I have been noticing a trend lately: when I tell people about my adventures in ham radio, their response is usually along the lines of, people still do that? Ham radio is not dead. It is alive and well, and you should check it out.
Why? Making a long distance international contact using just your equipment and the equipment on the other side of the radio wave is exhilarating. The ability to communicate thousands of miles with no infrastructure between your and your new friend is very freeing. You are no longer tied to the infrastructure of your power company or your internet provider.
Beginning in the late 1890’s with Marconi sending wireless signals at greater and greater distances, other experimenters began laying the foundation for amateur radio in the early 1900’s. More and more people began experimenting with spark gap transmitters, sending morse code wirelessly over long distances. Radio experimenters (paired with the sinking of the RMS Titanic) ultimately resulted in the Radio Act of 1912 to limit these experimenters to certain frequencies. And amateur radio — the original maker culture — was born.
Fast forward 100 years to present day, and you will find amateur radio has grown past spark gap transmitters and morse code. Transceivers have grown from spark gap transmitters and receivers into software-defined radio, which uses digital signal processing instead of hardware audio filters. Morse code, or CW, is no longer the only mode of communicating. Voice and various digital modes now fill the airwaves.
Voice modes are frequent on the airwaves. One of the more popular you may be aware of is frequency modulation, or FM. FM is often used by repeaters spread throughout the local area, which take in a signal and blast it back out at higher power. This allows you to use lower-powered radios and talk across farther distances. FM repeaters are usually good for at most 100 miles of communication due to the way the frequencies propagate through the air.
FM can also used for making satellite contacts. Groups of amateur radio operators such as AMSAT, launch repeaters into space on satellites. The satellite trajectory is tracked and predicted, and the repeaters can be used to communicate much farther than repeaters on land.
Amateur radio repeaters aren’t the only stations in space either, there is a full functioning ham station aboard the International Space Station. It is used not only for contact with schools but also having conversations with other amateurs here on earth. If you have the opportunity to chat with the ISS, make sure you send in for the beautiful QSL card to verify your contact. For more information, check out the ISS Fan Club.
FM isn’t the only voice mode, there is also amplitude modulation, AM, and it’s cousin, single side band, SSB. Single side band is popular for making longer distance voice contacts (due to its smaller bandwidth) and is popular in the HF range of the the spectrum.
Voice modes are fun, but I personally enjoy the digital modes. They allow me to combine 2 things that I enjoy: computers and radio. The easiest way to get started with digital modes is to use a special USB sound card to hook up the radio to the computer. This allows computer software to control the transmit receive switch, audio input and audio output. With an application like FLDigi, digital signal processing can be used to modulate and demodulate audio signals into binary data.
The advantage of digital modes over voice modes is their narrow bandwidth. Human voices are much more dynamic and take up a wider area of frequency, compared to a tone produced by a computer. This allows for more efficient radio wave propagation compared to voice modes since the RF power is more concentrated. For example, the typical bandwidth of a SSB voice signal is approximately 3kHz. PSK31 uses phase shift keying, which changes the phase of a carrier signal to represent binary bits with a bandwidth of 31.25 Hz, which is almost 100 times smaller than a voice signal.
The baud rate of PSK31 is approximately 32 bits per second, which seems impossible to use compared to today’s internet speeds. However, PSK31 is used to send a stream of characters, nothing more, and equates to approximately 50 words per minute. However there is one flaw with PSK31: no error correction.
Going to the extreme side of binary modes is JT-65, which includes a large amount of error correction making it very useful for less than ideal conditions. JT-65 is much slower compared to PSK31 and allows for the transmission of approximately 13 characters per minute. At first JT-65 may seem painfully slow, but the time passes quickly, and the minutes it takes to make an exchange allows for tension and excitement to build.
Adding to the error correction is time predictability; transmitters and receivers are synchronized around the minute mark. Transmissions start exactly 1 second after the minute and last exactly 48 seconds. Because of the precision of time required, JT-65 requires your computer to be synchronized within 1 second of the official NIST time at all times.
Getting a License
Amateur radio is the ideal hobby for experimenters, whether you want to build your own equipment, experiment with different modes, or just chat to someone. The good news is, it isn’t hard to get started. I first became interested in amateur radio from a neighbor that lived across the street from me in middle school. I bought a scanner from him and used it to listen, but the requirement for learning morse code to get a ham license scared me away. The morse code requirement has been dropped from the licensing process, making the test much less intimidating.
There are 3 stages of licensing in the US: Technician, General and Extra.
- The technician license is a 35 question-multiple choice written exam and allows for usage of all VHF and UHF amateur bands with limited operations of HF. This is ideal for local communication on FM repeaters.
- The general license builds upon the technicians license and is also a 35-question multiple choice written exam. It allows for all VHF and UHF amateur bands and opens up the HF frequencies for use. It is a large step up in privileges and allows for cross-country and world-wide communications.
- The extra license builds upon the general license and requires a passing grade on a 50-question multiple choice written examination. This opens up all the amateur bands for use and allows you to branch out into the edges of the amateur bands, which are less crowded.
Ham radio is a limitless hobby and opens up a world of communication. I urge you to learn more, find an exam session, get licensed, and get on the air. I hope to see you on the air soon.