[Elecraft] K3 rtty decode vs: computer decode

[Fred Jensen]

Well ... I'm not sure FSK is actually "foolproof," based on the number 
of posts to this list about problems getting FSK running using various 
external interfaces.  It is true that AFSK is "Audio in/out" and can 
overdrive things, not easy in a K3 but certainly possible.  Even cheap 
sound cards deliver essentially pure sine wave audio, the better ones do 
even better.

One should never underestimate the populations' ability to screw up any 
technology, but beyond that, and assuming that two hams are equally 
smart and equally adept at setting their gear up, is there really any 
discernable difference between the two methods with a K3?  I think 
that's my root question -- "What is it about direct FSK that makes folks 
want to go to lengths to get it working?"  And, I'm not so sure that 
"direct FSK" in a K3 is what it was in a T-368 45 years ago.

I grant that with older rigs, carrier and opposite sideband suppression 
could, being generous here, be questionable, and the AFSK result would 
not be pretty.  But that was a long time ago and we're talking about 
K3's now.

73,

Fred K6DGW
- Northern California Contest Club
- CU in the 2014 Cal QSO Party 4-5 Oct 2014
- www.cqp.org

On 3/24/2014 4:33 PM, Wes (N7WS) wrote:
> FSK might not have "excess" bandwidth, but AFSK can have narrower
> bandwidth.
>
> http://www.frontiernet.net/~aflowers/k3rtty/k3rtty.html#K3_AFSK_filter
>
>
> On 3/24/2014 5:27 AM, Barry wrote:
>> Fred,
>> If set correctly, there's no difference.  However, FSK is foolproof.  It
>> can't be overdriven with excessive audio input resulting in excess
>> bandwidth
>> and spurs.  Some of it is historical, as in some older radios, narrow
>> filters cannot be used in AFSK mode.
>> Barry w2UP