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.
Building a Motorized Satellite Tracker for HRIT/HRPT Reception and Radio Astronomy - Part 1
Last month we posted that the website for the popular NOAA APT weather satellite decoding software known as WxtoImg went down. Since then we've been in contact with the developer of the software, and he did indicate that he may restore the site at some time in the future, but is currently busy with other projects so doesn't have much time to devote to his old software at the moment.
In the meantime (or perhaps permanently) a WXtoImg fan has created a clone of the original website which he's called "WXtoImg Restored". The site contains most of the downloads as well as a professional edition update key, which was released for free by the original author before. If you don't trust the third party site, some downloads are also still available from the internet archival project's copies of the original WXtoImg website.
There are still some files missing on WXtoImg Restored, and these are outlined on the new website's homepage, so if you have them please contribute them to the site email.
Just a note that the website for the popular NOAA APT weather satellite decoding software WxtoImg is currently down, and may possibly never be revived. This software is commonly used with RTL-SDR dongles to download weather satellite images from the NOAA 15, 18 and 19 polar orbiting satellites.
It seems that the author of the software has not been maintaining the site and software for a while, although there was a brief update on the site back in 2017 when the professional version keys were released for free. But the keys reportedly no longer work. WXtoImg is closed source, so the code is not available either.
Some of the downloads are still available via archive.org, however it only seems to be the Windows and some of the Linux versions that were archived. Over on two Reddit threads  , some users are also collecting the last free versions and making them available for download again. If anyone has access to the last beta versions for ARM devices please upload them somewhere too.
Also if anyone happens to have the contact details of the author, or someone who knows the author please let us know as we'd like to ask for permission to mirror the files.
The software is based on the set up from this excellent tutorial, which creates scripts and a crontab entry that automatically activates whenever a NOAA weather satellite passes overhead. Once running, the script activates the RTL-SDR and APT decoder which creates the weather satellite image. He then uses some of his owns scripts in Twython which automatically posts the images to a Twitter account. His Twython scripts as well as a readme file that shows how to use them can be found in his Google Drive.
Back in December Tysonpower showed us how he was able to receive HRPT weather satellite images with a 80cm and 1.2m satellite dish, LNA and Airspy Mini.
If you didn't already know, HRPT signals are a little different to the more commonly received NOAA APT or Meteor M2 LRPT images which most readers may be more familiar with. HRPT images are more difficult to receive as they are broadcast in the L-band at about 1.7 GHz and so receiving them requires a dish antenna (or high gain Yagi antenna), L-band dish feed, LNA and a high bandwidth SDR such as an Airspy Mini. The result is a high resolution and uncompressed image with several more color channels compared to APT and LRPT images.
In the last video Tysonpower was successful with receiving HRPT images with his setup. But recently over on his YouTube channel and on his blog Tysonpower has shown how he has improved his HRPT reception by first optimizing the feed and adding in a copper matching line which helps improve the impedance matching of the feed. He also added an L-Band filter tuned to the HRPT signal which he notes made the biggest improvement, and he also moved all the components into a watertight box for permanent outdoor mounting. With these changes he's now able to consistently pull in some very nice imagery. All the images are still received by hand tracking the satellite dish as the satellite passes over, but he notes that he plans to experiment with motorized trackers in the future.
Note that the video shown below is narrated in German, but English subtitles are provided if you turn on YouTube captions.
[EN subs] HRPT - optimierungen und sehr gute Bilder
In addition to the above Tysonpower also writes that he has created a free HRPT decoder for the HRPT signals originating from NOAA satellites. He writes regarding HRPT decoders:
I found it quite complicated to find a decoder for HRPT when i started and there is still no one that you can just Download.
The only free Decoder is the gr-noaa example in gnu radio that has a depricated wx GUI and uses a input from a specific SDR. I used that gr-noaa example and created a decoder that uses the modern QT GUI and has a clean interface. You just put in a wav IQ file from SDR# for example and it will decode the Data into the file you entered. It is not the best one out there in form of signal processing, but a good start i would say.
The decoder can be downloaded from tynet.eu/hrpt-decoder. Below is a second YouTube video where Tysonpower explains how to use the decoder.
[EN subs] Kostenloser HRPT Decoder (GNU Radio) - Und wie man ihn nutzt
Most readers of this blog are probably familiar with the more commonly received APT images that are broadcast by the NOAA satellites at 137 MHz, or perhaps the LRPT images also broadcast at 137 MHz by the Russian Meteor M2 satellite. HRPT signals are a little different and more difficult to receive as they are broadcast in the L-band at about 1.7 GHz. Receiving them requires a dish antenna (or high gain Yagi antenna), L-band dish feed, LNA and a high bandwidth SDR such as an Airspy Mini. The result is a high resolution and uncompressed image with several more color channels compared to APT and LRPT images.
In his video Tysonpower shows how he receives the signal with his 3D printed L-band feed, a 80cm offset dish antenna (or 1.2m dish antenna), two SPF5189Z based LNAs and an Airspy Mini. As L-band signals are fairly directional Tysonpower points the dish antenna manually at the satellite as it passes over. He notes that a mechanised rotator would work a lot better though. For software he uses the commercial software available directly from USA-Satcom.com.
Over on YouTube user Fuzz has uploaded a video showing his solar powered NOAA weather satellite receiver.
The system is based on a Raspberry Pi connected to an RTL-SDR.com dongle. The front-end input of the RTL-SDR dongle consists of an LNA and FM reject filter, and this is all connected up to a QFH antenna in his front yard. The electronics are completely solar powered, with the solar system consisting of solar panel, solar controller and four 12v batteries used for energy storage. A 12V to 5V step down converter is used to power the Raspberry Pi, with the 12V LNA being powered directly by the batteries. The system is able to be accessed remotely via the Raspberry Pi’s WiFi connection.
Over on his YouTube channel user Tysonpower has uploaded a video that shows how to make a V-Dipole antenna. Back in March we posted about the V-Dipole which Adam 9A4QV first described. A V-Dipole is a simple antenna that normally consists of two metal rods, a terminal block and coax cable. It is particularly effective for reception of low Earth orbit satellites like the NOAA and Meteor M2 weather image satellites with an RTL-SDR or other similar SDR.
In his video Tysonpower shows how to build a slightly more rugged version using a 3D printed part instead of a terminal block. Aluminum welding rods are used for the elements. The 3D printed part ensures that the correct 120 degree ‘V’ angle is maintained and also provides a means for mounting the antenna to a pole. The 3D printing STL files are available on Thingiverse. Note that the video is in German, but English subtitles are available.