Ambient backscatter uses existing radio frequency signals, such as radio, television and digital telephony to transmit data without a battery or power grid connection. Each such device uses an antenna to pick up an existing signal and convert it into tens to hundreds of microwatts of electricity.[1] It uses that power to modify and reflect the signal with encoded data. Antennas on other devices in turn detect that signal, and can respond accordingly. Initial implementations can communicate over several feet of distance, even with transmission towers up to 10.5 kilometres (6.5 mi) away. Transmission rates were 1k bits per second between devices situated 1.5 feet apart outside and 2.5 feet apart inside, sufficient to handle text messages or other small data sets. Circuit sizes can be as small as 1 sq. mm.[1] This approach would let mobile and other devices to communicate without being turned on. It would also allow unpowered sensors to communicate, allowing them to be placed in places where external power cannot be conveniently supplied
Posted on: Sat, 17 Aug 2013 06:41:44 +0000
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