Contents
Amateur Radio Fundamentals
How Amateur Radio Works
Types of Amateur Radio
How to Get an Amateur Radio License
Amateur Radio Equipment
How to Set Up a Radio Shack
How to Get on the Air
Amateur Radio Clubs and Activities
Amateur Radio Codes, Abbreviations, and Lingo
FCC Rules and Regulations
Morse Code
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Types of Amateur Radio
The first step toward getting started in amateur radio is deciding which type you’d like to pursue. The most popular types are described below.
AM, FM, and Single Sideband Radio
AM, FM, and single sideband radio are three types of amateur radio used exclusively to transmit and receive audio content, such as voice or music.
Amplitude Modulation (AM) Radio
Modulation is the process of varying key aspects of waves, such as amplitude or frequency, in order to embed waves with information. In amplitude modulation (AM), only the wave’s amplitude—the distance between the base of the wave and its highest point—is modulated. AM radio is one of the oldest types of amateur radio communication, though it’s been mostly replaced by FM due to its susceptibility to static interference.
- How AM works: In a process known as double sideband transmission, the transceiver sends out two signals (called sidebands) simultaneously. One signal, the carrier wave, serves as a benchmark for the second signal (called the modulating signal), which modulates the amplitude of the original carrier. Radio transceivers interpret the contrasts between the waves as data in the form of 1s and 0s. (The carrier wave is often called the RF carrier—for “radio frequency” carrier, or the carrier for short.)
- Main band: Amateur AM radio uses HF bands. Commercial broadcast AM radio uses the same propagation method as amateur AM radio but operates on MF bands.
Frequency Modulation (FM) Radio
In frequency modulation (FM), only the wave’s frequency is modulated. FM signals have a considerably higher bandwidth than AM signals. Bandwidth refers to the range of frequencies in which a type of radio, such as AM or FM, can operate—the higher the bandwidth, the higher the capacity of the radio waves for transmitting data, video, and so on.
The relatively high bandwidth of FM radio makes FM signals well suited to carrying complex audio content, such as music, which requires a greater bandwidth to transmit than, say, voice over AM radio. FM signals are also much more resistant to static and noise interference than AM signals. These advantages have made FM popular not just for transmitting music—FM is also the most popular type of amateur radio for voice communication on VHF bands.
- How FM works: The modulating signal modulates the frequency, rather than the amplitude, of the carrier.
- Main band: VHF
Single Sideband (SSB) Radio
Single sideband (SSB) is the most popular type of radio for voice communication on HF bands.
- How FM works: Single sideband transceivers generate waves that merge the carrier and the modulating signal so that only one sideband is transmitted. This technology makes SSB radio more energy-efficient and less noisy than AM. Since SSD lacks the bandwidth and frequency modulation capacity of FM, it’s used to transmit voice, not music.
- Main band: HF
Continuous Wave Radio (CW)
Continuous wave radio (CW) is one of the oldest and most reliable methods of amateur radio communication. It’s particularly useful in emergency situations, such as natural disasters that involve bad weather, because CW signals can be received more clearly over great distances with minimal interference.
- How CW works: CW transceivers emit a wave with a fixed amplitude and frequency—no modulation occurs. The operator turns the signal on or off to convey information in code. The most popular form of CW communication is Morse code, in which the radio operator turns an audible tone on and off in various sequences that the listener at the other end can interpret as letters, numbers, or punctuation.
- Main bands: HF, VHF
Packet Radio
Packet radio is used to transmit computer data wirelessly from one radio transceiver to another. The data is sent in packets, or small clusters, of information.
- How packet radio works: Packet radio uses a technique called audio frequency-shift keying (AFSK), in which an audio signal switching between two tones is fed into the microphone input of a radio transceiver. The two tones—mark, which represents the number 1, and space, which represents 0—are transmitted in specific five-tone patterns that represent the different letters of the alphabet. These five-tone patterns are collectively referred to as the Baudot code.
- Main bands: HF, microwave
Radio Teletype (RTTY)
Radio teletype (RTTY) is a form of amateur transmission used to communicate text messages between two teletypewriters, which are printers designed to print out messages transmitted via radio. RTTY has very slow transfer rates but is very resistant to interference. This makes RTTY ideal for use at sea, where it’s used to transmit weather forecasts and related information. These days, amateur radio operators usually use transceivers instead of actual teletypewriters to exchange RTTY communications.
- How RTTY works: Similar to packet radio, RTTY uses AFSK and Baudot code to transmit data.
- Main band: HF
Satellite Radio
Satellite radio transmits radio signals via satellites orbiting the earth. It’s used primarily for long-distance communications and for making contact with vehicles in space, such as the space shuttle and the International Space Station (ISS).
- How it works: Radio waves that pass through the ionosphere are received and retransmitted by an OSCAR satellite. OSCAR stands for orbiting satellite carrying amateur radio. Satellite radio allows for communication over greater distances than other forms of amateur radio.
- Main bands: UHF, microwave
Slow-Scan Television (SSTV)
Hams use slow-scan television (SSTV) to transmit still images.
- How SSTV works: Hams use special software that allows a computer sound card to convert digital images into audio tones. These tones are then transmitted by a radio transceiver, received by another transceiver, and then converted back to images by software and the sound card in the receiving ham’s computer.
- Main bands: HF, UHF, microwave
Amateur Television (ATV)
Hams use amateur televsion (ATV) to transmit videos. Only subject matter of public interest is allowed, such as coverage of community activities and weather events. Commercial broadcasting and music videos are not permitted.
- How it works: Hams use a special ATV-ready transciever to transmit video and audio signals on UHF bands. Receiving hams must use a frequency converter, a device that transfers the amateur band signal to a higher UHF band, in order to view the video and hear its accompanying audio on a standard TV. Hams can also view local ATV transmissions by using a cable-ready TV tuned to channels 57–60.
- Main bands: UHF, microwave
What Type of Radio Suits You Best?
Most beginners start with one of the two most popular types of amateur radio used to transmit two-way voice communication—FM or SSB. Nearly all entry-level transceivers will allow you to do FM and SSB (for info on which gear to buy, see Amateur Radio Equipment).
If you’d like to . . . |
Try . . . |
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Speak with other hams |
SSB or FM radio |
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Explore the origins of
amateur radio technology |
Continuous-wave radio or radio teletype |
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Exchange computer data |
Packet radio |
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Speak with other hams over very long distances |
Satellite radio |
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Exchange still images |
Slow-scan television |
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Exchange video |
Amateur televsion |
| Acknowledgments & Disclaimer |
