Fred, it's called LiFi and uses the ability of LED light sources to handle high frequency modulation to send data securely since one has to intercept the actual beam to even get the data, much less decode the information. Apparently pretty high data rates are possible with the system.
Here's a press article from about a year ago. http://dailycaller.com/2016/08/10/revamped-100-year-old-lamp-will-help-the-navy-counter-russia-and-china/ I'm sure we Hams will find a use for the technology, Hi! Way back in 1955 when I was in High School I created a very popular display that used my S-38 receiver tuned to a popular station. Current powering a 6V lantern passed through the S38's audio output transformer to modulate the light. The lighet was received by a photoelectric tube across the table, amplified and the sound of the radio station played in a remote speaker. The sound could be interrupted by passing one's hand in from of the light. Even though it was an incandescent bulb with its thermal lag, it still reproduced good AM quality audio. It was good enough (in 1955) that I was encouraged to display it at the annual Science Fair where it worked too well. Someone stole the photoelectric tube from the display before it could be judged -- but I still got an A on the project! 73, Ron AC7AC -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Fred Jensen Sent: Monday, November 20, 2017 12:34 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] O.T. Morse is not dead, at least in the U.S. Navy OK, what's different then from WW2 signal lamp usage? I thought they were using a modified lamp with QRQ Morse decoded in some sort of hardward/software device, or a digital mode. 73, Fred ["Skip"] K6DGW Sparks NV DM09dn Washoe County ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
