Tagged: LRPT

A Tutorial on Receiving HRPT Weather Satellite Images with an SDRplay RSP2

RSP2user's HRPT equipment

Over on the SDRplay forums user 'RSP2user' has put up a quality post describing how he receives HRPT weather satellite images with his SDRplay RSP2. HRPT stands for 'High Resolution Picture Transmission' and provides a much higher resolution image compared to the APT weather satellite images typically downloaded from NOAA satellites. Somewhat confusingly the picture quality of HRPT is similar to LRPT (low rate picture transmission) which is used on the Russian Meteor M series weather satellite. HRPT provides 1.1 km resolution, whilst LRPT provides 1 km resolution.

Currently there are multiple satellites broadcasting HRPT signals including NOAA 19, NOAA 18, NOAA 15, Meteor M2, Fengyun 3B, Fengyun 3C, Metop A and Metop B.

The difference in difficulty of receiving APT and LRPT versus HRPT transmissions typically occur in the L-band at about 1.7 GHz, and requires a directive high gain antenna with tracking motor to track the satellite as it passes over. This makes these images many times more difficult to receive compared to APT and LRPT which only require a fixed position antenna for reception at the more forgiving 137 MHz.

Over on his post RSP2user shows how he uses a repurposed Meade Instruments telescope tracking mount and controller to drive the tracking of a 26 element loop Yagi antenna. A 0.36dB noise figure LNA modified with bias tee input is used to boost the signal and reduce the noise figure. The signal is received by a SDRplay RSP2 and processed on a PC with USA-satcoms HRPT decoder software, which is available for purchase by directly contacting him. The HRPT signal bandwidth appears to be about 2.4 MHz so possibly an RTL-SDR could also be used, but it might be pushing it to the limit.

If you are interested, RSP2user also uploaded an APT weather satellite image reception tutorial on another post. This tutorial shows how to build a quality quadrifilar helix antenna as well.

Receiving the HRPT signal on USA-Satcoms' HRPT decoder.
Receiving the HRPT signal on USA-Satcoms' HRPT decoder.

A New Meteor M LRPT Image Decoder for Windows, Linux, MacOS and Raspberry Pi

Thanks to twitter user @LinuxSocist for submitting a link to this new Meteor M weather satellite LRPT decoder called ‘meteor_decoder’ which can be run on both Linux and Windows. Pre-built binary of the software for Windows, Linux Raspberry Pi and MacOS are available at orbides.org.

This software decoder appears to be an excellent choice for those people who want to perform their reception and decoding of Meteor M satellites all in Linux. Previously as explained in this previous post, you were able to receive the QPSK data in Linux with an RTL-SDR and a GNU Radio program, but then you’d still need to boot into Windows or run Wine to run LRPTofflinedecoder in order to generate the image. Now it appears that the image generation can be performed natively in Linux too with meteor_decoder. This help with creating portable automated Raspberry Pi based Meteor M decoder servers.

Meteor M is a class of Russian weather satellites that transmit live weather images of the earth as they pass over your location. They are somewhat similar to the NOAA satellites, although the Meteor satellites transmit higher quality images via a digital LRPT signal, rather than the analog APT signals used by NOAA. With an RTL-SDR, an appropriate antenna and decoding software they can easily be received.

An Example LRPT Image Received with an RTL-SDR from the Meteor-2 M2.
An Example LRPT Image Received with an RTL-SDR from the Meteor M-N2 Satellite.

Real-Time decoding of Meteor-M2 on Linux

Recently RTL-SDR.com reader Mark wrote in and wanted to share his modified version of otti-soft’s GNU Radio flowgraph for decoding Meteor-M2 weather satellite images on Linux. The modified version allows for real time decoding, whereas the original version requires several offline decoding steps to be performed after recording the signal.

Mark writes:

I have modified one of otti-soft’s gnuradio flowgraphs so that they work with RTL-SDR and output the demodulated symbols to a TCP socket, from which the new version of LRPT Analizer (from robonuka.ru) can decode the data in real-time.

First, one needs to download and extract the AMIGOS version of the LRPT analyzer from robonuka.ru: ftp://meteor2soft:[email protected]/AMIGOS/AMIGOS2.zip.

(AFAIK, only the AMIGOS version is able to decode the data from a socket, which is required for real-time decoding).

The program is to be run under a 32-bit version of Wine.

When the satellite is overhead, open and run the flowgraph (attached) in gnuradio-companion and leave it running. You might need to adjust the gain.

Then, run the LRPToffLineDecoder.exe executable from the extracted archive.
It should display a constantly-updating constellation diagram. When the data is decoded, the channel images will start to appear in each section of the window.

That’s it, when the image is decoded, one can save it and close the windows of gnuradio-companion and the decoder.

Notes: when running the flowgraph, no other processes (rtl_sdr, rtl_power, gqrx, …) should use the SDR device.

The modified GRC file is available here.

The real-time Meteor M2 GNU Radio script for Linux
The real-time Meteor M2 GNU Radio script for Linux

Setting up an RTL-SDR based APT/Meteor Satellite Weather Station Receiver

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.

sdrsharp_apt

Meteor M-N1 Satellite Wakes up from the Dead

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.

Recent images received from the resurrected Meteor M-N1 weather satellite.
Recent images received from the resurrected Meteor M-N1 weather satellite.
Recent images received from the resurrected Meteor M-N1 weather satellite.
Recent images received from the resurrected Meteor M-N1 weather satellite. The stabilization system has failed so the earth’s curve can be seen.

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.

The Meteor M-N2 satellite is the currently official active satellite. It transmits weather satellite images with the LRPT protocol which can be received and decoded with an RTL-SDR dongle. We have a previous post on this showing an offline LRPT decoding tutorial and more recently a tutorial showing how to decode LRPT in real time. The same processes can now be adapted to the resurrected Meteor M-N1 satellite by choosing the 80K symbol rate option in the LRPT decoder.

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.

Some details:

https://directory.eoportal.org/web/eoportal/satellite-missions/m/meteor-m-1

http://planet.iitp.ru/english/spacecraft/meteor-m-n1_eng.htm

The Meteor M-N1 Satellite.
The Meteor M-N1 Satellite.
A color image received on Meteor M-N1. Colors may not be perfect. Submitted by Jan.
A color image received on Meteor M-N1. Colors may not be perfect. Submitted by Jan.

A Tutorial on Decoding NOAA and Meteor M2 Weather Satellite Images in Ubuntu

Recently an RTL-SDR.com reader by the name of Pete wrote in to let us know about a comprehensive tutorial that he has written about setting up NOAA and Meteor M2 weather satellite decoding in Ubuntu Linux with an RTL-SDR.

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.

The Windows LRPTOfflineDecoder tool running in Linux with Wine.
The Windows LRPTOfflineDecoder tool running in Linux with Wine.

Airspy GNU Radio Script for Receiving LRPT Meteor-M2 Weather Satellite Images

Previously we posted about receiving LRPT weather satellite images from the Russian Meteor-M2 weather satellite using the RTL-SDR. Now on GitHub, developer otti-soft has uploaded a LRPT decoder GNU Radio script for the Airspy. The script appears to be a modified version of the GNU Radio based real time decoder for the RTL-SDR, but optimized for the Airpsy and it’s 10 MSPS or 2.5 MSPS sampling rates. Note that although this is a real time receiver, the final image still needs to be processed on a Windows PC using LRPToffLineDecoder.

Also over on Twitter otti-soft has been uploading some images that he has received with his Airspy.

Real time LRPT Receiver for the Airspt
Real time LRPT Receiver for the Airspy