Tagged: rtl2832u

TechMinds: Building a Handheld MILSAT SATCOM Antenna with 3D Printed Parts and Tape Measures

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.

How To Build A MILSAT SATCOM Turnstile Antenna

Meteor M2-3 Now In Orbit and Transmitting Weather Images

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). 

More information about Meteor M2-3's operational status can be found on Happysat's page.

Over on Twitter we've already seen various Tweets about successful reception.

@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.

We also note that a Meteor Demodulator has also now just been added to SDR++.

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.

Possible fixes for new versions of SDR# crashing with RTL-SDRs

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.

Testing DAB Decoders: SDRAngel versus Welle.io

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

OpenWebRX+ Updates: HFDL, ISM Band, FLEX, SELCALL decoders added

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
SSTV Image received by the luarvique fork of OpenWebRX. Credit: Neil Howard

TechMinds: Detecting Meteors With Software Defined Radio

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.

Detecting Meteors With Software Defined Radio

DragonOS: KrakenSDR and DF Aggregator Connected via a 1km WiFi Link

DragonOS is a ready to use Ubuntu Linux image that comes preinstalled with multiple SDR software packages including a tool called DF Aggregator, which can be used for radio direction finding with a device like our KrakenSDR.

In his latest video, Aaron, creator of DragonOS tests out a long range one kilometer WiFi link between a KrakenSDR, and his base station running DF Aggregator. The WiFi link is achieved by using a ALFA Network 802.11ah (900 MHz US) adapter. The remote KrakenSDR is running on a 'DragonDeck', which is a SteamDeck gaming console with DragonOS installed on it.

In the video Aaron shows that when he transmits with his handheld radio, the remote KrakenSDR is able to provide an accurate bearing towards the transmitter. At the end Aaron also briefly tests out automatic speech transcribing via WhisperCPP.

Aarons tests were run together with @VibesGoon who shows a few great pictures of his KrakenSDR setup on his Twitter Feed.

DragonOS FocalX 1km Remote Connect to KrakenSDR/SDR4Space w/ 802.11ah (hackRF, Halow-U, SteamDeck)

Aaron also shows another picture on his Twitter feed, which also shows the SteamDeck.

An RTL-SDR telemetry decoder for the soon to be launched MRC-100 PocketQube Satellite

Thank you to Zoltan Doczi (HA7DCD) for submitting news about the MRC-100 Hungarian PocketQube Satellite that is scheduled to launch on a Falcon 9 on June 12. A PocketQube is smaller than a standard CubeSat as it is sized at only 5x5x15cm. Zoltan notes that the MRC-100 is the successor to the SMOG-1 satellite which we posted about back in March 2021. The satellite is named to honoring the 100th year anniversary of the HA5MRC Ham Radio Club at the Budapest University of Technology.

To help with decoding the Telemetry on the satellite an RTL-SDR based telemetry receiver was created by Peter and Miklos, and Levente HA7WEN has created an installation script for Raspberry Pi's and Linux PC's which installs OpenWebRX along with the satellite receiver software.

The satellite should be receivable with a simple satellite antenna, such as a handheld Yagi, Turnstile, Dipole or quadrifilar-helix antenna. It will be transmitting telemetry at 436.720 MHz. If you have a dish and tracking equipment for it, there is also a high speed downlink at 2267.5 MHz. Like SMOG-1 the satellite carries a sensor that is designed to measure human caused electromagnetic pollution. It also carries a camera and an AIS receiver for tracking marine vessels.

The MRC-100 CubeSat