Transmitting and Receiving Meshtastic with SDR

Last month we posted about Aaron's video on Meshtastic, and how it's possible to decode the Meshtastic protocol using an RTL-SDR and GNU Radio project called Meshtastic_SDR

If you weren't aware, Meshtastic is software that enables off-grid mesh network based communications and can run on cheap LoRa hardware. The mesh based nature of the system means that communications can be received over long distances, without any infrastructure, as long as there are sufficient Meshtastic nodes in an area that can route the message to the destination node. One example application of Meshtastic is to use it as a mesh-based text messaging system. This might be useful for teams of hikers, pilots, or skiers who operate in remote areas without cell phone coverage.

In his latest video, Aaron shows how Meshtatsic_SDR can also be used to transmit the Meshtastic Protocol using a transmit capable SDR like the HackRF. Aaron writes in the video description:

In this video, we take a deeper dive into the setup and usage of the meshtastic_SDR repository, which now enables the transmission and reception of Meshtastic using Software Defined Radios (SDRs). Recent updates have made this possible by partially leveraging GNU Radio flow graphs for both RX (receive) and TX (transmit), and integrating Python scripts that connect to ZMQ sources for message input and ZMQ outputs for message decoding.

I demonstrate the setup using a HackRF for the transmit side and an Airspy R2 for receiving. We also verify the results of TX and RX using a standard Meshtastic receiver to ensure accurate performance.

DragonOS FocalX Transmit and Receive Meshtastic w/ SDR (hackRF, Airspy R2, R36)

A Great Video Introduction to RTL-SDR

Over on YouTube Paul Lutus has recently posted a video that is a great introduction to software-defined radio, RTL-SDR, and some of the various signals that can be received with one. In the video he uses an RTL-SDR Blog V4, which has a built-in upconverter, allowing for good reception of HF signals.

Paul's video briefly explores SDR theory, before demonstrating various signals on both the HF and VHF+UHF bands that can be received with an RTL-SDR Blog V4. He also briefly touches on GNU Radio.

If you are a just getting started with RTL-SDR this might be a good overview video to watch. Paul has also set up a companion webpage for the video that outlines some of the software installation and usage steps mentioned in the video in greater detail.

Create Your Own Open-Source Software-Defined Radio

SignalsEverywhere: Monitoring Itron ERT Smart Meters on Android

Over on her YouTube channel SignalsEverywhere, Sarah has uploaded her latest video showing how it is possible to monitor Itron ERT smart meters on an Android device.  Smart meters are used to wirelessly monitor the usage of residential utilities such as water, gas, and electricity. With an RTL-SDR and some decoding software, it is possible to monitor the data coming from your own and your neighbours meters (at least for certain brands of meter).

In her video, Sarah shows how she compiled the rtl_amr decoder software for Android, and created her own Android app called "AndAMR" for displaying the data decoded by rtl_amr. The rest of the video shows how to set up and use the app.

Monitoring Itron ERT Smart Meters on Android?!

Tech Minds: Testing an Inmarsat L-Band Helix for Offset Satellite Dishes

In his latest video, Matt from the TechMinds YouTube channel tests out an LHCP L-band helix feed designed for receiving Inmarsat satellites. Matt pairs the feed with an 85cm satellite dish, an L-band LNA, and an Airspy Mini.

The L-band helix feed comes from a small German engineering company called nolle.engineering. The feed is priced at 94.70 Euros (incl. VAT) (~$102 USD), plus shipping costs. It is a passive antenna so it needs to be combined with an LNA to be usable with a typical SDR.

In the video Matt shows that the reception with the LHCP helix + dish setup is better than expected. He also compares it to a previous test he did with a longer RHCP helix antenna also produced by nolle.engineering. The RHCP antenna is used to be used without a dish, however, as expected the SNR is less than the dish + small LHCP feed setup. Matt then shows some Inmarsat signals being decoded including STD-C and Aero voice.

This L Band Helix Antenna Gives Amazing Performance

GOES-U Satellite Launched and on the way to Geostationary Orbit

On June 25 the NOAA GOES-U weather satellite was successfully launched on a SpaceX Falcon 9 Heavy rocket. Once it reaches geostationary orbit, this will be a new weather satellite that RTL-SDR hobbyists can receive with an RTL-SDR dongle, satellite dish, and LNA.

From launch, it will take about two weeks for GOES-U to reach geostationary orbit and once it gets there it will be renamed to GOES-19. It is due to be positioned where GOES-16 currently is, and GOES-16 will become the redundant backup satellite. This positioning will make the satellite visible to those in North and South America.

GOES-16 is where GOES-19 will be positioned.
GOES-16 is where GOES-19 will be positioned.

We are anxiously looking forward to the first images from GOES-19 received by hobbyists, but once positioned it will probably take several weeks to be tested and calibrated before hobbyists can receive any signals on L-band. 

Over on X, @WeatherWorks posted a short video showing that the launch plume was visible from GOES-16.

The @CIRA_CSU account has also posted a video from GOES-18 which shows the launch in the water vapor bands

Finally, @SpaceX has also posted a video showing the deployment of the satellite, with an impressive shot showing how far away it is from the Earth.

An Inspiring Video about Getting Hooked on SDRs

Thank you to 'Tuned Signal' (TS) for sharing his video with impressive production quality, detailing his story on how and why he became hooked on software-defined radio. TS notes how it all started with an Outernet receiver that he purchased, which came with an RTL-SDR dongle. From there he ended up purchasing higher end SDRs and learning more about the different types of signals he could receive.

If you're interested, check out some of his other videos on his YouTube channel which cover topics like how to receive train radios, how to listen to CB radio and more.

Secret Behind SDR: Why You Can’t Stop Listening

SDR# Big Guide Book: 2024 Edition Released

Paolo Romani (IZ1MLL) has recently released the 2024 version of his SDR# Big Book. The book is available for download on the Airspy downloads page, just scroll down to the title "SDR# Big Book" and choose your language. (At the time of this post only English and Italian are available in the 2024 edition, but multiple languages are available for the older guides).

Paolo writes that the book has been updated for the latest SDR# v1920 version, and now the editions will be labelled by date, instead of version number. He also writes that page 25 of the big book now includes information about the differences between RTL-SDR Blog V3 and V4 dongles. 

The Big Book of SDR# Studio 2024 Edition

Tech Minds: Testing the NooElec FlyCatcher RTL-SDR ADS-B+UAT Raspberry Pi Hat

Over on YouTube Matt from the Tech Minds YouTube channel has tested out NooElec's new 'FlyCatcher', which is an RTl-SDR ADS-B hat for the Raspberry Pi. The FlyCatcher has two RTL-SDRs built into it, each with it's own LNA and SAW filter. One SAW filter is tuned for 978 MHz UAT, and the other for 1090 MHz ADS-B.

The device also has buttons that allow you to bypass the LNA stage, and just use filtering, in case you have an external LNA. They appear to be using the Qorvo TQL9063 LNA chip, which has a built-in bypass.

In the video Matt tests out the FlyCatcher, but only on 1090 MHz as 978 MHz UAT is not used in his country. He shows how to set up the software on the Raspberry Pi and then shows some results.

Easily Create Your Own Aircraft Virtual Radar Using The NooElec FlyCatcher Pi Hat