A few days ago we posted about the successful launch and deployment of the latest Russian Meteor M2-3 weather satellite. The satellite is currently actively transmitting LRPT weather images.
Over on his YouTube channel, "saveitforparts" has uploaded a video showing how he received images from the new satellite using his RTL-SDR. His method involves first recording the signal pass on a Raspberry Pi with rtl_fm, and then passing that wav file into SatDump for decoding and image generation.
We note that it is also possible to directly live decode the pass using SatDump, however a Raspberry Pi may be a little too slow to run the GUI version of SatDump. Instead you could use rtl_tcp on the Pi and run SatDump on a networked PC, or simply run the RTL-SDR and SatDump on the PC or a more powerful device like an Orange Pi 5.
Ultimately he experiences some unresolved problems with the decoding process, but is able to end up with a decent image.
Grabbing Images From New Russian Satellite (Meteor M2-3)
If you weren't already aware, KrakenSDR is our 5-channel coherent radio based on RTL-SDRs, and it can be used for applications like radio direction finding. KrakenSDR is in stock and can be purchased from CrowdSupply or Mouser. More information is also available on our website at krakenrf.com.
In this video we are using a KrakenSDR to hunt for the location of a low power FM transmitter (LPFM) station at 106.7 MHz. These low power FM transmitters are legal as unlicensed transmitters as long as they operate under certain restrictions, the main one being that they transmit at under 1 watt EIRP. LPFM stations are typically operated by local communities or niche radio stations.
Because they are unlicensed, there is no official record and their location doesn't show up in the radio spectrum management database. A requirement of LPFM is that the station broadcast the contact information of the owners regularly, but it can be difficult to locate non-compliant stations that don't do this. But the KrakenSDR makes finding them easy.
The array is 45cm in radius, which is about the maximum that my RAV4 car roof can fit. Some of the antennas sit on a slight curve on the roof, but this appears to have negligible effect. The spacing factor is about 0.19 (optimal is 0.5 - a much larger radius), but even 0.19 is sufficient to find the transmitter fairly easily.
In his latest video Matt from the TechMinds YouTube channel shows us how to build a home made turnstile antenna for receiving the MILSAT SATCOM satellites where radio pirates from Brazil and other countries can often be heard.
The build involves 3D printed parts, metal measuring tape for the elements, some aluminum tubes and a coax phasing harness. After testing the VSWR with a meter, Matt tests the antenna with a handheld and finds it to be working well. He also later tests it with his SDRplay RSPdx and finds that the Turnstile outperforms his roof mounted vertical.
Meteor-M satellites are Russian owned weather imaging satellites that are in polar orbit. They transmit images to earth in the LRPT format at 137 MHz, making them almost as easy to receive as the older NOAA APT satellites. Unfortunately all prior Meteor M satellites have suffered an early ending or partial ending to their mission from technical faults or micro-meteorite collisions.
However, on June 27th 2023 the latest Meteor M2-3 satellite was successfully launched on a Soyuz-2 and has been reported to be already transmitting LRPT images of the earth.
Soyuz-2 Launch of Meteor M2-3 and 42 Cubesats
To receive images from the Meteor M2-3 satellite you will need an appropriate 137 MHz satellite antenna such as a v-dipole, Turnstile or QFH. An RTL-SDR or any similar SDR can be used as the receiver.
These days, the easiest software to use to receive Meteor M2-3 is probably SatDump, whose Windows and Android binary releases can be downloaded from the GitHub Releases page. Linux users can follow the build guide in the SatDump Readme. We note that we've found the SatDump GUI to run well on an Orange Pi 5, which makes this a good portable solution too.
To determine when the satellite is over your location you can use satellite tracking software such as Gpredict on Linux and Mac, or Orbitron on Windows. (For Orbitron, remember to run the software as Administrator, and to update the TLEs so that the Meteor M2-3 weather.txt TLE tracking data is downloaded).
Over on Twitter we've already seen various Tweets about successful reception.
1st try w/ 137 MHz LRPT from the new METEOR-M N2-3 1500utc. So nice to have a higher resolution weather sat back on VHF! Images from I/Q replay in SatDump (https://t.co/A7V0MeqeGE) pic.twitter.com/OMs1zjpKb4
Second pass of the newly launched Meteor-M 2-3
This time all worked like a charm and the picture is superb. I tried dual band to compare both LRPT in 137.900 and HRPT in 1700. Although decoded shown picture is from the HRPT stream.
@aang254, the author of SatDump has also noted that he is working on finalizing projections for Meteor M2-3 and this should be ready to use in SatDump shortly.
METEOR-M 2-3 is active, and I have added initial support including projections in SatDump already.
We also note that a Meteor Demodulator has also now just been added to SDR++.
The OQPSK mode has been added to the #Meteor demodulator to decode Meteor M N2-3. Enable it when receiving said satellite. It will be available for download in a few minutes when the nightly build is done building.
Note that some more tuning will be done in the coming days.#SDRpic.twitter.com/DB307Q5ObD
Another interesting fact is that along with Meteor M2-3 the UmKA cubesat was launched will transmit astronomical images at 2.4 GHz. To receive this, you will most likely need a 2.4 GHz WiFi dish, and also a motorized tracking system to track the satellite as it fly's overhead. Decoding of this is already supported in SatDump according to the programmer.
METEOR-M 2-3 is launching tomorrow, and with it UmKA that @HRPTEgor worked on.
It will transmit astronomical imagery on amateur bands 2.4Ghz. As such, I have added support for it in SatDump just now :-)
SDR# (SDRSharp) is our recommend software for RTL-SDRs due to it's high popularity in the community, relatively simple to learn and use interface, and host of features and third party plugins available.
Recently we're starting to see a lot of Facebook and forum posts about a new bug introduced in SDR# 1911 - 1913 so we thought we'd make a global post. This new bug has introduced a problem which causes a crash when attempting to change frequencies with RTL-SDR dongles (of any make or brand). It appears to be an issue stemming from libusb, but the exact issue is still unknown. The SDR# author is aware of the issue, but as RTL-SDR dongles are supported in SDR# for free with no guarantee, it may be several weeks until he has the time to investigate the issue fully. In the meantime we want to note some some partial fixes that we have found.
The first fix is to use our "rtl-sdr-blog" drivers instead of the default osmocom drivers. Our Quickstart guide now shows how to download these drivers and install them into SDR#, so if you want to try this solution, please see the guide. We're not exactly sure why this driver helps, but it may be due to our version being compiled against a newer version of libusb. However, this fix is only partial. While it no longer crashes on every frequency change, it will still crash approximately 5% of the time on a frequency change, which can add up when surfing through the spectrum rapidly, or when using frequency scanners.
We have also found a second fix that almost completely eliminates the crash, but it appears that it only works on some PCs. This fix is to use our rtl-sdr-blog drivers, and at the same time use Zadig to install the "libusb-win32" version of libusb, instead of the WinUSB version. However, the libusb-win32 is old, and it only appears to work on some PCs. On others it causes SDR# to crash as soon as the RTL-SDR is loaded.
Alternatively you can simply use a legacy version of SDR# by clicking the "Latest dotnet x.x build" links on the SDR# downloads page.
The final alternative would be to use another program like SDR++, which is very similar to SDR#, but without a large amount of plugins available yet. We have also added a SDR++ installation guide to our quickstart guide.
Thank you to the team from DXing.org for submitting their video where they compare the DAB decoding performance of SDRAngel and Welle.io using an RTL-SDR Blog V3 dongle.
Digital Audio Broadcast (DAB) is a digital replacement for analog broadcast FM. It provides high quality digital audio at the expense of higher cost receivers, and possibly greater difficulty with reception in weak or challenging RF environments. DAB is mostly only used in Europe and Asia Pacific regions, and is not found in the USA. SDRAngel and Welle.io are both RTL-SDR compatible programs with DAB decoding capabilities. Both can run on Android, PC, MacOS and Linux devices.
In their tests they find that the Welle.io DAB decoder works perfectly without issues, however the SDRAngel DAB decoder struggles and has difficulty with decoding. Given that Welle.io is a dedicated DAB decoder, and SDRAngel is a multipurpose tool this could be expected. But we are unsure what is wrong with the DAB implementation in SDRAngel.
The team note that the test was carried out in Sofia, Bulgaria, Europe, using a Serbian DAB+ signal from Yastrebac, with a distance of 175km.
Test android apps with DAB+ signal Welle.io vs. SDRangel, receiver rtl-sdr v.3
Back in March of this year we posted about an OpenWebRX fork called OpenWebRX+, which adds multiple built-in and ready to use decoders such as SSTV, AIS, CW and RTTY. OpenWebRX+ is a fork of the OpenWebRX project which is now officially maintained by DD5JFK.
Since our last post OpenWebRX+ has progressed in development further, and now includes a HFDL decoder via dumphfdl, various ISM band equipment decoders via rtl_433, FLEX pager decoding via multimon-ng, and a SELCALL decoder has also been added. Many other improvements and changes to the software have also been added, and the full changelog can be viewed here.
OpenWebRX+ is software for Linux. If you want to install OpenWebRX+, an easy path is to use the ready to use Raspberry Pi 4 image available on the releases page, or to use their PPA.
SSTV Image received by the luarvique fork of OpenWebRX. Credit: Neil Howard
In his latest video Matt from the TechMinds YouTube channel has shown how it's possible to detect the RF echoes of meteors falling in the earths atmosphere which a software defined radio.
The concept is relatively straightforward. Meteors falling in the atmosphere generate an RF reflective ionized trail, which is highly reflective to RF. In the UK where Matt lives, the Sherwood Observatory of the Mansfield and Sutton Astronomical Society (MSAS) have set up a meteor detection beacon "GB3MBA" which transmits an 80W CW signal at 50.408 MHz.
When tuned to this frequency with an SDRplay RSPdx SDR, Matt shows how the shifted reflections of meteors can be seen as blips around the beacon's carrier frequency. What is also seen are reflections from aircraft which show up as longer doppler shifted lines. Matt notes that if you live within 200km of the beacon a simple dipole antenna is sufficient, however any further might require an antenna system with more gain like a Moxon or Yagi.
We note that in Europe a similar beacon called the GRAVES space radar in France which operates at 143.050 MHz can be used.
