: >I'm curious if anyone knows what the purpose of the massive antenna farm
: >is near Cutler Maine, which I believe is US Navy. My guess is that maybe this is used for communication with submerged subs
: >(the scale seems about right)
: You are correct. The call sign is NAA. The operating frequency is
: 24KHz. The modulation is MSK. All of this info is contained in the
: Shortwave Directory, Grove, ISBN 0-944543-00-6.
: The Jasik and Johnson Antenna Engineering Handbook, Second Edition,
: Table 24-1 published by Mc Graw Hill ISBN0-07-032291-0 gives the
: following information about these antennas:
: 1 megawatt at 17.8KHz.
: I don't know which reference is correct but you get the idea. The USN
: has been experimenting with direct satellite communications to
: submarines using high-speed bursts to a small Ku-band antenna that is
: extended to the surface similar to a periscope. The data rates
: available will likely make this the medium of choice soon. The VLF
: links will likely continue to serve subs that are deeply submerged.
Apparently they have changed frequency to the 24kHz range. There is a
similar (?) station about a wavelength from here, the Jim Creek Naval
Transmitting Station, which as I understand also moved from a slightly
lower frequency. These things aren't exactly frequency-agile, since the
antenna tuning is rather critical and done with rather large coils. I
believe they can operate anywhere in about a 10kHz range, with
appropriate retuning. At 1 megawatt, it makes for a rather high voltage
at the base of the antenna(s). At Jim Creek, there are half a dozen "T"
shaped antennas strung out in a line following the valley below the
transmitting shack, and another half dozen above. Each "T" is something
like 3000 feet high and 3000 feet across the top, suspended between
parallel mountain ranges that are about 8000 feet apart. The
transmitter is actually two half megawatt transmitters in phase. Each
has a push-pull pair of tubes in the output.
Perhaps I'm wrong, but my impression is that they communicate information
quite slowly--a very low baud rate. Their purpose seems to be to tell a
sub that they need to put up an antenna to get more info, or similar
pre-arranged signals. Just how much information can you push through a
very high Q antenna system with a 20kHz center frequency??