Editing Transmitter (section)

==Description== 
[[File:Signal processing system.png|thumb|upright=1.5|A radio transmitter is usually part of a [[radio communication]] system which uses [[electromagnetic wave]]s ([[radio wave]]s) to transport information (in this case sound) over a distance.]]

A transmitter can be a separate piece of electronic equipment, or an [[Electrical network|electrical circuit]] within another electronic device.  A transmitter and a [[Radio receiver|receiver]] combined in one unit is called a [[transceiver]].  The purpose of most transmitters is [[radio communication]] of information over a distance. The information is provided to the transmitter in the form of an electronic signal called the modulation signal, such as an [[audio signal|audio]] (sound) signal from a microphone, a [[Video signal|video]] (TV) signal from a video camera, or in [[wireless networking]] devices, a [[Digital signal (electronics)|digital signal]] from a computer. The transmitter generates a [[radio frequency]] signal which when applied to the antenna produces the radio waves, called the [[carrier signal]].  It combines the carrier with the modulation signal, a process called [[modulation]]. The information can be added to the carrier in several different ways, in different types of transmitters. In an [[amplitude modulation]] (AM) transmitter, the information is added to the radio signal by varying its [[amplitude]]. In a [[frequency modulation]] (FM) transmitter, it is added by varying the radio signal's [[frequency]] slightly. Many other types of modulation are also used.

The radio signal from the transmitter is applied to the [[antenna (radio)|antenna]], which radiates the energy as radio waves. The antenna may be enclosed inside the case or attached to the outside of the transmitter, as in portable devices such as cell phones, walkie-talkies, and [[garage door opener]]s. In more powerful transmitters, the antenna may be located on top of a building or on a separate tower, and connected to the transmitter by a [[feed line]], that is a [[transmission line]].

{{multiple image
| align = center
| header = Radio transmitters
| image1   = Transmisor de bulbos AM Elcom Bauer 701 B XEQK.jpg
| caption1 = Elcom Bauer model 701B 1100 watt AM broadcast transmitter
| width1   = 100
| image2   = KWNR Continental 816R-5B SN 247.jpg
| caption2 = 35&nbsp;kW, Continental 816R-5B FM transmitter, belonging to American FM radio station KWNR broadcasting on 95.5&nbsp;MHz in Las Vegas 
| width2   = 197
| image3   = Icom IC-746PRO.jpg
| caption3   = Modern [[amateur radio]] [[transceiver]], the ICOM IC-746PRO. It can transmit on the amateur bands from 1.8&nbsp;MHz to 144&nbsp;MHz with an output power of 100&nbsp;W
| width3 =  270
| image4   = CB-Funkgerät im LKW.JPG
| caption4 = A [[citizens band radio|CB radio]] transceiver in a truck, a [[two way radio]] transmitting on 27&nbsp;MHz with a power of 4&nbsp;W, that can be operated without a license
| width4   = 170
| image5   =
| caption5 = Emergency Locator Beacon transmitter carried on ships. If the ship sinks, the beacon broadcasts a distress radio signal on 406&nbsp;MHz which is picked up by a Search and Rescue satellite to find the ship. 
| width5   = 125
}}
{{multiple image
| align = center
| header = Consumer products that contain transmitters
| image1   = HA0478-006 (6011470974).jpg
| caption1 = A cellphone has several transmitters: a duplex cell transceiver, a Wi-Fi modem, and a Bluetooth modem. 
| width1   = 120
| image2   = Cordless phone icon.svg
| caption2 = Both the handset and the base of a [[cordless phone]] contain low power 2.4&nbsp;GHz radio transmitters to communicate with each other.
| width2   = 98
| image3   = Garage-door-opener-remote-control.png
| caption3  = A [[garage door opener]] control contains a low-power 2.4&nbsp;GHz transmitter that sends coded commands to the garage door mechanism to open or close.
| width3 = 122
| width4   = 130
| image5   = Wireless network.jpg
| caption5 = A [[laptop computer]] and home [[wireless router]] (background) which connects it to the Internet, creating a home Wi-Fi network.  Both have Wi-Fi [[wireless network interface controller|modems]], automated microwave transmitters and receivers operating on 2.4&nbsp;GHz which exchange data packets with the [[internet service provider]] (ISP). 
| width5   = 175
| image6   = Plantronics Voyager Legend.JPG
| caption6 = A [[Bluetooth]] earbud with microphone. It has a Bluetooth modem to exchange audio with a cell phone
| width6   = 230
}}