“Hamming It Up” with Atsign’s Colin Constable, Creator of CATWEB Mobile App For and By the Ham Radio Community.

5 min readApr 7, 2022


Colin Constable, AI6BH

When the South Londoner, Colin Constable, traipsed down the road to the local amateur radio society–at the behest of his mother–his 11-year-old self likely never would have guessed that decades later he would be developing an application aimed at fellow “ham” enthusiasts. Although his first experience with radio was less than stellar–he hadn’t realized he’d need to know morse code, and pass an array of exams–the fledgling “ham” would become firmly ensconced in the world of radio through CB (Citizens Band) radio.

Despite Colin’s evident love of radio, life seemed to have other plans in store for him; after landing a job, it would be two decades before he found himself back in the radio saddle, this time, trading the cobbled streets of London for the mountainous vistas of California.

It is there, in the Golden State, where Colin’s aptitude for software development would create a fruitful marriage with his radio hobby, but only after having a chance encounter with amateur radio while stranded in the desert.

In 2014, Colin’s friend Dave cajoled him into taking an overland, 4-wheel-drive trip across the Sierra. This particular trail, the Dusy-Ershim, carries a rating of “Most Difficult.” While he accepted Dave’s offer with trepidation, Colin did voice his concern about what they would do if they got stuck, “out in the middle of nowhere.” Dave assured him that they wouldn’t get stuck, but Colin’s foresight won out–Spoiler Alert: they would end up getting stuck during the trip. After some back and forth, Colin’s suggestion that they buy an amateur radio, instead of an expensive satellite phone, would prove to be a boon to their endeavor.

With a newly acquired amateur radio license under his belt, and amateur radio in hand, Colin successfully, “crossed the Rubicon,” and thankfully did not need to be rescued, and also reclaimed his stake in the ham radio game. Ironically, since then he’s spent much more money on ham radio equipment than he ever would have spent on that satellite phone.

Colin’s software development expertise would be put to the test seven years later during October of 2021, when friend and fellow co-founder of Atsign, Kevin Nickels, would challenge Colin to develop a Flutter app. Flutter is a Google-developed framework that allows for apps to be easily deployed across various platforms, e.g. iOS, Android, Windows, Linux, and Raspberry Pi computers. This means that developers can write one bit of code without worrying about changing or modifying it to fit each different platform.

The free, open-source nature of Flutter development appealed to Colin, and it also served as a method of testing out the atPlatform, Atsign’s answer to clearing the murky waters of data privacy. The atPlatform is an architecture that allows for true end-to-end encryption of data. Only the sender of the data and the recipient of the data can see the information that is transferred. This means no one–not even the creators of the platform–can see your data without your express permission. Atsign’s mission is to “flip the Internet,” placing data ownership back in the hands of the people.

Kevin’s challenge afforded Colin the opportunity to work outside of his comfort zone. A self-professed command-line devotee, working in Flutter made his new app, called CATWEB, more aesthetically appealing to people. While the command-line scripts made the app eminently functional, having a UI, or User Interface, was the ideal way to go. And it only took him four months.

What is CATWEB? And why did Colin want to take up Kevin’s challenge by building a seemingly niche app? Well, the ham radio community is a devoted one, with great diversity in their interests. For example, Colin noted that while the majority of community members hail from an older demographic, there is a younger group of ham enthusiasts joining from the drone community, where holders of amateur radio licenses can use ham radios to control their drones. This diversity in ham radio interest is celebrated and encouraged.

Colin noticed a fundamental problem within the amateur radio community, and that was the fact that it is quite difficult for people to even find each other. He noted that it can be a bit of a guessing game figuring out which frequency and modulation type someone might be transmitting from and listening to. It’s almost as if ham radio broadcasters are a bit like ships passing in the night.

But what if one could eliminate the guessing game? What if people knew exactly which frequency and modulation any given “operator” was listening to?

Colin wanted a place to be able to share that information publicly. So, he decided to host the app using atWavi, a micropublishing app built on the atPlatform. atWavi allows people to publish anything from business profiles to location data. What separates atplatform apps from the rest of the internet ecosystem, is that they allow people full control over what is sent, what can be accessed, and by whom their data can be accessed.

atPlatform apps use a unique identifier called an atSign. An atSign is a new digital identity. Instead of inputting a new username and password for each new application, and spreading your data out across every company’s server, you have a unique atSign, and each app or person within an app ecosystem comes to you to ask for permission to see your data. You get to choose what data they see, when they see it, and for how long they have access to it. Importantly, from a developer’s perspective, no usernames and passwords means no backend management, which can be both an utter time sink, and a money pit.

atSigns can either be auto-generated for free, or customized for a fee. For ham radio enthusiasts, they might choose their call sign as their atSign, like Colin did with his: @AI6BH

By visiting @AI6BH ham radio enthusiasts can see which frequency Colin is listening to. While CATWEB allows Colin to publish his data in a public forum, the atPlatform’s privacy standards are also ideal for sharing data peer-to-peer (P2P), or in layman’s terms, person-to-person. For example, the app, atmospherePro is end-to-end encrypted (E2EE) meaning that the file-sharing is just as secure as if two people were meeting up and giving their data in person.

What does this mean for ham radio enthusiasts who have different interests, or who aren’t flying drones? Well, the sky’s the limit. You never know what or whom you might find on any given frequency. Colin has randomly called out people from all over the world. He enjoys a good “rag-chew,” and has reached out to far places, like Alaska and Italy; he even found an Italian Scientist at the South Pole. What makes the venture fun for Colin is communicating with as little power as possible. Normally, he simply runs a 160-foot wire from his backyard using 5 watts of power, and he’s able to converse with a worldwide community.

Whatever one’s desires are, one thing is clear, ham radio is community-focused, and built on the concept of human interaction. In fact, having taken the advice of a Silicon-Valley ham radio club member, Colin’s next mission is to build a CATWEB Community page, where ham radio enthusiasts can see each other’s call signs. But in the meantime, here’s Colin’s advice: get your amateur radio license, find out where he is on CATWEB, and have a chat.




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