HRIT and LRIT Geostationary Weather Satellite Image Reception

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jsalsburg
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Joined: Sat Dec 30, 2017 5:06 am

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby jsalsburg » Sat Dec 30, 2017 5:26 am

After examining the photo of the loop yagi I noticed a fault. Since this antenna is receiving near the microwave region (below 2 GHz) and is open, or not a horn, it is susceptible to interference from nearby objects; the ground, any metal, large surfaces like buildings or walls, and plants or foliage. If the antenna elements are spaced over a 6 foot span, to reduce interference, there cannot be any interfering objects within 6 feet of the antenna elements, more distance the better. This translates to the entire antenna being more than 6 feet off the ground and more than 6 feet away for the tripod; no metal or metallic mounting hardware within 6 feet of any of the antenna. It is especially important not to have any metallic or dielectric materials within 6 feet of the driven element at the base of the antenna. Notice in images of antenna arrays for satellite communications that the antenne are isolated in front of a large reflecting screen at the antenna base, with all pointing and steering mechanisms behind the screen.
Last edited by jsalsburg on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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RSP2user
Posts: 85
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Sat Dec 30, 2017 7:23 pm

The intent of the article was to show a viable example applying slightly modified or off-the-shelf components, allowing for both HRIT/LRIT as well as HRPT operation, knowing that there would be some tradeoffs. Keep in mind that the proof of the quality of operation is in the results. The images posted show viable results, particularly considering the FEC, low bit error rate, and the posted images of LRIT and HRIT signals. If you read the article a little more closely and read what is in Section 2 of 4 and on the diagram for the antenna elements, you will find the reasons for the addition of the third reflector element and the placement of the mount connection to the loop Yagi antenna (which are to help overcome issues that you have described). It is no surprise that the half-metal clamshell on the mount does impact the reception as does the location of the mounting point of the antenna, and this is all described in the article. These are the two most critical issues in mounting the antenna to the Meade tripod mount and you should note that the article describes the mounting of the antenna from behind the first reflector element and adding the third reflector as a means of remediation. Section 2 of 4 of the article even describes the issue of getting any metal too close to the antenna. Something else to consider is the power used by the Alt-Az control motors in the Meade mount. Given the light weight and comparatively small size of the loop Yagi antenna, not much power is required to move it, so the amount of potentially interfering energy emitted from the already shielded motors is far less than that of higher power motors applied in moving the larger antennas you described. Consequently, an additional large EMI reduction screen such as you have described is not necessary in this setup. From actual experience (not armchair conjecture) with the antenna and mount described in the article, there is little impact from the remainder of the tripod mount or the ground under it. Yes, metal within 6 feet can "potentially" have an impact, but the questions that arise are what size of metal do you want to put close to the antenna, how close do you want it, and how relevant is the actual impact? For example, in the image shown of the setup for HRIT/LRIT signal reception, the ground, the metal garage door, and the aluminum tripod have little impact, given the way the antenna is mounted plus its third reflector, its position relative to its surroundings, and the direction it is pointed. The importance of how and where an antenna is mounted and positioned is true of any antenna. A little forethought and real world testing should be applied in positioning and mounting any antenna.

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

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Sat Jan 27, 2018 8:14 pm

GOES 16 image from today (January 27, 2018) colorized with Adobe Photoshop. The USA-Satom XRIT decoding software is now operable with both the RSP1A and the RSP2.

GOES 16 Earth Image 27 Jan 2018.jpg
GOES 16 Earth Image 27 Jan 2018.jpg (193.44 KiB) Viewed 5274 times

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leoha
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Joined: Tue Jan 30, 2018 9:02 pm

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby leoha » Wed Jan 31, 2018 8:36 am

Hi @RSP2user,
I'm thinking of getting data (mainly images) from geostationary satellites as well for quite some time now. I'm based in central Europe so this won't be GEOS satellites but AFAIK there are satellites that broadcast HRIT signals also covering Europe. I have some experience in LRPR receptions (successful ones) but it was much easier compared to xRIT as I had no problem to find instruction to build antennas for this (my QFH antenna). Now... I kind of stuck because at first I was thinking of using satellite dish (1.8m) but this renders to be very impractical mostly due to weight of the structure so I'm considering using a similar setup to yours (i.e. loop yagi antenna), hence my question. Do you have any materials (public or your private you could share) that could help me build a loop yagi antenna? Or is there any place where I can buy ready to use loop yagi? Or maybe you could recommend different kind of antenna like "regular" yagi? I'm software engineer so hardware/antenna-wise I'm a noob :) and apparently I am also really bad at finding information on building loop yagi antennas. I would appreciate any help in this matters (specific dimensions would be perfect).
Thanks!
PS. Normally I would send this via private messages but I'm a newly registered user and this feature is blocked for me.
Last edited by leoha on Thu Jan 01, 1970 12:00 am, edited 0 times in total.
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RSP2user
Posts: 85
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Thu Feb 01, 2018 2:19 am

Nice LRPT image and QFH. The amount of gain required by your antenna depends on factors such as your location in relation to the geostationary satellite (distance), the transmitted power of the satellite, and the SNR and gain of your LNA. There are European weather satellites that are designed to transmit HRIT and LRIT images, such as Meteosat 8, 9, 10, and 11 (HRIT on 1.69515 GHz and LRIT on 1.691 GHz). You will need to research Eumetsat for active geostationary weather satellites, transmission times, and whether or not broadcasts are encrypted, requiring payment for a decoding key/unit. There are global software developers who may be able to provide additional information for you with respect to receiving images from European geostationary weather satellites. These developers contribute to the Open Satellite Project and you can find them here – https://github.com/opensatelliteproject . As far as off-the-shelf antennas, the L-Com Hyperlink Brand HG1922EG 1 meter grid antenna (22 dBi gain) has been found to work well receiving signals from GOES 16 from as far away as Ontario, Canada and also note that M2, Inc has a 1625 MHZ to 1725 MHz Yagi antenna (18 dBi standard) and you may want to contact them to see if they can modify it to provide additional gain (http://www.m2inc.com/FG170026). Also, Directive Systems & Engineering offers a 20dBi loop Yagi antenna on their web site http://directivesystems.com/commercial/dse1844ly/. A 1.8m diameter parabolic dish antenna is going to have a gain of around 28 dBi at 1.69 GHz. If you need that much gain at your location, then your best bet is likely to just use a 1.8m parabolic antenna. If you need a lighter weight parabolic antenna, you might consider one with a grid or metal screen structure instead of a solid metal construction. For a Yagi antenna, you effectively have to double the length of it for every 3dBi of gain added. So if you had a 1.45m long Yagi antenna producing 18 dBi of gain, you would only get 21 dBi of gain out of it by doubling the length to 2.9m. After the Yagi antenna gets long enough, it becomes a problem to keep it straight along its length and maneuver it, if you want to change its position with a motorized mount. The alternative to increasing length is to add more Yagi antennas in an array, which then takes up more space and becomes more challenging with respect to impedance matching to the LNA. Yagi antennas become more and more challenging to build in the 1.69 GHz range as the gain extends beyond around 20dBi. So if you need more gain than that, you should consider finding a way to implement a large parabolic dish antenna. You may want to see if you can find others in your area who have successfully built amateur systems to receive images from the geostationary satellites you are interested in. They could provide useful information on what works in your area as far as antennas for receiving HRIT and LRIT signals. Once you get it all working, please consider posting information to help others interested in building similar systems. Posted images are also of interest.

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RSP2user
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Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Sun Feb 04, 2018 10:47 pm

A nice full Earth GOES 16 HRIT image from today - February 4, 2018.
G16 Full Earth 2-4-2018.JPG
G16 Full Earth 2-4-2018.JPG (186.6 KiB) Viewed 5109 times

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RSP2user
Posts: 85
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Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Sun May 27, 2018 12:35 am

An additional post of interest is the HRIT and LRIT Low-Cost System found here: viewtopic.php?f=5&t=3262

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RSP2user
Posts: 85
Joined: Mon Oct 09, 2017 7:11 am

Re: HRIT and LRIT Geostationary Weather Satellite Image Reception

Postby RSP2user » Mon Nov 12, 2018 12:10 am

USA-Satcom has just released v2.1.0.0 of the XRIT Decoder. Along with enhancements for the XRIT Decoder, a new RSP Streamer X has been released and is operable with the RSP1A, RSP2, and RSPduo - new features include operation with two streams simultaneously (provided that the PC being used has sufficient processing power and an RSPduo or more than one compatible RSP are being used). Also new is the XRIT File manager which allows for improved operation with both LRIT and HRIT files, improved LUT for excellent false color images, user-selectable automated black filling of the white background on full disk visual and false color HRIT images, and country as well as state map overlays.

The new color enhancements are excellent:

GOES 16 Earth Full Disk LR.JPG
GOES 16 Earth Full Disk LR.JPG (92.35 KiB) Viewed 1761 times

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