Tyler Perkins

Junior Software Engineer - KE8TIZ

Intro to weather satellites

Tyler - 2021-06-18 16:13:04

Views - 108

Tyler Perkins - Intro to weather satellites

Early in quarantine I saw this wonderful video on how to grab images from satellites, and I was super interested in the idea. The idea is that there are satellites called NOAA-15, NOAA-18, and NOAA-19 that orbit the earth roughly every 102 minutes. They are broadcasting through their entire journey and anyone can listen in and receive images of earth that they are broadcasting.

The biggest problem is getting the images where I live (the suburb). There is just so much stuff in the way to block the signal. Compared to other satellites, its signal is pretty strong, but still not strong enough to go through the concrete jungle. Therefore, I did a few months of research into how to get a good signal from where I am. And thankfully, alot of people have gotten good results with easy to make/buy antennas. I chose to buy a dipole kit off of amazon to start, then attempted (but failed) to build a cross dipole out of stuff from Home Depot, and some printed parts.

The other tools required were pretty easy to source (for me at least). The hardest one would be the SDR, however I already owned a HackRF, so that was pretty easy. If you don't have one already I would just get a RTL-SDR, they're only 30 bucks and operate on a pretty solid range of frequencies. They also have the biggest aftermarket support out of any of the SDRs I have seen.

Beyond those two and the miscellaneous bits (SMA/Coax, places to mount the antenna, measuring tape, etc), all you need is the right software. I used CubicSDR to receive the talk with the SDR because it was simple and worked with the HackRF out of the box (at least on windows), and WXtoIMG to convert the audio to an actual image.

So more of the technical details:

  • NOAA-19
    • Broadcast : 137.1 Mhz
    • Bandwidth : 37.5 Khz
    • Period : 102 Mins
    • Inclination: 98.7 Deg
  • NOAA-15
    • Broadcast : 137.62 Mhz
    • Bandwidth : 37.5 Khz
    • Period : 101.2 Mins
    • Inclination: 98.7 Deg
NOAA-19 before it was launched

Here are some example images before we get into a how-to:

NOAA-19, 08-07-20, 22:54 UTC
NOAA-19, 08-25-20, 22:44 UTC

You can pretty clearly see the mitten of Michigan in both (its upside down in the image on the left). The orientation of the image is determined by the direction that the satellite is traveling when it flys overhead.

Hopefully you find this cool enough that you want to try this out yourself. Its alot of fun and feels great to see the progress over time.

To get started with this hobby you won't need much, just a laptop/desktop/raspberry pi, an SDR, and a decent antenna (sometimes comes with the SDR). I've provided some amazon links to the hardware I've actually used.

With this I would watch some of the tutorials on youtube, or maybe I'll put a tutorial up myself at some point. It's suprisingly easy to do and only takes maybe 10 mins to setup each time.

A full repository of every attempt I've had can be found here.