Researchers at the Georgia Institute of Technology have developed a system that encodes information onto chaos, transmits it, and then decodes the information away from the chaos. Rajarshi Roy, one of the researchers and chair of Georgia Tech's School of Physics, explains how it works. "In an ordinary digital signal, the message can immediately be seen," Roy reports. "But in our system, digital information is encoded in the chaos, so the message would not be obvious to a person who may intercept it." In the experimental system, a stable semiconductor diode laser produces a square wave "message" signal. That signal, amplified by an erbium-doped fiber amplifier (EDFA), is introduced into a chaotic signal produced by an erbium-doped fiber ring laser like that used in today's communications industry. The resulting combined signal, containing a mix of the message and chaotic carrier, moves through an optical fiber to a second EDFA nearly identical to the first. Upon encountering the combined signal, the receiving EDFA begins generating chaotic fluctuations synchronized with those produced by the transmitting laser. The chaotic portion of the signal, measured by a digital oscilloscope, is subtracted from the combined signal and low-pass filter to recover the original "coded" message. E-mail email@example.com.
Independent science safety company Underwriters Laboratories is providing new guidance for manufacturers about how to follow the latest IEC standards for implementing safety features in programmable logic controllers.
Automakers are adding greater digital capabilities to their design and engineering activities to promote collaboration among staff and suppliers, input consumer feedback, shorten product development cycles, and meet evolving end-use needs.
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