Time is on Your Side

Or at least it will be, once you build this network-based clock

4 min read
Time is on Your Side

There’s no longer any excuse for having the wrong time. Computers, set-top boxes, and even some wristwatches can get their time from the U.S. Naval Observatory or some other authoritative source. But what about a device you build yourself? Many will come with a timing chip that you can use as a counter, but they won’t tell you what time it is in the real world or self-adjust for daylight saving time. What you want is a microprocessor on a computer board that will query a network for the correct time and pass it on to the rest of your device. This month’s project is just that, a clock on a single-board computer that uses the Network Time Protocol (NTP) to give you millisecond accuracy for about US $115.

Single-board computers (SBCs) are cool because they pack a lot of functionality into a very tight package. They’re scary, too, because they involve you in technologies that are usually taken care of by off-the-shelf computing hardware. For one thing, SBCs don’t usually come with such niceties as displays and USB ports. And when you get down to the smallest of the small, you are pretty much dealing with a processor, some flash memory, a few input/output ports, and a way to burn an image to an electrically erasable programmable read-only memory (EEPROM).

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From WinZips to Cat GIFs, Jacob Ziv’s Algorithms Have Powered Decades of Compression

The lossless-compression pioneer received the 2021 IEEE Medal of Honor

11 min read
Photo of Jacob Ziv
Photo: Rami Shlush

Lossless data compression seems a bit like a magic trick. Its cousin, lossy compression, is easier to comprehend. Lossy algorithms are used to get music into the popular MP3 format and turn a digital image into a standard JPEG file. They do this by selectively removing bits, taking what scientists know about the way we see and hear to determine which bits we'd least miss. But no one can make the case that the resulting file is a perfect replica of the original.

Not so with lossless data compression. Bits do disappear, making the data file dramatically smaller and thus easier to store and transmit. The important difference is that the bits reappear on command. It's as if the bits are rabbits in a magician's act, disappearing and then reappearing from inside a hat at the wave of a wand.

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