radio

572 Articles

Web Tool Cranks Up The Power On DJI’s FPV Drone

March 31, 2021 by 22 Comments

Apparently, if the GPS on your shiny new DJI FPV Drone detects that it’s not in the United States, it will turn down its transmitter power so as not to run afoul of the more restrictive radio limits elsewhere around the globe. So while all the countries that have put boots on the Moon get to enjoy the full 1,412 mW of power the hardware is capable of, the drone’s software limits everyone else to a paltry 25 mW. As you can imagine, that leads to a considerable performance penalty in terms of range.

But not anymore. A web-based tool called B3YOND promises to reinstate the full power of your DJI FPV Drone no matter where you live by tricking it into believing it’s in the USA. Developed by the team at [D3VL], the unlocking tool uses the new Web Serial API to send the appropriate “FCC Mode” command to the drone’s FPV goggles over USB. Everything is automated, so this hack is available to anyone who’s running a recent version of Chrome or Edge and can click a button a few times.

There’s no source code available yet, though the page does mention they will be putting up a GitHub repository soon. In the meantime, [D3VL] have documented the command packet that needs to be sent to the drone over its MODBUS-like serial protocol for others who might want to roll their own solution. There’s currently an offline Windows-only tool up for download as well, and it sounds like stand-alone versions for Mac and Android are also in the works.

It should probably go without saying that if you need to use this tool, you’ll potentially be violating some laws. In many European countries, 25 mW is the maximum unlicensed transmitter power allowed for UAVs, so that’s certainly something to keep in mind before you flip the switch. Hackaday isn’t in the business of dispensing legal advice, but that said, we wouldn’t want to be caught transmitting at nearly 60 times the legal limit.

Even if you’re not interested in fiddling with drone radios, it’s interesting to see another practical application of the Web Serial API. From impromptu oscilloscopes to communicating with development boards and conference badges, clever developers are already finding ways to make hardware hacking easier with this new capability.

[Thanks to Jules for the tip.]

Web Pages (and More) Via Shortwave

March 13, 2021 by 30 Comments

If you are a ham radio operator, the idea of sending pictures and data over voice channels is nothing new. Hams have lots of techniques for doing that and — not so long ago — even most data transmissions were over phone lines. However, now everyone can get in on the game thanks to the cheap availability of software-defined radio. Several commercial shortwave broadcasters are sending encoded data including images and even entire web pages. You can find out more at the Swradiogram website. You can also find step-by-step instructions.

WINB in Pennsylvania and WRMI Florida both have shows that include interspersed data. To play along, you’ll need a decoder like Fldigi or TIVAR. If you don’t have sufficient radio gear, you can probably borrow some from the Internet.

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Getting On The Air With A 10-Minute-ish Ham Transmitter

March 11, 2021 by 30 Comments

Artificially constrained designs can be among the most challenging projects to build, and the most interesting to consider. The amateur radio world is no stranger to this, with homebrew radio designs that set some sort of line in the sand. Such designs usually end up being delightfully minimalist and deeply instructive of first principles, which is one reason we like them so much.

For a perfect example of this design philosophy, take a look at [VK3YE]’s twist on the classic “10-Minute Transmitter”. (Video, embedded below.)

The design dates back to at least the 1980s, when [G4RAW] laid down the challenge to whip up a working transmitter from junk bin parts and make a contact within 15 minutes — ten for the build and five for working the bands. [VK3YE] used the “oner” — one-transistor — design for his 10-minute transmitter, but invested some additional time into adding a low-pass filter to keep his signal clean, and a power amplifier to boost the output a bit.

Even with the elaborations, the design is very simple and easy to understand. Construction is the standard “ugly style” that hams favor for quick builds like this. There are no parts that would be terribly hard to find, and everything fits into a small metal box. The video below shows the design and build, along with some experiments with WebSDR receivers to check out range both with and without the power amplifier.

Seeing these kinds of builds really puts us in the mood for some low-power action. Could something like this pop up in “The $50 Ham” series? Quite possibly yes.

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Monitor SpaceX Rocket Launches With Software-Defined Radio

March 11, 2021 by 15 Comments

The amateur radio community has exploded with activity lately especially in the software-defined radio (SDR) area since it was found that a small inexpensive TV tuner could be wrangled to do what only expensive equipment was able to do before. One common build with these cards is monitoring air traffic, which send data about their flights out in packets over the radio and can easily be received and decoded now. It turns out another type of vehicle, SpaceX’s Falcon 9 spacecraft, reports data via radio as well and with some slightly upgraded hardware it’s possible to “listen in” to these flights in a similar way.

Reddit users [derekcz] and [Xerbot] used a HackRF module to listen in to the Falcon 9’s data transmissions during its latest launch. While the HackRF is a much more expensive piece of equipment compared to the RTL-SDR dongles used to listen in on aircraft, it is much more capable as well, with a range from 1 MHz to 6 GHz. Using this SDR peripheral as well as a 1.2 m repurposed satellite dish, the duo were able to intercept the radio transmissions from the in-flight rocket. From there, they were recorded with GNU Radio, converted into binary data, and then translated into text.

It seems as though the data feed included a number of different elements including time, location information, and other real-time data about the rocket’s flight. It’s a great build that demonstrates the wide appeal of software-defined radio, and if you want to get started it’s pretty easy to grab a much cheaper dongle and use it for all kinds of applications like this. Go check out [Tom Nardi]’s piece on the last seven years of RTL-SDR to get caught up to speed.

Thanks to [Adrian] for the tip!

The Digital Radio Era (Partially) Ends In Ireland

March 7, 2021 by 96 Comments

It’s commonly agreed that the future of broadcast radio lies in the eventual replacement of AM and FM analogue transmissions with digital services. A wide range of technologies exist to service this change-over, and for much of the world the most visible of them has been Digital Audio Broadcasting, or DAB. This VHF service has slowly increased in popularity to the extent that in some countries the FM or AM switch-off process has already happened or is well under way. It’s thus a surprise to hear a piece of news from a country that’s going the other way, as the Irish broadcaster RTÉ is about to turn off its national DAB multiplex.

The reason cited is cost-effectiveness, the take up of DAB in the Republic by listeners is low (Northern Ireland having the UK multiplexes instead), and that the broadcaster is the only one maintaining a national multiplex. Our Irish friends tell us that as in other parts of the world the rural coverage can be patchy, and with only RTÉ and no commercial stations on offer it’s easy to see why the allure of a DAB set is lacking.

In case anyone is tempted to prophecy the demise of digital broadcasting from this news, that’s not the real story. This is simply an abandonment of DAB. Plenty of Irish people listen to the radio through digital media just as anywhere else, this is simply an indication that they’re choosing not to do so via DAB. The Irish DVB television multiplexes carry the same stations and more, and meanwhile, the inexorable rise of online listening through smart speakers and mobile phones has eaten DAB’s lunch. But it does raise the point for other places: when your mobile phone delivers any radio station or streaming service you desire and is always in your pocket, why would you want a radio?

For more on DAB including some of its shortcomings, a few years ago we took an in-depth look at the system.

Thanks [Laura] for the header image.

Retrotechtacular: Philips Factory Tour, Circa 1930s

March 3, 2021 by 34 Comments

If you’ve got a half-hour or so to spare, you could do worse than this video trip through a Philips factory in the 1930s.

The film is presented without narration, but from the Dutch title cards and the fact that it’s Philips, we gather that this factory of gigantic proportions was somewhere in the Netherlands. In any case, it looks like something right out of [Fritz Lang]’s Metropolis and turned the rawest of materials into finished consumer products.

Much of the film focuses on the making of vacuum tubes; the sheer physicality of the job is what really stands out here. The upper body strength that the glassblowers had to have boggles the mind. Check out the chops — and the soon-to-be very unfashionable mustache — on the glassblower at the 12:00 mark. And it wasn’t just the gents who had mad skills — the fine motor control needed for the delicate assembly of the innards of the tubes, which seems to be mostly staffed by women, is just as impressive. We were also surprised by the amount these manual crafts were assisted by automated systems.

Especially interesting is the section where they build the luidspreker. Without narration or captions, it’s a little hard to tell what’s going on, but it appears that they used an enormous press to form chips of Bakelite into sleek covers for the speakers, which themselves are super-chunky affairs made from scratch in the factory. We’re also treated to assembly of the radios, packaging of finished products, and a group of dockworkers who clearly didn’t read the “Fragile” labels pasted on the boxes.

One can’t help but wonder if these people had the slightest inkling of what was about to sweep over them and the rest of the world. And if they did, would they even begin to comprehend how much the very products that they were making would contribute to both the slaughter of the coming war as well as to the sparing of so many lives? Likely not, but the film is still an interesting glimpse into the creation of an industry, one that relied very much on craftsmanship to get it started.

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1938 Radio Has Awesome Dial

February 10, 2021 by 19 Comments

[Mr. Carlson] is truly an old radio surgeon. The evidence? He recently restored an 83-year-old DeForest radio by transplanting an identical chassis from another similar radio. The restoration is fun to watch, but the 7D832 radio dial looks amazing. The dial is very colorful and the wooden knobs and preset selector are beautiful. To seal the deal, the center of the dial has a magic eye tube, giving the radio a retro high tech look.

The donor chassis needed some work before the surgery. In addition, [Carlson] makes some improvements along the way. The radio showed signs of previous service work, which is not surprising after 83 years.

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