[Elecraft] Re: K3 DSP Filtering

[wayne burdick]

On Apr 29, 2007, at 5:20 PM, Mike Bates wrote:

> I am looking at the information so far on the new K3, it looks to be a 
> really nice rig. I have a question on the DSP filtering, that has not 
> been asked, or answered yet. How many filters are there in the DSP 
> Filter?

They're calculated instantly, on demand, so essentially they're 
unlimited. If you wanted to put a number on it, I'd say 500-1000. But 
you never have to think of it in those terms; simply adjust the WIDTH, 
SHIFT, HICUT or LOCUT controls as required.


> Are they mode dependent in their selection, or are they selectable 
> independent of mode?

DSP settings are stored per-mode and per-preset (I discussed presets 
I/II in an earlier posting). Crystal filters are selected either 
automatically as you adjust the DSP settings, or manually by tapping 
XFIL.


> Are they steppable by a single control as is done in the Ten-Tec 
> Orion, or are they settable using a fixed filter, and using shift 
> controls to change the filtering, as in the ICOM rigs.

We use two knobs that each have two functions. You can treat the knobs 
as SHIFT and WIDTH, or LOCUT and HICUT, easily toggling between the two 
representations. The LCD's DSP filter graphic, centered directly 
between the controls, shows you instantly how you have the passband 
configured.


> What is the frequnecy variance per filter(ie 10 Hz between filters, 50 
> Hz or some other number)?

We could set this up as the operator prefers, but at present we're 
using 50 Hz per step, which provides quite adequate resolution. At 10 
Hz it can take too long to change the passband. But again, this could 
be configured in a menu entry.


> One more question, How is good image rejection obtained on the general 
> Coverage Receiver?

We'll post this and other numbers after measuring a large sample of 
beta-test units.


> Also, is the synchrnous detector sideband selectable for AM mode...

This is Lyle's area, so I'll let him take the question (from the DSP 
perspective).


> and can it work with the passband shift/tuning control??

I'm pretty sure it will. Small matter of programming  :)

73,
Wayne
N6KR

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