[Skimmertalk] CW frequencies for 6m?

[Björn Ekelund]

Thanks Bob!

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?

I would have no problem shifting my subbands down, though, since i
typically stop each band's CwSegment
around 70kHz above the lower band edge.

Björn SM7IUN


Den ons 5 dec. 2018 kl 23:27 skrev Bob Wilson, N6TV <n6tv at arrl.net>:

> On Wed, Dec 5, 2018 at 6:37 AM Björn Ekelund <bjorn at ekelund.nu> wrote:
>
> > Now the question is which frequency range I should chose?
> >
>
> With my "secondary" Red Pitaya, I scan the 7 least-used bands, including
> 6m, CW only.  Center frequencies were modified to get the most sensitivity
> at the lower band edges (with the default skimmer settings, sensitivity
> rolls off before you get to the band edge, as seen on HDSDR):
>
>
> CenterFreqs192=136750,475000,1885000,3585000,5417000,7085000,10185000,14085000,18153000,21085000,24975000,28085000,28255
> 000,50085000,50255000
> SegmentSel192=111010000010110
>
> CwSegments=135700-137800,472000-479000,1800000-2000000,3500000-3600000,5330000-5407000,7000000-7125000,10100000-10130000
>
> ,14000000-14150000,18068000-18115000,21000000-21200000,24890000-24935000,28000000-28300000,50000000-50200000
>
> For my "primary" Red PItaya, I scan the 7 "most-used" bands, *both* CW and
> RTTY:
>
>
> CenterFreqs192=475000,1885000,3585000,5417000,7085000,10185000,14085000,18153000,21085000,24975000,28085000,28255000,500
> 85000,50255000
> SegmentSel192=00101111101000
>
> CwSegments=472000-479000,1800000-2000000,3500000-3600000,5330000-5407000,7000000-7125000,10100000-10130000,14000000-1415
>
> 0000,18068000-18115000,21000000-21200000,24890000-24935000,28000000-28300000,50000000-50200000
>
> The RTTY Segments are carefully selected to exclude FT8 frequencies,
> otherwise RTTY Skimmer wastes much CPU time on your PC trying to decode
> FT8.
>
>
> RttySegments=1800000-1820000,3520000-3571000,3577000-3600000,5330000-5407000,7020000-7071000,7077000-7100000,10130000-10
>
> 132000,10139000-10150000,14060000-14071000,14077000-14150000,18109000-18115000,21060000-21071000,21077000-21150000,24910
> 000-24930000,28060000-28150000,50250000-54000000
>
>
> > I am currently running my skimmer at the 96kHz setting and it would of
> > course be easy to step that up to 192kHz but that means noticably
> increased
> > heat
> > in both my Red Pitaya and skimmer PC.
> >
>
> Red Pitaya should have a 5V fan powered via the two header pins next to the
> Ethernet connector (positive pin is the one closest to the center of the
> board).  i7 PC should be able to handle RTTY skimming better if you exclude
> the FT8 segments as shown above.  CW skimming alone should not stress a
> modern CPU at all even with 8 bands x 192 kHz.
>
> My current setting is running the skimmer to cover the 50,060-50,151 range
> > with the 96kHz setting.
> >
>
> Try 192 kHz.
>
>
> > What you have others set it to?
>
>
> FYI, you can see the ranges scanned (and FT8 frequencies ignored in my
> case) at http://reversebeacon.net/nodes/detail.php (Detailed node list).
> I
> don't have a decent 6m antenna yet so I never get any spots there though.
>
>
> > Are there other considerations, like beacons?
> >
>
> All CW beacons should definitely be spotted by Skimmers if possible.  See:
>
> http://reversebeacon.blogspot.com/2017/09/beacons-revisited-checklist.html
>
> 73,
> Bob, N6TV
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