The Many Methods Of Communicating With Submarines

July 15, 2020 by Dan Maloney 36 Comments

It sometimes seems hard to believe that we humans have managed to explore so little of what we have so much of: the seas. Oceans cover something like 70 percent of the world’s surface, but we’ve only mapped 20 percent of the ocean floor. The 228,000 ocean-dwelling species that we know about represents about ten percent of the estimated total aquatic species. And almost all the life we know about, and the area that we’ve explored thoroughly, is limited to the first few hundred meters from the surface.

The paucity of our deep-water investigatory efforts has a lot to do with the hostility of the sea to those who haven’t evolved to survive in it. It takes extreme engineering and fantastically expensive machines to live and work even a few meters down, and even then submariners quickly become completely isolated from the rest of the world once they’re down there. Underwater communication is particularly challenging, since the properties of seawater confound efforts to use it as a communications medium.

Challenging though it may be, underwater communication is possible, and in this article we’ll take a look at a few modalities that have made operating under the sea possible, and a new technology that might just extend the Internet below the waves.

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Don’t Wait, You Need To See Comet NEOWISE Right Now

July 14, 2020 by Tom Nardi 74 Comments

By now you’ve heard of NEOWISE, the most spectacular comet to visit our little corner of the galaxy since Hale-Bopp passed through over 20 years ago. But we’re willing to bet you haven’t actually seen it with your own eyes. That’s because up until now, the only way to view this interstellar traveler was to wake up in the pre-dawn hours; an especially difficult requirement considering a large chunk of the population has gotten used to sleeping-in over the last few months.

But things are about to change as NEOWISE begins a new phase of its trip through our celestial neck of the woods. Having come to within 44.5 million km (27.7 million miles) of the sun on July 3rd, the comet is now making its way back out of our solar system. Thanks to the complex dance of the heavens, that means that observers in the Northern Hemisphere will now be able to see NEOWISE in the evening sky just above the horizon.

NEOWISE is on a kind of “up and over” trajectory compared to the orbital paths of the planets. Get a better feel for it with JPL’s interactive solar dynamics tool.

While NEOWISE might be beating a hasty retreat from Sol right now, the comet it actually getting closer to us in the process. On July 22nd it will reach perigee, that is, the point in its orbit closest to Earth. On that evening the comet will be approximately 103 million km (64 million miles) away. Not exactly a stone’s throw, but pretty close in astronomical terms. The comet will appear to be getting higher in the sky as it approaches Earth, and should be visible with the naked eye between 10 and 20 degrees above the northern horizon.

Most estimates say that NEOWISE should remain visible until at least the middle of August, though it will be dimming rapidly. After that, you’re going to have to wait awhile for a repeat showing. Given the orbit of this particular comet, it won’t come around our way again for approximately 6,800 years, give or take a few lifetimes.

NASA will be hosting a NEOWISE live stream tomorrow afternoon where researchers will answer questions about this once in a lifetime celestial event, though we think you’ll get a lot more out of it if you just go outside and look up.

Jerry Lawson And The Fairchild Channel F; Father Of The Video Game Cartridge

July 14, 2020 by Jenny List 14 Comments

The video game console is now a home entertainment hub that pulls in all forms of entertainment via an internet connection, but probably for most readers it was first experienced as an offline device that hooked up to the TV and for which new game software had to be bought as cartridges or for later models, discs. Stepping back through the history of gaming is an unbroken line to the 1970s, but which manufacturer had the first machine whose games could be purchased separately from the console? The answer is not that which first comes to mind, and the story behind its creation doesn’t contain the names you are familiar with today.

The Fairchild Channel F never managed to beat its rival, the Atari 2600, in the hearts of American youngsters so its creator Jerry Lawson isn’t a well-known figure mentioned in the same breath as Atari’s Nolan Bushnell or Apple’s two Steves, but without this now-forgotten console the history of gaming would have been considerably different.

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Tales From The Sysadmin: Impending Hard Drive Doom

July 14, 2020 by Jonathan Bennett 70 Comments

It should have been another fine day, but not all was well in paradise. Few things bring a creeping feeling of doom like a computer that hardlocks and then refuses to boot. The clicking sound coming from the tower probably isn’t a good sign either. Those backups are up to date, right? Right?

There are some legends and old stories about hard drive repair. One of my favorites is the official solution to stiction for old drives: Smack it with a mallet. Another trick I’ve heard repeatedly is to freeze a hard drive before trying to read data off of it. This could actually be useful in a couple instances. The temperature change can help with stiction, and freezing the drive could potentially help an overheating drive last a bit longer. The downside is the potential for condensation inside the drive. Don’t turn to one of these questionable fixes unless you’ve exhausted the safer options.

For the purpose of this article, we’ll assume the problem is the hard drive, and not another component like a power supply or SATA cable causing problems. A truly dead drive is a topic for another time, but if the drive is alive enough to show up as a block device when plugged in, then there’s hope for recovering the data. One of the USB to SATA cables available on your favorite online store is a great way to recover data. Another option is booting off a Linux DVD or flash drive, and accessing the drive in place. If you’re lucky, you can just copy your files and call it a day. If the file transfer fails because of the dying drive, or you need a full disk image, it’s time to pull out some tools and get to work. Continue reading “Tales From The Sysadmin: Impending Hard Drive Doom” →

Surgery On The Arduino IDE Makes Bigger Serial Buffers

July 13, 2020 by Al Williams 20 Comments

It is pretty well-known that I’m not a big fan of the Arduino infrastructure. Granted, these days you have more options with the pro IDE and Platform IO, for example. But the original IDE always gives me heartburn. I realized just how much heartburn the other day when I wanted to something very simple: increase the receive buffer on an ATmega32 serial port. The solution I arrived at might help you do some other things, so even if you don’t need that exact feature, you still might find it useful to see what I did.

Following this experience I am genuinely torn. On the one hand, I despise the lackluster editor for hiding too much detail from me and providing little in the way of useful tools. On the other hand, I was impressed with how extensible it was if you can dig out the details of how it works internally.

First, you might wonder why I use the IDE. The short answer is I don’t. But when you produce things for other people to use, you almost can’t ignore it. No matter how you craft your personal environment, the minute your code hits the Internet, someone will try to use it in the IDE. A while back I’d written about the $4 Z80 computer by [Just4Fun]. I rarely have time to build things I write about, but I really wanted to try this little computer. The parts sat partially assembled for a while and then a PCB came out for it. I got the PCB and — you guessed it — it sat some more, partially assembled. But I finally found time to finish it and had CP/M booted up.

The only problem was there were not many good options for transferring data back and forth to the PC. It looked like the best bet was to do Intel hex files and transfer them copy and paste across the terminal. I wanted better, and that sent me down a Saturday morning rabbit hole. What I ended up with is a way to make your own menus in the Arduino IDE to set compiler options based on the target hardware for the project. It’s a trick worth knowing as it will come in handy beyond this single problem.

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Changing System Architectures And The Complexities Of Apple’s Butterfly Approach To ISAs

July 13, 2020 by Maya Posch 64 Comments

Apple computers will be moving away from Intel chips to its own ARM-based design. An interesting thing about Apple as a company is that it has never felt the need to tie itself to a particular system architecture or ISA. Whereas a company like Microsoft mostly tied its fortunes to Intel’s x86 architecture, and IBM, Sun, HP and other giants preferred vertical integration, Apple is currently moving towards its fifth system architecture for its computers since the company was formed.

What makes this latest change possibly unique, however, is that instead of Apple relying on an external supplier for CPUs and peripheral ICs, they are now targeting a vertical integration approach. Although the ARM ISA is licensed to Apple by Arm Holdings, the ‘Apple Silicon’ design that is used in Apple’s ARM processors is their own, produced by Apple’s own engineers and produced by foundries at the behest of Apple.

In this article I would like to take a look back at Apple’s architectural decisions over the decades and how they made Apple’s move towards vertical integration practically a certainty.

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How Early Radio Receivers Worked

July 10, 2020 by Al Williams 43 Comments

If you’ve ever built a crystal radio, there’s something magical about being able to pull voices and music from far away out of thin air. If you haven’t built one, maybe you should while there’s still something on the AM band. Of course, nowadays the equivalent might be an SDR. But barring a computer solution, there are not many ways to convert radio waves into intelligence. From a pocket radio to advanced RADAR to a satellite in orbit, receiving a radio wave is accomplished in pretty much the same way.

There are, however, many ways to modulate and demodulate that radio wave. Of course, an AM radio works differently than an FM radio. A satellite data downlink works differently, too. But the process of capturing the radio wave from the air and getting them into a form ready for further processing hasn’t changed much over the years.

In this article, I’ll talk about the most common radio receiver architectures you may have seen in years past, and next week I’ll talk about modern architectures. Either way, understanding receiver architectures will help you design new radios or troubleshoot them.

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