A Linux Distro For All Your Ham Needs

February 23, 2023 by Bryan Cockfield 29 Comments

For anyone new to the world of ham radio, one of the things that takes a little getting used to is visiting the websites of authoritative experts in various fields and feeling like you’ve traveled back to the Internet of 1999. As a hobby that lends itself to extremely utilitarian amateurs, the software side can feel a little left behind like that. [Andy] aka [KB1OIQ], on the other hand, is also a Linux enthusiast and has been putting together a complete Linux distribution with everything needed to operate a radio in the modern era.

While most ham radio software seems to be developed for Windows, there is a lot available for Linux. It just takes a bit of tinkering and experimentation to get everything configured just right. Andy’s Ham Radio Linux, or AHRL, takes a lot of the guesswork out of this. The distribution includes everything from contact logging software to antenna modeling, propagation forecasting, and electronic design. While tools like this are largely optional for operating radios themselves, there are also tools included to allow the user to operate various digital modes as well, which require some sort of computer interface to use.

The other design consideration [Andy] made was something that most hams consider when choosing software, which is that it should be able to run on extremely modest hardware. To that end, the distribution is based around Xubuntu and can run on ten-year-old machines with as little as 2 GB of RAM. And, for those interested more in software-defined radio specifically, there is another Debian-based Linux distribution called DragonOS that we’ve featured a few other times as well which is also worth checking out.

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Hackaday Links: February 12, 2023

February 12, 2023 by Dan Maloney 24 Comments

So, maybe right now isn’t the best time to get into the high-altitude ballooning hobby? At least in the US, which with the downing of another — whatever? — over Alaska, seems to have taken a “Sidewinders first, threat identification later” approach to anything that floats by. The latest incident involved an aircraft of unknown type, described as “the size of a small car” — there’s that units problem again — that was operating over Prudhoe Bay off the northern coast of Alaska. The reason that was given for this one earning a Sidewinder was that it was operating much lower than the balloon from last week, only about 40,000 feet, which is well within the ceiling of commercial aviation. It was also over sea ice at the time of the shootdown, making the chance of bothering anyone besides a polar bear unlikely. We’re not taking any political position on this whole thing, but there certainly are engineering and technical aspects of these shootdowns that are pretty interesting, as well as the aforementioned potential for liability if your HAB goes astray. Nobody ever really benefits from having an international incident on their resume, after all.

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Laptop connected via Ethernet to Raspberry Pi-based secure radio device with antenna

Secure LoRa Mesh Communication Network

January 25, 2023 by Dave Walker 20 Comments

The Internet has allowed us to communicate more easily than ever before, and thanks to modern cell-phone networks, we don’t even have to be tied down to a hard line anymore. But what if you want something a little more direct? Maybe you’re in an area with no cell-phone coverage, or you don’t want to use public networks for whatever reason. For those cases, you might be interested in this Secure Communication Network project by [Thomas].

By leveraging the plug-and-play qualities of the Raspberry Pi 4 and the Adafruit LoRa Radio Bonnet, [Thomas] has been able to focus on the software side of this system that really turns these parts into something useful.

Window showing secure text communications — Messages are tagged as “authenticated” when a shared hashing code is included in the message

Rather than a simple point-to-point radio link, a mesh network is built up of any transceivers in range, extending the maximum distance a message can be sent, and building in resilience in case a node goes down. Each node is connected to a PC via Ethernet, and messages are distributed via a “controlled flooding” algorithm that aims to reduce unnecessary network congestion from the blind re-transmission of messages that have already been received.

Security is handled via RSA encryption with 256-byte public/private keys and additional SHA256 hashes for authentication.

The packet-size available through the LoRa device is limited to 256 bytes, of which 80 bytes are reserved for headers. To make matters worse, the remaining 176 bytes must contain encrypted data, which is almost always more lengthy than the raw message it represents. Because of this, longer messages are fragmented by the software, with the fragments sent out individually and re-assembled at the receiving end.

If you’re in need of a decentralized secure radio communications system, then there’s a lot to like about the project that [Thomas] has documented on his Hackaday.io page. He even includes an STL file for a 3D printed case. If you need to send more than text, then this Voice-over-LoRa Mesh Network project may be more your style.

Translating And Broadcasting Spoken Morse Code

January 24, 2023 by Bryan Cockfield 24 Comments

When the first radios and telegraph lines were put into service, essentially the only way to communicate was to use Morse code. The first transmitters had extremely inefficient designs by today’s standards, so this was more a practical limitation than a choice. As the technology evolved there became less and less reason to use Morse to communicate, but plenty of amateur radio operators still use this mode including [Kevin] aka [KB9RLW] who has built a circuit which can translate spoken Morse code into a broadcasted Morse radio signal.

The circuit works by feeding the signal from a microphone into an Arduino. The Arduino listens for a certain threshold and keys the radio when it detects a word being spoken. Radio operators use the words “dit” and “dah” for dots and dashes respectively, and the Arduino isn’t really translating the words so much as it is sending a signal for the duration of however long each word takes to say. The software for the Arduino is provided on the project’s GitHub page as well, and uses a number of approaches to make sure the keyed signal is as clean as possible.

[Kevin] mentions that this device could be used by anyone who wishes to operate a radio in this mode who might have difficulty using a traditional Morse key and who doesn’t want to retrain their brain to use other available equipment like a puff straw or a foot key. The circuit is remarkably straightforward for what it does, and in the video below it seems [Kevin] is having a blast using it. If you’re still looking to learn to “speak” Morse code, though, take a look at this guide which goes into detail about it.

Thanks to [Dragan] for the tip!

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Supercon 2022: Mooneer Salem Goes Ham With An ESP32

December 28, 2022 by Matthew Carlson 10 Comments

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” →

Working With I2S-Compatible FM Tuners

December 23, 2022 by Lewin Day 9 Comments

While the Internet is a great place to get access to any music or audio you can dream of, there’s still a place for broadcast radio. [mit41301] has recently been exploring implementing a simple FM tuner chip in various projects.

The chip in question is the RDA7088, which is designed to require the bare minimum in external components, and is available in a compact SOP16 package. As per the datasheet, it was intended for use in applications like portable radios, PDAs, cell phones, and MP3 players.

[mit41301]’s first attempt involved using the chip as a simple tuner, hooked up to a PIC10F200 for control. Investigation revealed it was capable of outputting digital audio via I2S, while being commanded via I2C. By default, it spits out audio at a low sample rate of 8 kHz, but reconfiguration will jump that up to 44.1 or 48 kHz. Piping that digital I2S stream out to a DAC then delivers analog output that can be fed to an amplifier. The build also got remote control, with the PIC handling decoding IR signals and outputting commands to the radio chip.

Following this success, [mit41301] then went further, hooking up an ESP-01 to the chip to try and get RDS going. If you’re unfamiliar with the Radio Data System, it’s a way for short textual messages to be sent out by FM broadcasters. In addition to the duties carried out by the PIC module, the ESP-01 is also charged with receiving RDS data from the RDA7088, and outputting it to a display.

While using such chips is routine in industry, it’s always great to see a DIY guide to interfacing with specific hardware. If you want to integrate FM radio into your own projects, the RDA7088 is a simple and easy way to do so. We’ve seen similar work before, adding FM radio to the Raspberry Pi.

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Supercon 2022: Sam Mulvey Shows You How To FM Radio

December 15, 2022 by Elliot Williams 19 Comments

Sam Mulvey built his own radio station in Tacoma, WA. Is there a better way to meld ham radio practice with a colossal number of DIY electrical and computer projects? Sam would say there isn’t one! This 45-minute talk is basically the lessons-learned review of setting up KTQA 95.3 – the radio station on the hill.

Sam starts out the talk by introducing you to LPFM. And maybe you didn’t know that there’s a special type of license issued by the US FCC allowing non-profit community radio stations up to 100 W, covering an radius of around 5 km. It’s like running a pirate radio station, but by jumping through a few legal hoops, made legal.

Trash on the Radio

Putting a radio station together on a budget requires a ton of clever choices, flexibility, and above all, luck. But if you’re willing to repair a busted CD player or turntable, scrounge up some used computers, and work on your own amplifiers, the budget doesn’t have to be the limiting factor.

Being cheap means a lot of DIY. For instance, Sam and friends made a custom console to support all the gear and hide all the wiring. Some hot tips from the physical build-out: painted cinderblocks make great studio monitor stands, and Cat-5 can carry two channels of balanced audio along with power, with sufficient isolation that it all sounds clean. Continue reading “Supercon 2022: Sam Mulvey Shows You How To FM Radio” →