M17 Digital Communications Go From Strength To Strength

The world of amateur radio is like many other fields in that there has been a move underway from analogue to digital modes. In fact, amateur radio has often led the way in digital innovation.  There’s a snag, though: many of the digital speech modes are proprietary. To address this along comes the M17 project, an effort to create an open digital communication protocol for radio amateurs. We’ve looked at them more than once in the past few years, and as they’ve come up with several pieces of new hardware it’s time for another peek.

First up is the Remote Radio Unit, described as “a comprehensive, UHF FM/M17 “repeater in a box,” optimally designed for close antenna placement, enhancing signal strength and reliability.” The repeater forms the “other half” of the UHF handheld radio chain and will be crucial to the uptake of the protocol.

Continue reading “M17 Digital Communications Go From Strength To Strength”

Supercon 2022: Mooneer Salem Goes Ham With An ESP32

After being licensed as a ham radio operator since the early 2000s, you tend to start thinking about combining your love for the radio with other talents. In a 20-minute talk at Hackaday Supercon 2022, [Mooneer Salem] tells the story of one such passion project that combined software and radio to miniaturize a digital ham radio modulator.

[Mooneer] works as a software developer and contributes to a project called FreeDV (free digital voice), a digital voice mode for HF radio. FreeDV first compresses the digital audio stream, then converts it into a modulation scheme sent out over a radio. The appeal is that this can be understandable down to very low signal-to-noise ratios and includes metadata and all the other niceties that digital signals bring.

Traditionally, this has required a computer to compress the audio and modulate the signal in addition to two sound cards. One card processes the audio in and out of your headset, and another for the audio coming in and out of the radio. [David Rowe] and [Rick Barnich] developed the SM1000, a portable FreeDV adapter based around the STM32F4 microcontroller. However, flash space was running low, and the cost was more than they wanted. Continue reading “Supercon 2022: Mooneer Salem Goes Ham With An ESP32”

Helping Secure Amateur Radio’s Digital Future

The average person’s perception of a ham radio operator, assuming they even know what that means, is more than likely some graybeard huddled over the knobs of a war-surplus transmitter in the wee small hours of the morning. It’s a mental image that, admittedly, isn’t entirely off the mark in some cases. But it’s also a gross over-simplification, and a generalization that isn’t doing the hobby any favors when it comes to bringing in new blood.

In reality, a modern ham’s toolkit includes a wide array of technologies that are about as far away from your grandfather’s kit-built rig as could be — and there’s exciting new protocols and tools on the horizon. To ensure a bright future for amateur radio, these technologies need to be nurtured the word needs to be spread about what they can do. Along the way, we’ll also need to push back against stereotypes that can hinder younger operators from signing on.

On the forefront of these efforts is Amateur Radio Digital Communications (ARDC), a private foundation dedicated to supporting amateur radio and digital communication by providing grants to scholarships, educational programs, and promising open source technical projects. For this week’s Hack Chat, ARDC Executive Director Rosy Schechter (KJ7RYV) and Staff Lead John Hays (K7VE) dropped by to talk about the future of radio and digital communications.

Rosy kicked things off with a brief overview of ARDC’s fascinating history. The story starts in 1981, when Hank Magnuski had the incredible foresight to realize that amateur radio packet networks could benefit from having a dedicated block of IP addresses. In those early days, running out of addresses was all but unimaginable, so he had no trouble securing 16.7 million IPs for use by licensed amateur radio operators. This block of addresses, known as AMPRNet and then later 44Net, was administered by volunteers until ARDC was formed in 2011 and took over ownership. In 2019, the decision was made to sell off about four million of the remaining IP addresses — the proceeds of which went into an endowment that now funds the foundation’s grant programs.

So where does the money go? The ARDC maintains a list of recipients, which provides for some interesting reading. The foundation has helped fund development of GNU Radio, supported the development of an open hardware CubeSat frame by the Radio Amateur Satellite Corporation (AMSAT), and cut a check to the San Francisco Wireless Emergency Mesh to improve communications in wildfire-prone areas. They even provided $1.6 million towards the restoration of the MIT Radio Society’s radome and 18-foot dish.

Of all the recipients of ARDC grants, the M17 project garnered the most interest during the Chat. This community of open source developers and radio enthusiasts is developing a next-generation digital radio protocol for data and voice that’s unencumbered by patents and royalties. In their own words, M17 is focused on “radio hardware designs that can be copied and built by anyone, software that anyone has the freedom to modify and share to suit their own needs, and other open systems that respect your freedom to tinker.” They’re definitely our kind of folks — we first covered the project in 2020, and are keen to see it develop further.

John says the foundation has approximately $6 million each year they can dole out, and that while there’s certainly no shortage of worthwhile projects to support as it is, they’re always looking for new applicants. The instructions and guides for grant applications are still being refined, but there’s at least one hard requirement for any project that wants to be funded by the ARDC: it must be open source and available to the general amateur population.

Of course, all this new technology is moot if there’s nobody to use it. It’s no secret that getting young people interested in amateur radio has been a challenge, and frankly, it’s little surprise. When a teenager can already contact anyone on the planet using the smartphone in their pocket, getting a ham license doesn’t hold quite the same allure as it did to earlier generations.

Depending on how old you are, this might have been one of the most shocking moments in Stranger Things.

The end result is that awareness among youth is low. During the Chat, one participant recounted how he had to put Netflix’s Stranger Things on pause so he could explain to his teenage son how the characters in the 1980s set show were able to communicate across long distances using a homemade radio. Think about that for a minute — in a show about nightmarish creatures invading our world from an alternate dimension, the hardest thing for this young man to wrap his head around was the fact a group of teenagers would be able to keep in touch with each other without the Internet or phone lines to connect them.

So its no surprise that John says the ARDC is actively looking for programs which can help improve the demographics of amateur radio. The foundation is looking to not only bring younger people onboard, but also reach out to groups that have been traditionally underrepresented in the hobby. As an example, he points to a grant awarded to the Bridgerland Amateur Radio Club (BARC) last year to bolster their youth engagement program. Funds went towards putting together a portable rig that would allow students to communicate with the International Space Station, and the development of hands-on workshops where teens will be able to launch, track, and recover payloads on a high altitude balloon. Let’s see them do that on their fancy new smartphone.

We want to not only thank Rosy Schechter and John Hays for taking part in this week’s Hack Chat, but everyone else at Amateur Radio Digital Communications for their efforts to support the present and future of amateur radio and digital communication.

The Hack Chat is a weekly online chat session hosted by leading experts from all corners of the hardware hacking universe. It’s a great way for hackers connect in a fun and informal way, but if you can’t make it live, these overview posts as well as the transcripts posted to Hackaday.io make sure you don’t miss out.

Finally An Inexpensive Route To Digital Radio Listening

An inexorable trend over the last decade or more has been the exodus of AM radio stations from the low frequency and HF broadcast bands. The bandwidth and thus audio quality at these frequencies puts them at a disadvantage against FM and internet streamed services, and the long-distance advantage of HF has been reduced by easy online access to overseas content. The world has largely moved on from these early-20th-century technologies, leaving them ever more a niche service.

Happily for medium- and long-wave enthusiasts there is a solution to their decline, in the form of DRM, or Digital Radio Mondiale, a digital scheme that delivers cleaner audio and a range of other services in the same space as a standard-sized AM channel. DRM receivers are somewhat rare and usually not cheap though, so news of an Android app DRM receiver from Starwaves is very interesting indeed.

DRM uses a licensed encoding scheme from the Fraunhofer Institute, and this product follows on from a line of hardware DRM receivers that Starwave have developed using their technology. It uses the Android device as a front-end for any of a number of SDR receivers, including the popular RTL-SDR series. It supports the VHF variant of DRM, though we’re guessing that since the best chance of finding a DRM channel for experimentation is on HF that an RTL-SDR with the HF modification will be required. We think it’s an interesting development because the growth of DRM is a chicken-and-egg situation where there must be enough receivers in the wild for broadcasters to consider it viable.

Decoding NRSC-5 With SDR To Get In Your Car

NRSC-5 is a high-definition radio standard, used primarily in the United States. It allows for digital and analog transmissions to share the original FM bandwidth allocations. Theori are a cybersecurity research startup in the US, and have set out to build a receiver that can capture and decode these signals for research purposes, and documented it online.

Their research began on the NRSC website, where the NRSC-5 standard is documented, however the team notes that the audio compression details are conspicuously missing. They then step through the physical layer, multiplexing layer, and finally the application layer, taking apart the standard piece by piece. This all culminates in the group’s development of an open-source receiver for NRSC-5 that works with RTL-SDR – perhaps the most ubiquitous SDR platform in the world. 

The group’s primary interest in NRSC-5 is its presence in cars as a part of in-car entertainment systems. As NRSC-5 allows data to be transmitted in various formats, the group suspects there may be security implications for vehicles that do not securely process this data — getting inside your car through the entertainment system by sending bad ID3 tags, for instance. We look forward to seeing results of this ongoing research.

[Thanks to Gary McMaster for the tip!]

Anatomy Of A Digital Broadcast Radio System

What does a Hackaday writer do when a couple of days after Christmas she’s having a beer or two with a long-term friend from her university days who’s made a career in the technical side of digital broadcasting? Pick his brains about the transmission scheme and write it all down of course, for behind the consumer’s shiny digital radio lies a wealth of interesting technology to try to squeeze the most from the available resources.

In the UK, our digital broadcast radio uses a system called DAB, for Digital Audio Broadcasting. There are a variety of standards used around the world for digital radio, and it’s fair to say that DAB as one of the older ones is not necessarily the best in today’s marketplace. This aside there is still a lot to be learned from its transmission scheme, and from how some of its shortcomings were addressed in later standards. Continue reading “Anatomy Of A Digital Broadcast Radio System”