Archive for the ‘
Technical Info ’ Category
Monday, July 14th, 2008
Digital Advanced Mobile Phone System
D-AMPS is designed to be compatible with the older analog AMPS technology, which is widely deployed in the U.S. TDMA is used as an enhancement to the AMPS network by the use of dual band AMPS / TDMA (or D-AMPS) phones. Use of these phones gives the widespread coverage of the AMPS networks along with some advantages of digital systems in areas where TDMA networks are available.
Thursday, July 10th, 2008
Global System for Mobile Communications
The GSM network was developed in response to a need for a system, which could be used all over Europe and would allow its users to receive and make calls from a number which was not attributable to any geographical area. The GSM system was designed to also enable the customer to be billed by just one operator and pay for only one line rental.
GSM is the most widespread mobile system and is now used by more than 50% of the phones worldwide, which was largely as a result of early standardisation by the European authorities. It is available in over 170 countries, although there are now four different frequencies upon which it operates; 450, 900, 1800 and 1900MHz.
Monday, July 7th, 2008
Code Division Multiple Access
CDMA sends every signal at once, but encodes each one differently so that they can be separated by receivers. Developed by Qualcomm Inc. and is characterised by high capacity and small cell radius. It was adopted by the Telecommunications Industry Association (TIA) in 1993. The first CDMA based networks are now operational.
Monday, July 7th, 2008
Time Division Multiple Access
Most present-day digital systems, including the European GSM standard, rely on TDMA. To American consumers, the name TDMA has come to mean the digital version of AMPS, but to engineers this is just one of many TDMA systems. It is also used by the Japanese PDC (Personal Digital Cellular), the world’s second most popular cellphone standard.
Monday, July 7th, 2008
Korea has a very advanced mobile phone network system, which has much higher data transfer rates [144kbps] than Europe or North America.
Their mobile phone technology is also reported to be some 3-5 years ahead and the third generation of phones is in widespread usage. For this reason their technology is totally incompatible with other older technology used in Europe, North America and other parts of the world and therefore it is necessary to hire a mobile phone for use there.
Monday, July 7th, 2008
The systems used for mobile phone communication in Japan, are completely different to those, used in other parts of the world and therefore, your handset, regardless of whether it has tri-band capabilities or not, will be incompatible with the Japanese networks.
The original system in Japan was the J-TACS analogue system, which operated at 25MHz, but it has now developed a digital system based on the D-AMPS technology that was designed for use at 30MHz. The new system is now known as Personal Digital Cellular, [PDC], or Japanese Digital Cellular, [JDC] and has become the second most popular mobile system, the first being the GSM network.
Monday, July 7th, 2008
The Iridium system works by the handset sending a signal to one of several satellites, which orbit the Earth. There are 66 Iridium satellites in 6 different polar orbits, and one complete orbit of the Earth takes 100 minutes, since they travel at 16,832 miles per hour.
Each satellite has a link with four others, two of which are in the same orbit and two of which are in adjacent orbits. At any one time there will be a minimum of two satellites in contact with the handset.
The system works by transferring the call to other satellites as the satellite with the initial contact moves out of contact with the handset. The signal is then re-bounced back to one of the base stations on Earth and then transferred to a land-line to its’ final destination.
Iridium hire package
Monday, July 7th, 2008
In the USA there are several different types of mobile phone networks available. The Advanced Mobile Phone System, [AMPS], which may also be known as Analogue Mobile Phone System or American Mobile Phone System. This is an analogue network, which operates at 800MHz.
The Time Division Multiple Access, [TDMA], is a digital network that also works at 800MHz, but has less coverage than AMPS.
In the USA the TDMA system is used in conjunction with the more widespread AMPS network to offer a service which uses the benefits of both networks. By using dual band mobile phones known as D-AMPS, the user has the benefits of the digital system when available, but also has the advantage of a good coverage area by being able to operate on the AMPS network.
There is also GSM 1900 coverage in parts of North America, however coverage is restricted, so we advise that you contact your GSM Service Provider to ensure that GSM 1900 service is available in the areas you intend to visit.
Monday, July 7th, 2008
The Caribbean is another area of the world, which is not covered by the GSM mobile phone network. Instead it uses the D-AMPS network, working at 800MHz. This network makes use of a dual band mobile phone, which is compatible, with digital and analogue systems. Therefore, if you are travelling to the Caribbean from Europe, you will need a Caribbean compatible mobile phone, which is different to those available in Europe.
Initially mobile phone coverage in the Caribbean concentrated around the main islands eg. Barbados, but it has recently been expanded to cover the majority of the smaller islands too.
If you are travelling from North America and have a phone, which is compatible with the 800MHz AMPS, or TDMA network, (i.e. a D-AMPS phone), then it is possible that you may be able to continue using the phone. This is providing that a roaming agreement has been set-up with your service provider in North America and the Caribbean networks.
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