AIOC: The Ham Radio All-In-One Cable For Audio And APRS

The Ham Radio All-in-one cable (AIOC) is a small PCB attachment for a popular series of radio transceivers which adds a USB-attached audio interface and virtual TTY port for programming and the push-to-talk function. The STM32F373 microcontroller (which, sadly is still hard to find in the usual channels) is a perfect fit for this application, with all the needed hardware resources.

With USB-C connectivity, the AIOC enumerates as a sound card as well as a virtual serial device, so interfacing to practically any host computer should be plug-and-play. Connection to the radio uses 12mm separation 3.5mm and 2.5mm TRS connectors, so is compatible with at least the Baofeng UV-5R but likely many other cheap transceivers that have the same physical setup.

Instructions are provided to use the AIOC with Dire Wolf for easy access to APRS applications, which makes a nice out-of-the-box demo to get you going. APRS is not all about tracking things though since other applications can sit atop the APRS/AX.25 network, for example, HROT: the ham radio of things.

We’ve seen quite a few Baofeng (and related products) hacks, like this sketchy pile of wires allowing one to experiment with the guts of the radio for APRS. Of course, such cheap radio transceivers cut so many engineering corners that there are movements to ban their sale, so maybe a new batch of better radios from our friends in the East is on the horizon?

Thanks to [Hspil] for the tip!

This Standalone Camera Gets The Picture Through With SSTV

These days, sending a picture to someone else is as simple as pulling out your smartphone and sending it by email or text message. It’s so simple a child can do it, but that simple user experience masks a huge amount of complexity, from the compression algorithms in the phones to the huge amount of distributed infrastructure needed to connect them together. As wonderful and enabling as all that infrastructure can be, sometimes it’s just too much for the job.

That seems to have been the case for [Dzl TheEvilGenius], who just wanted to send a low-resolution image from a remote location. It turns out that hams solved that problem about 70 years ago with slow-scan television, or SSTV. While most of the world was settling down in front of “I Love Lucy” on the regular tube, amateur radio operators were figuring out how to use their equipment to send pictures around the world. But where hams of yore had to throw a considerable amount of gear at the problem, [Dzl] just used an ESP-32 with a camera and some custom code to process the image. The output from one of the MCU’s GPIO pins is a PWM audio signal which can be fed directly into the microphone input of a cheap portable transceiver.

To decode the signal, [Dzl] used one of the many SSTV programs available. There’s no mention of the receiver, although it could be pretty much anything from another Baofeng to an SDR dongle. The code is available in the article, as is an audio file of an encoded image, if you just want to play around with the receiving and decoding side of the equation.

We could see something like this working for a remote security camera, or even for scouting hunting spots. If you want to replicate this, remember that you’ll need a license if you want to transmit on the ham bands — relax, it’s easy.

Getting To The Heart Of A Baofeng

In amateur radio circles, almost no single piece of equipment serves as more of a magnet for controversy than the humble Baofeng handheld transceiver. It’s understandable — the radio is a shining example of value engineering, with just enough parts to its job while staying just on the edge of FCC rules. And at about $25 a pop, the radios are cheap enough that experimentation is practically a requirement of ownership.

But stripped down as the Baofeng may be, it holds secrets inside that are even more tempting to play with than the radio itself. And who better than [HB9BLA], a guy who has a suspiciously familiar Swiss accent, to guide us through the RF module at the heart of the Baofeng, the SA818. For about $8 you can get one of these little marvels off AliExpress and have nearly all the important parts of a VHF or UHF radio — an SDR transceiver, a power amp, and all the glue logic to make it work.

In the video below, [Andreas] puts the SA818 module through its paces with the help of a board that pairs the module with a few accessories, like an audio amp and a low-pass RF filter. With a Raspberry Pi and a Python library to control the module, it’s a decent imitation of the functionality of a Baofeng. But that’s only the beginning. By adding a USB sound card to the Pi, the setup was able to get into every ham’s favorite packet radio system, APRS. There are a ton of other applications for the SA818 modules, some of which [Andreas] mentions at the end of the video. Pocket-sized repeaters, a ridiculously small EchoLink hotspot, and even an AllStar node in an Altoids tin.

Of course, if you want to get in on the fun, you’re going to need an amateur radio license. Don’t worry, it’s easy — we’ll help you get there.

Continue reading “Getting To The Heart Of A Baofeng”

2022 Hackaday Prize: Boondock Echo Connects Your Radios With The Cloud

[Mark J Hughes] volunteers as a part of a local community fire watch which coordinates by radio. The La Habra Heights region of Los Angeles is an area of peaks and valleys, which makes direct radio connections challenging. Repeaters work well for range improvement, but in such areas, there is no good place to locate these. [Mark] says that during an emergency (such as a wildfire) the radio usage explodes, with him regularly tracking as many as eight radio frequencies and trying to make sense of it, whilst working out how to send the information on and to whom.

This led him together with collaborator [Kaushlesh Chandel] to create Project Boondock Echo, to help alleviate some of the stress of it all. The concept is to use a cheap Baofeng radio to feed into a gateway based around an ESP32 audio development kit. Mount this in a box with a LiPo based power supply, and you’ve got yourself a movable radio-to-cloud time-shift audio recorder.

By placing one or more of these units in the properties of several of the community group radio operators, all messages can be captured to an audio file, tagged with the radio frequency and time of transmission, and uploaded to a central server. From there they can be retrieved by anybody with access, no matter the physical location, only an internet connection is needed.

The next trick that can be performed, is to reverse the process and queue up previous recordings, and send it back over the cloud to remote locations for re-transmission via radio into the field. This is obviously a massive asset, because wherever there is some urbanization, there is likely an internet connection. With the addition of a Boondock Echo unit, anyone that has a receiver within a few miles can be fully connected with what’s going on outside the range of direct radio communications.

Source for the ESP32’s firmware as well as the web side of things can found on the project Boondock Echo GitHub, complete with some STLs for a 3D printed box to sit it in. Like always, there’s more than one way to solve a particular problem. Here’s an amateur radio repeater based using an RTL-SDR and a Raspberry Pi.

Is The Game Up For Baofeng In Europe?

For radio enthusiasts worldwide, the inexpensive Chinese handheld radios produced by the likes of Baofeng and other brands have been a welcome addition to their arsenal. They make an ideal first transceiver for a new licensee, a handy portable for any radio amateur, and an inexpensive basis for UHF or VHF experimentation. Unfortunately with the low cost comes something of a reputation for not having the cleanest spectral output, and it seems that this has caught the attention of regulators in Germany and Poland. In Germany this has resulted in the announcement of a sales prohibition (PDF in German) which seems likely to be repeated across the rest of the EU.

It seems what has happened is that the quality of the Baofeng radios on sale doesn’t match that claimed in their conformity documents, which should honestly come as a surprise to nobody. It is interesting that the paperwork mentions the Baofeng UV-5R specifically, as it seems likely to us that an inevitable game of whack-a-mole will ensue with the same radios appearing under ever more brand names and part numbers. The basic UV-5R already appears under a number of variants, for example the one where this is being written is a near-identical but slightly more powerful BF-F8, so this should again come as no surprise.

If you live in Europe should you panic buy a Baofeng while you still can? Probably not, unless you really need one. Something tells us they will remain readily available from the usual overseas sources for years to come. Meanwhile this isn’t the first time a regulator has raised questions about this type of radio.

Thanks [2ftg] for the tip.

Header image: Варвара Каминская, CC BY-SA 4.0.

Ham Radio Traffic Logger Using A Bug In Baofeng Electronics

A Baofeng radio is often one of the first purchases a new ham radio operator makes these days due to the decent features and low price tag. They are far from perfect, but with a bit of creative inspiration, it’s possible to make the quirks work in your favor. By taking advantage of a loud pop on the earphone outputs whenever the LCD backlight turns on, [WhiskeyTangoHotel] built a radio traffic counter using an ESP8266.

Whenever there is a transmission on one of the frequencies the radio is tuned to, the backlight turns on. Connecting the audio output to an oscilloscope, [WhiskeyTangoHotel] measured a 5V spike whenever this happens. Using a pair of diodes in series to drop the voltage to a safe level, the ESP8266 detects the voltage spike and updates a Google spreadsheet with the timestamp via IFTTT.

This gave [WhiskeyTangoHotel] empirical data on how much traffic passes through the local VHF repeater, but we wouldn’t blame them if the hack itself was the real motivator.

Of course, this would also be a perfect application for the RTL-SDR, which should allow you to do the above and much more, all in software. Add a bit of AI and you can even extract the call signs. The RTL-SDR is also a good tool for learning about RF modulation.

UV5-R image via PE1RQM

Alarm System Defeated By $2 Wireless Dongle, Nobody Surprised

It seems a bit unfair to pile on a product that has already been roundly criticized for its security vulnerabilities. But when that product is a device that is ostensibly deployed to keep one’s family and belongings safe, it’s plenty fair. And when that device is an alarm system that can be defeated by a two-dollar wireless remote, it’s practically a responsibility.

The item in question is the SimpliSafe alarm system, a fully wireless, install-it-yourself system available online and from various big-box retailers. We’ve covered the system’s deeply flawed security model before, whereby SDRs can be used to execute a low-effort replay attack. As simple as that exploit is, it looks positively elegant next to [LockPickingLawyer]’s brute-force attack, which uses a $2 RF remote as a jammer for the 433-MHz wireless signal between sensors and the base unit.

With the remote in close proximity to the system, he demonstrates how easy it would be to open a door or window and enter a property guarded by SimpliSafe without leaving a trace. Yes, a little remote probably won’t jam the system from a distance, but a cheap programmable dual-band transceiver like those offered by Baofeng would certainly do the trick. Not being a licensed amateur operator, [LockPickingLawyer] didn’t test this, but we doubt thieves would have the respect for the law that an officer of the court does.

The bottom line with alarm systems is that you get what you pay for, or sadly, significantly less. Hats off to [LockPickingLawyer] for demonstrating this vulnerability, and for his many other lockpicking videos, which are well worth watching.

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