[Elecraft] K3 RTTY Audio Thru External DSP

[Don Wilhelm]

Jim,

As I recall, there is a reason NR is not available in digital modes - it 
distorts the signal and reduces copy capability..
The digital decoding is happy to extract a signal from the noise - some 
more so that others, and some data modes can extract a signal 
significantly under the noise level, so NR is inherent in the digital 
decoding.  You can try it, but I suspect your digital reception will be 
reduced with the presence of external DSP NR between the K3 and the 
computer soundcard.

This is not intended to put a damper on your experiment, so give it a 
try and let us know the results.  If you can provide some repeatable 
stimulus and output data with the no DSP vs. the DSP added, that would 
be informative and useful.

73,
Don W3FPR

On 12/24/2011 5:08 PM, Jim Harris wrote:
> Hi to the group and Merry Christmas
> Has anyone used an external DSP (noise reduction) between the output of the K3 and a computer sound card?  What was your experience with it?  Before telling me the K3 provides all the noise reduction needed, remember the NR is turned off in digital modes.  I'm contemplating using a JPS NIR-12, Noise/Interference Reduction Unit.  
> If anyone has any experience with this setup how did you hook it up?  Which output from the K3 did you use; headphone, speaker or lineout?  Which output from the DSP; headphone, speaker or lineout?  Did you use or find necessary to use an isolation transformer between the K3 and the DSP and the computer sound card?
> My primary concern is to prevent ground loops.  The NIR-12 schematic appears not to have any isolation on the outputs as does the K3 on the lineout.
> I would appreciate any meaningful comments.  
> Take pride in the USA. 73
>
>