[Elecraft] DSP, PSK31 and stuff

[Dave Gingrich K9DC]

At 10:06 7/3/2002 +0000, Nicholas Lokuciewski wrote:

>I have all the filters in my K2 setup as suggested in the manual 
>(including tweaking with spectogram), but I notice that when I select the 
>1.8khz filter, the signal strength and volume of the signal goes down. I 
>presume this is to do with the selectivity and properties of the crystal 
>filter?

It is abnormal for there to be a significant decrease in signal at 1.8 KHz 
bandwidth (assuming the desired sig is still in the passband). I do not 
notice a significant overall decrease with My K2, until I reduce the 
bandwidth to less than about 0.3 KHz.  I think I would re-do the alignment 
of the CW filter.

>Therefore, I thought that by using DSP I could leave the K2 filter in OP1 
>and use the DSP to do the audio filtering and get much better selectivity 
>(ie much straighter sides to the filters) and therefore the signal would 
>not go down as much. For example, have one filter set for normal SSB 
>bandwidth, one for 1.8Kz bandwidth, one for PSK31 and CW, etc... would 
>this work?

Would it work? Yes.  Would it work well?  Not nearly as well as the having 
I.F. filters do as much as possible.

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Dave Gingrich, K9DC - Indianapolis, Indiana  USA
K2 #2211, K1 #931, QRP-L #2376, ARS #1109,
FPQRP #389, IRLP 473/573,  k9dc.ampr.org
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