Recently a reader of our blog, Initrd, wrote in to let us know about a new tutorial he created that shows how to set up a dual NOAA APT and Meteor LRPT weather satellite monitoring station with an RTL-SDR dongle. These weather satellites transmit a live image of the portion of the earth that they are currently over, providing a valuable tool for weather analysis. APT transmissions are analogue and are transmitted by the American NOAA satellites, and the newer Meteor M2 satellite transmits a higher resolution image in the LRPT format. We also have posted separate tutorials that show how to set up NOAA APT and Meteor M2 LRPT decoding with an RTL-SDR, but Initrd’s tutorial appears to be a good all in one guide.
His tutorial takes you step by step through a process that involves setting up the satellite tracking software Orbitron, all the required SDR# plugins, the APT decoder WXtoIMG and the LRPT decoder. The tutorial also shows how to connect them all together and set them up so that APT and LRPT decoding can coexist.
RTL-SDR.com reader Happysat recently wrote in with some news. A few days ago a weather satellite image decoding enthusiast from Argentina was waiting for a pass of the Russian Meteor M-N2 satellite when he discovered a strong LRPT signal at 137.1 MHz, even though the Meteor M-N2 satellite was not in sight yet. It turns out that the signal was coming from the old Meteor M-N1 satellite which was supposed to have been shut down in September 2014 due to several problems it had. The received signal is strong enough to produce a good black and white weather image, but because the satellite is not longer physically stable, sometimes the Earth’s curve can be seen in the images.
The exact reason as to why it is transmitting again is unknown, but it is speculated that it is due to a breakdown of the chemicals in the batteries. Last year we posted about how sometimes satellites which have been decommissioned and shut down can spontaneously begin transmitting again when their batteries undergo a chemical change due to thousands of failed recharge cycles. The chemical change allows the batteries to conduct electricity from the solar panels directly to the electronics, which on Meteor M-N1 could be reactivating the transmitters and imaging sensors. If this is what happened then the satellite will only be able to transmit during the day.
Happysat who submitted this news originally writes:
A few days ago some guy in Argentina was waiting for the pass of Meteor M-N2 and on SDRSharp waterfall he did see LRPT Digital signals on 137.100MHz, but Meteor M-N2 was not in sight yet…
This relatively strong signal was coming from the defunct Meteor M-N1 satellite left out of control in September 2014 last year and was shutdown, although LRPT Transmissions in the past where very limited and sporadic.
Meteor M-N1 did suffer from many problems at this was the first Russian digital weather satellite in the M-series onboard many hardware in experimental stages.
After this report I tried also to capture some signals from Meteor M-N1 (some other amateurs already got small portions of images) but the satellite only transmits in direct sunlight, batteries are not charging any more.
Indicating maybe like the other older ‘deadsat’ some chemical reaction did occur inside the batteries so the power goes from the solar panels directly to the transmission parts. It did happen before, mostly on older satellite’s only a unmodulated carrier is present when the sunlight conditions are optimal.
Surprisingly after I did record and process the 80K symbol rate QPSK signal from Meteor M-N1 with Vasili’s excellent QPSK Plugin a very nice image was generated!
Not only the sunlight provides power to the transmission part but also there is enough power to activate the imaging system which is quite amazing!
Visible channels 1-2-3 are fully working but the image is only Black and White Calibaration of the sensor are not okay so no color images can be created.
Nevertheless its a very nice addition for current LRPT weather amateurs and a big surprise its even working better when nobody controls it 😉
Because the stabilisation system failed there is no proper correction to orientate the camera and on some passes one can see the earths curve!
There are some conflicting reports about the status of Meteor M-N1 found on the internet:
Status Inactive Details on Status (as available)
MSU-MR was functional with limitations (calibration issues and higher noise level in the IR channels).
MTVZA-GY instrument was functional with limitations due to failures of on-board memory and atmospheric sounding channels.
Severjanin instrument non-operational.
DCS was functional with limitations due to interferences to signals from ground sources.
GGAK-M was operational with significant limitations.
LRPT was functional with limitations due to information compression errors.
Finally, the stabilisation system failed on 23 September 2014 and the instruments could longer be operated.
On October 1, 2014 Meteor-M No 1 was withdrawn from operational use and transferred to the study of the chief designer. The decision on further operation of the spacecraft will be taken upon completion of the research program.
Its not clear the problems did got solved, and I ‘think’ M-N1 started a second life on his own. Time will tell how long the satelitte will function.
Pete’s tutorial starts from a fresh install of Ubuntu and uses GQRX, GNU Radio Companion, WxtoIMG and the MeteorM2 decoding tools. He shows how to set up the audio piping within Linux, how to run the MeteorM2 LRPT Offline decoder Windows tool in Wine, a Linux Windows emulator and how to use WxtoIMG together with GQRX.
The NOAA and Meteor M2 weather satellites transmit images that they have taken of the earth. With an RTL-SDR and appropriate antenna you can receive these images. On this blog we have Windows tutorials on receiving NOAA and Meteor M2 satellites.