Hackaday Prize 2023: A Software-Defined Radio With Real Knobs And Switches

A software-defined radio system in a 3D-printed case with a 7" display and an array of knobs and switches

When cheap digital TV dongles enabled radio enthusiasts to set up software defined radio (SDR) systems at almost zero cost, it caused a revolution in the amateur radio world: now anyone could tune in to any frequency, with any modulation type, by just pointing and clicking in a computer program. While this undoubtably made exploring the radio waves much more accessible, we can imagine that some people miss the feeling of manipulating physical buttons on a radio while hunting for that one faint signal in a sea of noise. If you’re one of those people, you’re in luck: [Kaushlesh C.] has built a portable, self-contained SDR system with real knobs and switches, called SDR Dock 1.0.

The heart of the system is a Raspberry Pi running GQRX, an open-source SDR program that supports many different RF modules. [Kaushlesh] used an Airspy HF+ Discovery, a compact receiver that can work the HF and VHF bands, but it’s easy to modify the SDR Dock to accept other types like those ubiquitous RTL dongles. A seven-inch LCD screen with integrated speakers forms the main output device, with everything powered by a 10,000 mAh lithium-polymer battery.

All of this is pretty neat already, but the real beauty of the SDR Dock is in its enclosure. It’s a 3D-printed case with a swivelling handle on the side, an antenna connector at the top and a convenient user interface at the front. There are pushbuttons to change device settings, rotary knobs for frequency tuning and volume control, and sliders to adjust things like gains and bandwidths. All of these are read out by an ESP32 which communicates with the Pi through I2C.

As an open-source design, everything is of course fully customizable, from the radio receiver type to the functions of those dials and switches. The simple, user-friendly design should also make it an ideal SDR system for absolute beginners. It’s not [Kaushlesh]’s first portable Pi-based SDR system, however: he’s also submitted a somewhat more hardcore version to this year’s Cyberdeck competition. For those completely new to the SDR game, [Josh]’s video at the 2020 Remoticon is a great introduction.

16 thoughts on “Hackaday Prize 2023: A Software-Defined Radio With Real Knobs And Switches

      1. My read on it was Receive was 0.5 to 30.0 MHz, which sounds like “full coverage” over the usual HF bands. It was the Transmit that comes in slices, basically the ones allotted to amateur license holders.

  1. I’m a fan of the concept.

    I have a Fuji X-T4, a mirrorless camera with physical controls for major aspect you might want on the fly, menus for everything else. I love the ease I can switch between manual and auto.

    I have an IC-705, it’s SDR based and the controls are often frustrating. Balancing analog controls with a digital services is challenging.

    1. Cars are the classic example of that. My buddy got a new truck as soon as it came out. He was making good money at the time and wanted to blow it, so he got one of the deluxe packages where I got one of the low end packages. I did not get a truck but apparently the electronic packages are pretty much the same. He had one big touchscreen and it turned out he hated it. If you wanted to do anything from change the temperature in the car to tune in another radio station, you had to go through the big touchscreen. Every car function was on it, and there were not good old knobs for anything. It was neat in that you could drill into some pretty neat things while you were moving but really not super practical. And to make it even funnier, you could not program the GPS if the thing was even in gear. Like the passenger could not program it. My buddy liked my lesser trim level a lot more. I have a small screen for displaying some stuff, but the cabin temp is a knob, the volume and frequency for the radio are knobs. Much more workable. However..
      My trim level lacks the GPS and lacks a backup cam. I figured that would be easy, get the GPS module and the cam and plug them in right? Oh no. I guess they did not want people upgrading after the fact like they have been doing with the cruise on some GMC trucks where you can buy the steering wheel switch for a few bucks and find a mechanic with the right box to enable the feature. So they went as far as changing the electronics package so the GPS and backup cam are not supported. Also on mine kind of surprisingly and not so much on his, but they have pretty much made it impossible to put in an aftermarket sound system. Apparently the “controls” for the stereo and the controls for the HVAC are all on the same assembly and just spew out data onto one of the cars busses. Nothing is a standard DIN size. I saw one kit to let you put a 2 din stereo in and just the replacement plastic parts and electronics to not kill other stuff on the bus was over $400, and that is before you even get the damn stereo.

  2. simplifying the UI is the hard part of a project like this and the photo doesn’t make it look like that happened. at least, it looks like there are still clickable icons on the screen, and a taskbar? i don’t know how those are accessed but that tramples my hopes for the project.

    coming up with good simple idioms for interfacing with something as generally powerful as an SDR radio is a real challenge. if all that sophistication was really reduced to a dozen control inputs, that would really be an accomplishment that would be useful even to people who don’t build the physical button and knob assembly

  3. That’s a nice build.

    If you want to get the full, this is a radio appliance, not a computer feel you might want to get rid of the taskbar, window decorations and any other OS features and just have the radio software automatically start full-screen upon boot.

    For an easy way to do that you can just install stumpwm, make it the default and set it in stumps config file to load the sdr software. I’m pretty sure that is how all those touch interfaces for OctoPrint do it.

    Technically you could still plug in a keyboard and split the screen into windows, load other programs, etc to use it as a computer. But so long as you don’t do that it would just be a radio.

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