parnass@ihuxf.UUCP (07/14/83)
I think other newcomers or casual readers of "net.ham-radio"
may be interested in my response to Tim Sullivan, who sub-
mitted the following query recently:
-------------
I have recently bought an auto with a german
radio. The radio has scanning capabilities for
both short wave and long wave (I assume this is
what "LW" on the button stands for.)
My question is what capabilities do both options
have ? From reading previous articles, it sounds
as if my short wave can pick up police radios but
this has not been done yet. On one clear night I
listened to what appeared to be a german radio
station, as everything spoken was german. The long
wave option hasn't picked up anything yet.
I would appreciate any advice that net.world could
give me. please send mail and I will post a
response for others who are interested. Thanks in
advance.
------------
Listening to radio signals on the short wave and long wave
bands is a fascinating hobby to many. Although you cannot
receive local police transmissions on your automobile radio,
you may be able to receive many interesting signals in the
long wave and short wave bands. Police transmitters use
frequency modulation (FM) in the VHF and UHF bands of 30 -
50, 150 - 174, and 450 - 520 mHz.
The long wave (LW) band (also known as low frequency, LF) is
used in many European countries as a regular broadcast band,
just like the 535 - 1650 kHz. medium wave (MW) band is in
the United States. It is not uncommon to find capabilities
for this band provided in radios of European origin. When I
was a child, I always got a thrill out of tuning those large
German Grundig radios, which had an "LW" band position. My
reception on LW with these radios was limited by the lack of
a suitable antenna.
The dials of some European radios indicate wavelength in
meters rather frequency in kHz or mHz. To determine a fre-
quency in mHz, divide 300 by the wavelength in meters.
In this country, the long wave band is used for several
types of broadcasting, none of which is intended for the
entertainment of the general public. Some stations you may
find on long wave include:
o+ radio navigation beacons - these stations usually
transmit their 2 or 3 letter call signs in Morse code
continuously, and are used by aircraft for radio loca-
tion purposes.
o+ weather reporting station - an announcer reads the
weather forecast continuously. Often times, the
station's Morse code identifier will be noted in the
background.
o+ wireless intercoms - some wireless intercoms work by
modulating a carrier frequency in the LW band with the
user's voice and using the house AC wiring as a
transmission line. Sometimes, a small amount of this
radiation escapes and may be received on a nearby
receiver. I noticed this when, at age 11 I built my
first radio. Its lowest coverage included the 200 -
400 kHz LW band. I used a wireless intercom and was
able to hear myself on the newly assembled radio!
o+ experimental - there is even a license-free band from
160 - 190 kHz. which experimenters may use. They are
limited to antennas less than 50 feet in length, and
transmitters with less than one watt output.
The very low frequencies (below the capabilities of most car
radio receivers) are used for such things as:
o+ communications with submarines - usually using very
narrow shift radioteletype
o+ time standard signals - the U.S. National Bureau of
Standards maintains a standard time station, WWVL,
which transmits the exact time in Binary Coded Decimal
(BCD) on 60 kHz.
o+ utility company control signals - some electric com-
panies transmit control signals at very low frequen-
cies, using the power lines as transmission lines. The
length of these power lines makes them act like anten-
nas.
o+ long range navigation (LORAN) - a pair of powerful
transmitters emit synchronized, pulsed signals. Ships
may determine their (ship) position by using special
equipment which analyzes the timing of the signals
reaching the ship from the two LORAN transmitters.
Short wave, on the other hand, contains a larger variety of
stations. A typical car radio will only be able to detect
those which use amplitude modulation (AM). Such stations
include:
o+ foreign broadcast - Voice of America, Radio Moscow,
Voice of the Andes, Kol Israel, etc.
o+ time signals - WWV at 2.5, 5, 10, 15, 20 mHz. CHU
(Canada) at 3.330, 7.335, and 14.670 mHz.
There are may other stations on short wave. Some use Morse
code telegraphy (CW), which may sound like "thumps" in an AM
receiver. Some use single sideband (SSB) voice, which may
sound like Donald Duck in an AM receiver. Others use
radioteletype (RTTY). Weather pictures are sent using fac-
simile (FAX).
Ham radio operators use all of these modes and more. The
FCC has allocated 6 short wave bands for amateur usage. The
short wave spectrum is used by ship-to-shore telephone, off
shore oil rig platforms, spy stations, the military, embas-
sies, the FBI, cordless telephones, CB operators, etc.
The radio antenna found on the typical car is a rather poor
performer on LW, and not that much better on short wave.
Robert S. Parnass, AJ9S (Technical Advisor to ARRL)
Bell Laboratories
Naperville, Illinois
ihnp4!ihuxf!parnass