In the HobbySpace Radio section I describe a weather satellite image receiving station I set up many years ago consisting of a simple antenna, a PC controllable receiver and a PC with a sound card. When a satellite passed overhead, and the receiver was set to the proper frequency band, the sound card would digitize the receiver output and programs running on the PC would convert this data into an image. (I also had a program running to track satellites to know when a low earth orbit weathersat would be in range.)
A LEO weather satellite image (Colors assigned to gray scale values.)
That was a fairly inexpensive station but now there are even cheaper ways to do weathersat imaging at home.
A few times I’ve mentioned the FUNcube Dongle project that was created as part of the UK FUNcube satellite project to get students and the general public involved in receiving signals from that satellite. The FUNcube Dongle is based on Software-defined radio (SDR).
SDR uses the power of modern microprocessors to allow a software program to replace many of the tasks previously done in a hardware receiver to isolate and process and demodulate a signal of interest in a particular frequency band. The software works on data obtained from digitizing the raw electromagnetic wave patterns from an antenna.
Ideally an antenna output would straight into an analog to digital converter (ADC) in the PC, such as that available in the sound card, and the SDR program would work on the ADC output. However, that is not practical with real world noisy, weak signals. So some interface hardware is still needed. This can be provided by a “dongle” USB device that might include a low noise amplifier, a tuner to obain signals in a given frequency range, a ADC, plus a processor to control all this and talk with the PC. The output of the dongle is then used by the SDR program running on the PC.
From Introduction to the FUNcube Dongle (pdf)
So a system to receive low earth orbit weather satellite images can now be as simple as an antenna connected to a small low cost dongle plugged into the USB port of a computer running the SDR program. which analyzes the digitized signal in the frequency range selected by the user. For satellite imaging, there would, as with the standard hardware tuner case, be another program to decode the signal into a weather image.
Besides the FUNcube Dongle, the company NooElec offers kits with an antenna and a SDR dongle. (Available at Amazon: Terratec DVB-T USB Receiver & Low-Cost Software Defined Radio (SDR)
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A free program to operate such systems is available at SDR-RADIO.com. Here is a tutorial for using it to pick up weather satellite images: Software Defined Radio for Mariners: Weather Satellites.
Find more SDR resources here.
The signal environment where you are located, say in the middle of a city with high buildings, could be very poor for satellite reception. In that case, you can still do SDR satellite reception by getting the signal data from other locations via the web. See SDRSPACE.com for details.
