Weather Satellite Decoding
Weather Satellite Decoding can be done by anyone with a few simple programs, a digital TV dongle, a computer & an antenna.
Noaa weather satellites orbit the earth, transmitting signals as they pass. These can be received as radio signals and decoded, giving full colour images of the earths weather systems. Programs on a laptop or desktop are linked together to decode the signals.
Signals are received using a inexpensive Digital TV dongle, purchased for as little as $20. Usually used for TV reception, they are reprogrammed by loading a different driver than the one supplied. This can be downloaded from the internet.
Once the dongle is ready it sends the signal to a radio program, there are several around on the net. I use HDSDR, a nice colorful layout & easy to use. As the satellite passes, it is subject to doppler shift on the signal. Orbitron, a satellite tracking program is used to control this by controlling the frequency on the SDR (Software Defined Radio) radio. It is also used to track the satellites and for future pass prediction.
Once the signal has been received it is then decoded using one of several decoding programs downloaded from the net. WXtoImg is a easy to use program.Images are processed similar to digital photographs. Cameras on the satellite record images in grayscale & infrared and the decoding is done by applying Colour Lookup Tables (CLUT). Each pixel records a colour temperature in shades of grey.which when processed is replaced by it`s colour value, resulting in a colour image.
it does take a bit of playing around with recording volumes & integration of programs, but once up and running it can be set to automatically record passes by all three Noaa satellites. The antenna I use is a QFH (Quadrifilar Helix), but there are a few out there that work, the Turnstile & Lindenblad as well as the QFH can be built at home using plans off the web and easily gathered materials.
For more information and links to the programs I use visit the RTL-SDR page on my blog.
There are many more applications for Digital TV dongles, from FM broadcasts to listening to the astronauts on ISS. I will do a post on some of these down the track.