hope all of u r fine and good health, today i get u some technical infromation about IRIDIUM system for who is interesting.
i think that it will be very interesting for most engineers.
Jazakom allah 7ayren
What is IRIDIUM ?
The Iridium satellite constellation is a system of 66 active communication satellites and spares around the earth.The system was originally to have 77 active satellites, and was named for the element iridium, which has atomic number 77. Iridium allows worldwide voice and data communications using handheld devices.
The Iridium Satellite System is the only provider of truly global, truly mobile satellite voice and data solutions with complete coverage of the Earth (including oceans, airways and Polar regions). Through a constellation of 66 low-earth orbiting (LEO) satellites operated by Boeing, Iridium delivers essential communications services to and from remote areas where terrestrial communications are not available.
The system will employ 15-20 ground station with a master control complex in lands down.
How the system work ?
When an Iridium telephone is activated, the nearest satellite in conjunction with the IRIDIUM network automatically will determine account validity and the location of the user.
The subscriber will select amoung cellular or satellite transmission
alternatives depend on compatibility and system availability, to dispatch a call.
If the subscribers local cellular system is unavailable, the telephone will communicate directly with a satellite overhead. The call then will be transferred from satellite through the network to its designation, either another IRIDIUM telephone or an IRIDIUM ground station.
IRIDIUM system getaways interconnect the satellite network with land-based fixed or wireless infrastructures worldwide.
The current growth of cellular services and the market outlook for broader personal communications point to a strong demand for IRIDIUM services. By year 2000, the number of cellular subscribers worldwide is expected to reach 294 million, along with 202 million paging subscribers. Iridium LLC anticipates servicing 650,000 voice subscribers and 350,000 paging subscribers worldwide, representing less than a quarter of one percent of those markets.
Plans for the IRIDIUM network call for the first satellite to be launched in 1996, with commercial service commencing in late 1998. in january 1995, the U.S federal communications commission awarded Motorola a license to construct, launch, and operate the IRIDIUM system. Iridium LLC and its investors now are negotiating agreements with regulators and service providers worldwide. Construction of the space system already is well underway as part of a
$ 3.37 billion contract with Motorolas satellite Communications Group. Lockhead Martin corporation is building the satellite buses, which will be shipped to Motorolas facility in chandler, arizona for the integration of communications hardware and other components.
Raytheon company has designed the phased array antenna for communication between ground stations and IRIDIUM telephones. Beehtel, Scientific-atlanta, Com Dev , Siemens, and Nuova Telepazio are also providingkey elements of the system.
McDonnel Douglas Corporation, Khrunichev State research and production space center, and china wall industry Corporation will provide launch services.
IRIDIUM SYSTEM FACTS :-
ORBITAL PLANES 6
ORBIT HEIGHT 780 kilometers (421.5 nautical miles)
INCLINATION OF ORBITAL PLANES 86.4 degrees
ORBITAL PERIOD 100 minutes, 28 seconds
SATELLITE WEIGHT 689 kilograms
SPOT BEAMS 48 per satellite
LINK MARGIN 16 decibels (average)
LIFE TIME 5-8 years
TELEPHONE AND MESSAGING 1616-1626.5 MHZ, L-Band
INTERSATELLITE LINKS 23.18-23.38 GHZ, Ka-Band
GROUND SEGMENT LINKS
Downlinks 19.4-19.6 GHZ, Ka-Band
Uplinks 29.1-29.3 GHZ, Ka-Band
GATEWAY TO INTERNATIONAL
SWITCHING CENTER PCM transmission and SS7-ISUP or MFCR2
IRIDIUM TELEPHONE Frequency Division/Time Division (FDMA/TDMA) Quadrature phase shift keying (QPSK)
DIGITAL VOICE, FAX, AND DATA 2.4 kilobits per second
McDonnell DOUGLAS (DELTA 2) Five IRIDIUM satellite per launch
KHRUNICHEV (PROTON) Seven IRIDIUM satellite per launch
CHINA GREAT WALL ( LONG Two IRIDIUM satellite per launch
IRIDIUM APPLICATION: -
IRIDIUM SATELLITE :-
With 66 satellite forming across linked grid above the earth, the iridium system is the first low earth orbit (LEO) system for wireless telephone service. Only 780 k.m (450 miles) high, these satellites work different from those at a much higher orbit 36000 k.m in two major ways :-
(1) They are close enough to receive the signals of a handheld device.
(2) They act like cellular towers in the sky where wireless signals can move overhead instead of through ground-based cells.
IRIDIUM PHONE :-
The iridium phone is the primary means by which callers will communicate directly through the iridium network. One telephone number, through the use of a mini personal subscriber identity module (SIM), keeps a subscriber connected.
IRIDIUM PAGER :-
Pocket-sized iridium pagers are capable of receiving alphanumeric messages. For worldwide applicability, the message display will feature an international character set. An off-the-shelf disposable battery will provide an average lifetime of one month.
IRIDIUM GATEWAY :-
Iridium gateways interconnect the iridium constellation with public switched telephone network (PSTN), making communication possible between iridium phones and any other telephone in the world.
This figure shows an Overview for the IRIDIUM system gateways, Iridium telephone, Iridium pager, Iridium satellite, and PSTN.
Prepared By :
Eng. Mohamed Kamal
Smart Card Technology Dept.
Cleopatra Silicon Valley
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Thursday, April 5, 2007