Getting NOAA sat images using an RTL-SDR

NOAA (National Oceanic and Atmospheric Administration) is the USA meteorological agency. They have a set of satellites orbiting the earth, imaging the Earth and sending it via radio. The downlink of the working satellites are on VHF so you can easily receive them. On this article, I’m sharing my experience receiving them with an rtl-sdr.

Of the original sats the constellation has, only 3 are reported to be working. They are NOAA 15, 18, and 19. Their downlink frequency is around 137MHz. The following procedure is for Windows OS.

So what do you need?

  • An RTL-SDR stick (or any other receiver capable of tuning W-FM (wide FM) on 137MHz, like some ham radios, airspy, etc);
    • If you use Windows I really recommend SDR# as the software to use your usb tuner, case it’s supported.
  • An audio routing tool. In case you use a “tabletop” receiver you might need only an audio cable to route the audio into your computer. If you use an rtl-sdr stick, you need a virtual audio routing solution like VB-Cable (unless you really feel like using a cable between your soundcard line out and line in plugs);
  • WxToImg. This is the software piece that will decode the image while your tuner receives it;
  • A right-hand circularly polarized antenna (like the QFH). Or not. While a circularly polarized antenna is ideal for sat work, for this project I used only my disconne antenna. But I like on a good place of radio. Adequate your antenna solution to whatever conditions you have.
Receiving NOAA 19 with rtl-sdr and SDR#
Receiving NOAA 19 with rtl-sdr and SDR#

The process is very simple. If you have ever decoded any digital modes with your rtl-sdr or radio, the process is more or less the same. WxToImg comes with a sat pass prediction tool, so you know when to record. You can fiddle a bit with the options of WxToImg to set them to you taste.

You might wanna take a look to the images I got.

Here’s an example:

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