Shortwave (SWL)

Let’s talk about shortwave radio for a bit. Shortwave communications take place in the High Frequency (HF) bands from about 1.9 Megahertz (MHz) to roughly 30 MHz. This particular band really starts at the top of the regular AM band that runs from 590-1700 or so KHz.

HF has a very unique property that Ultrahigh Frequencies (UHF), Very High Frequencies (VHF) and the bands above UHF do not have. That is something called ionospheric propagation. If you’re familiar with Citizen’s Band (CB) then you might have heard the term “skip” or “skip conditions”. Basically, this is what happens when the ionosphere, a layer of rarified atmosphere at the highest altitudes becomes excited by solar radiation. These various layers of the ionosphere become like mirrors at radio frequencies (RF) and will reflect (more accurately, refract) back to the surface of the Earth at some distant location. When a station is heard via this method, we call it DX listening. DX stands for distance.

Shortwave stations are all over the world, in most countries, in almost every language of the world. Most stations are directed “somewhere”, that is stations tend to aim their signals at someone in another country for news, views or propaganda. They also carry a lot of news, and are a really great place to hear others’ views, even if you disagree (which you most likely will). Shortwave stations carry a lot of religion too.

The main reason for listening to shortwave in my opinion is to hear what is happening elsewhere in the world, since often you won’t hear from other countries on the local news stations. Even with cable and satellite television sometimes you will hear things you won’t hear even on the major cable news networks.

Shortwave bands also contain all of the amateur radio bands, so you might consider a shortwave radio first, if you’re interested in ham radio. You can listen in to many hams, but you will need a shortwave radio capable of tuning in Single Side band intelligence (SSB). This type of radio will let you hear CW or morse code signals as well (something else you can learn from the shortwave radio).

Antennas for HF shortwave are rather long, and I’ll cover antennas for shortwave and HF radios in another article at a later time, since there’s a lot of math involved. Ok, some math, nothing too difficult for someone who can do addition, subtraction, multiplication and division… with an occasional square root, and or sine and cosine thrown in for good measure.

In an emergency, a shortwave radio almost always has the AM band on it as well. This will usually give you local and regional news, especially if there is some kind of real, declared emergency. The ENS or Emergency Notification System will notify you with some tones and data packets, and then announcements will come through by voice warning of anything from tornadoes, to flash floods to nuclear war.

By the way, an AM radio’s frequencies are also susceptible to ionospheric propagation (or skip) especially at night time. Some night try tuning around the AM radio band and you will hear stations that might be hundreds or even thousands of miles distant from you. AM DX listening is a hobby onto itself.

What kind of shortwave radio should you get? Well, depends on two things. What do you want to listen to, and how nice of a radio do you want?

In the first case, decide if you want it for just causal listening, and pick out one of the radios with a built in battery pack and a hand cranked dynamo (generator). Many of these types can be found in hardware stores now, Radio Shack I believe still has a model and Baygen Radio (found on the net) has several models as well. Get one that is within your budget if you want to just listen in.

If you’re going to be more than a casual listener, I’d look into a bit more expensive desk model, whether you get an older “slide rule dial” (used probably) or a newer digitally tuned radio is really a matter of preference. Personally, I prefer the older radios with band-spread tuning dials, perhaps vacuum tubes or older solid state design, which will perhaps even run from direct current (DC – batteries) as well as alternating current (AC – wall current).

If you would like to try listening to a shortwave radio without buying one, try this link:

http://www.chilton.com/scripts/radio/R8-receiver

The site, called “The Listening Post” has a web-controlled shortwave receiver you can change frequencies on, and listen in. If you look up a station ahead of time, say the BBC, you can tune to one of their frequencies and perhaps listen in for a few moments. At least you will see what it sounds like.

This link: http://www.chilton.com/radio/others.html from the same site has a list of other internet controllable radios that you can try on various frequencies. This will give you a chance to try some of them out.

Shortwave radios do not require any sort of licensing to operate, as they are receivers only. Also, you can hear a lot of other things I haven’t yet listed, like military radios, aircraft, weather systems – both automated and live voice, as well as many sorts of signal types like facsimile (fax), radio teletype (RTTY), morse code (CW), single side band signals and many others. Some will require external devices connected to computers to copy, like fax, tty signals and weather data, but many times you can build inexpensive adaptive devices to collect the audio, feed to a computer sound card and then use a computer program to decode.

This is especially useful if you’re trying to listen to morse code and just don’t know it. You can download programs which will control your sound card in your computer, feed it the audio from the shortwave and then have the computer decode the signals. Most programs are free or shareware, and many will have instructions on putting together simple electronic interface devices to connect between the PC and the SW. Radio Shack is a good source for parts if there are no other electronics supply places in your area.

That’s all for now.

Stay tuned, more to follow.