Tagged: claude shannon Toggle Comment Threads | Keyboard Shortcuts

  • feedwordpress 08:01:00 on 2019/04/30 Permalink
    Tags: circuit design, claude shannon, , communications theory, cryptanalysis, , , information theory, ,   

    “Information is a difference that makes a difference”*… 


    Warning: preg_match_all(): Compilation failed: invalid range in character class at offset 7 in /homepages/23/d339537987/htdocs/pb/wp-content/themes/p2/inc/mentions.php on line 77

     

    Shannon information

     

    Information was something guessed at rather than spoken of, something implied in a dozen ways before it was finally tied down. Information was a presence offstage. It was there in the studies of the physiologist Hermann von Helmholtz, who, electrifying frog muscles, first timed the speed of messages in animal nerves just as Thomson was timing the speed of messages in wires. It was there in the work of physicists like Rudolf Clausius and Ludwig Boltzmann, who were pioneering ways to quantify disorder—entropy—little suspecting that information might one day be quantified in the same way. Above all, information was in the networks that descended in part from the first attempt to bridge the Atlantic with underwater cables. In the attack on the practical engineering problems of connecting Points A and B—what is the smallest number of wires we need to string up to handle a day’s load of messages? how do we encrypt a top-secret telephone call?—the properties of information itself, in general, were gradually uncovered.

    By the time of Claude Shannon’s childhood, the world’s communications networks were no longer passive wires acting as conduits for electricity, a kind of electron plumbing. They were continent-spanning machines, arguably the most complex machines in existence. Vacuum-tube amplifiers strung along the telephone lines added power to voice signals that would have otherwise attenuated and died out on their thousand-mile journeys. A year before Shannon was born, in fact, Bell and Watson inaugurated the transcontinental phone line by reenacting their first call, this time with Bell in New York and Watson in San Francisco. By the time Shannon was in elementary school, feedback systems managed the phone network’s amplifiers automatically, holding the voice signals stable and silencing the “howling” or “singing” noises that plagued early phone calls, even as the seasons turned and the weather changed around the sensitive wires that carried them. Each year that Shannon placed a call, he was less likely to speak to a human operator and more likely to have his call placed by machine, by one of the automated switchboards that Bell Labs grandly called a “mechanical brain.” In the process of assembling and refining these sprawling machines, Shannon’s generation of scientists came to understand information in much the same way that an earlier generation of scientists came to understand heat in the process of building steam engines.

    It was Shannon who made the final synthesis, who defined the concept of information and effectively solved the problem of noise. It was Shannon who was credited with gathering the threads into a new science…

    The story of Claude Shannon, his colorful life–  and the birth of the Information Age: “How Information Got Re-Invented.”

    * Gregory Bateson

    ###

    As we separate the signal from the noise, we might send communicative birthday greetings to the subject of today’s main post, Claude Elwood Shannon; he was born on this date in 1916.  A mathematician, electrical engineer, and cryptographer, he is, for reasons explained in the article featured above, known as “the father of information theory.”  But he is also remembered for his contributions to digital circuit design theory and for his cryptanalysis work during World War II, both as a codebreaker and as a designer fo secure communications systems.

    220px-ClaudeShannon_MFO3807 source

     

     
  • feedwordpress 08:01:29 on 2018/09/24 Permalink
    Tags: Alan Turing, claude shannon, , phone, SIGSALY, , , ,   

    “Encryption works”*… 


    Warning: preg_match_all(): Compilation failed: invalid range in character class at offset 7 in /homepages/23/d339537987/htdocs/pb/wp-content/themes/p2/inc/mentions.php on line 77

     

    SIGSALY-1943

    A SIGSALY terminal in 1943

     

    During World War II, a British-American team that included Claude Shannon and Alan Turing created the first digitally scrambled, wireless phone known as SIGSALY…

    Declassified only in 1976, it was a joint effort of Bell Labs and Britain’s Government Code and Cipher School at Bletchley Park, north of London. It had a scientific pedigree rivaling that of the Manhattan Project, for the British-American team included not only Shannon but also Alan Turing. They were building a system known as SIGSALY. That was not an acronym, just a random string of letters to confuse the Germans, should they learn of it.

    SIGSALY was the first digitally scrambled, wireless phone. Each SIGSALY terminal was a room-sized, 55-ton computer with an iso­lation booth for the user and an air-conditioning system to prevent its banks of vacuum tubes from melting down. It was a way for Al­lied leaders to talk openly, confident that the enemy could not eavesdrop. The Allies built one SIGSALY at the Pentagon for Roo­sevelt and another in the basement of Selfridges department store for Churchill. Others were established for Field Marshal Mont­gomery in North Africa and General MacArthur in Guam. SIGSALY used the only cryptographic system that is known to be uncrackable, the ‘onetime pad.’ In a onetime pad, the ‘key’ used for scrambling and decoding a message is random. Traditionally, this key consisted of a block of random letters or numbers on a pad of paper. The encoded message therefore is random and contains none of the telltale patterns by which cryptograms can be deciphered. The problem with the onetime pad is that the key must be delivered by courier to everyone using the system, a challenge in wartime.

    SIGSALY encoded voice rather than a written message. Its key was a vinyl LP record of random ‘white noise.’ ‘Adding’ this noise to Roosevelt’s voice produced an indecipherable hiss. The only way to recover Roosevelt’s words was to ‘subtract’ the same key noise from an identical vinyl record. After pressing the exact number of key records needed, the master was destroyed and the LPs distrib­uted by trusted couriers to the SIGSALY terminals. It was vitally important that the SIGSALY phonographs play at precisely the same speed and in sync. Were one phonograph slightly off, the out­put was abruptly replaced by noise.

    Alan Turing cracked the German ‘Enigma’ cipher, allowing the Allies to eavesdrop on the German command’s messages. The point of SIGSALY was to ensure that the Germans couldn’t do the same. Part of Shannon’s job was to prove that the system was indeed im­possible for anyone lacking a key to crack. Without that mathemat­ical assurance, the Allied commanders could not have spoken freely. SIGSALY put several other of Shannon’s ideas into practice for the first time, among them some relating to pulse code modulation. AT&T patented and commercialized many of Shannon’s ideas in the postwar years…

    The first wireless “phone”: an excerpt from William Poundstone’s Fortune’s Formula, via Delancey Place.

    * Edward Snowden

    ###

    As we keep a secret, we might recall that it was on this date in 1909 that Thomas M. Flaherty filed for the first U.S. patent for a “Signal for Crossings”– a traffic signal.  His signal used a large horizontal arrow pivoted on a post, which turned to indicate the right of way direction, and was activated by an electric solenoid operated by a policeman beside the road.

    Flaherty’s was the first U.S. application for a traffic signal design, later issued as No. 991,964 on May 9, 1911. But though it was filed first, it was not the first patent actually issued for a traffic signal: Ernest E. Sirrine filed a different design seven months after Flaherty; but his patent was issued earlier, and thus he held the first U.S. patent for a “Street Traffic System.”

     source (and larger version)

     

     
  • feedwordpress 08:01:35 on 2015/08/16 Permalink
    Tags: claude shannon, dalek, Farnsworth, , , , , ,   

    “I visualize a time when we will be to robots what dogs are to humans”*… 


    Warning: preg_match_all(): Compilation failed: invalid range in character class at offset 7 in /homepages/23/d339537987/htdocs/pb/wp-content/themes/p2/inc/mentions.php on line 77

     

    It patrols your grounds continuously, no need for sitting down or going outside to smoke. It’s a “physically commanding presence,” warding off intruders and no-gooders. And, most importantly, it’s relatively cheap. At $6.25 an hour, it costs about one quarter of what mall-owners might normally pay for a human patrol.

    That, at least, is the pitch from Stacy Stephens, VP of marketing for Knightscope, the California startup behind the machine. He says there are now two dozen K5s in operation in the Silicon Valley area, including on corporate campuses, shopping malls, and data centers. He also, apparently, doesn’t think human workers are very good at their jobs. “We’re the opposite of the mall cop,” he says. “They sit around for 45 minutes to an hour, then they get up and walk around five minutes. The robot is going to patrol for 45 minutes to an hour, then it’s going to seek out its charge-pad for five minutes.”…

    Capable of object- and pattern-recognition, pathogen-detection, and “audio event detection,” it is not (yet) armed.

    Readers– who will be forgiven for observing an eerie similarity to the Daleks— can learn more at “Meet The Scary Little Security Robot That’s Patrolling Silicon Valley.”

    Claude Shannon (the “Father of Information Theory”)

    ###

    As we hope that resistance is not, in fact, futile, we might send fantastically far-sighted birthday greetings to Hugo Gernsback, a Luxemborgian-American inventor, broadcast pioneer, writer, and publisher; he was born on this date in 1884.

    Gernsback held 80 patents at the time of his death; he founded radio station WRNY, was involved in the first television broadcasts, and is considered a pioneer in amateur radio.  But it was as a writer and publisher that he probably left his most lasting mark:  In 1926, as owner/publisher of the magazine Modern Electrics, he filled a blank spot in his publication by dashing off the first chapter of a series called “Ralph 124C 41+.” The twelve installments of “Ralph” were filled with inventions unknown in 1926, including “television” (Gernsback is credited with introducing the word), fluorescent lighting, juke boxes, solar energy, television, microfilm, vending machines, and the device we now call radar.

    The “Ralph” series was an astounding success with readers; and later that year Gernsback founded the first magazine devoted to science fiction, Amazing Stories.  Believing that the perfect sci-fi story is “75 percent literature interwoven with 25 percent science,” he coined the term “science fiction.”

    Gernsback was a “careful” businessman, who was tight with the fees that he paid his writers– so tight that H. P. Lovecraft and Clark Ashton Smith referred to him as “Hugo the Rat.”

    Still, his contributions to the genre as publisher were so significant that, along with H.G. Wells and Jules Verne, he is sometimes called “The Father of Science Fiction”; in his honor, the annual Science Fiction Achievement awards are called the “Hugos.”

    (Coincidentally, today is also the birthday– in 1906– of Philo T. Farnsworth, the man who actually did invent television… and was thus the inspiration for the name “Philco.”)

    Gernsback, wearing one of his inventions, TV Glasses

    source

     
c
compose new post
j
next post/next comment
k
previous post/previous comment
r
reply
e
edit
o
show/hide comments
t
go to top
l
go to login
h
show/hide help
esc
cancel