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Silent Antenna Tuning

October 23, 2024 by 56 Comments

If you want to deliver the maximum power to a load — say from a transmitter to an antenna — then both the source and the load need to have the same impedance. In much of the radio communication world, that impedance happens to be 50Ω. But in the real world, your antenna may not give you quite the match you hoped for. For that reason, many hams use antenna tuners. This is especially important for modern radios that tend to fold their power output back if the mismatch is too great to protect their circuitry from high voltage spikes. But a tuner has to be adjusted, and often, you have to put a signal out over the air to make the adjustments to match your antenna to your transmitter.

There are several common designs of antenna tuners, but they all rely on some set of adjustable capacitors and inductors. The operator keys the transmitter and adjusts the knobs looking for a dip in the SWR reading. Once you know the settings for a particular frequency, you can probably just dial it back in later, but if you change frequency by too much or your antenna changes, you may have to retune.

It is polite to turn down the power as much as possible, but to make the measurements, you have to send some signal out the antenna. Or do you?

Several methods have been used in the past to adjust antennas, ranging from grid dip meters to antenna analyzers. Of course, these instruments also send a signal to the antenna, but usually, they are tiny signals, unlike the main transmitter, which may have trouble going below a watt or even five watts.

New Gear

However, a recent piece of gear can make this task almost trivial: the vector network analyzer (VNA). Ok, so the VNA isn’t really that new, but until recently, they were quite expensive and unusual. Now, you can pick one up for nearly nothing in the form of the NanoVNA.

The VNA is, of course, a little transmitter that typically has a wide range coupled with a power detector. The transmitter can sweep a band, and the device can determine how much power goes forward and backward into the device under test. That allows it to calculate the SWR easily, among other parameters.

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Will .IO Domain Names Survive A Geopolitical Rearrangement?

October 23, 2024 by 47 Comments

The Domain Name System (DNS) is a major functional component of the modern Internet. We rely on it for just about everything! It’s responsible for translating human-friendly domain names into numerical IP addresses that get traffic where it needs to go. At the heart of the system are the top-level domains (TLDs)—these sit atop the whole domain name hierarchy.

You might think these TLDs are largely immutable—rock solid objects that seldom change. That’s mostly true, but the problem is that these TLDs are sometimes linked to real-world concepts that are changeable. Like the political status of various countries! Then, things get altogether more complex. The .io top level domain is the latest example of that.

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In Its Second Year, JawnCon Was Bigger And Better

October 22, 2024 by 7 Comments

Starting a hacker con is hardly what anyone would describe as easy — but arguably, the truly difficult part is keeping the momentum going into the second year and beyond. For the first year, you can get away with a few missed opportunities and glitches, but by the time you’ve got one event under your belt, you’ll have set the bar for what comes next. There’s pressure to grow, to make each year bigger and better than before. All the while, making sure you don’t go broke in the process. Putting on a single hacker con is an achievement in and of itself, but establishing a long-running hacker con is a feat that relatively few groups have managed to pull off.

With this in mind, the incredible success of the second annual JawnCon is all the more impressive. The Philadelphia-area event not only met the expectations of a sophomore effort, but exceeded them in pretty much every quantifiable way. From doubling attendance to providing a unique and immersive experience with their electronic badge, the team seized every opportunity to build upon the already strong foundation laid last year. If this was the make-or-break moment for the Northeast’s newest hacker con, the future looks very bright indeed.

But before setting our sights on next year, let’s take a look at some of the highlights from JawnCon 0x1. While you can watch all of this year’s talks on YouTube, the aspect of a hacker on that can’t easily be recorded is the quality time spent with like-minded individuals. Unfortunately, there’s no way to encompass everything that happened during a two-day con into a single article. Instead, this following will cover a few of the things that stood out to me personally.

If you’d like to experience the rest of JawnCon, you’ll just have to make the trip out to Philly for 2025.

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An SAO For Hams

October 21, 2024 by 18 Comments

Generally speaking, the Hackaday Supercon badge will always have a place for SAO (rebranded as “Supercon add-ons”), and that makes sense. We did originate them, after all. This year, though, we’ve gone all in on SAO, and, in particular, we’ve asked to see more SAOs with communication capabilities. The standard has always had an I2C bus, but few people use them. I decided I wanted to set an example and cook up a badge for Supercon. Was it hard? Yes and no. I’ll share with you a little about the board’s genesis and the issues I found. At the end, I’ll make you a special offer, if you are going to Supercon.

The Idea

The front of the SAOGNR — the SAO connector is, of course, on the back

I’ve been a ham radio operator for a very long time. In fact, July was my 47th anniversary in the radio hobby. Well, that’s not true. It was my 47th year with a license. I had been listening to shortwave long before then. So, I wanted to do something with Morse code. You don’t have to know Morse code to get a license these days, but a lot of hams enjoy it.

I set out to do a simple board that would play some Morse code messages. But that’s just another blinking light LED with a buzzer on it, too. So, naturally, I decided it would also provide Morse code output for the I2C host. That is, the SAO could be used to convert ASCII to Morse code. Sounds simple, right? Sure.

Getting Started

I wanted to use a Raspberry Pi Pico but didn’t want to violate the SAO size requirements. Luckily, there’s an RP2040-Zero module that is quite tiny and looks more or less like a normal Pico. The two big differences are plusses: they have a reset button, and instead of a normal LED, they have a WS2812b-style LED.

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Hackaday Links: October 20, 2024

October 20, 2024 by 44 Comments

When all else fails, there’s radio. Hurricane Helene’s path of destruction through Appalachia stripped away every shred of modern infrastructure in some areas, leaving millions of residents with no ability to reach out to family members or call for assistance, and depriving them of any news from the outside world. But radio seems to be carrying the day, with amateur radio operators and commercial broadcasters alike stepping up to the challenge.

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A Hacker’s Travel Guide To Europe

October 18, 2024 by 55 Comments

This summer, I was pleasantly surprised when a friend of mine from Chicago turned up at one of the hacker camps I attended. A few days of hanging out in the sun ensued, doing cool hacker camp stuff, drinking unusual beverages, and generally having fun. It strikes me as a shame that this is such a rare occurrence, and since Hackaday is an American organisation and I am in a sense writing from its European outpost, I should do what I can to encourage my other friends from the USA and other parts of the world to visit. So here I’m trying to write a hacker’s guide to visiting Europe, in the hope that I’ll see more of you at future camps and other events.

It’s Intimidating. But Don’t Worry.

Danish road sign: "Se efter tog", or according to Google Translate: "Look for trains".
Yes. We’d find this intimidating, too. Bewitchedroutine, Public domain.

First of all, I know that it’s intimidating to travel to an unfamiliar place where the language and customs may be different. I’m from England, which sits on a small island in the North Atlantic, and believe it or not it’s intimidating for us to start traveling too. It involves leaving the safety of home and crossing the sea whether by flight, ferry, or tunnel, and that lies outside one’s regular comfort zone.

Americans live in a country that’s almost a continent in its own right, so you can satisfy your travel lust without leaving home. Thus of course the idea of landing in Germany or the Netherlands is intimidating. But transatlantic flights are surprisingly cheap in the scheme of international travel because of intense competition, so I’m here to reassure you that you can travel my continent ‘s hacker community without either feeling out of your depth, or breaking the bank.

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Ubiquitous Successful Bus: Version 2

October 17, 2024 by 52 Comments

I’ve talked a fair bit about USB-C before, explaining how it all works, from many different angles. That said, USB-C is just the physical connector standard, plus the PD part that takes care of voltages and altmodes – things like data transfer are still delegated to the two interfaces you invariably end up using on USB-C ports, USB 2, and USB 3.

You might think USB 2 and USB 3 are tightly related, but in many crucial ways, they couldn’t be more different. I have experience working with both, and, as you might guess, I want to share it all with you. You might be surprised to hear there’s plenty to learn about USB 2 in particular – after all, we’ve had it hang around for 30 years now. Well, let’s make sure you’re fully caught up!

The Ingredients

USB 2 is a point-to-point link – one side is “host” and another is “device”, with the host typically being a PC chipset or a single-board computer. USB 2 relies on a single pseudodifferential pair. It’s “pseudodifferential” because the wires don’t just do differential signaling – they also use digital logic levels and pullup/pulldown resistors to signal device presence, especially in the beginning when the USB link is still getting established. Indeed, you can imitate a USB device’s presence with just a resistor.
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