Stay Safe !.......
Posted on 09/26/2004 4:05:33 PM PDT by 68skylark
Stay Safe !.......
In was an open secret that ELF was designed to send nuclear launch orders to Ballistic Missile submarines. As you note, it penetrates the ocean whereas other radio waves don't. It wasn't the only method that the Tridents had of getting "the word." But I agree that we should keep ELF, for the redundency.
Were they asking for the formula for transparent aluminum?
You've got a technical 'salad' of terms there that isn't very clear; a) they are phasing out the ELF system in favor of b) a VLF system with 12 different transmitting sites.
I've got to believe that the information 'data rate' will go up with the new system compared to the old system at ELF ...
A VLF system with 12 different globally-located system may well outdo the olf VLF system; penetration of seawater is a matter of how much attenuation you're willing to accept, it's not a show stopper as far as propagation below the surface is concerned. We've got a lot of techniques we can use today to, using DSP technology and various 'synchronous' demodulation techniques that allow a raw noise to signal ratio to exist *prior* to signal processing ...
IIRC, the predecessor to this system was called Big Jim, which was a transmitter with its antenna stretched between two mountain tops. The data rate was woefully slow, but that was how we talked to submerged subs.
The main advantage to Low band VHF is - lessened attenuation due to intervening terrain (knife edge diffraction isn't as lossy) and lessened attenuation due to forestation (foliage, trees, etc.).
Other than that, VHF Low band is noisy (power line noise, urban noise like switching power supplies et al), inefficient for portable (hand-held) equipment and prone to 'skip' (ionospheric propagation that can 'cover' weaker, local traffic).
Low band VHF, BTW, is a line-of-sight propagation band (well, line of sight plus 10% or so) - ZERO ground wave propagation as on AM broadcast (I know, I know MANY people 'claim' GW prop, but it ain't so) ...
Yup, GWEN's gone - no more modem-sounding data bursts to compete with the hobby beacons within the 'license free' band of 160 - 190 KHz band ...
I can't get much into the specifics of how the system worked, but it was one of those "gee-whiz" systems that was ultimately very limited in its usefulness.
That's an interesting 'band' to work with, antenna efficiencies are low (unless you can stretch something huge between mountain tops!), something even a few thousand feet long is only a fraction of percent efficient ...
I notice you have links to some stuff on your profile page from Brad Dye. It wouldn't surprise me to find out he was a Navy radioman in the early sixties, stationed for a time at Northwest Receiver site in North Carolina. I was there at the same time and had a run-in with him. LOL
Its going to suck if we ever have to fight more than terrorists. The "lighter, faster, cheaper" Rumsfeld mentality is going to come back and bite us big time.
Its going to suck if we ever have to fight more than terrorists. The "lighter, faster, cheaper" Rumsfeld mentality is going to come back and bite us big time.
It never occurred to me that we were now immune from nuclear war. Quite the oppisite, I thought that it would be inevitable given all the different countries that have the bomb.
Thanks for the ping!
Never thought much of the sub radio. For that matter, I didn't think the burger radio was all that hot either.
You have freepmail.
I know that data rate is inversely proportional to frequency. So ELF yields Extremely Low Data Rate. But the number of bits needed to order a nuclear weapons launch is fairly small, and the number of bits needed to tell a sub to come shallow to get a vital message is even smaller.
I just don't like giving up technology to the Greens if we might want it someday.
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