Software problems: Building DIY radio telescope to observe the 21cm-line of neutral hydrogen

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Paulina S.

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May 3, 2026, 11:59:51 AM (8 days ago) May 3
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Hello,

I am a high school student from Germany. For an important school project, I want to build a DIY Radio telescope to observe the 21cm-line of neutral hydrogen. It is part of my final grades.

I followed the instructions on this website: https://www.rtl-sdr.com/cheap-and-easy-hydrogen-line-radio-astronomy-with-a-rtl-sdr-wifi-parabolic-grid-dish-lna-and-sdrsharp/

I hope this was a good choice to get directions. I already have the complete hardware and the software “Stellarium” works very well.

My problem is the SDRSharp Software. I tried to install the software multiple times. I cannot select the If Aver plugin. It is the fourth step of “receiving and averaging the hydrogen line fft”. I tried the software on two laptops and tried the older version too, but nothing works. By not enabling the plugin, I cannot follow the next steps.

Do you have feedback? Have I made mistakes while installing the software or might be the problem somewhere else?

Thank you,

Paulina Sebald


Alex P

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May 3, 2026, 1:07:34 PM (8 days ago) May 3
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Hello Paulina,

What version of Windows are you using ?

See if this info helps.
Look at steps 2A-2D
There are links to SDR# w/ IFavg installed



Regards,
Alex Pettit

Paulina S.

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May 3, 2026, 3:53:49 PM (8 days ago) May 3
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Hello,
I'm using Windows 11.
Thank you very much, I will try again with your new instructions.
Regards,
Paulina Sebald

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b alex pettit jr

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May 3, 2026, 4:28:07 PM (8 days ago) May 3
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Hello Paulina,

The link installs SDR# V1919 w/ IFavg .. Let me know if that works for you.

Within a week or so, there should be a new release of IFavg which is compatible with the
most recent version of SDR#  and includes several enhancements.

Alex Pettit

b alex pettit jr

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May 3, 2026, 6:56:20 PM (8 days ago) May 3
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Hello Paulina,

What components are you using :
   You have the nooelec 1m  Dish & H1 Feed ?
   Which LNA  and SDR ?

Alex

Paulina S.

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May 4, 2026, 5:44:05 AM (8 days ago) May 4
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Hello,
these are my components:
- 2.4 GHz WiFi parabolic dish 70 x 90 cm
- NooElec SAWBird+ H1
- RTL-SDR Blog V4
Did that answer your question?
Thank you for you help.
Paulina

b alex pettit jr

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May 4, 2026, 6:25:50 AM (8 days ago) May 4
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Hi Paulina,

Yes, Thanks.

Can you run the RTL-SDR with SDR#  alone ?  
( That requires installation of the Zadig driver )

Alex
==============================

Paulina S.

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May 4, 2026, 9:00:49 AM (7 days ago) May 4
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Hi,
I think so. I can select "RTL- SDR USB" under "Source" and it detects frequencies after pushing the "Play-Button".
Paulina

b alex pettit jr

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May 4, 2026, 9:05:41 AM (7 days ago) May 4
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Ok .. so if you can get SDR# 1919 & IFavg installed, you may be nearly operational.

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