Tech + Engineering

12
May

WiFi Screws Up Weather Radar, but a New Algorithm Could Fix It

It’s no secret that WiFi has changed how we use computers. In fact, there’s a good chance you’re reading this on a WiFi connection right now. Part of what had made WiFi so appealing is that it operates on unlicensed spectrum—in other words, you don’t need permission to operate a WiFi hotspot. But neither does anyone else, and that can be a problem.

For many years, WiFi operated on bands in the 2.4 GHz range, but the demand for higher data speeds and crowding of that portion of the spectrum by microwaves, cordless phones, and more have pushed WiFi engineers to adopt bands around 5 GHz, too. Unfortunately, that’s the same region where airport weather radar operates.

may-9-2014-weather-radar
Airport weather radar operates in the same bands used by many WiFi routers.

WiFi devices that use the 5 GHz range are supposed to monitor the bands for radar use and switch frequencies if they detect any. In practice, though, that doesn’t seem to have worked. Meteorologists still see WiFi interference on radar images, which shoot out from the radar station like in telltale lines like spokes from a hub.

It’s more than just a frustration for forecasters. Weather radar is used by air traffic controllers deciding how to route planes. That’s why Harald Ganaster of Joanneum Research in Graz, Austria and his colleagues decided to tackle the WiFi interference problem.

Technology Review:

Ganster and co have developed an algorithm that maps all straight lines in an image into vertical ones, which are then easy to remove. Since there are no naturally occurring structures that are straight, at least not on weather radar images, this removes Wi-Fi interference with high accuracy.

Removing such systematic interference isn’t uncommon—remote sensing specialists have been repairing images using similar techniques for decades, though the interference there isn’t usually caused by consumer electronics. Short of modifying millions of WiFi routers, there wasn’t much meteorologists could do. But thanks to Ganaster and his colleagues, those aberrant stripes on weather radar could soon be a thing of the past.

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