Building a Tracking Mount for HRPT Weather Satellite Reception
Over on YouTube channel The Thought Emporium recently released a new video where they show the first steps they've taken towards building a home made satellite tracking mount for receiving HRIT and HRPT low earth orbit weather satellites. In their build they use a 2.4 GHz WiFi parabolic grid antenna, gears and mounts made from milled wood, and some metal supports. The build is not yet finished, but they intend to show their progress in future videos. Note that we're not confident that the 2.4 GHz grid antenna will actually work for them. In the past people have had success with 1.9 GHz Grid antennas however.
If you didn't already know, receiving HRPT weather satellite signals is a little different to the more commonly received NOAA APT or Meteor M2 LRPT images which most readers may already be familiar with. HRPT is broadcast by the same NOAA satellites that provide the APT signal at 137 MHz, but is found in the L-band at around 1.7 GHz. The signal is much weaker, so a high gain dish antenna with motorized tracking mount, LNA and high bandwidth SDR like an Airspy is required. The payoff is that HRPT images are much higher in resolution compared to APT.
Actually, it's not entirely true that a tracking mount is required, although it certainly makes things easier. We've seen in the past that 'Tysonpower' was able to receive HRPT by tracking his dish by hand.
The Thought Emporium also note that they hope to use their tracking mount in the future for other purposes like amateur radio astronomy. In one of their previous experiments they've build a smaller version which was able to create a heat map of WiFi signal strengths in their area.
I simply bought a Meade automated mount off eBay and changed the data tables to reflect satellites. Much easier!
RSP2user provided an article on applying a Meade telescope mount as a satellite tracker in the SDRplay forum. The standard Meade 497 controller comes with built in tables that can track satellites. Simply download the software update program from Meade and you can use it to track any satellite with TLE data. Refer to the article here: https://www.sdrplay.com/community/viewtopic.php?f=5&t=2624
I don’t think that it matters – a parabolic dish is a parabolic dish. RF at 2.4 GHz will have a shorter focal length than RF at 1.7GHz. So the waveguide/antenna will need to be ~41% further away from the surface of the dish, along the same central axis. And they have done that, but I’m no expert.
Hello Timmy
to my defense I missed the part about modification. Thanks for clarifying this point.
Take care and have a great weekend
Hi Timmy,
Consider taking a little closer look at your 8th grade math book.. The formula for finding the focal point of a parabola is not based on frequency and will be the same regardless of frequency. Here is an example:
https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=12&ved=2ahUKEwiWooP_j9DdAhVBMnwKHeFNCKUQFjALegQIBhAC&url=https%3A%2F%2Fwww-tc.pbs.org%2Fwgbh%2Fnova%2Feducation%2Factivities%2Fpdf%2F3406_solar_03.pdf&usg=AOvVaw33PkBHHwUoH56f1gUROUR6
“Consider taking a little closer look at your 8th grade math book”. Nice attitude Mr know it all. Folks come here to learn and exchance ideas. Not everyone knows as muck as you.
Phil – “Nice attitude Mr. know it all.” I suppose I deserved that. But do note that I am not one who believes in giving participation awards for wrong answers. I agree that people do come here to learn. And if they learn the wrong way to do things (e.g., Timmy’s response), that does not help them any. For those looking for how to find the focal point of a parabolic microwave antenna, here is a link to an article by Down East Microwave, Inc. Again, the determination of the focal point of a parabola is independent of frequency. http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=23&cad=rja&uact=8&ved=2ahUKEwiPvfHGstLdAhVT7VQKHQHpCaEQFjAWegQIBxAC&url=http%3A%2F%2F01895fa.netsolhost.com%2FPDF%2Fdishfp.PDF&usg=AOvVaw2q8ga0SuPms2EVIvMQ50VI
Sorry, you are totally right, I was thinking of a spherical dish (e.g. Arecibo), which is far less efficient but does have multiple focal points. I had to lookup 8th grade, that is 13-14 years old kids, I don’t think I learned about 3D surfaces back then, I don’t remember back that far.
Timmy – Hang in there. Clearly you have a strong interest in science and engineering. Keep in mind that accuracy is important, if you want to design and build things that work well.
Errr I’m not an expert but if I remember well the goes signal is at 1.7 Ghz, that antenna is build for 2.4 Ghz thats 500 Mhz off. Maybe that should be mentioned too before people are starting buying stuff
Good luck getting that Tracker working, but i think it will have Problems with HRPT Tracking if there is not a major change coming. The Grid Antenna is okay, but a Dish with a custom Feed will give a way better SIgnal.
The Dish will cause more wind load on the Tracker what could be a Problem for the construction.
You also need quite a good tracking accuracy to get a nice image, so the Gears should be smaller.
@admin : I would remove HRIT from the post because it is on stationary sats that don’t need tracking 🙂
Yeah i’m looking forward to seeing if they can actually get anything with that small WiFi grid. If they can it would be great since those are so common and cheap.
They wrote it’s also for HRIT in their video. I’m guessing they intend to have it auto point at the geosynchronous GOES sats, so the tracking mount might still be a little worthwhile in terms of ease of use and not having to manually align the antenna.
i think that the antenna they are using is for 1.9 GHz band so it can be done. The mechanical solution is not promising but this is the learning curve they should pass.
In the video description they link to the 2.4 GHz WiFi antenna that they bought. It’s not the 1.9 GHz L-Com antenna that people have been using for GOES in the past. I don’t think the 2.4 GHz grid is going to work, but hopefully i’m wrong.
A Premiertek 2.4GHz ANT-GRID-24DBI grid antenna has been adapted to operate at 1.69GHz for HRIT/LRIT, and HRPT reception using an SDRplay RSP2. Refer to the article here: https://www.sdrplay.com/community/viewtopic.php?f=5&t=3262