Just a thought on Mini PC's for Amateur Radio Astronomy

[Stephen Arbogast]

I  was wondering  if  it  would  be worth while to do a  survey on  the  RFI  that is  generated   by  mini pc's.     For ten months  now  I have been learning/experimenting  with Amateur  Radio Astronomy/Hydrogen Line.  My experience has been  with three  computing  hardware platforms   and numerous   software  packages.  Many people  have offered  suggestions on how  to  reduce  RFI  and  I tried them all,    with  some  success.

I have  found;

  2012 iMac Intel  runinng  Ubuntu...   no problems 

  2025  BeeLink  AMD   Ubuntu ..  no problems

  OrangePi 5 Plus  running    Ubuntu  terrible !!!!

I am  not  suggesting a  detailed ,  critical scientific  analysis  just  some  general observations   from  experience. 

As for   software  I  am   settling on, in no order.

Ted Cline's  ezRA     very cool stuff

Alex  Pettit   very cool stuff

Marcus Leech's BAA  GNU Radio    extremely  cool  stuff.

Just  my  thoughts...   I think when  Ted Cline solves  the problem   of  using  GNURadio  for  ezRA  this  will be a  giant leap  forward....   with built in thread  management   and   scheduling. 

[edhar...@gmail.com]

For curiosity:

1. What case did you use?
2. What did you do to try to mitigate it’s RFI?
1. Cover any exposed data ports.
2. Metal case/enclosure.
3. “Good” ferrite on the power at a minimum.

Just curious as to what you’ve done.  (Curious to see what develops from this.  Personally I am interested as to what extent is needed to quite an Orange or Raspberry down to be useful.)

 

I know from prior discussions on RFI that exposed (unconnected) USB/Ethernet (and I’ll assume HDMI) are known RFI sources… I believe even on the ‘best’ machines.  Also some things that can be done to reduce RFI (software/hardware shutdown of unconnected ports) are not typically implemented on ‘experimenter’ devices.

 

Raspberry Pi (and cousins)/Arduino/ESP/… are NOT RFI qualified as they are not ‘complete’ systems that the manufacturer has to get certified.  Any basic assumption that they should be RFI quite I believe is flawed.

 

Personally, I like the price point of the various Pi’s, but am concerned about the RFI factor and have wanted to know whether the effort/cost of quieting down the device tips the balance to the mini-PCs.

 

I look forward to the discussion and thoughts!

Ed

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[Stephen Arbogast]

t other  tasks.

[Stephen Arbogast]

Very  sorry,  I  pushed  the  wrong  button..   

..  

I  agree    with  Ed..    I used this  case...   https://www.amazon.com/GeeekPi-Orange-Cooling-Heatsinks-Compatible/dp/B0C8HDS2NB/ref=sr_1_3?dib=eyJ2IjoiMSJ9.SuE3xIKN5x5UzqWF71MebObIYAA6rl9Lu-JABtUq6BxKYXPL93A8ax4jLNKePKY4vPoaf8__DlxhG0ulWZz3RtyoAAdLVEbWxcN70i803k-m3Mr16nUOvddMa7YtYuZ94AJ52-PaEa6DmqsjVYbVms2X4Ux9s_zfYe0KvJPAoiibOh9sBQ1e4J0MtgN-3b3oWtNGrQzm0R9f-DtuOBXo0nAba4QJZhKI0FmpjwG07bo.ffXDDmRYLb26uEEecXnHihsN5kyvGm4GbtMlL4erU9c&dib_tag=se&hvadid=693619266631&hvdev=c&hvexpln=67&hvlocphy=9029146&hvnetw=g&hvocijid=4949170276375553655--&hvqmt=e&hvrand=4949170276375553655&hvtargid=kwd-2482849808607&hydadcr=24363_13517587&keywords=orange+pi+5+plus+enclosure&mcid=183edf27df9e359a9a8b60eed54b6155&qid=1761094760&sr=8-3

I  tried    all   suggestions from numerous  people...  most  helped a  little .     I found the  most helpful  to be  put  your    mini pc in a  Faraday  cage  removed  from you    antenna.....

Just    curious  about    other's  observations .

[Marcus D. Leech]

One of the issues is that the mini-X86-PC technical "line-up" changes really frequently.  Even something that is marketed under the same model number may have chips changed
  on the motherboard throughout the product life-cycle.  It's very much a "moving target".

[kb3puw]

From my experience my old Toshiba laptop was terrible.  My new ROX Strix laptop is very good.  Don't know for sure, but I think it may be related to internal shielding.  If you are using a motor guided mount, that matters too.  I have an iEXOS-100 and a Celestron AVX.  The iEXOS generates far to much RFI to use - the AVX works very nicely.

Here is a sample of some data I evaluated.  All of the Toshiba data sets were very "spikey" - the ROG was pretty clean (the Cyg A):

[Pablo Lewin]

I'm using the MeLE Fanless Mini PC Quieter3Q N5105 4GB 128GB with Windows 11 Home, Micro Computer on my 2.1 meter dish with no noticeable RFI, from $144 to about $250 (Amazon) depending on the RAM/hard drive combination. The ONLY caveat is that it gets HOT!!, I mean VERY HOT but it's engineered that way...it runs well and lasts a long time!.

Pablo WA6RSV

[andrew....@googlemail.com]

I use Intel i5 miniPCs (Levono/Dell/HP) with 8GB RAM and 256GB SSD – available in UK for £50-£100.

Andy

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[Edmund Harfmann]

One thing I've wondered about is the fanless mini PCs such as  Amazon.com: KINGDEL Powerful Mini Desktop Computer, Fanless Industrial PC, i5 Dual Core CPU, 8GB RAM, 256GB SSD, 2xNICs, 4xUSB 3.0, 4xCOM RS232, HD Port, WiFi, Metal Case, Silent Working : Electronics.

"Pluses":

• "industrial" - should be able to handle outdoor temperatures and humidity better.
• Available in various processors so you could get lower prices.
• No moving parts (fans)
• "industrial" implies more rugged.
• Metal case on many 'might help' in RFI..  Might still have to do some work.. Especially on the brick.

Minuses:

• Price is more.

Ive been leery about using laptops unless they are in climate controlled (at least for consumer grade).  They always have been a bit fragile despite careful handling.

Ed

[Stephen Arbogast]

Further  comments on the use  of my Orange Pi 5  plus both  good  and  bad..

1.  I can still  use  it for post processing (ezRA) of  data  I have collected not  using  it.

2. It is not  well supported   by  Linux.

In  summary,  if you have one it  can be useful  but  I would not  recommend   buying  one.

[andrew....@googlemail.com]

According to copilot, The Orange Pi 5 supports several operating systems, including:

• Orange Pi OS (the official OS developed by Orange Pi)
• Android 12.1
• Debian 11
• Ubuntu 20.04
• Ubuntu 22.04

 

So, Stephen, are you saying the claim it runs Ubuntu is not correct?

 

Andy

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[Stephen Arbogast]

Andy,

I   am  running  this  software...   https://github.com/Joshua-Riek/ubuntu-rockchip

It is  working ok for me for now but   Joshua-Riek  is  no  longer supporting  it.  He notified us  that  he  had  reached  the  maximum free space allowed  on GitHUb  for  his project  and no one  was willing  to contribute to pay for  more  storage space.

I am  still  using  my  Orange Pi 5 Plus  for tasks  where  RFI    is not  a  problem   such as  post  processing  using  ezRA..    It just  does not  meet  RFI  compliance.

I plan  to keep using it for a while but  will eventually drop it.

How is  your  SDR-Play  project going?  I am  following  your  posts on the GNU-Radio list-server.   

Stephen

[Stephen Arbogast]

I have a  .grc file  I use   with  my  Air Spy R2  that  works...  not  exactly  like  ezRACol  in that it does not  shift frequency   to collect a  background  reference.   It is  cool to watch ...   You  would have  have to insert the  correct   source  block  for  SDRPlay.   

[Stephen Arbogast]

Andy,

Be careful  with copilot  it is  not  reliable.

[Stephen Arbogast]

If  AI  is   go great  why haven't the mysteries  of  Physics  been  solved?

[Steve Berl]

Because AI only knows what it reads on the Internet. It has no concept of "In Real Life". -steve

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[Andrew Thornett]

I think I have managed to adapt Ted's GRC flowchart to an SDRplay RSPduo one which saves data in ezCol format. Currently got that running on 150cm dish to test it and on couple days will analyse the data.

However that flowchart does not calibrate data. So I have attempted to produce another version that simultaneously calibrates using 1423MHz on a second orthogonal probe. No idea if it works or even whether it is good idea - that is scheduled to be trialed after the current one.

I will give more information about all of this at BAA GNU Radio group meeting tonight.

Andy

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[Stephen Arbogast]

Very   cool   ....   but...  keep   in mind   we   are not calibrating   to   any  standard   ref   here.......   

I  am using   an  AirSpy   R2   with   gnu  radio..........   

[Alex P]

Data can be referenced/standardized/calibrated to Cold Sky, and that value can be obtained from within Non Frequency Shifted spectral data samples.

I suspect "1423" is from the Spectra-Cyber Era when stepped frequency analysis was the norm

such that a 256 point freq spectrum might have required 256 seconds  but had a poor S/N  as each frequency was measured for only One Second.

And, as a sample at 1423 MHz 'would be beyond any H Line influence'  another 1 second  made little difference to the total acquisition time.

Spending 50% of the time collecting a spectrum of data at a shifted 1423 MHz band is a different story.

Prof P

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" ... keep in mind we are not calibrating to any standard ref here....... "
" ... I have attempted to produce another version that simultaneously calibrates using 1423MHz  "