Within the wireless spectrum there are several different type of wireless communications including satellite, Microwave Signals, Radio frequency, and Infrared Systems. Below is a table comparing the properties of these four signals such as cost and speed of data transmission.
|Type||Frequency Range||Cost||Installation difficulty||Attenuation||Communication range||Interference and capture|
|Satellite Transmission||4 GHz to 40 GHz||Hundreds of millions||Difficult||Variable||Up to 10 MBPS||Low|
|Microwave Signals||11 GHz to 14 GHz||Millions depending on the system||Difficult||Variable||Up to 10 MBPS||Low|
|Radio frequency||Up to 6 MBPS||Variable||Simple||High||Up to 10 MBPS||Moderate|
|Infrared||Up to 16 MBPS||Variable||Simple||Low||Up to 16 MBPS||High|
(*Data in graph according to Wireless Technology Used in WANs chapter 18, University of Phoenix reading.)
Satellite transmission has given the ability to cover large areas with data and voice transmission almost anywhere around the globe. Satellite communications require a transmission station, satellite, and a receiving station to complete their ring. Companies such as Sprint Nextel use satellite communications to set up both cellular communications and wide area networks to assist with natural disasters or major events. Satellites used for communications are placed in a geo orbits which allows a transmission station to be able to lock onto the satellite with little hassle and use the signal spectrum between 4 GHz and 40 GHz.
Another type of wireless signal is Microwave Signals and is used to transmit data, voice, and video in a digital format. Microwave communications can be costly due to the install but can be cheaper than laying fiber optic or copper cable and is often more secure. To be able to implement a microwave communication system both the transmitting and receiving stations but have a digital modem to communicate with the digital interface, a RF unit for conversion of the signal to a microwave signal, and a antenna to transmit and or receive. Microwave signal are between the 11 GHz and 14 GHz range and provide companies such as Oklahoma Gas & Electric the ability to communicate with substations located throughout Oklahoma at a cheaper cost than laying wire between the stations.
Radio frequency is another very common form of wireless communications and is used in almost everyone’s daily activities regardless if it is known or not. Radio frequency is located between 10 KHz and 1 GHz range and can provide up to a 10 MB transfer rate at the low end of the spectrum. HAM radio operators can use radio transmissions to communicate with the space shuttle while in orbit and companies such as NASA use RF to communicate with their employee’s over long distances via video chat. To be able to use most radio frequencies you must be licensed by the FCC to ensure that you do not interfere with another RF transmission.
The last type of wireless communication that we will be discussing is Infrared Systems which again are part of almost everyone’s daily life with such things as remotes for your TV. Infrared Systems can transmit data between the 100 GHz–1000 THz range at speeds ranging from 1 MBPS with omnidirectional and 16 MBPS with directional communications. The US Navy is looking into using IR communications to communicate between ships in a battle group without the need to encrypt the data due to the limited range of 25 meters with a low power system and up to 1000 meters with a high power transmission. IR transmission systems are already used to communicate between stations within factories and between devices such as cell phones or computers.
M. Gray, 2009 Personal Experience
Sprint Nextel ERT http://shop.sprint.com/assets/pdfs/en/solutions/case_studies/emergency_response_top_deployments.pdf