[Lf] history question

[hal]

Hi Frank,

I've heard that the pionering work on LF was done by Marconi and his original
ship-shore
Marconi Wireless company.  So, seeing a good thing, copies were made of this
basic
design by naval forces of different countries, including US.  Since the
existance of the
Heavyside layers was not yet known,  improvements were made to Marconi's
model:
more power and larger antennas to increase reliability.  I surmise that this
could
explain many of the original maritime and naval allocations in the LF region
prior
to the cold war.  I suspect interest in LF began to wane when the merits of
high frequency
became known.  The established martime ship to shore infrastructure probably
was
kept in place and operated in parallel (using 500Khz as a calling frequency)
while
use of the new HF allocations grew.   A second generation of LF system dates
post WW II,
primarily as post- and trans-nuclear attack communications systems.

Are there conventional propagation modes in LF that maintain military
interest?

I have a self published book
called QTC  "A seagoing radio officers scrapbook"  that talks about the early
days.
Perhaps this has some LF history in it.
--H.
Frank Gentges wrote:

> Hal,
>
> Good questions.  I went for my copy of NRL's "Evolution of Naval
> Radio-Electronics and Contributions of the Naval Research Laboratory"
> written in 1979 and written as a technical report in a hard-back binding
> by Louis A. Gerhard who spent over 58 years there.  I'll try to get some
> answers to your questions as follows....
>
> On Tue, 1 Feb 2000, hal wrote:
>
> >
> >
> > On the original uses of lf can anyone tell me if these facts are true?
> >
> > 1) It was the German Navy prior to 1940 who began using LF to
> > communicate with
> > the submarine fleet?   If so, what year was it that they began?
> >
> > 2) Radio Luxemburg was the first international LF broadcast station?  I
> > recall
> > reading that some British engineers were involved with its design and
> > construction.
> > Anyone know the year.  This was pre-WWII, in the late 1920's or early
> > 1930's.
> >
> > 3). The frequency of Hertz's spark resonator?   Was it LF?
>
> No.  His experiments are listed as 31.3 to 1250 mHz.
> >
> > 4). Marconi's first transmitters, did these operate on LF or higher up?
> > What about
> > the famous transatlantic (Europe to Canada) transmission?
>
> Marconi's famous transatlantic test on 12 Dec, 1901 from Poldhu, England
> to Saint Johns, Newfoundland used a frequency of approx 313 kHz.
>
> The standard frequency of Navy spark transmission was first 938 kHz (320
> meters wavelength) and then expanded to cover 300 to 500 kHz.
> >
> > 5) How did NDB find themselves clustered around 200Khz and up?  When did
> > this start.
>
> Today all we have are NDBs (non-directional beacons) but in the 30s there
> were directional beacons which could be heard as morse "n"s or "a"s if
> you were off the beam and a steady tone when on the beam.  The antenna
> was directional and switched its lobes to create the dit-dah and dah-dit
> sound.
>
> > NDB began before
> WWII along short hop flight routes in the US and > elsewhere. Why LF and
> > why there?  Is there an international convention where this was first
> > recognized?
> >
> > 6)The first US Navy transmitter that used long wave operated from Ft
> > Meyer in Arlington VA (?)
>
> No much went on before Arlington.  The first shore sites were at the
> Washington Navy Yard and at the Naval Academy at Annapolis in the fall of
> 1902.  Arlington was outfitted in 1912 with a 100 kw synchronous rotary
> spark-gap transmitter at 120 kHz.  Earlier work may very well have been
> done there.  The book lists Arlington as the "Navy's Primary Radio
> Station" from 1913 to 1956.
>
> > Were other nations were also operating LF transmitters for their naval
> > forces?  Does anyone
> > know of a reference to early US Navy communications experiments?
>
> The Germans were using VLF/LF during WWII.  They had shortages of copper
> wire so built a VLF antenna out of steel wire that work remarkably well.
> It was named the "Goliath" and the US subsequently used the basic design
> on almost all VLF stations since building Cutler Maine.
>
> I have this NRL book and a similar NBS book on radio history that may be
> more useful in your hands for now.  There is a wealth of information
> here. I'll try to get them to you.
>
> Frank
>
> > > --Hal > >
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> >