[Elecraft] K3 Reduced BW FSK

[Mark n2qt]

I had missed that this wasn’t discussed on  this reflector, so first a little history

At the end of December, on the RTTY reflector, Andy K0SM/2 produced measurements showing that the 
use of FSK, which had been the ‘gold standard’ for generating RTTY was actually not as spectrally efficient 
as correctly adjusted, shaped AFSK generated RTTY.   This was shown in his write-up posted at 

http://www.frontiernet.net/~aflowers/k3rtty/k3rtty.html

Note that this does NOT indicate that there was any sort of problem with the K3, just that there was a chance
to be better.  Other manufacturers also have this same chance to improve.

A little later, Ed, W0YK, also known as P49X in many contests, announced that he had successfully used
experimental DSP firmware from Elecraft in the BARTG rtty contest.  

“The K3 DSP firmware engineer coded a  wave-shaping filter that narrows the transmit bandwidth similar to 
what their AFSK filter provides. The resulting spectrum image looks  like the better, i.e., narrowest, of the 
images in K0SM's  recent work.”

Elecraft then allowed Ed to share this firmware with others who were interested in trying it, which is how I got it. 

As anyone who was in the WPX RTTY contest this past weekend knows, anything that can help reduce the
unnecessary interference from overly wide transmissions is more than welcome.  It is great that Elecraft has 
reacted so quickly to this opportunity.  (Would we expect anything less from these guys??)

Mark N2QT/WE4M

From: Stephen Prior 
Sent: Wednesday, February 13, 2013 3:22 AM
To: Mark 
Cc: elecraft at mailman.qth.net 
Subject: Re: [Elecraft] K3 Reduced BW FSK

Mark,

You will have to enlighten us (well, me anyway) - just what pre-beta software are you referring to?

73 Stephen G4SJP



On 13 February 2013 04:10, Mark <n2qt at verizon.net> wrote:

  Just a report that I used the pre beta low bandwidth fsk software on both k3s during the
  WPX RTTY contest.  Made over 1900 low power contacts, with no apparent problems
  (As expected).  As close as some stations felt comfortable operating next to me, it looks
  like it helps.

  With the ever increasing popularity of rtty contesting, improvements like this helps
  us all.


  Mark. N2QT/WE4M
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