[Skimmertalk] WSJT-X/FT8 skimming: high PC CPU utilization limiting count of spots

[Bob Wilson, N6TV]

I use the RP-16 to skim 15 bands of CW, divided as follows

RP-16A: 7 "main" Bands:  80, 40, 30, 20, 17, 15, Low 10 - CW and RTTY
Skimming
RP-16B: 8 "secondary" Bands: 2200, 630, 160, 60, 12, High 10, Low 6, High 6
- CW Skimming only

RP14:  8 bands of FT8 with automatic Day/Twilight/Night rotation via SM7IUN
scripts, 160 to 6m.

73,
Bob, N6TV


On Sat, Jul 27, 2019 at 11:26 AM Andy KU7T <ku7t at ku7t.org> wrote:

> Hi,
>
> I am using a single Z400 PC with the new RP 16 bit SDR to skim CW and FT8.
>
> I made a few experiments. It seems if I run 8 bands FT8/WSJT-X, I often
> get time periods with no decodes. If I reduce the number of bands to 2 - 3,
> so that the CPU utilization spikes stay below 100%, I actually get more
> spots out.  Last night, my number of spots in 24 hours increased by 100%
> after I only skimmed 40,30,20 on FT8 (10 on CW).
>
> So, it seems to me, WSJT-X is very time critical and if it cannot decode
> things in time, it just drops the data. That is unfortunate, as for
> skimming, I would not mind waiting 5 seconds to get the decodes out, as
> that would probably level the CPU util spikes more... Anyway, it is what it
> is, and I am not sure if the WSJT-X guys would be interested in looking
> into an optimization like that.
>
> I am trying to evaluate my options. I list them here in case someone sees
> other options or errors in my thinking.
>
>
>    1. 2nd PC: PC1 skims maybe 6 bands in CW and FT8 from first receiver,
>    PC2 skims the rest from the 2nd receiver
>    2. 2nd RP: Run all FT8 bands on an RP with the Linux skimmer (not
>    WSJT-X) and use PC1 for CW (and maybe one or two bands of RTTY)
>
> I believe the 2nd option is much cheaper on equipment and running costs.
> Comments? What do others do?
>
> Thanks,
> Andy
> KU7T
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