Kiwiweather captures data from the South Korean GK-2A and this page will describe how this happens.
We also work with other people around the world who capture images from a wide range of geostationary satellites covering most of the planet other than the polar regions. They obtain their data using essentially the same technique, although for GOES 15 GVAR a 2 metre+ dish is required rather than a WiFi antenna.
There is an excellent article on the RTL-SDR.com website which covers how to get a ground station set up to receive either GOES 16 / 17 or GK-2A.
This is what I followed, although I adapted the process slightly to fully automate the solution.
The kit I am using is:
- Raspberry Pi 4 with 4GB of RAM
- HyperLink Technologies ANT-95 2.4 GHz 24 dBi Die-cast Wireless Grid Antenna
- Nooelec SAWbird+ GOES – Premium SAW Filter & Cascaded Ultra-Low Noise LNA
- RTL-SDR.com SDR
My first target was GOES 17 and I’ve described my attempts to receive images from this satellite in multiple posts on this site with the main one being:
I managed to get some images with the WiFi antenna mounted on a pedestal fan stand. This arrangement was good enough to test that the process was working, however far from ideal due to a tall palm tree being located to block a good line of sight. There were also some minor problems in that the solution was far from weather proof both for wind and rain.
This had been my main target as I’d be able to get not just GOES 17 but also rebroadcasts from GOES 16 and Himawari 8 at the time of writing, but now Himawari 9 since December 2022.
With GOES 17 not being a good option, I shifted my attention to GK-2A which can be captured using the same kit. Even more importantly there was a sheltered position where I could set everything up and it had a good line of sight to the satellite too!
First change was to use a large PA speaker stand which was heavy enough to hold the dish, keep it pointed in the right direction (mostly) and it is suitable for use outdoors.
To weatherproof the SDR and GOES SAWbird I knew that there was a combination of issues as the SDR can get pretty hot but equally they need to be kept dry. My solution which has worked so far is a thick plastic bag which is wrapped around the SDR and GOES SAWbird, with the ends sealed using electrical insulation tape. This has been working well for over a year.
The USB connection from the SDR goes to the Raspberry Pi which is sat on a table next to the stand. It is protected from the elements with a plastic bucket over it weighted down by a heavy stone. A very Kiwi #8 wire solution which works well too.
The Raspberry Pi connects to my network using a WiFi connection, so it only needs mains power for the Pi.
The software to receive the signal and to extract the images is:
- goestools (https://github.com/pietern/goestools) – GOES demodulation and image creation set of tools
- xrit-rx (https://github.com/sam210723/xrit-rx/) – GK-2A decoder and image creation
I’ve updated WxCapture to include code to support GK-2A including:
- Process the image with clahe and Sanchez
- Create animations using ffmpeg
- Move the outputs to end up on the web server for this site
- Tweet the outputs
- Discord webhook the outputs
- A watchdog to ensure that all the code is working as intended and to take corrective action as required
The latest outputs from GK-2A are on this site: