whatever that model is), etc. 
 I've found all to produce artifacts on an SSB audio signal, including 
the NIR-12 (which is an improved NIR-10).  But in most cases the overall 
result was improved intelligibility and reduced noise.  The "having your 
speaker under water" may be a good characterization. of the artifacts, 
particularly with aggressive processing; I've always thought of it as a 
"watery signal".

It seems inevitable that shoving any signal through a filter will 
"distort" it by removing some part of it.  But usually you can temper 
that by choosing how aggressive to make the digital signal processing.  

Based on the technical discussion ("Design Notes"?) written by Lyle and 
posted at the website, I expect the KDSP to outshine any I've used in 
the past, because of the way the design is integrated into the K2 and 
the excellent (and adjustable) xtal filters ahead of the DSP.

73, Phil