Using an old satellite to see Earth in a new light
Spying on satellites is becoming quite popular, enough that the number of people advancing the state of the art - not to mention the wealth of satellites transmitting signals in the clear - has almost made the hobby too easy. An SDR, a homemade antenna and some ready-to-use software, and you too can see weather satellite images on your screen in real time.
But where is the challenge? This appears to be the question [dereksgc] posed and answered by tapping into S-band telemetry from an outdated satellite. Most satellite hunters focus on downlinks in the L-band or even the VHF part of the spectrum, which are within easy reach of most RTL-SDR dongles. However, the Coriolis satellite, which was launched in 2003, has a downlink firmly in the S-band, which at 2.2 GHz puts it just outside the high end of an RTL-SDR. To circumvent this problem, [dereksgc] purchased a counterfeit HackRF SDR and coupled it to a low-noise broadband amplifier (LNA) of its own design. The dish antenna is also made in house from a used 1.8m dish and a custom helical antenna for the right circular polarized downlink signal.
As the video below shows, receiving downlink signals from Coriolis with the platform was not that difficult. Even when manually flying the dish, [dereksgc] was able to record a few decent passes with SDR#. Making sense of the data from WINDSAT, a passive microwave polarimetric radiometer that is the main instrument still operating on the satellite, was another matter. Decoded with SatDump and massaged with Gimp, the microwave images of Europe are at least recognizable, mostly due to Italy's distinctive shape.
Despite the distortion, seeing the planet's surface through microwaves emitted by water vapor is still pretty cool. If you're looking for more traditional weather satellite images, these are great too.
Spying on satellites is becoming quite popular, enough that the number of people advancing the state of the art - not to mention the wealth of satellites transmitting signals in the clear - has almost made the hobby too easy. An SDR, a homemade antenna and some ready-to-use software, and you too can see weather satellite images on your screen in real time.
But where is the challenge? This appears to be the question [dereksgc] posed and answered by tapping into S-band telemetry from an outdated satellite. Most satellite hunters focus on downlinks in the L-band or even the VHF part of the spectrum, which are within easy reach of most RTL-SDR dongles. However, the Coriolis satellite, which was launched in 2003, has a downlink firmly in the S-band, which at 2.2 GHz puts it just outside the high end of an RTL-SDR. To circumvent this problem, [dereksgc] purchased a counterfeit HackRF SDR and coupled it to a low-noise broadband amplifier (LNA) of its own design. The dish antenna is also made in house from a used 1.8m dish and a custom helical antenna for the right circular polarized downlink signal.
As the video below shows, receiving downlink signals from Coriolis with the platform was not that difficult. Even when manually flying the dish, [dereksgc] was able to record a few decent passes with SDR#. Making sense of the data from WINDSAT, a passive microwave polarimetric radiometer that is the main instrument still operating on the satellite, was another matter. Decoded with SatDump and massaged with Gimp, the microwave images of Europe are at least recognizable, mostly due to Italy's distinctive shape.
Despite the distortion, seeing the planet's surface through microwaves emitted by water vapor is still pretty cool. If you're looking for more traditional weather satellite images, these are great too.
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