The craze for Wi-Fi networks could interfere with military radars, says Agere Systems of Allentown, Pennsylvania. The 802.11a specification for Wi-Fi works at 5 gigahertz, which is the band where many defence radars operate. Wi-Fi networks already detect radar and switch frequency to avoid it, but a PC cannot detect radar while it is transmitting, so it risks causing interference. Agere鈥檚 solution (US 2005/0032524) gets round the problem for networks with a base station and more than one PC. All the PCs listen and if one detects radar it switches the network鈥檚 frequency.
Advertisement
The latest hacker trick, revealed by Silverbrook Research of Balmain, Australia, is to eavesdrop on secure chips using a light sensor (US 2005/0033705). Many of the latest chips are popular with designers because they consume very little power, but they generate pulses of infrared light while processing data. Although the pulses are very weak, sensitive detectors can record them and decode secrets or passwords circulating inside. Silverbrook鈥檚 answer is to include extra circuits that produce bright random flashes of infrared light, dazzling the hackers鈥� detectors and preventing them reading sensitive data.
A new kind of aircraft wing that reduces drag at high cruising speeds, cutting fuel consumption and pollution, is being patented by Boeing and NASA (WO 2005/002962). Aircraft wings have a curved leading edge and sharp trailing edge to make the air flow fast over the top surface and create lift. But at high speeds the airspeed over the top can reach the speed of sound, causing shock waves, turbulence and increased drag. The remedy is surprisingly simple. Cutting a slot through the wing along most of its length allows some of the air under the wing to leak up through the slot and mix with the air over the upper surface. This slows enough to prevent or reduce the shock waves.
