Last September, Denmark was gripped by a spate of drone sightings near airports. It’s familiar territory for Hackaday, as we reported on a similar drone panic saga at British airports back in the last decade. Back then the British police dragged their feet and hid behind secrecy laws for years to avoid admitting they overreacted, but it seems in Denmark they do things differently (Danish language, Google Translate link.).
The Danish police in Jutland have rolled back their report, and noted that a reported observation alone is not enough to confirm a drone was present. It’s not confirmed why they’ve taken this step, but we’ve been told that there’s been an effort within the drone community to identify possible aircraft flight paths which could have resulted in a false drone sighting at the times in question.
We welcome this correction, and hope that its important message travels widely. Of course it is the right thing to do for a police force to take drone reports seriously, but overreacting as the British police did is of little help. We commend the Danish police for taking this step, and we’re likely to trust any drone reports from them a little bit more in the future. If you’d like to read our plea for a sensible response at the time, it’s here.
When you’re driving your car, you’re probably regularly looking at the speedometer to make sure you comply with the local speed limits. The method by which it works is simple enough: the rotation of the wheels is sent mechanically via a cable to a dial on the dash, or an electronic sensor counts the rotations of the drivetrain and an electronically-controlled needle or display shows the speed.
But what about if you were in an aircraft, and the wheels had nothing to do with how fast you were going? How would you even begin to measure speed? There are two ways: there’s a convenient solution to this problem rooted in simple fluid mechanics, and a far-more-complex modern solution. Today, we’ll explore how planes and helicopters are able to figure out how fast they’re going, by the old ways and the new.
Something happened this morning which will have been unnoticed by many, but which for a certain breed of radio enthusiast marks the end of an era. The BBC stopped broadcasting Radio 4 on their 198 kHz Long Wave frequency, ending over a century of transmission in the band. For now the transmitter carries a recorded message telling listeners that the service has ended, but it’s expected that this will soon be turned off.
The main 198kHz BBC transmitter, at Droitwich. Bob Nienhuis, Public domain.
American readers may be unfamiliar with Long Wave as it’s a band not allocated in their region. Covering 153 to 279 kHz, it’s a relic from the earliest days of high-power broadcasting in the 1920s, used because of the enormous distances that could be covered with its lower frequencies. The main long wave transmitter for the BBC is at Droitwich, and its demise comes because there are no more spares for its high-power transmitter tubes. It joins many Medium Wave, or AM, as it is commonly known, stations in leaving the airwaves, as increased interference from switch mode electronics and the availability of higher quality alternatives took away their listeners. It’s fair to say that there will be few whose lives are inconvenienced by the switch-off in 2026, but it’s worth taking a moment to remember.
The first BBC Long Wave transmissions in the mid-1920s were on a 1600 metre wavelength, or 187.5 kHz. A series of international agreements saw them move to 193 kHz, and then 200 KHz or 1500 metres in 1934. They stayed on that frequency until another shift down 2 KHz to 198 kHz in 1988. They were atomic-controlled, and thus usable as a frequency standard. The programming started with station names redolent of their era, first the BBC National Service, then the Light Programme you’ll see on the dial in the header image, and finally the more modern-sounding Radio 4. A famous BBC programme tied to Long Wave is the Shipping Forecast, a weather bulletin for deep-sea fishermen which became cult listening on land and now features on FM and digital services too, and there’s even a probably-apocryphal tale that British nuclear submarine captains would once use its presence or absence to judge whether nuclear war had occurred.
In an Oxfordshire farmhouse not far short of fifty years ago, a young child who would later become a Hackaday writer heard a radio show like nothing before, which made an impression that continues to this day. The show was one of the earliest airings of the original Hitchhikers Guide To The Galaxy radio series, through a 1970s ITT radio tuned to BBC Radio 4 on (then) 200 kHz Long Wave. So long, Droitwich, and thanks for all the fish.
The train was one of the game-changing inventions that defined the Industrial Age. No more would humanity rely on tempestuous animals to haul goods and passengers great distances across the land. Fire and steam came along to rapidly increase the speed of travel and transformed the very fabric of society itself.
To this day, the vast majority of train networks rely on the same basic principle—heavy locomotives and carriages running steel wheels on steel tracks. Yet, there is a curious alternative twist on this concept that sees trains of carriages riding on tires instead. But what would possess anyone to build a rubber tired train?
As announced by [André] on Bluesky, next month the much loved Rpilocator.com website will cease displaying the stock status and pricing of Raspberry Pi computers from various online retailers.
One of the main reasons is that the indexing bot used by the site has been blocked by most shopping sites. It’s not clear whether this blocking is on purpose or just another consequence of website owners protecting themselves from the onslaught of obnoxious ‘AI’ scraping bots. But in any event, the effort of finding workarounds that may only work for a few days or weeks was becoming too much.
According to [André] there are still about 11,000 users of the site each month, which even when accounting for the human-bot ratio is still a sizable number of visitors who’ll now have to get their fix somewhere else. He also indicates that he receives numerous emails from presumably real people about the site to point out small issues they have noticed.
Although the site may still be back in the future, it’s also important to recognize how much the single-board computer landscape and raison d’être for this tracking site have shifted since the 2020s Chip Crisis days. Currently it’s less about finding where these boards are in stock, and more about taking the hits to one’s wallet as memory prices continue to spiral out of control. Making what were once fun, cheap little hobby boards into luxury items that cut into your rent-food-and-gas budget.
A pervasive story is that electric vehicles (EVs or BEVs) are actually dirtier than combustion vehicles if charged by a fossil fuel-based electricity grid. A new study reaffirms others that show, at least in the US, EVs have lower lifetime emissions than an internal combustion engine (ICE) vehicle, regardless of the grid mix.
Comparing data on the mix of generation types by ZIP code using data from OpenGrid and eGRID, the researchers were able to create maps and comparisons of the efficiency of ICE, hybrid, plug-in hybrid (PHEV), and electric vehicles. If you want to compare some specific examples, there’s an interactive chart using the research data at carboncounter.com.
PHEVs can achieve 80-90% of the emissions reductions of a full EV in urban environments, but become less beneficial as distances increase or if drivers choose not to charge the battery. The researchers have extensive breakdowns of the comparisons including total cost to operate the vehicle compared with emissions if you want to look more in the paper. Emissions benefits are particularly noticeable in larger vehicle classes or with drivers who put more miles on their cars.
Although it’s unlikely to change anytime soon, they also note that if the industry trend toward larger and larger vehicles were to be reversed, emissions targets could be hit with much fewer hybrids and EVs at the current grid mix. The advantage of full EVs is that they get cleaner as the grid gets cleaner, unlike combustion vehicles that typically get worse as their emissions systems degrade.
If you’re not ready for an EV, maybe you’d like to reuse a pack for a house battery. If you’re feeling more adventurous, then maybe try out an EV conversion that still needs oil changes?
GPS has become fairly common in our everyday lives, not only able to pinpoint our locations on Earth but also as an incredibly accurate timekeeping method. But since these satellites are around 20,000 km above Earth, the received signals on the surface of the planet can be incredibly weak. This makes them prone to jamming and spoofing, a weakness of the technology that has long been known. Although attempts to mitigate these problems have been ongoing, there has recently been a large-scale attempt to interfere with these signals that put all mitigation efforts to the test.
One proposed way to improve resilience is to supplement existing GNSS systems with low-Earth-orbit navigation satellites. In this example, a company called Xona is using a satellite called Pulsar-0 that operates in low-Earth orbit (LEO) and provides positioning and timing signals that are around 100 times stronger than standard signals from GPS/GNSS satellites. It is able to receive GPS signals as well, ensuring the two systems agree on one another. And, because Pulsar’s navigation signals originate from LEO and are much stronger than conventional GNSS signals, Xona expects them to be significantly more resistant to jamming.
