Automatic Ground Station

The open-weather Automatic Ground Station (AGS) is a radio receiver of Automatic Picture Transmissions (APT) from weather satellites NOAA-15, NOAA-18 and NOAA-19.

We developed the AGS because manual satellite image capture can be time intensive and so, while still foundational to open-weather, is not always practical or possible. Its design and build adds open source hardware to our public resources for DIY satellite reception and decoding.

The AGS project is a collaboration with artist and activist Grayson Earle. Its API was developed by Rectangle.

Open-weather’s AGS builds on existing open and closed source hardware and software for automating the reception of satellite imagery to create an easy to assemble and intuitive to operate ground station.

These values are hardcoded into the project through decisions, such as to calculate the satellite orbits on the device rather than use third party software, the use of a simple config file for variables, and the option to 3D print casing. Combined with a ‘more is less’ approach, these design decisions mean that open-weather’s AGS can be an entry point into learning about radio and satellites, weather and climate, hardware and code.

What can an open-weather AGS do?

The open-weather AGS can:

• download Two-Line Element (TLE) data and calculate when the NOAA satellites will pass over the its location
• select the ‘best’ satellite pass to receive, e.g. the satellite pass with the highest altitude orbit over its location
• record the selected satellite pass at the correct frequency, bandwidth and modulation
• save the sound file (.wav) to a USB stick and then send it over wifi to a server*
• display messages on an LCD screen that describe what it is doing and common errors
• fetch and install updates to its code daily

* This is set to an API for the open-weather Public Archive by default but can be changed

An intuitive config file stored on the AGS’s externally accessible USB stick contains the editable variables:

• unique ID
• latitude and longitude
• antenna gain
• number of ‘buffer minutes’ i.e. the amount of time the AGS waits after a satellite pass has begun before recording
• WiFi network name and password
• API key

Build your own

The AGS code and 3D file for printing the casing are open source. They can be accessed here via the project’s GitHub repository.

Open-weather is working with Grayson Earle to document the project and test the AGS in different locations, so that others can easily replicate our work. Over the coming months, we will publish project updates and further documentation.