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Secure Digital Voice Communications In World War II

Posted by michael on from the good-use-for-a-phonograph dept.

mercury7 writes: "Saw this one on Memepool. A very interesting paper from the U.S. National Security Agency site on the first digital encyrpted voice communication system. It is incredible how hard it was to manipulate data before the existence of computers."

6 of 34 comments (clear)

  1. Re:Key distribution on vinyl disks! by Detritus · · Score: 3

    You can listen to examples of vocoder audio on this web page.

    --
    Mea navis aericumbens anguillis abundat
  2. encryption, etc by Alien54 · · Score: 3
    In many communications of this type, the aim is to try to make could be intelligible speech indistinguishable from noise.

    Note that many politicians and spin doctor seem to have this done to a fine art.

    The reverse is slightly more difficult, which is the fine art of taking something indistinguishable from noise, and try to extract intelligible speech from it.

    How similar this is to public forums such as slashdot, etc is left as a exercise for the reader.

    ;-)

    --
    "It is a greater offense to steal men's labor, than their clothes"
  3. Key distribution on vinyl disks! by anticypher · · Score: 3

    I knew it. We need to criminalise the production and possession of vinyl as a munition. :-)

    The technical hurdles they had to overcome for this first "digital" voice system were pretty impressive. And each station weighed in at a mere 55 tons. I'd love to hear a recording of what the recovered speech sounded like.

    the AC

    --
    Hemos is like...sci-fi fans;he thinks technology is cool, but he hasn't bothered to understand the science it's based on
  4. Computers did exist! by the+red+pen · · Score: 3
    This is a trivia sidebar.

    Another thing that was tough in this age was aiming artillery. If you know the distance, the characteristic of the gun, the characteristics of the shell, and the windspeed, physics equations tell you how to aim the gun to hit your target. Realistically, the equations cannot be solved in battlefield conditions where time is a factor and competent mathematicians are in short supply.

    The solution to this problem was to issue huge books of pre-computed tables to artillery gunners. Each new gun and new shell needed a new book generated. That involved many hours of computation to be done by a small army of geeks. Because the guy-geeks were busy cracking codes, inventing atomic weapons, running logistics and stopping lead, a cadre of girl geeks was assembled in Annapolis and tasked with generating these artillery tables. The women were brought up to speed on Calculus and Physics (if they needed to be) and they were know as (you guessed it) "Computers."

    While the lady Computers toiled, some other geeks were trying to automate their task using analog and digital electronic systems. Because the first automated calculation machines were targetted to the labor-intensive task of generating artillery tables, these devices were called "electronic computers."

    Every time I see a flame session about the lack of women in computer engineering, I find it ironic that the word "computer" itself is an artifact of a group of geek girls.

  5. Meanwhile, in the 21stC by BenBenBen · · Score: 3

    If you want to look at cool modern-day intel. stuff, the GCHQ website is actually pretty detailed.

    The largest LAN in Europe, one of the highest data storage capacities in the world, and free healthcare =)

    Also, they seem to think they can pass secret instructions to spies the world over by inserting 'random' bold tags on one of their pages

    Ben^3
    --
    The Slashdot Paradox: "100% Overrated"
  6. incredible by burris · · Score: 5
    The system required that the key be used in twenty millisecond segments. Therefore, it was necessary for each record to be kept in synchronism within a few milliseconds for fairly long periods of time (one hour or so). This was accomplished by the use of very precisely driven turntables. The turntables themselves were remarkable machines. Each was driven by a large (about thirty-pound) synchronous electric motor with hundreds of poles. The motor was kept in constant operation, and the power for it was derived directly from dividing down the terminal's frequency standard. The frequency standard was a 100 kHz crystal oscillator. The accuracy of the standard had to be maintained within about one part in ten million so that the system would stay in synchronism for long periods of time. The system frequency standard could be corrected by comparing it to an available national frequency standard (which was WWV in the U.S.).
    For reference, the clock in a high performance modern digital audio device is only accurate to within about 1-10ppm. A cheap consumer device like a CD player or walkman type DAT deck will only have about 50-100ppm accuracy. This is 0.1ppm, in 1943, for a freakin' record player. Absolutely amazing.

    Burris