Shortwave Listening
Shortwave listening would generally be beyond the scope of our website, but many of our HF radios can easily receive on most of these bands. Plus, if you already have a long-wire antenna set up to do some DX listening, this might help you spot some of those unusual transmitters or stations. Just another part of the hobby. Thanks to the information by Al Lutins and found on KC2KLC's website This was well-written and posted with little editing. Here is a link to his home page.
Shortwave Listening Bands
CLICK HERE to use KFS WebSDR tunable receiver located in San Mateo, California.
TIME & FREQUENCY STANDARDS
Many countries operate "standards" stations so that the time and frequency can be measured precisely. The U.S. National Institute of Standards and Technology runs two such stations, WWV (Colorado) and WWVH (in Hawaii). Both stations operate on 2.5, 5, 10, 15 and 20 MHz, and are easy to hear because they operate at very high power. These stations provide the shortwave listener with three useful functions:
Time: WWV and WWVH announce the time every minute. Their atomic clocks are accurate to 2 millionths of a second per day!
Immediate propagation assessment: By tuning to each of the frequencies they operate on, one can get a quick feel for which parts of the shortwave dial are active and which are "dead."
Propagation forecasts: At 18 (WWV) and 45 (WWVH) minutes past each hour the "solar terrestrial activity report" is broadcast. This is kind of a weather forecast for the sun, and with experience one can learn to use this information to direct one's listening activities (for example, during severe solar storms, most of the shortwave dial will be dead). This information can also be accessed at any time online at www.solen.info/solar.
WWV has a male voice announcing the minutes, while WWVH has a female voice, so that you can tell them apart. These stations operate in "AM" mode so you do not need a radio equipped with sideband capability to receive them.
Many other countries operate standards stations as well; in North America, Canada's CHU can often be heard on 3.33, 7.85 and/or 14.67 MHz. You can occasionally heard HD2IOA in Ecuador on 3.81 MHz, and sometimes LOL in Buenos Aires, Argentina or PPU in Rio de Janeiro, Brazil on 10 MHz if the American broadcast isn't overwhelming it.
INTERNATIONAL BROADCAST
International broadcasters use high power and "AM" mode, and so are also very easy to receive. If you tune around a shortwave radio randomly you will hear them - they sound just like AM and FM radio stations, except that they may be in foreign languages. At one time just about every country had a shortwave broadcast service, but due to budget cuts and a shrinking audience a lot of these stations are being shut down. There are still plenty left, though, and you can listen to broadcasts from countries very far from you (many broadcast in English). Shortwave broadcasters are a wonderful source of news (often with a very different slant from the one you're used to) and music from around the globe.
These are some of the popular frequencies used by International broadcasters:
3.9 - 4 MHz ("75 meters")
4.75 - 5 MHz ("60 meters")
5.7 - 6.3 MHz ("49 meters")
6.9 - 7.6 MHz ("41 meters")
9.2 - 9.9 MHz ("31 meters")
11.5 - 12.2 MHz ("25 meters")
13.5 - 13.9 MHz ("22 meters")
15.0 - 15.8 MHz ("19 meters")
17.4 - 17.9 MHz ("16 meters")
18.9 - 19.0 MHz ("15 meters")
21.4 - 21.9 MHz ("13 meters")
There are also a number of broadcasters who transmit outside these ranges, especially the growing number of Christian evangelical stations.
AVIATION
Airplanes use VHF (not shortwave) radios for most of their communications, but when traveling far out over the ocean they need to use shortwave radios because of their superior ability to transmit long distances. There are a number of MWAR (Major World Air Route) and LDOC (Long Distance Operations Controls) stations throughout the shortwave dial that can be heard around world. There are also "Volmet" stations that broadcast nothing but weather conditions to pilots worldwide. Most aviation communications can be found in the following frequency ranges:
2.85 - 3.155 MHz
3.40 - 3.5 MHz
4.65 - 4.75 MHz
5.45 - 5.73 MHz
6.525 - 6.765 MHz
8.815 - 9.04 MHz
11.175 - 11.4 MHz
13.2 - 13.36 MHz
15.01 - 15.1 MHz
17.9 - 18.03 MHz
21.85 - 22 MHz
23.2 - 23.35 MHz
The most commonly heard in northeastern North America include:
New York City: 6.604, 8.933 & 10.051 MHz
North Atlantic: 4.675, 5.598, 5.616, 5.649, 6.628, 8.825, 8.864, 8.891 and 8.906 MHz
Gander, Newfoundland: 4.677 and 13.27 MHz
Shannon, Ireland: 5.505 & 8.957 MHz
Aviation communications use sideband mode, so you will need a radio with this feature to listen to these types of signals.
MARITIME
Like airplanes, ships need to switch from their short-range VHF radios to long-range shortwave radios when they're far out at sea. Ship-to-ship and ship-to-shore communications also use sideband mode, most commonly in the ranges of 4.35-4.44 MHz & 6.2-6.5 MHz. Unfortunately for the shortwave listener, a lot of maritime communication is being converted to encrypted digital transmissions which cannot be decoded by third parties.
There are also stations devoted to providing ships with information on conditions at sea, such as wave height, the presence of icebergs, storms, and other hazards, etc. These also operate in sideband mode. The most commonly heard in northeastern North America are:
Boston: 4.235, 6.3405, 9.11 & 12.757 MHz
Halifax: 4.271, 6.496, 10.536 & 13.51 MHz
Portsmouth, NH: 4.316, 4.426, 6.314, 8.43 & 8.764 MHz
These stations alternate between voice reports and FAXed maps that can be decoded using inexpensive software (my favorite application for decoding weather FAXes is MultiPSK, which is available free from DXzone.com).
Two frequencies are set aside for distress purposes: 2.182 & 4.125 MHz. I've never had the fortune to hear a distress call in person, but you may want to park your radio on one of these from time to time - you never know!
(Note from Gil: The Maritime Mobile Service Net is operational every day from 12:00pm until 9:00pm Eastern Standard Time, and from 12:00pm until 10:00pm Eastern Daylight Time, on the 20-meter Global Emergency Center Of Activity frequency of 14.300 MHz (USB) as specified by the International Radio Union.)
MILITARY
Although most military communications use encrypted digital modes these days, voice communications in the clear (again, sideband mode) are still out there. The easiest to receive in the eastern U.S. are:
CAMSLANT Chesapeake (Communications Area Master Station - Atlantic in Chesapeake, Virginia): 5.69, 5.696, 8.980 & 8.983 MHz
U.S. Global High Frequency System: 6.712, 6.739, 8.992 & 11.175 MHz
These signals (as well as maritime voice signals) require single-sideband capability.
CB & AMATEUR
CB operators (mostly truckers) use a portion of the shortwave "spectrum", from 26.965 to 27.405 MHz, for their communications. Almost all CB users utilize AM mode, so sideband capability is not necessary. The busiest frequency is 27.185 MHz, which is Channel 19.
Amateur ("ham") radio operators are major users of shortwave radio. Most talk using sideband mode, and many still use morse code (because it typically reaches farther than voice), which can be decrypted by numerous computer applications. Amateur radio operators use the following frequencies:
1.8 - 2 MHz ("160 meters")
3.5 - 4 MHz ("80 meters")
5.33 - 5.4 MHz ("60 meters")
7 - 7.3 MHz ("40 meters")
10.1 - 10.15 MHz ("30 meters")
14 - 14.35 MHz ("20 meters")
18.068 - 18.168 MHz ("17 meters")
21 - 21.45 MHz ("15 meters")
24.89 - 24.99 MHz ("12 meters")
28 - 29.7 MHz ("10 meters")
CLANDESTINE
Since shortwave equipment is easy to purchase or build, there are a number of people who use it for illicit purposes. In the western hemisphere you will frequently hear Spanish-speaking individuals carrying our personal conversations (generally sideband mode); these are often what's called "Echo Charlie" operations, and many fall in the 6.52-6.8 MHz range (typically using modified amateur radio equipment). There are also a number of "pirate" radio broadcasters on the air. Most broadcast in the 6.885-6.965 MHz range, especially around 6.925 MHz.
Various governments also utilize the shortwave spectrum for nefarius purposes. One is to jam the broadcasts of other countries' stations in an attempt to keep propaganda from reaching its intended audience. I used to frequently hear a "bubble" jammer (so called because it sounds like bubbling water) used by Cuba on 6.03 MHz used to jam the U.S.'s Radio Martí broadcasts (I don't know if they're still active on that frequency).
There are also active spy networks using shortwave radios (because the radio signals reach around the world, and the radios can be easily concealed). Most consist of "numbers" stations, broadcasting strings of numbers (typically in groups of five), often in English or Spanish. The U.S., England, Cuba and Israel are all heavy users of numbers stations. Since they are clandestine, they do not generally stick to particular frequencies or schedules (although Cuba's spies are often on quite predictable schedules!), but if you're ever perusing the dial and come across a voice (usually sideband; sometimes AM) that's simply reading a long list of numbers in groups, you've found a numbers station (they also use other formats, like morse code).
OTHER SERVICES
Numerous other services make use of the shortwave spectrum. Rutgers University's CODAR system (for measuring ocean wave height) transmits around 4.9 MHz every evening (in AM mode it beeps; in sideband mode it goes "shwoop - shwoop - shwoop"). The federal government, the Red Cross, and numerous other groups also use shortwave radios.
There is also unlicensed use of the shortwave bands. Some CB radio users operate outside their designated frequency range in order to make illicit long-distance contacts. There are also "peskies", usually speaking Spanish, who engage in CB-like conversations (typically around 6.8 - 7.0 MHz; they are so named because they originally started as, or were though to be, "pescaderos", or fishermen). The CB operators use both AM and single sideband, whereas the peskies use sideband almost exclusively.