For example, high-frequency-signal attenuation prevents military submarines and underground surveying operations from taking advantage of GPS location, and can cause GPS to cut out in the dense, skyscraper-lined canyons of urban downtowns. But the problem goes much further than simple inconvenience. The skin-depth conundrumĪnyone who’s struggled to get a decent cell signal in a building basement knows the penetration limits of the high-frequency RF bands used by mobile phones. And the team has coupled that sensitive detection technology with a modulation scheme that can pack more information into the otherwise limited bandwidth of VLF fields. In the NIST setup, the OPM is used to pull in modulated signals encoded in very low frequency (VLF) magnetic fields, which are less prone to attenuation by the surrounding environment than a typical cell or GPS signal. Instr., doi: 10.1063/1.5003821).Īt the heart of the team’s approach is an optically pumped magnetometer (OPM)-a highly sensitive, room-temperature quantum detector that can do double duty as a kind of magnetic-radio receiver.
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National Institute of Standards (NIST) are working on ways to overcome a vexing problem of a wireless world: how to get usable signals in crowded built environments, underground and even underwater (Rev. National Institutes of Standards and Technology (NIST) leads an effort to use optically pumped magnetometers (OPMs) as receivers for low-frequency “magnetic radio,” to enable better wireless communications underground, underwater and in other environments that are challenging for conventional RF communications.