Tech Minds: Using the RK888 MK2 to Receive the Entire HF Band

In one of his latest videos Matt from the Tech Minds YouTube channel tests out the RX888 MK2 software defined radio at HF frequencies. Matt notes that while the bandwidth of this SDR is limited to 10 MHz at VHF/UHF, you can actually use it in direct sampling mode to achieve a massive bandwidth of 64 MHz, allowing you to receive the entire HF band at simultaneously.  

In his video, Matt uses SDR-Console V3 and he shows the entire HF band being received at once. He also shows the SDR-Console V3 matrix bands organizer, which allows you to create multiple windows of zoomed-in spectrum. That combined with the multi-receiver feature could allow you to have multiple audio outputs for digital decoding across the HF band.

Amazing! ALL HF Bands at the SAME time with the RX888 Mk2

Airspy 2024 Summer Sale: 15% Off All Airspy Products

Airspy is currently holding their annual summer sale which gives 15% off their line of products until June 30 2024. The sale brings the price of the popular Airspy receiver products down to the following in US dollars (note that actual pricing may vary across local resellers):

  • Airspy R2: $169.00 $143.65
  • Airspy Mini: $99.00 $84.15 
  • Airspy HF+ Discovery: $169.00 $143.65
  • Airspy SpyVerter R2: $49.00 $41.65
  • YouLoop Antenna: $39.95 $33.95

The sale is active at all participating resellers, which includes our own store where we have the YouLoop on sale for US$33.95 including free shipping to most countries in the world. 

Some good reviews of the YouLoop include the YouTube videos done by Frugal Radio where he reviews HF reception and VLF & LF reception with an Airspy HF+, and later tests it with an RTL-SDR Blog V3 using direct sampling. Techminds also has an excellent review on his YouTube channel. 

If you are on Twitter/X, make sure to also retweet the sale post for a chance at winning something.

Decoding Meshtastic in Realtime with an RTL-SDR and GNU Radio

Over on his YouTube channel, Aaron, creator of DragonOS and WarDragon has uploaded a video showing how it is possible to decode Meshtastic with an RTL-SDR and GNU Radio project called Meshtastic_SDR

If you weren't aware of it, 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 are able to 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 skiiers who operate in remote areas without cell phone coverage.

In the video, Aaron shows how to install the Meshtastic GNU Radio software on DragonOS (Linux), and how to run the GNU Radio flowgraph and Python decoder script. Later in the video Aaron shows some test text messages being received by the software.

The Meshtastic_SDR project can also be used to transmit Meshtastic messages with an appropriate TX-capable SDR.

WarDragon Real-Time Decoding Meshtastic w/ GNU Radio & SDR (RTLSDR v3)

An Atmega328 + SI5351 Based WSPR Beacon

Thank you to Ihar Yatsevich for writing in and sharing with us his open-source WSPR beacon project. The WSPR beacon consists of a custom PCB with ATMega328 microcontroller, GPS module, single transistor amplifier, and Si5351 with TCXO.

The result is a very simple, portable WSPR beacon that can be heard all over the world. However, it appears that no band filters are built into this, so you will need to add a bandpass filter for the WSPR band that you are using.

WSPR (Weak Signal Propagation Reporter) (pronounced "whisper") is an amateur radio digital HF mode designed to be decodable even if the signal is received with very low power. Because of this design, even low-power transmitters can be received from all over the world. It can also be used to help determine HF radio propagation conditions as WSPR reception reports are typically automatically uploaded to wsprnet.

If you are interested, Ihar has written about his project in more detail over on Reddit

Ihar's Microcontroller Based WSPR Beacon
Ihar's Microcontroller Based WSPR Beacon

Artemis 4 Released: Offline Signal Identification Database

Back in 2019 we posted about the release of Artemis 3, an open-source multi-platform program that makes searching through the Signal Identification Wiki offline possible and easy to do.

Recently Artemis 4 has been released which is an entire rewrite of the code, resulting in some substantial improvements, and paving the way for future features like machine learning based identification. Author Marco Dalla Tiezza writes:

  • Artemis was initially designed to provide an offline solution for consulting the library of signals provided by the community on sigidwiki, but the database was formerly a simple .csv with all its limitations. Now the database is a proper relational sqlite which is much easier handled and offers many other possibilities like: additional fields (for example, each frequency of a signal can contain a description and this is true for every single parameter), faster db operations (for example, filtering signals is done by a simple query), increased extensibility due to the fact that new fields/parameters can be introduced in the future or by the user itself.
  • The only searchable database with Artemis 3 was the Sigid wiki database.Now, with Artemis 4, users can create their own custom databases, enter an arbitrary number of signals and parameters, attach documents or any useful information, and export it by sharing it with their friends.
  • The documentation has been completely revised to be as clear as possible and to be able to take the user from installation to advanced use of the program by giving instructions on how they can contribute to the project. DOCUMENTATION
  • As usual, the program provides a real-time interface to be able to track space weather in near real-time, but now this module is more focused on RF propagation such as meteor scatter, EME, sporadic E, aurora spots, DRAP, aurora forecasts and many more (we are actively adding useful descriptors).
  • Artemis 4 now relies on the PySide 6 graphics framework, which not only allows for a modern and newer, user-customizable GUI but also allows for less use of third-party libraries to run the program.
  • Given the flexibility and especially the modularity of the new software, it is very likely that signal analysis functions will be introduced in the future (such as automatic recognition of signals via machine learning/neural network or simpler ones like FFT for obtaining ACF from an audio file, etc.)
  • The homepage of the project (https://www.aresvalley.com) as been updated as well and there you can see some screenshots or directly download the software to give it a try.

If you weren't aware, the Signal Identification Wiki (sigidwiki) is our sister site, which we started a few years ago to collect and catalog various types of signals that an SDR user might see and hear on the airwaves. The idea is that a user could search the database to learn about and identify unknown signals. Over time it has grown significantly, now over 500 known signals with both waterfall images and sound samples available in the database. We have since handed over the operation of the Wiki to the community, with Carl Colena taking on the lead.

Artemis 4 Screenshot

xMASS SDR – 8×8 MIMO Transceiver for 4G/5G Applications to be Crowd Funded

Thank you to creators Sergey and Andrew who have submitted news about their upcoming software defined radio called 'xMASS SDR'. xMASS will be a SDR with 8 RX and 8 TX channels, with a max sample rate of 60 MSPS per 8 channels, or 100 MSPS per 4 channels, and a frequency range of 30 - 3800 MHz.

The board comes in a modular PCIe form factor, with 4x FPGAs, and GPS/PPS clock sync input. The system is designed in mind for 4G/5G applications but should be useful for other applications too.

xMASS SDR will be crowd-funded on CrowdSupply, and they note that they expect to launch the campaign soon. So if you are interested, sign up for email updates on their CrowdSupply page.

Sergey and Andrew write:

We’re creators (Sergey Kostanbaev and Anrew Avtushenko) of the M.2 uSDR board that we successfully crowdsourced a year ago. Now we want to share our new invention called xMASS SDR, a modular, high-performance MIMO transceiver. It has 8 RX and 8 TX channels that can be synchronized for directional finding, beamforming and more applications. Each SDR module, called xSDR, is based on the LMS7002M chip and can deliver 2 RX and 2 TX channels. Like uSDR, xSDR shares the same form factor and M.2 pinout and both use the same open-source software and gateware stack.

xMASS SDR is ideal for 4G/5G but can be interesting among academic, industrial and advanced hobbyists. 

The xMASS SDR board connected via PCIe on a motherboard.
The xMASS SDR board connected via PCIe on a motherboard.
The xMASS SDR board with 4x uSDR modules by itself.
The xMASS SDR board with 4x modules by itself.

SignalsEverywhere: Build an RTL-SDR Based OP25 Radio Scanner with a Mobile Control Head Android App

Welcome back to Sarah from the SignalsEverywhere YouTube channel who has recently returned to producing videos from a hiatus. In her latest video, Sarah shows off her new OP25 Mobile Control Head Android App which allows you to implement a full P25 digital radio scanner at a fraction of the cost of a commercial digital scanner. In the past, Sarah had released a similar application written for the Raspberry Pi but has decided to shift her focus to writing an equivalent Android app that is less clunky and can be deployed for a lower cost. 

The app controls and displays information from the OP25 software that runs on a Raspberry Pi with RTL-SDR connected. It works by using a server application on the Raspberry Pi that manipulates the OP25 instance and its configuration files.

Sarah writes:

The application is a wrapper for OP25 that uses a raspberry pi and an android device to provide users with a mobile control head for their OP25 P25 scanner setup. Currently it's just a basic application but I'll be adding features like automatic site switching, etc.

OP25MCH: https://github.com/SarahRoseLives/OP25MCH

There is also a separate application I call the OP25Display which is just a display for a users existing OP25 instance.

OP25Display: https://github.com/SarahRoseLives/op25display

Build Your Own Digital Radio Scanner With OP25 Mobile Control Head App

A 3D Printed Enclosure with USB Hub for RTL-SDR Blog Units

Over on Hackaday, we've seen a post about Jay Doscher's clever 3D printed enclosure that can hold two RTL-SDR Blog V4 units and a USB hub. The enclosure is designed to make it easy to take the two units mobile, and the USB hub inside means that only one USB connection is required to run the two units.

Jay has also thought about cooling, allowing for space between the two dongles, and adding vent holes. He has also ensured that the SMA ports on the dongles are protected while allowing space to hand-tighten the connectors.

Jay writes that he has tested his enclosure with RTL-SDR Blog V4 units, but given that the dimensions of the V3 (and V2) are the same, it will work for those units too.

A 3D Printed RTL-SDR Blog Enclosure with USB Hub
A 3D Printed RTL-SDR Blog Enclosure with USB Hub