Cell ph unitary is actually a radio receiver -- an extremely sophisticated radio, but a radio n iodinetheless. The tele skirt was invented by Alexander Graham Bell in 1876, and wireless communion can trace its roots to the invention of the radio by Nikolai Tesla in the 1880s (formally presented in 1894 by a five-year-old Italian named Guglielmo Marconi). twain combined is a cubicle remember
Full-duplex vs. half-duplex - both(prenominal) walkie-talkies and CB radios are half-duplex devices. That is, two people communicating on a CB radio use the same frequency, so only one person can talk at a time. A cell phone is a wide-duplex device. That means that you use one frequency for talking and a second, separate frequency for listening. Both people on the call can talk at once.
Channels - A walkie-talkie classifiablely has one channel, and a CB radio has 40 channels. A typical cell phone can communicate on 1,664 channels or more!
Range - A walkie-talkie can transmit near 1 mile (1.6 km) using a 0.25-watt transmitter. A CB radio, because it has much(prenominal) higher power, can transmit about 5 miles (8 km) using a 5-watt transmitter. Cell phones operate within cells, and they can trade cells as they move around. Someone using a cell phone can drive hundreds of miles and maintain a converse the entire time because of the cellular approach.
In a typical analog cell-phone system in the United States, the cell-phone carrier receives about 800 frequencies to use across the city. The carrier chops up the city into cells. individually cell is typically sized at about 10 square miles.
? A cell-phone carrier typically gets 832 radio frequencies to use in a city.
? severally cell phone uses two frequencies per call -- a duplex channel -- so there are typically 395 voice channels per carrier.
? Each cell has about 56 voice channels open (56 talking people).
? The transmissions of a base station
and the phones within its cell do not
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