[Elecraft] Shortwave filters for K3

[Don Wilhelm]

Steve,

Please do not be confused.  The DSP *is* at the IF frequency, *and it 
does* process AM at the full bandwidth for all modes as required.

The AM bandwidth *used to be* displayed as the IF bandwidth, but many 
were confused because it was double the bandwidth that could be heard - 
so it was changed to *display* the audio bandwidth.
It is a matter of display only, and not the actual operating IF width.

The display of the audio bandwidth in AM is consistent with the 
bandwidth displayed for other modes - the audio bandwidth is what is 
displayed.  (FM might be different, I don't have the FM filter to try).  
In any case, now the DSP displayed bandwidth is equal to the audio 
bandwidth, no matter what the actual IF processing width may be.

73,
Don W3FPR

Steve Ellington wrote:
> Don
> I understand the demodulation theory just fine but the concept of having the 
> DSP act as an audio filter instead of an IF filter causes some confusion 
> since we've been hyping up "IF-DSP" filtering for several years now and 
> suddenly we talk about AF-DSP in only one mode, AM.
> Maybe if the BW display showed 10 Khz instead of 5 Khz it would limit the 
> confusion since that seems to be what most of us are used to. We understand 
> that we only hear one of the two sidebands anyway. Oh well,,, I guess the 
> question will keep coming up.
> Steve Ellington
> N4LQ at carolina.rr.com
>   
>