Hi everyone, I just have found some long wave materials here on the web at
http://www.dxing.com See below, and there is also a link here to a pretty
good organization that I read a little on.
"
Longwave" refers to all frequencies below the lower end of the AM
broadcasting band at 540 kHz. The lower limit of what frequencies
constitute "radio" is
not precisely defined, but 5 kHz is a widely accepted starting point for
the radio spectrum.
For many years, radio hobbyists ignored longwave because most commonly
available communications receivers only tuned down to 540 kHz. However,
most new
receivers today tune down to at least 150 kHz and longwave DXing is enjoy
new popularity.
One big problem when tuning longwave is electrical noise from power lines,
electrical devices, motors, etc. Longwave is far more susceptible to such
noise
than higher frequencies, and you might hear only a loud "buzz" when you
tune across longwave from your location. Also, static crashes from
thunderstorms
can be severe, especially in summer. To combat noise, many longwave DXers
use an indoor "loop" antenna that allows rejection of nearby electrical
noise
sources. Other longwave DXers use special phasing units to reduce noise
levels.
Reception distance on longwave is similar to that on the AM broadcast
band, as are reception patterns. Greater range is possible when the signal
is reaching
you over a water path, as is often the case in coastal regions. At night,
reception of stations from hundreds or even thousands of miles away is
possible.
Night reception on longwave is better in winter than in summer, and the
equinoxes often give the best propagation.
Unlike the shortwave frequencies above 1700 kHz, the longwave spectrum is
allocated on a more "ad hoc" basis, with different users and services
frequently
sharing the same frequency range. Here is a general description of the
world below 540 kHz:
Below 155 kHz: Signals below 155 kHz don't propagate very well via the
ionosphere; the absorption is too great even at night during winter. These
signals
can travel for thousands of miles via ground wave, but high transmitter
powers are required. Signals at very low frequencies, about 50 kHz and
lower, can
penetrate sea water very well. As a result, these frequencies are used by
military forces of the major powers, especially for communication with
submarines.
The U.S. Navy's "Omega" navigation system is found on 10.2, 12, and 13.6
kHz. The Russian navy operates a similar system on 15.62 kHz. The U.S. Air
Force
has a FSK-based communications system on 29.5 and 37.2 kHz. This system
was established to provide a backup in case nuclear explosions rendered
the ionosphere
useless for propagation. Miscellaneous FSK-based stations are found here
for direct communications with submarines and naval forces.
150 to 175 kHz: In the United States, this range is used by the U.S. Air
Force's ground wave emergency network (GWEN), a packet-based network to
provide
communications during a nuclear war. Transmitters are kept continuously
operational here on a "standby" basis, and it's easy to hear their loud,
"raspy"
signal bursts.
155 to 281 kHz: This is another AM broadcasting band in Europe and parts
of Asia. In Europe, there are numerous high powered (1,000,000 watts or
more) stations
here. These stations are capable of covering an entire European nation
like France or Germany with reliable signals around the clock. Although
ionospheric
propagation is not good at these frequencies, the high powers used means
that many of these broadcasters can be heard along the Atlantic seaboard
during
the fall and winter. Best reception is usually from local sunset to about
0600 UTC. A few longwave stations in Asiatic Russia can be heard on the
Pacific
Coast beginning an hour or so before local sunrise.
160 to 190 kHz: In the United States, this range is open to unlicensed
experimental transmissions. Transmitter power is restricted to one watt,
and the
maximum antenna length (including feedline) can be no more than 50 feet.
Any mode can be used. Some of these "lowfer" (as they are known)
unlicensed stations
have been heard several hundreds of miles away under favorable conditions.
200 to 430 kHz: This range is used mainly by navigation beacons, which
continuously repeat their call signs in Morse code. Call signs do not
follow the
international allocations given elsewhere on this site. Instead, the call
signs usually give an idea of the location of the beacon. For example,
beacon
"FT" on 365 kHz is located at Fort Worth, Texas.
430 to 500 kHz: This range is used for two-way Morse code communications
between ships at sea and shore stations. Shore stations use three-letter
callsigns,
while ship station callsigns consist of four letters. All callsigns are
from international allocations. The number of stations you can hear in
this range
is rapidly declining due to a shift in maritime communications to
satellites and shortwave frequencies. After February, 1999, radio
operators skilled in
Morse code will no longer be required on ships sailing in international
waters, and the number of stations you can hear in this range should drop
precipitously
after that date.
500 kHz: This is an international ship calling and distress frequency for
maritime communications in Morse code. It is very lightly used, and after
February,
1999, ship stations and shore stations will no longer be required to
monitor this frequency for calls.
500 to 540 kHz: This segment is populated by miscellaneous beacons and
stations. Perhaps the most interesting frequency here is 518 kHz, used for
transmission
of maritime safety and navigation information via FSK. This system is
known as NAVTEX, and includes weather bulletins as well as notices of
missing and
overdue vessels. 530 kHz is used in the United States and Canada for low
powered road and traffic information broadcasts.
A good source of information about longwave reception techniques, stations
currently being heard, and experimental stations currently being heard is
the
Longwave Club of America
(LWCA). A good directory of beacon stations active in North America is the
Aero/Marine Beacon Guide published by Ken Stryker. Information on the
latest
edition can be obtained by sending a self-addressed stamped envelope to
Ken Stryker, 2856-G West Touhy Ave., Chicago, IL, 60645.
For further information on longwave DXing we recommend . . .
World Below 500 kHz
The World Below 500 KiloHerz
An Introduction to the Longwave Spectrum
By J. Zondlo.
A handy introduction to the world of longwave listening. Covers VLF, GWEN,
Loran, Omega, ELF, Lowfers, frequency use, receiver and antenna
information,
tuning tips and much more. Not a beacon directory. 1985 Universal Radio
Research 64 pages.
Out of Print
A replacement for this book will be available June 2004.
Click here to visit Universal Radio's online catalog.
1999-2004 by Universal Radio Research. All rights reserved.
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