> I found that the width control is optimized between 500 and 450 Hz.
> Less than 450, the non-coherent phase shifts are introduced, as you
> mentioned "is caused by filter ringing".
What roofing filter are you using? If it is an Elecraft 5-pole filter
is the the offset properly set?
Are you using the K3's Dual PB filter?
Remember, the K3's DSP filters have very steep skirts. The selectivity
in most other rigs is entirely related to the skirts of the IF filters;
the filters in other "modern" DSP based are much "softer" and tend to
emulated the 1;8:1 - 2.2:1 shape factor (depending on bandwidth) of the
crystal filters. "Ringing" tends to be directly related to the nature
of the filter in the area of the "knee" and once the bandwidth is less
than 450 Hz the knee is impacting the keying sidebands.
73,
... Joe, W4TV
On 9/3/2011 12:32 PM, wa9fvp wrote:
> The butterfly filters are tuned exactly to the tone frequency. When the
> cross pattern is vertical, it's spot on 2125Hz, horizontal is exactly
> 2295Hz. I changed the DATA Mode to AFSK using a single filter and that
> works the best. I found that the width control is optimized between 500 and
> 450 Hz. Less than 450, the non-coherent phase shifts are introduced, as
> you mentioned "is caused by filter ringing".
>
> -----
> Jack WA9FVP
> Willco Electronics
> --
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