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The L-carrier system was one of a series of carrier systems developed by AT&T for high-capacity transmission for long-distance communications. Over a period from the late 1930s to the 1970s, the system evolved in six significant phases of development, designated by Bell System engineers as L-1 through L-5, and L-5E.
The standard IEEE 802.11 protocol implementations can be modified to make them more suitable for long distance, point-to-point usage, at the risk of breaking interoperability with other Wi-Fi devices and suffering interference from transmitters located near the antenna. These approaches are used by the TIER project.
An antenna such as the one described above is usable for both local and medium-long-distance communication across a frequency range of about 1:6 . For example, an antenna for the lower portion of shortwave (say, 3–18 MHz) will be roughly 33 m (110 feet) long, with conductors spaced 1 m (3.3 feet). For the higher portion of shortwave (5–30 ...
On June 3, 1880, Bell conducted the world's first wireless telephone transmission between two buildings, some 213 meters (699 feet) apart. [2] [3] Its first practical use came in military communication systems many decades later, first for optical telegraphy.
In telecommunications, a long line is a transmission line in a long-distance communications network such as carrier systems, microwave radio relay links, geosynchronous satellite links, underground cables, aerial cables and open wire, and Submarine communications cables.
Very high power transmitters (~1 megawatt) are required for long-distance communication, so the efficiency of the antenna is an important factor. A "triatic" or "flattop" antenna, another common VLF transmitting antenna. It consists of vertical radiator wires each connected at top to parallel horizontal capacitive topload wires stretching up to ...
It is especially advantageous for long-distance communications, ... For example, most high-definition ... of silica optical fibers over four decades from ~1000 dB/km ...
Most long-distance shortwave (high frequency) radio communication – between 3 and 30 MHz – is a result of skywave propagation. Since the early 1920s amateur radio operators (or "hams"), limited to lower transmitter power than broadcast stations , have taken advantage of skywave for long-distance (or " DX ") communication.