HRIT and LRIT Low-Cost System

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RSP2user
Posts: 77
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Low-Cost System

Postby RSP2user » Sun Aug 12, 2018 4:15 pm

Rob,

Some additional information for you to consider. The grid antenna choice was made for this post with careful research and a considerable amount of effort went into testing, modification, and seeing what worked well. The 1 meter diameter grid parabolic antennas, regardless of brand, typically employ a quarter-wave to half-wave dipole as the receiving element. So it is not too difficult to modify one to set it to the exact frequency desired. What was found in testing the Premiertek ANT-GRID-24DBI antenna was that the biggest increase in gain in the 1.69GHz frequency range came from simply flipping over the existing secondary reflector as described in the post. Alternate secondary reflectors and optimizing the dipole for 1.69 GHz were also tested. The results were only marginally better, not enough to propose going through all the trouble to make extensive antenna changes, when you can obtain similar results without modifying the dipole and by simply flipping over the existing secondary reflector.

Here are some numbers from testing using the RSP2, the SAWBird GOES LNA, and the ANT-GRID-24DBI antenna:

1) Premiertek ANT-GRID-24DBI out of the box constructed as instructed by Premiertek operating at 1.69 GHz on GOES 16: Signal Quality 69.7 Viterbi Corrects 455
2) Premiertek ANT-GRID-24DBI with secondary reflector flipped over at 1.69GHz on GOES 16: Signal Quality 95.7 Viterbi Corrects 65
3) Premiertek ANT-GRID-24DBI with dipole modification for 1.69 GHz and optimized secondary reflector for 1.69 GHz: Signal Quality: 98.0 Viterbi Corrects 30

As mentioned, given that the greatest positive change for operation of the ANT-GRID-24DBI at 1.69 GHz was made simply by flipping over the secondary reflector as described in the post, other modifications were not described. This also makes setup easier and does not void the warranty on the antenna.

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rdale
Posts: 11
Joined: Thu Aug 09, 2018 6:31 pm

Re: HRIT and LRIT Low-Cost System

Postby rdale » Sun Aug 12, 2018 4:54 pm

Great info - thanks! I'm excited to start piecing this together... I'm one of the original EMWIN software developers from the 90s and while I'm completely satisfied with the Internet feed - going back to the "satellite" roots sounds fun.

- Rob
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RSP2user
Posts: 77
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Low-Cost System

Postby RSP2user » Sun Aug 12, 2018 6:04 pm

Rob,

If you are interested in compiling your own GOES demodulation and decoding software using free, readily available, tested modules, refer to work done by Lucas Teske and others on GitHub (Open Satellite Project): https://github.com/opensatelliteproject/xritdemod and https://www.teske.net.br/lucas/2017/04/ ... k-results/ . Lucas and others have tested their software using SDRs including the RSP1A and RSP2. If you are not interested in developing your own software, the solution from USA-Satcom is reasonable in cost.

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IZ5RZR
Posts: 1
Joined: Tue Aug 14, 2018 3:05 pm

Re: HRIT and LRIT Low-Cost System

Postby IZ5RZR » Tue Aug 14, 2018 3:08 pm

Hi, does anyone know how to get in touch with the XHRPT software authors to get a copy ?, the contact form of the USA_SATCOM website does not seem to work
Ciao, qualcuno sa come mettersi in contatto con gli autori del software XHRPT per averne una copia?, il contact form del sito USA_SATCOM sembra non funzionare,
Many thanks
IZ5RZR Massimiliano
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RSP2user
Posts: 77
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Low-Cost System

Postby RSP2user » Tue Aug 14, 2018 11:22 pm

Success in contacting USA-Satcom has been accomplished using the Chrome browser and with Gmail e-mail accounts. That being said, you can follow USA-Satcom on Twitter and then USA-Satcom can direct message you. USA-Satcom on Twitter: https://twitter.com/usa_satcom?ref_src= ... r%5Eauthor

Il successo nel contattare USA-Satcom è stato raggiunto utilizzando il browser Chrome e gli account di posta elettronica di Gmail. Detto questo, puoi seguire USA-Satcom su Twitter e poi USA-Satcom può contattarti. USA-Satcom su Twitter: https://twitter.com/usa_satcom?ref_src= ... r%5Eauthor

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raulandresmoch
Posts: 1
Joined: Mon Aug 20, 2018 7:28 pm

Re: HRIT and LRIT Low-Cost System

Postby raulandresmoch » Mon Aug 20, 2018 7:34 pm

Hello!!! I just started my own Rig, I bought a 2.4 ghz antenna that was in a great price, could you please post pics on the Reflector that you flip over, My antenna came with no manual or instructions for mounting so I have no idea what reflector you are talking about. Thank you so much for the info and kudos on the great images you got!!!

Best regards from Mexico!!!!
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RSP2user
Posts: 77
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Low-Cost System

Postby RSP2user » Tue Aug 21, 2018 4:41 am

The frequency of operation for GOES 15 LRIT is 1.691GHz and the frequency of operation for GOES 16 and 17 HRIT is 1.6941 GHz. The modification described in this post is only for the Premiertek ANT-GRID-24DBI antenna so that it will operate better in the target frequency range of 1.69 GHz rather than its originally intended 2.4 GHz operating range. If you are using the Premiertek ANT-GRID-24DBI antenna, then the information and pictures provided in this post are sufficient. Just set up the ANT-GRID-24DBI antenna and place the smaller secondary reflector in the position shown in the pictures provided earlier on the first page of this post. If you are using a different antenna, then you are on your own in making that work and you may have to modify the existing feed or build a new one from scratch for operation at 1.69 GHz. Before making any changes to the antenna, first get a baseline signal measurement by connecting your antenna up unmodified and pointing it at GOES 16, taking into account the signal polarization, and tuning your receiver to 1.6941 GHz. If you are able to see a signal like the one shown on the first page of this post where the signal top level is about 6 dB to 7 dB or higher above the noise floor, then you can probably get the antenna to work well enough unmodified (it may have a broad enough raw bandwidth to work well enough at 1.69 GHz). Otherwise, you can use this method to test improvements to your antenna from your baseline measurement. Once you are getting a signal level at least 6 dB above the noise floor, then you can try operation and image generation with XRIT demodulation and decoding software. This, of course, assumes that you are using an appropriate LNA and filter, such as the SAWBird GOES from NooElec, Inc. combined with a receiver such as the SDRplay RSP1A or RSP2.

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rdale
Posts: 11
Joined: Thu Aug 09, 2018 6:31 pm

Re: HRIT and LRIT Low-Cost System

Postby rdale » Fri Aug 31, 2018 1:16 pm

To update the thread - ProVantage no longer stocks this antenna, so their price has gone up and the shipping time as well. Google will help you find it cheaper and quicker.

And the Sawbird is now available directly.

https://www.rtl-sdr.com/nooelec-sawbird ... available/
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RSP2user
Posts: 77
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Low-Cost System

Postby RSP2user » Thu Sep 06, 2018 2:19 am

Link for additional information from others who have used various brands of low-cost 2.4 GHz WiFi parabolic grid antennas modified for GOES HRIT reception at 1.6941 GHz: https://www.reddit.com/r/RTLSDR/comment ... e_it_work/

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rdale
Posts: 11
Joined: Thu Aug 09, 2018 6:31 pm

Re: HRIT and LRIT Low-Cost System

Postby rdale » Thu Sep 06, 2018 2:59 am

Thanks - the price on the ANT in this post is now exceeding $65...

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