How Etak Paved The Way To Personal Navigation

June 29, 2018 by Dan Maloney 29 Comments

Our recent “Retrotechtacular” feature on an early 1970s dead-reckoning car navigation system stirred a memory of another pre-GPS solution for the question that had vexed the motoring public on road trips into unfamiliar areas for decades: “Where the heck are we?” In an age when the tattered remains of long-outdated paper roadmaps were often the best navigational aid a driver had, the dream of an in-dash scrolling map seemed like something Q would build for James Bond to destroy.

And yet, in the mid-1980s, just such a device was designed and made available to the public. Dubbed Etak, the system was simultaneously far ahead of its time and doomed to failure by the constellation of global positioning satellites being assembled overhead as it was being rolled out. Given the constraints it was operating under, Etak worked very well, and even managed to introduce some of the features of modern GPS that we take for granted, such as searching for services and businesses. Here’s a little bit about how the system came to be and how it worked.

Continue reading “How Etak Paved The Way To Personal Navigation” →

Linux Fu: Scripting For Binary Files

June 29, 2018 by Al Williams 31 Comments

If you ever need to write a binary file from a traditional language like C, it isn’t all that hard to do. About the worst thing you might have to deal with is attempts to fake line endings across Windows and Linux, but there’s usually a way to turn that off if it is on by default. However, if you are using some type of scripting language, binary file support might be a bit more difficult. One answer is to use a tool like xxd or t2b (text-to-binary) to handle the details. You can find the code for t2b on GitHub including prebuilt binaries for many platforms. You should be able to install xxd from your system repository.

These tools take very different approaches. You might be familiar with tools like od or hexdump for producing readable representations of binary files. The xxd tool can actually do the same thing — although it is not as flexible. What xxd can even reverse itself so that it can rebuild a binary file from a hex dump it creates (something other tools can’t do). The t2b tool takes a much different approach. You issue commands to it that causes it to write an original hex file.

Both of these approaches have some merit. If you are editing a binary file in a scripting language, xxd makes perfect sense. You can convert the file to text, process it, and then roll it back to binary using one program. On the other hand, if you are creating a binary file from scratch, the t2b program has some advantages, too.

I decided to write a few test scripts using bash to show how it all works. These aren’t production scripts so they won’t be as hardened as they could be, but there is no reason they couldn’t be made as robust as you were willing to make them.

Continue reading “Linux Fu: Scripting For Binary Files” →

Keep It Close: A Private Git Server Crash Course

June 27, 2018 by Tom Nardi 65 Comments

At this point, everyone has already heard that Microsoft is buying GitHub. Acquisitions of this scale take time, but most expect everything to be official by 2019. The general opinion online seems to be one of unease, and rightfully so. Even if we ignore Microsoft’s history of shady practices, there’s always an element of unease when somebody new takes over something you love. Sometimes it ends up being beneficial, the beginning of a new and better era. But sometimes…

Let’s not dwell on what might become of GitHub. While GitHub is the most popular web-based interface for Git, it’s not the only one. For example GitLab, a fully open source competitor to GitHub, is reporting record numbers of new repositories being created after word of the Microsoft buyout was confirmed. But even GitLab, while certainly worth checking out in these uncertain times, might be more than you strictly need.

Let’s be realistic. Most of the software projects hackers work on don’t need even half the features that GitHub/GitLab offer. Whether you’ve simply got a private project you want to maintain revisions of, or you’re working with a small group collaboratively in a hackerspace setting, you don’t need anything that isn’t already provided by the core Git software.

Let’s take a look at how quickly and easily you can setup a private Git server for you and your colleagues without having to worry about Microsoft (or anyone else) having their fingers around your code.

Continue reading “Keep It Close: A Private Git Server Crash Course” →

Hackers Want Cambridge Dictionary To Change Their Definition

June 26, 2018 by Jenny List 83 Comments

Maybe it’s the silly season of high summer, or maybe a PR bunny at a cybersecurity company has simply hit the jackpot with a story syndicated by the Press Association, but the non-tech media has been earnestly talking about a call upon the Cambridge Dictionary to remove the word “illegal” from their definition of “Hacker”. The weighty tome from the famous British university lists the word as either “a person who is skilled in the use of computer systems, often one who illegally obtains access to private computer systems:” in its learners dictionary, or as “someone who illegally uses a computer to access information stored on another computer system or to spread a computer virus” in its academic dictionary. The cybersecurity company in question argues that hackers in fact do a lot of the work that improves cybersecurity and are thus all-round Good Eggs, and not those nasty computer crooks we hear so much about in the papers.

We’re right behind them on the point about illegality, because while there are those who adopt the hacker sobriquet that wear hats of all colours including black, for us being a hacker is about having the curiosity to tinker with anything presented to us, whatever it is. It’s a word that originated among railway modelers (Internet Archived version), hardly a community that’s known for its criminal tendencies!

Popular Usage Informs Definition

It is however futile to attempt to influence a dictionary in this way. There are two types of lexicography: Prescriptive and Descriptive. With prescriptive lexicography, the dictionary instructs what something must mean or how it should be spelled, while descriptive lexicography tells you how something is used in the real world based on extensive usage research. Thus venerable lexicographers such as Samuel Johnson or Noah Webster told you a particular way to use your English, while their modern equivalents lead you towards current usage with plenty of examples.

It’s something that can cause significant discontent among some dictionary users as we can see from our consternation over the word “hacker”. The administration team at all dictionaries will be familiar with the constant stream of letters of complaint from people outraged that their pet piece of language is not reflected in the volume they regard as an authority. But while modern lexicographers admit that they sometimes walk in an uneasy balance between the two approaches, they are at heart scientists with a rigorous approach to evidence-based research, and are very proud of their efforts.

Big Data Makes for Big Dictionaries

Lexicographic research comes from huge corpora, databases of tens or hundreds of millions of words of written English, from which they can extract the subtlest of language trends to see where a word is going. These can be interesting and engrossing tools for anyone, not just linguists, so we’d urge you to have a go for yourself.

Sadly for us the corpus evidence shows the definition for “Hacker” has very firmly trended toward the tabloid newspaper meaning that associates cybercriminality. All we can do is subvert that trend by doing our best to own the word as we would prefer it to be used, re-appropriating it. At least the other weighty tome from a well-known British university has a secondary sense that we do agree with: “An enthusiastic and skilful computer programmer or user“.

Disclosure: Jenny List used to work in the dictionary business.

A Real Time Data Compression Technique

June 25, 2018 by Al Williams 41 Comments

With more and more embedded systems being connected, sending state information from one machine to another has become more common. However, sending large packets of data around on the network can be bad both for bandwidth consumption and for power usage. Sure, if you are talking between two PCs connected with a gigabit LAN and powered from the wall, just shoot that 100 Kbyte packet across the network 10 times a second. But if you want to be more efficient, you may find this trick useful.

As a thought experiment, I’m going to posit a system that has a database of state information that has 1,000 items in it. It looks like an array of RECORDs:

typedef struct
{
  short topic;
  int data;
} RECORD;

It doesn’t really matter what the topics and the data are. It doesn’t really matter if your state information looks like this at all, really. This is just an example. Given that it is state information, we are going to make an important assumption, though. Most of the data doesn’t change frequently. What most and frequently mean could be debated, of course. But the idea is that if I’m sending data every half second or whatever, that a large amount isn’t going to change between one send and the next.

Continue reading “A Real Time Data Compression Technique” →

Nvidia Transforms Standard Video Into Slow Motion Using AI

June 25, 2018 by Ben James 43 Comments

Nvidia is back at it again with another awesome demo of applied machine learning: artificially transforming standard video into slow motion – they’re so good at showing off what AI can do that anyone would think they were trying to sell hardware for it.

Though most modern phones and cameras have an option to record in slow motion, it often comes at the expense of resolution, and always at the expense of storage space. For really high frame rates you’ll need a specialist camera, and you often don’t know that you should be filming in slow motion until after an event has occurred. Wouldn’t it be nice if we could just convert standard video to slow motion after it was recorded?

That’s just what Nvidia has done, all nicely documented in a paper. At its heart, the algorithm must take two frames, and artificially create one or more frames in between. This is not a manual algorithm that interpolates frames, this is a fully fledged deep-learning system. The Convolutional Neural Network (CNN) was trained on over a thousand videos – roughly 300k individual frames.

Since none of the parameters of the CNN are time-dependent, it’s possible to generate as many intermediate frames as required, something which sets this solution apart from previous approaches. In some of the shots in their demo video, 30fps video is converted to 240fps; this requires the creation of 7 additional frames for every pair of consecutive frames.

The video after the break is seriously impressive, though if you look carefully you can see the odd imperfection, like the hockey player’s skate or dancer’s arm. Deep learning is as much an art as a science, and if you understood all of the research paper then you’re doing pretty darn well. For the rest of us, get up to speed by wrapping your head around neural networks, and trying out the simplest Tensorflow example.

Continue reading “Nvidia Transforms Standard Video Into Slow Motion Using AI” →

A Cleverly Concealed Magnetic Loop Antenna

June 23, 2018 by Jenny List 39 Comments

We’re sure all radio amateurs must have encountered the problem faced by [Alexandre Grimberg PY1AHD] frequently enough that they nod their heads sagely. There you are, relaxing in the sun on the lounger next to the crystal-blue pool, and you fancy working a bit of DX. But the sheer horror of it all, a tower, rotator, and HF Yagi would ruin the aesthetic, so what can be done?

[Alexandre]’s solution is simple and elegant: conceal a circular magnetic loop antenna beneath the rim of a circular plastic poolside table. Construction is the usual copper pipe with a co-axial coupling loop and a large air-gapped variable capacitor, and tuning comes via a long plastic rod that emerges as a discreet knob on the opposite side of the table. It has a 10 MHz to 30 MHz bandwidth, and should provide a decent antenna for such a small space. We can’t help some concern about how easy to access that capacitor is, on these antennas there is induced a surprisingly large RF voltage across its vanes, and anyone unwary enough to sit at the table to enjoy a poolside drink might suffer a nasty RF burn to the knee. Perhaps we’d go for a remotely tuned model instead, for this reason.

[Alexandre] has many unusual loop projects under his belt, as well as producing commercial loops. Most interesting to us on his YouTube feed is this one with a capacitor formed from co-axial soft drink cans.

Thanks [Geekabit] for the tip.