[Skimmertalk] CW frequencies for 6m?

Bob Wilson, N6TV n6tv at arrl.net
Thu Dec 6 12:22:31 EST 2018


On Thu, Dec 6, 2018 at 6:40 AM Björn Ekelund <bjorn at ekelund.nu> wrote:

> I did know that sensitivity rolls off close to the edges of the sampled
> subband, but I thought this catered for by
> the difference between the 182kHz "bandwidth" (twice the center offset) and
> 192kHz "sample width".
> Or have I got this wrong?
>

With those default settings on a Red Pitaya, using CWSL_Extio and HDSDR, I
could still see reduced sensitivity (roll-off) *above* the band edge, so I
shifted all the center frequencies down by another 6 kHz (for 192 kHz
spans), and by 3 kHz (for 96 kHz spans,) and by 1.5 kHz (for 48 kHz spans).

More details and links to a screen shot here:

https://groups.io/g/RBN-OPS/message/1793

However, if the noise floor doesn't seem to roll off at all above the band
edges with your Red Pitaya, then there's no need to make any changes.  It
all depends on what you're seeing with HDSDR and your RP.

73,
Bob, N6TV


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