[Skimmertalk] red pitaya, for real?

Pete Smith N4ZR n4zr at contesting.com
Thu Sep 1 09:52:14 EDT 2016


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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