[Skimmertalk] red pitaya, for real?

[David Robbins]

My cw skimmer server with the qs1r runs on an older intel core-2 quad core
at 2.3ghz with 8gb of ram and does just fine.  The extra memory isn't really
needed for the skimmer server as it rarely goes over 120mb of use.  The
whole win7x64 machine is also running my local version of the ar-cluster and
some other stuff and is usually under 3gb total use.  I normally run the
skimmer with 7 bands at 192khz but for big contests scale it back to 6 bands
or less depending on load.

My rtty skimmer with the red pitaya is on an i-7 3.6ghz 8 core with 8gb ram.
Again ram usage is not an issue, but when there are lots of decoders even
that cpu has to throttle back the rtty skimmer.  I normally run it at 6
bands at 96khz which pretty well covers most rtty activity in and out of
contests.  I haven't seen it in a big contest yet, probably the end of the
month we'll see how it does in cqww rtty.

David Robbins K1TTT
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net:7373



-----Original Message-----
From: Skimmertalk [mailto:skimmertalk-bounces at contesting.com] On Behalf Of
Pete Smith N4ZR
Sent: Thursday, September 01, 2016 13:52
To: skimmertalk at contesting.com
Subject: Re: [Skimmertalk] red pitaya, for real?

Good advice from Nathaniel.  However, my personal Skimmer machine is acheapo
ASUS mobo with onboard video and audio, 8 GB of RAM, and an AMD FX-8350,
which I built for less than $450 including Windows 7..  It is more than
adequate for CW Skimmer on 6 bands in CQWWCW, but, like even a fast i7,
suffers under the load from RTTY Skimserv during a contest. I believe that
WZ7I has gone to the fastest i7 he could get for a dedicated RTTY Skimmer
machine, and may even be skimming some of the bands with another machine.

73, Pete N4ZR
Download the new N1MM Logger+ at
<http://N1MM.hamdocs.com>. Check
out the Reverse Beacon Network at
<http://reversebeacon.net>, now
spotting RTTY activity worldwide.
For spots, please use your favorite
"retail" DX cluster.

On 8/31/2016 7:47 PM, Nathaniel A. Frissell wrote:
> Again, I agree with Pete. My personal experience is that lower end 
> machines struggle. This includes 2-core machines that are 2 to 3 years 
> old with 4 GB RAM.
>
> I recently upgraded to a Dell XPS8900 with a Core i7-6700 processor 
> and 16 GB of RAM. So far, that machine does very well. My 
> recommendation is that if you can afford it, it is good to go with 
> that class of machine. It will handle the CW Skimmer Server with room 
> to spare. Although I haven't tested it, a good Core i5 with 8 GB of 
> RAM might also perform reasonably. But, that is just speculation!
>
> So far, I found every time I buy a "cheaper" computer, it ends up 
> costing me more because I very quickly outgrow it and I need to 
> replace with something that will actually get the job done.
>
> 73,
>
> Nathaniel, W2NAF
>
> On 08/31/2016 12:55 PM, Pete Smith N4ZR wrote:
>> Just one guy's opinion, but I don't think we'll really know until 
>> someone runs an RP on CQWW weekend. RTTY Skimserv is a much heavier 
>> CPU user- the hottest i7 is none too strong for a big RTTY contest.
>>
>>
>> My next project here is to compare my RP and a QS1R off the same 
>> antenna and preamp (through a splitter), both running Skimserv and/or 
>> HDSDR.
>>
>> 73, Pete N4ZR
>> Download the new N1MM Logger+ at
>> <http://N1MM.hamdocs.com>. Check
>> out the Reverse Beacon Network at
>> <http://reversebeacon.net>, now
>> spotting RTTY activity worldwide.
>> For spots, please use your favorite
>> "retail" DX cluster.
>>
>> On 8/31/2016 11:31 AM, kazeringue--- via Skimmertalk wrote:
>>> Alright, thanks folks.
>>>
>>> The Red Pitaya looks pretty interesting just for its capabilities as 
>>> a test device, which should improve with software over time. That 
>>> would be a lot of help with testing on the band pass filter 
>>> projects. I foresee another project..... a bank of W3LPL design rx 
>>> bandpass filters as a preselector between the antenna and preamp 
>>> going into a Red Pitaya SDR, and use the Red Pitaya to tune them.
>>> [50kw 680 AM broadcast antenna is 1.2 miles from my house]
>>>
>>> Being able to run RP as a skimmer server would be a big bonus.
>>>
>>> Idle speculation, the high impedance on the inputs is there for its 
>>> use as a scope/test instrument.  Bypassing them per K1TTT jumper fix 
>>> might be easier than trying to match them for SDR use. Figuring out 
>>> a good match for the amp block following JP5 might be worth the time 
>>> tinkering.
>>>
>>> Interested to hear more from Dai on the S9-C also.  More options is 
>>> good.
>>>
>>> So, one last question.  What sort of CPU is sufficient for a Red 
>>> Pitaya based SDR?  What sort of CPU's have been used and what sort 
>>> of CPU % usage is the skimmer server drawing?
>>>
>>> I have been running up to five softrocks on a single Dell core 2 
>>> quad box(2 physical threads, 2 virtual threads) under windows 8.1.
>>> With all five running on a contest weekend, the CPU is over 50%, 
>>> usually closer to 70%.  The tough part of that kludged skimmer 
>>> station was finding five different sound devices that could coexist.
>>> (Four plus the onboard sound.) Since the 15m softrock kludge 
>>> generates more bad mirror image spots than the others, I generally 
>>> just run four skimmers, 160/80/40/20.
>>>
>>> 73 de w4kaz
>>>
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>>
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