ELF transmission

Discussion in 'U.S. Navy' started by surya kiran, Aug 25, 2016.

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  1. surya kiran

    surya kiran 2nd Lieutenant

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    Hi,

    Was reading on another forum about ELF transmission to communicate with submarines. Did a little reading and found, that, while Russia and India have built this, US has stopped using this.

    Any idea why? And what is the USN now using to communicate with the subs?

    @Technofox @Pathfinder @Vergennes @Parikrama
     
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  2. Technofox

    Technofox That Norwegian girl Staff Member Ret. Military Developer

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    The USN is using either shorter ranged VLF waves from sites like Cutler:

    [​IMG]

    And Lualualei:
    [​IMG]

    Or communications buoys:
    [​IMG]

    For communication with submarines underwater. A satellite system is also in place. This is the Submarine Satellite Information Exchange Sub-System:

    Several FLTSATCOM comprised the sub-system initially:
    [​IMG]

    Two of the FLTSATCOM satellites are still operational, the rest were replaced by the UFO program:
    [​IMG]

    These are UHF rather then VLF or ELF.

    ELF has limitations. It's one-way because the transmitter needed for a submarine to return communications is the size of a small city and buried deep underground to form part of a lead, often using ground dipoles.

    The right of way in this ELF array actually forms part of the lead:
    [​IMG]

    ELF also requires an area with low ground conductivity, which could interfere with the mammoth signals - we're talking about a signal who's wave length size is roughly 3,656.0 kilometers!! To generate that you need space, hence the leads which help generate the signal and you need land that wont interfere with it.

    ELF is just too power hungry, too large and too complicated to employ. Environmental concerns, political pressure and alternatives like satellite communications helped doom the US' ELF programs.

    ...

    I forgot about this:D. I did a bit on Subcoms once:

    http://defence.pk/threads/learn-to-...to-submarine-terms.378981/page-2#post-7231875

    And one cool piece of trivia. Norway's Fjords are very pretty, but did you know many of them also hide VLF transmitters? it's true. VLF arrays are often worked into natural surroundings to avoid prying eyes or ears:
    [​IMG]

    One such tower-less radio array is the Noviken VLF Transmitter.

    They are used for, you guessed it, communicating with our submarines - the Ula class:
    [​IMG]
     
    Last edited: Aug 25, 2016