Tagged: Meteor-M2

Meteor M N2-2 Successfully Launched: Awaiting LRPT Signal

On July 5 the Russian Meteor M N2-2 weather satellite was successfully launched into orbit and appears to be healthy. The LRPT weather camera signal is not yet broadcasting however, and we expect it to still take roughly 1-2 months before it begins (if all goes well) as satellites typically run through a long list of qualification tests before becoming operational. During this time there may be broadcasts of test patterns that can be caught. Meteor M N2-2 can currently be tracked in Orbitron and online at N2YO.

To try and dispel any confusion over the naming scheme, "Meteor M N2" is the currently operational LRPT satellite. "Meteor M N2-1" unfortunately failed in 2017 as it did not separate from the rocket. "Meteor M N2-2" is the new satellite which has just been successfully launched. Meteor M N2 and M N2-2 is often abbreviated as just "Meteor M2" and "Meteor M2-2". In the past there was Meteor M N1, but this satellite is no longer operational. We have upcoming launches for Meteor M2-3, M2-4, MP-1 and M3 to look forward to which are scheduled for 2020 and 2021.

Back on June 28 we posted about how Meteor M2 was experiencing orientation issues for a few days. Those issues appear to have been rectified now. Hopefully if M2 remains stable we'll have two Meteor LRPT weather satellites to receive alongside the three NOAA APT satellites.

If you're interested, there were also several other payloads onboard the rocket carrying M2-2, including a low cost Czech experimental cubesat called Lucky7 whose telemetry can be received in the amateur radio band at 437.525 MHz. There is an onboard camera too, but no details on how to receive it yet.

Soyuz Rocket carrying Meteor M2-2 Launched successfully. [Source: spaceflightnow]

Meteor M2 is Currently Experiencing Orientation Issues

Russian weather satellite Meteor M2 is a popular reception target for RTL-SDR radio enthusiasts, as it allows you to receive high resolution images of the Earth. However, currently it appears to be exhibiting orientation issues, causing off center and skewed images and sometimes poor/no reception. Russian blog "aboutspacejornal", writes that the orientation of the satellite can sometimes be restored presumably by a reset command from Earth, but shortly after goes back into uncontrolled rotation.

These sorts of off-axis images were commonly received from the older decommissioned Meteor-M1 satellite, which woke up from the dead in 2015. The resurrection was speculated to be from the batteries shorting out, allowing power to directly flow from the solar panels while in full sunlight. These days Meteor-M1 is no longer transmitting.

Meteor M2 proving the curvature of the earth due to it's orientation issues.
Meteor M2 proving the curvature of the earth due to it's orientation issues.  Image source aboutspacejornal.

Hopefully Meteor-M2 can be fixed, but if not, Meteor M2-2 is due to be launched on July 5 which should also have an LRPT signal that can be received easily with an RTL-SDR. Hopefully the launch is more successful than the November 2017 launch of Meteor M2-1 which unfortunately was a complete loss as it failed to separate from the rocket.

Video Showing How to Decode Meteor M2 with an SDRPlay in Windows

Thanks to "Lolo sdr" for submitting his videos that show his process for receiving and decoding Meteor M2 weather satellite images in Windows with an SDRplay and SDR-Console V3. Since the SDRplay is not supported by SDR#, it is not possible to use Vasilli's excellent Meteor Demodulator plugin (site in Russian, please use the Google Translate option) which is only available for SDR#.

Lolo's method gets around this limitation by initially recording an IQ file of the satellite pass in SDR-Console V3, then opening that IQ file in SDR# via the Fileplayer plugin, which is also by Vasilli and available here. The process is a bit of extra work, and the image isn't live, but the image comes out clearly in the end.

The videos are shown below, and subtitles are available in English, French and Italian via the YouTube player options.

Recibir y decodificar Satélite Meteor M2 con SDRplay, parte 1 de 2, grabar el pase, con subtitulos.

Recibir y decodificar Satélite Meteor M2 con SDRplay, parte 2 de 2, decodificar imagen y corrección.

A Complete Linux based Receiver and Decoder Application for Meteor M2

Thank you to Neoklis (5B4AZ) for writing in and letting us know about his recently completed project which is a RTL-SDR compatible receiver and decoder application for the Meteor M2 weather satellite. It is a combination of other open source programs and he writes:

I combined the recently released Meteor-M2 LRPT demodulator by Davide Belloli (dbdexter-dev), and the older image decoder (translated to C) released by Artem Litvinovich (artlav), with relevant code from my own "sdrx" SDR Receiver application to create a complete monolithic Meteor-M2 Receiver and Image Decoder application, "glrpt".

Neoklis' glrpt application is available on his website www.5b4az.org under the "Weather Imaging -> Meteor M LRPT Receiver" menu. The application is open source and appears to be Linux only. In order to install it you'll need to download and compile the source code, and compilation instructions are available in the documentation stored in the doc folder. Neoklis also writes that you can find his older APT image decoder called "xwxapt" under the same Weather Imaging heading of his website.

GLRPT User Interface Showing Processed Meteor M2 Images
GLRPT User Interface Showing Processed Meteor M2 Images

New GNU Radio Block for Decoding Meteor M2 Images

Thank you to Reiichiro Nakano for submitting news about his work on converting the Pascal based meteor_decoder software into a C++ GNU Radio block. meteor_decoder is a decoder for the Meteor M2 weather image satellite. Meteor M2 is a Russian weather satellite that transmits images down in the digital LRPT format. This provides much higher resolution images compared to the NOAA APT signals. With an RTL-SDR, appropriate satellite antenna and decoding software it is possible to receive these images.

Reiichiro works for Infostellar, which appears to be a Japanese company aiming to connect satellites to the internet via distributed and shared ground stations. It appears to be somewhat similar to the SatNOGs project. Reiichiro writes:

Just wanted to share a simple project I built for my company Infostellar, in the past week. I converted https://github.com/artlav/meteor_decoder to C++ and placed it within a GNURadio block for direct decoding of Meteor M2 images. It's a sink that expects soft QPSK demodulated signed bytes. Once the flowgraph stops running, it parses out received packets and dumps the received Meteor images in a specified location. 

The block is part of our Starcoder repository and can be installed from here (https://github.com/infostellarinc/starcoder/blob/master/gr-starcoder/lib/meteor_decoder_sink_impl.cc ).

A Lightweight Meteor M2 Demodulator

Over on GitHub dbdexter-dev has released a new lightweight and open source Meteor M2 demodulator. Meteor M2 is a Russian weather satellite that transmits images down in the digital LRPT format. This provides much higher resolution images compared to the NOAA APT signals. With an RTL-SDR, appropriate satellite antenna and decoding software it is possible to receive these images.

This new lightweight demodulator may be especially useful for single board PCs like the Raspberry Pi. Previously, on Linux GNU Radio based demodulators have been used, and GNU Radio isn't exactly a light weight piece of software. To use the software you first need to record an IQ file of the Meteor M2 LRPT signal, downsample the IQ file to 140 kHz (if required), then pass it into the demodulator. This will spit out an 8-bit soft-QPSK file which can be used with LRPTofflinedecoder (now known as M2_LRPT_Decoder) on Windows or meteor_decoder on Linux to generate an image.

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

Improving HRPT Reception + A Free HRPT Decoder

Back in December Tysonpower showed us  how he was able to receive HRPT weather satellite images with a 80cm and 1.2m satellite dish, LNA and Airspy Mini. 

If you didn't already know, HRPT signals are a little different to the more commonly received NOAA APT or Meteor M2 LRPT images which most readers may be more familiar with. HRPT images are more difficult to receive as they are broadcast in the L-band at about 1.7 GHz and so receiving them requires a dish antenna (or high gain Yagi antenna), L-band dish feed, LNA and a high bandwidth SDR such as an Airspy Mini. The result is a high resolution and uncompressed image with several more color channels compared to APT and LRPT images.

In the last video Tysonpower was successful with receiving HRPT images with his setup. But recently over on his YouTube channel and on his blog Tysonpower has shown how he has improved his HRPT reception by first optimizing the feed and adding in a copper matching line which helps improve the impedance matching of the feed. He also added an L-Band filter tuned to the HRPT signal which he notes made the biggest improvement, and he also moved all the components into a watertight box for permanent outdoor mounting. With these changes he's now able to consistently pull in some very nice imagery. All the images are still received by hand tracking the satellite dish as the satellite passes over, but he notes that he plans to experiment with motorized trackers in the future.

Note that the video shown below is narrated in German, but English subtitles are provided if you turn on YouTube captions.

[EN subs] HRPT - optimierungen und sehr gute Bilder

A sample HRPT image received by Tysonpower.
A sample HRPT image received by Tysonpower.

In addition to the above Tysonpower also writes that he has created a free HRPT decoder for the HRPT signals originating from NOAA satellites. He writes regarding HRPT decoders:

I found it quite complicated to find a decoder for HRPT when i started and there is still no one that you can just Download.

The only free Decoder is the gr-noaa example in gnu radio that has a depricated wx GUI and uses a input from a specific SDR. I used that gr-noaa example and created a decoder that uses the modern QT GUI and has a clean interface. You just put in a wav IQ file from SDR# for example and it will decode the Data into the file you entered. It is not the best one out there in form of signal processing, but a good start i would say.

The decoder can be downloaded from tynet.eu/hrpt-decoder. Below is a second YouTube video where Tysonpower explains how to use the decoder.

[EN subs] Kostenloser HRPT Decoder (GNU Radio) - Und wie man ihn nutzt

3D Printing a V-Dipole Bracket

Over on his YouTube channel user Tysonpower has uploaded a video that shows how to make a V-Dipole antenna. Back in March we posted about the V-Dipole which Adam 9A4QV first described. A V-Dipole is a simple antenna that normally consists of two metal rods, a terminal block and coax cable. It is particularly effective for reception of low Earth orbit satellites like the NOAA and Meteor M2 weather image satellites with an RTL-SDR or other similar SDR.

In his video Tysonpower shows how to build a slightly more rugged version using a 3D printed part instead of a terminal block. Aluminum welding rods are used for the elements. The 3D printed part ensures that the correct 120 degree ‘V’ angle is maintained and also provides a means for mounting the antenna to a pole. The 3D printing STL files are available on Thingiverse. Note that the video is in German, but English subtitles are available.

Note that we will also have a dipole antenna capable of being used as a V-Dipole available in our store in a few weeks time.

[EN subs] Bau einer V-Dipole Antenne – 3D Druck für mehr Genauigkeit und Stabilität