[Elecraft] K3 AFSK TX Filter

[David Woolley]

On 04/12/14 18:20, Joe Subich, W4TV wrote:

> The K3 does not generate AFSK internally.  AFSK is only transmitted
> in response to external audio.

But that is exactly how SDR architecture transmitters do generate FSK. 
The only difference from what is popularly called AFSK is that the tone 
starts as digital sine waves.

The ones may be a bit higher pitch than one normally expects from AFSK, 
but they are still audio tones.

(As the K3 uses an I/Q structure, you could, theoretically, generate the 
two tones as positive and negative tones at the same frequency, but the 
problems with handling the DC crossover means that it is unlikely that 
anyone would do that.)

In case it is not clear, I consider both the K3 and KX3 to be SDR designs.

-- 
David Woolley
Owner K2 06123