User:Anonym1ty/Testbed

20 Meters
Between 14.000 MHz to 14.350 MHz, the 20 meter amateur radio band is one of the premier Amateur radio High Frequency or "HF" bands and is considered one of the most popular band for long distance and intercontinental communication.

Methods of Communication
Radio amateurs use a variety of modes of transmission to communicate with one another, all based on three basic means of communication phone (voice); image; and data.

Phone
In the terms of Amateur radio, phone simply means to modulate a signal with sound and is usually applied to voice communications. Common forms of phone modulation include Amplitude Modulation (AM); Single Sideband (SSB); and Frequency Modulation (FM).

Image
Amateur radio operators send images over radio using standard television, called Fast Scan Television (FSTV); by Slow Scan Television (SSTV) which is similar to a slide show of still images; or by Facsimile (FAX).

Data
Various means of sending data over radio have been devised, the first being Interrupted Continuous Wave (ICW) or commonly just CW where an unmodulated signal is sent and keyed on or off, most commonly this radio telegraphy is sent in Morse Code. Most other forms of data are sent and decoded using computers or dedicated devices such as Radio Teletype (RTTY), Packet Radio, Phased-Shift Keying (PSK). Most commonly digital signals are used to encode text based data however any type of data may be sent.

Bandwidth
The amount of radio spectrum needed to send any given signal is directly proportional to the amount of information the signal is encoding. A simple keyed carrier in Morse code may require as little as 50 Hz of bandwidth whereas a fast scan television signal may require as much as 6 MHz.

Means of Signal Propagation
Amateur radio operators employ various means to get their signals from one point to another.

Direct Line of Sight
The simplest form of propagation is direct line of site. Radio waves travel much as light does and line of sight communications refers to a direct path of communication. Line of sight communications are limited by the surrounding terrain and by the curvature of the Earth.

Signal Refraction
Ionization of the upper atmosphere can refract a signal back towards the Earth. This method is the most common employed by hams for world wide communication.

Signal Reflection
Radio waves can be reflected off of some surfaces which may include buildings; airplanes; mountains; moisture; thermal layers of the atmosphere; an aurora; the Earth; or even the Moon.

Signal Repeating
To help extend range, signals can be received by a station and retransmitted automatically. Such a device is simply called a repeater. Repeaters are usually located on the top of a mountain; a tall building or they may also be installed on satellites to enable communication over a very large area.

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Timeline
Around 1978, group of amateur radio operators in British Columbia, Canada began experimenting with Packet radio using a Terminal node controller (TNC) developed by Doug Lockhart, VE7APU.

The IP address allocation was obtained by Hank Magnuski, KA6M in the late 1970s.

After the Federal Communications Commission approved the transmission of ASCII for Amateur radio in the United States in 1980, Magnuski, put up a digipeater near San Francisco on 2 meters using a TNC that he had developed.

Many groups of amateur radio operators interested Packet radio soon formed throughout the country including the Pacific Packet Radio Society (PPRS) in California, the Tucson Amateur Packet Radio Corporation (TAPR) in Arizona and the Amateur Radio Research and Development Corporation (AMRAD) in Washington, DC.

By 1983, TAPR was offering the first TNC was available in kit form.

Packet radio started becoming more and more popular across North America and by 1984 the first packet based Bulletin board systems began to appear.