30-03-2011, 10:47 AM
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ADVANCED COMMUNICATION TRENDS SATELLITE PHONE
ABSTRACT
Many times people have to travel to remote areas or places where service is simply not available for their cell phone. The service systems which don’t run into this problem and can always count on having communication service any where at all time is providence.
Types of communication systems:
Wired
Wireless
An advanced wireless communication system includes the following types;
Satellite communication
Mobile communication
What makes it superior?
Differences between ordinary communication and the satellite phone communication is it involves the other towers for the sake of the communication if they are not available the network fails but as the satellite phones does not have no intermediate towers so communication page link rarely get breaked.
TYPES OF SATELLITE PHONE SYSTEMS:
Globalstar
Inmarsat
Iridium
Thuraya
INMARSAT: It was the first mobile satellite system conceptualized and brought to reality. Inmarset uses four geo-stationary satellites set at different locations over the equator.
IRIDIUM: Iridium uses 66 satellites that orbit the earth on six different planes. Each individual Iridium satellite is able to orbit the earth once every 100 minutes. This arrangement allows Iridium to make sure that any Iridium handset can receive and make satellite phone calls from anywhere on the planet.
GLOBALSTAR: This satellite service plans were specifically designed to meet the needs of those who travel extensively. Consequently, they designed a phone that is a compact, tri-band handset that is able to operate on both the cellular CDMA and AMPS networks as well as the Globalstar network that consists of 48 low earth orbiting satellites
THURAYA: It allows us to switch between the satellite system and the GSM system. The Thuraya service can roam on the local cellular network by replacing the Thuraya SIM card with a local prepaid SIM card. On the local network you are charged the local rates and not the Thuraya roaming rates. Thuraya satellite phones are capable of Internet connectivity, and data is available at no extra charge. Thuraya covers entire Europe and then Middle East, parts of India, Asia, and Africa.
It sends signals directly to a satellite . When you turn on your satellite phone the signal goes up to any number of satellites in a compatible constellation where it is then registered with the constellation.
Those signals are then sent back to earth to a station. The Gateway(earth station) processes and takes care of the switching of the calls rather than the satellite network. This station then directs the call to the Public Switched Telephone Network (PSTN) or to a cellular network. If you are calling from a cell or wired phone to a satellite phone, the system works in reverse.
The signal goes up to the satellite, down to earth, back up to a satellite and then back down to earth again.
Frequency specification of a satellite phone is 626.5 to 1660.5 Mhz for transmitter and 1525.0 to 1559.0 MHz for receiver.
ADVANTAGES:
This system covers the entire globe.
Tracking the data transmitted is impossible.
This communication does not relay on land line systems.
Towers on the Earth are not required.
APPLICATIONS:
It is highly useful in rescue operations at the times of disasters.
It is also used by the deep sea vessels for communication.
The phones are mostly used by the confidential system of any nation.
DISADVANTAGES
DELAY: The signal must first travel to the satellite, then to an earthbound gateway before being routed to the receiver. The receiver's response will follow the same path in reverse, taking equally long to reach the caller.
BANDWIDTH: Some satellite phones use a narrow band, sending along our audio signal, but they cannot handle the high bandwidth information at near the speeds we find at home.
AFFORDABILITY: The cost at which the service is being provided is high.
CONCLUSION:
However, these drawbacks are irrelevant when considering the function that a satellite phone serves. It can create a page link to civilization from places where no other page link is available. It also allows loved ones to stay in touch, as in the case of researchers, adventurers and those in the military, and it can provide backup communication in disasters when cellular towers or landlines might not be functional.