Updated March 2021
Weather Satellites transmit High Resolution Pictures (HRPT) at 1.7 GHz. The transmission is not encrypted and all needed is a low noise antenna and LNA , an SDR and suitable software for demodulation, decoding and visualization.
The minimal, portable setup regularly in use here is an Airspy Mini USB SDR , a 40cm diameter helicone on a tripod tracking sats by hand and a 0.2 dB NF LNA.
SDR Airspy Mini and USRP1 (modified clock 48 MHz, streaming 6 MSPS)
Antenna and Tracking :
a) Hand tracking using a small low noise helicone antenna (see dimensions below)
b) Automated tracking is done using my own Satellite FUN software and a SPID BIG RAS rotator or 2x DiSEqC motors in X-Y configuration.
Relays in the Rot2Prog controller have been replaced by BTS7960 H bridges, see here.
See also my X band feed page and the dual band L/X feed setup currently in use
Low Noise Amplifier:
Modified G4DDK VLNA NF 0.2dB – absolutely important when the low noise helicone antenna is used. If such an LNA is not available I strongly recommend the use of an antenna with higher G/T . I designed the helicone just for experimentation to see e.g what is the minimum aperture that works given a 0.2 dB LNA is used.
For demodulation and decoding one could use one of the following:
a) Aang254’s excellent free SatDump which supports VHF/ L//S/ X band weather satellites and much more :
For visualization / false color images :
a) David Taylor’s HRPT reader and
b) Fred Jansen’s weathersat
Some pictures showing this small portable setup and what it can do , can be found below.
1.7 GHz helicone design:
The helicone antenna below has been simulated and optimized in CST Microwave Studio.
The goal was minimum dimensions for acceptable G/T performance.
If you decide to build this antenna, it is absolutely important to use a very low noise amplifier (0.2 -0.3 dB) like G4DDK’s excellent VLNA.
Performance will be poor with the popular Nooelec ~1.2 dB Noise Figure LNAs…Those LNA are nice especially if there is interference as they employ a band pass filter. They require antennas with higher G/T than the helicone to compensate for the higher LNA noise.
2 thoughts on “L BAND WEATHER SATELLITE RECEPTION”
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