[Skimmertalk] Red Pitaya STEMlab SDR 122-16 now online at N6TV

[Björn Ekelund]

 Bob,

On my skimmer PC (an old Core i5 NUC) I start Aggregator and my two
instances of CW Skimmer Server via
Window's built-in autostart at boot. I however found that if I start the
two Skimmer Server instances at the
same time, they somehow interfere with each other and after trying to
connect to "their" HPSDR receiver
a few times they both crash. This in spite of each instance being "locked"
to a particular receiver via the
MAC-address suffix on HermesIntf.

The remedy was to delay the start of the second Skimmer Server with 15
seconds or so.
I use https://www.r2.com.au/page/products/download/startup-delayer/

73,

Björn SM7IUN

Den ons 5 juni 2019 kl 06:05 skrev Bob Wilson, N6TV <n6tv at arrl.net>:

> I've replaced two (2) Red Pitaya 125-14 boards with a single STEMlab SDR
> 122-16, which is now online.  It is currently set up to skim 192 kHz slices
> on 3.5, 7, 10, 14, 18, 21, and 28 MHz, running CW Skimmer Server and RTTY
> Skimmer Server via CWSL_Tee on the first MAC address, and 45, 384, 1800,
> 5330, 24890, 28200 and 50000 kHz CW only skimming on the second MAC
> address.  The "top" command on Alpine Linux reports about 35% CPU
> Utilization for the first MAC address (eth0), and 44% CPU for the second
> virtual MAC address (mvl0 - "Mac VLAN") (total, 79%).  I removed the 14:1
> impedance transformer, but kept the 10 dB Clifton Labs preamp for now,
> which I may end up removing.
>
> The critical thing I had to remember to do was to update CWSL_Tee.cfg in
> the RBN directory to use the new MAC address, as well as renaming
> HermesIntf_XXXX.dll to match the address I wanted each skimmer to use.
>
> The only problem I'm seeing is very broad and loud AM or FM broadcast band
> (?) inter-mod at the top and bottom ends of the two 10m segments, as shown
> here:
>
> https://www.kkn.net/~n6tv/STEMlab_SDR_122-16_Intermod_N6TV.png
>
> The screen shots are from HDSDR via Extio_CWSL.dll and Extio_CWSL2.dll.
>
> There are FM broadcast stations very close to me, but the closest AM
> broadcast station is a few miles away.
>
> The antenna is a VE3DO loop
> <http://www.ok1rr.com/index.php/antennas/8-the-ve3do-receiving-loop>
> (passive
> antenna) which isn't particularly sensitive on 10m, but I saw some of the
> same inter-mod issues on my Pixel loop (active preamp).
>
> Switching back to the STEMlab SDR 125-14 with the same VE3DO loop antenna
> and preamp, but with the 14:1 transformer inline, I see only a little bit
> of the same interference (it is much weaker).  It disappears completely
> when I disconnect the antenna.
>
> I tried bypassing the preamp, but it made little difference.  Maybe I need
> a high-pass or low-pass filter on the SDR input, or both, or a broadcast
> band filter.  I haven't identified the station yet.
>
> Other than those issues, I'm pleased with the replacement, as now I can do
> with a single Red Pitaya SDR what I was previously doing with two different
> boards.
>
> Now if only there was a way to start both instances of CW Skimmer Server
> automatically from the Aggregator.  For now, the second has to be started
> manually, same as before.  Terminating the second skimmer immediately stops
> the first, so  have to restart (the "NOW" button the the Aggregator .INI
> tab is very handy for this).
>
> The CPU is an Intel i7-7700 3.6 GHz, CPU Mark 10731.  I think 7 bands of
> RTTY Skimming is the maximum it can handle.  The Windows CPU utilization
> runs about 65-70%, but much higher when there are lots of RTTY signals on
> the bands.  Network throughput to the SDR seems to be a steady 150 Mbps
> over 1 Gb Ethernet with 14 bands x 192 kHz.
>
> This web site below is a good reference to check CPU speed for just about
> any processor you might consider using for RTTY Skimming:
>
> https://www.cpubenchmark.net/CPU_mega_page.html
>
> Just about any processor can handle CW Skimming.
>
> 73,
> Bob, N6TV
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