Updated July 2020
Weather satellites transmit High Resolution Pictures at 1.7 GHz. The transmission is not encrypted and all needed is a low noise antenna and LNA , an SDR and GNU-RADIO or third party software.
The minimal, portable setup regularly in use here is an Airspy Mini , a 40cm diameter helicone on a tripod, a 0.2 dB NF G4DDK LNA and XHRPT software .
There are also GNU Radio scripts available.
Some pictures showing this small portable setup and what it can do , can be found below.
The first picture is from a NOAA15 pass which is the weakest of all NOAA,Metop,FY satellites on L-band. Second picture is from the strong NOAA19. Third is from a Meteor MN2-2 pass .
The helicone antenna below has been simulated and optimized in CST Microwave Studio.
The goal was minimum dimensions for acceptable G/T performance.
All in all, no big antennas are required to get excellent pictures.
Some more details also about the larger antenna I use:
1) For automated tracking and reception the 2.5 m EME dish is used. Rotator is a SPID BIG RAS . The feed illuminating the dish is a 3 turn helix off-set to the 23cm N2UO/W2IMU feed . Directly attached to the feed is a a slightly modified G4DDK 23cm VLNA (NF=0.2dB) To protect the L-Band LNA during TX , a low loss PTT-activated coaxial switch is placed in front of the LNA . After the LNA a Lorch 5DF6 band pass filter suppresses any cellular interference.
But as explained above, the setup can also be lightweight and portable ! Satellites can be tracked by hand as well so I use a small helicone antenna (D=40 cm) on a tripod and a G4DDK LNA directly attached to it. Especially when using a low gain / low noise antenna like a small helicone it is important to use a really low noise amplifier.
See below 2.5 m dish for moonbounce.
Note: Need to make a nicer, balanced counterweight. That box only was a quick workaround 🙂
2) Automated tracking is done either with USA_SATCOM’s UltraTrack software or my own EME FUN software and the EME FUN antenna controller
3) SDR is an Airspy Mini or the USRP1 (modified clock 48 MHz,streaming 6 MSPS)
4 ) When I started reception some years ago I used to use GNU-Radio-based POES-USRP on Linux . Then found a way to install GNU-Radio (3.6.4.1) on Windows and used the following flowgraph:
Download HRPT GNU-radio companion .grc file from my dropbox .
As of July 2020, I mostly use USA_SATCOM’s excellent XHRPT software on Windows 10 which supports all active weather satellites of interest : NOAA 15,18,19 / Meteor MN2, MN2-2 and FengYun .
There are also GNU Radio scripts available.
5) For visualization/false color images I use either David Taylor’s HRPT reader or Fred Jansen’s weathersat
73 de SV1CAL – Michael Margaras
Very good article. I see that the USRP is using sample rate of 2 MSPS. Would that be means RTL SDR also can be used?
Hello, thanks for reading. I haven’t played with the RTL SDR. It may work with some modifications of course. If you give it a try, please share your results. Regards, Michael