Decode signals from weather satellites
Satellite-based images of the Earth showing cloud cover have been a regular sight in TV weather broadcasts since the TIROS 1 satellite launched in 1960. Yet while the end result is familiar, the technology that brings us those images is much less well-appreciated. If you want to learn about the technology involved, though, it’s not too difficult to get a basic understanding.
However, you can gain some hands-on experience, as we demonstrate here, and a practical approach is often one of the best ways of learning. So, we’ll show you how to receive the radio signals transmitted by these satellites and how to decode that data to generate pictures. In addition, we’ll also investigate some ways of image processing to improve that image and perhaps introduce some false colour into the inherently monochrome images transmitted by the satellites.
NOAA satellites
Here we’re going to be looking at the so-called NOAA polar orbiting satellites – NOAA-15, NOAA-18 and NOAA-19 – that are operated by America’s National Oceanic and Atmospheric Administration. We’ve chosen these satellites because they orbit the Earth at an altitude of just 850km. Since they aren’t too far above our heads, their radio signals are quite strong and easy to receive.
If you’re wondering why the satellite numbers aren’t contiguous, all satellites from NOAA-6 have existed but most are no longer operational, including NOAA-16 and NOAA-17 even though they were launched after NOAA-15. However, NOAA-15 has been experiencing operational problems since 2019 so there are no guarantees that you’ll be able to receive and decode its transmissions, even though we had no difficulties. There’s also an NOAA-20, but this is the first of a new generation of
