[Elecraft] Wrong Filter Question - 8 pole vs. 5 Pole Filters

[Bill W4ZV]

Bill W4ZV wrote:
> 
> 
> 
> Toby Deinhardt wrote:
>> 
>>> DSP filter responses can be calculated exactly, they don't actually
>>> have to be measured.
>> 
>> As long as we don't have exact and detailed information about the  
>> implementation of the filters in the K3, the responses curves cannot  
>> be calculated by third parties.
>> 
> 
> Correct.  Even within the K3 there are two choices for calculation of the
> DSP filters...Finite Impulse Response (FIR) or Infinite Impulse Response
> (IIR).  These can be toggled by pressing "7" when you are in any CONFIG
> filter menu.  I forget the exact range of applicable bandwidths but
> believe both are available at the narrowest WIDTH settings (~150 Hz and
> below).
> 
> 73,  Bill
> 
> 

Actually only for the 100 and 50 Hz filters...from the Elecraft Software
Page:
http://www.elecraft.com/K3/k3_software.htm

In Our Previous Release  -   MCU 1.58  and  DSP 1.48

    *

      NEW 100- AND 50-Hz DSP FILTERS: We've completed the addition of
high-performance 100- and 50-Hz "FIR" (finite impulse response) DSP filters.
These are flatter than the  original "IIR" (infinite impulse response)
filters, and exhibit less ringing, which is especially noticeable in the
presence of high noise. Some operators may prefer the original filters,
      which have a slightly different sound. To switch between IIR (old) and
FIR (new), tap '7'  on the keypad when you're in any filter setup menu entry
(e.g., CONFIG:FLx BW).
      To use the FIR (new) filters, tap '7' until you see "IIR OFF". This is
now the default for newly-shipped K3s. 

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