Build an Early-Warning System for Your Bike

A new low-cost lidar can detect approaching cars

4 min read
Build an Early-Warning System for Your Bike

img of Paul Wallich bikePhoto: Paul Wallich

In the summer months, I really enjoy riding a bike along some of the flatter roads and trails around my small Vermont town. But sharing some of those roads with cars can be a dicey proposition. There’s one dirt road in particular, where no matter how often I scan my mirror or sneak a look over my shoulder, it seems that sooner or later I get surprised by a car zipping by.

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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
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Photo of Jacob Ziv
Photo: Rami Shlush
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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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