First Digital Phone Call

Discussion in 'Off-Topic' started by djsfantasi, Apr 16, 2014.

  1. djsfantasi

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    The first use of digital communications was discussed elsewhere. However Analogkid has asked the trivia question of when was the first digital phone call.

    So as not to hijack the thread in which he asked, I am presenting it here.

    Without research, I posit that it happened in the Fifties? Anyone else?

    Note: after research, I think I was close but incorrect. No cigar!
     
    Last edited: Apr 16, 2014
  2. Brownout

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    Dunno, but if you watch closely, there is a commercial paying homage to Marty Cooper's first cell phone call, 40 years ago.
     
  3. nsaspook

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    The first digital phone network service device I saw were the Autosevocom voice scrambler devices designed in the early 1960s.
    http://www.jproc.ca/crypto/autosevocom.html
    We had an old set in the training lab when I went to crypto/radio school in the 70's.
     
    Last edited: Apr 17, 2014
  4. GopherT

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    I guess we need some clarification, like,
    - is multiplexing (for increased capacity or scrambling) of analog connections considered digital?
    - mobile or land line?
    - does the voice have to be converted to "zeros and ones" to be "digital"
     
  5. atferrari

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    Do we have options?
     
  6. nsaspook

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    Yes, there are multilevel digital encoding/decoding methods like QPSK that encode multiple-bits per digital symbol and it's not really new, 'Polar Modulation' (a form of multilevel digital) dates back to Edison and the http://en.wikipedia.org/wiki/Quadruplex_telegraph
     
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  7. djsfantasi

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    All of these options were not specified in AnalogKid's post. The first wireless mobile technology was invented in 1947. Niche uses were developed in the following years. However, in Wikipedia's mobile phone entry on mobile(http://en.wikipedia.org/wiki/Mobile_phone ), states "In 1991, the second generation (2G) digital cellular technology was launched in Finland by Radiolinja on the GSM standard, which sparked competition in the sector, as the new operators challenged the incumbent 1G network operators" (Note 1G technology was still analog)
     
  8. shteii01

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    To keep it simply I would say:
    * digital as in 0 and 1
    * voice
    * land line
    * civilian
     
  9. atferrari

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    I always thought of "digital" as when you use 0 and 1 levels combined somehow to convey information.
     
  10. JoeJester

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    Digital technology still relies on Analog RF to transmit the signals in cellular phones.

    So ... with respect to digital phone calls, I still think that NSASpook gave the best answer.
     
  11. THE_RB

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    I thought this was going to be a trick question, where the correct answer was "telegraph using morse code".

    Hey, that's digital. It's even binary as there are only two symbols, 0 and 1 which are "digitally encoded" into patterns of numbers. ;)
     
  12. GopherT

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    Back on analogkid's original about digital communication, I liked "smoke signals" as the answer. This thread, RB, is about telephone calls - not telegraph.
     
  13. WBahn

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    It is not binary, it's trinary. If it were binary, then you could record a message as a string of 0s and 1s. But you can't. For instance, if a 0 is a dit and a 1 is a dah, does 0000 represent EEEE, ES, SE, II, or H? You need a third symbol, commonly known as a space, in order for the code to work.
     
  14. alfacliff

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    Actually, American morse has more than on and off, it uses different timing of the on and off periods, the long dash being one differnce, and the lengths of spaces between characters and sentences for another.
     
  15. THE_RB

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    There are only two symbols, and a pause or pauses of different lengths.

    Nobody said binary can't have pauses. Some binary comms protocols have pauses.
     
  16. WBahn

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    Where the pause carries information?
     
  17. WBahn

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    It actual quinary since it has five fundamental elements (two ON symbols of three OFF symbols).

    If you want to make it binary, you have to define your two symbols as ON and OFF (as opposed to dit and dash or dot and dash). Then the two ON symbols become either ON or ON-ON-ON (dit and dah, respectively) and your three spaces become OFF, OFF-OFF-OFF, and OFF-OFF-OFF-OFF-OFF-OFF-OFF for the intersymbol, intercharacter, and interword spaces, respectively.
     
  18. djsfantasi

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    But is digital necessarily binary? One definition of digital is signaling by discrete states. Hence quaternary or higher signaling can still be considered digital. And what prevents these discrete states from being specific values of an analog stream? My definition seems to be broader than some.
     
  19. WBahn

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    Oh, quaternary and such is definitely digital. The recent discussion centered on the claim that Morse code was binary.

    What's the difference between "specific values of an analog stream" and "discrete states". ALL systems are inherently analog (well, I suppose if you get into really obscure physics that isn't necessarily true, but for now, for us, it is), it is how we choose to assign information to things that makes them "digital".
     
  20. THE_RB

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    The pause does not carry information! It only separates the data blocks.

    All the data is contained within two symbols.

    By your logic, this series of binary numbers;
    10 011 1010 10010 101
    is also "trinary" because there are pauses separating the data blocks?

    And this series of decimal numbers;
    9 234 21 30 071
    is actually in "undecimal" (base-11) because there are 10 digits and pauses? :eek:

    Morse has data blocks consisting of only two data symbols, dot and dash. The fact that there are pauses between data blocks is irrelevant and is standard in binary comms. Morse is binary.
    :)
     
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