We came across a very interesting project by user ThePhotoChemist on Reddit. At the intersection of art and science, ThePhotoChemist has designed a system to receive and display weather satellite images directly using an Ikea picture frame, a Raspberry Pi, an SDR and an E-ink display.
Weather satellites are used to monitor the weather and climate of our planet. The National Oceanic and Atmospheric Administration (NOAA) weather satellite passes over us periodically while continuously transmitting images of the weather using RF signals at 137 MHz. The bandwidth of these signals is only 34 kHz. Here is an image of Hurricane Zeta as seen by a weather satellite.
The good news here is that you can demodulate these signals and turn them into pictures using a low cost SDR dongle. The following picture by @sophied shows how this works.
The satellites use something called Automatic Picture Transmission (APT) to broadcast the weather images. This is an analog format specifically designed for use with weather satellites. A software-defined radio can receive these images at least twice a day as the satellite passes overhead.
Here are three NOAA satellites that currently transmit this data:
NOAA-15 137.620 MHz
NOAA-18 137.9125 MHz
NOAA-19 137.100 MHz
Additionally there is a Russian satellite called METEOR M N2 transmitting at 137.900 MHz.
In this tutorial, Jim Haslett goes through his satellite image reception setup in detail using a Raspberry Pi 3B with an enclosure, a NooElec SDR and cables.
In addition to these parts, ThePhotoChemist has also used a Sawbird LNA with an FM blocker. The SAWbird LNA is used to amplify signals in the range of 137 MHz. The FM blocker is a notch filter that is used to block strong FM signals that might otherwise interfere with the signal reception. You can read more about why you need an FM notch filter with your SDR.
What about the antenna? For receiving NOAA signals you could use either:
- a Crossed Dipole or
- a QFH antenna
While these antennas cannot be purchased commercially, you can find DIY instructions for both the crossed dipole and the QFH.
The software that does the magic is WXtoImg – a fully automated APT and WEFAX weather satellite (WXsat) decoder. To display the images you will need an e-ink display from Waveshare. This display includes a HAT which stands for “Hardware Attached on Top”. The HAT is a small PCB that enables the e-ink display to be interfaced with the Raspberry Pi.
This is a really interesting project to get you started with satellite weather images while creating a piece of art for your home at the same time.
Here is a parts list for this project:
DIY antenna with the appropriate cable to connect to your SDR
RF cables for the antenna and SDR
