“There will be one mast per ‘cell’, which is the maximum area in which the mast can pick up a mobile signal”
TECHNOLOGY
How mobile calls work The tech behind making phone calls Our mobiles are portable gaming consoles, computers, alarm clocks and personal assistants all in one, but they’re still pretty useful for calling someone without being tethered by a cord. Unlike land lines, mobile phones work by sending electric signals via radio waves to mobile phone towers or masts. These masts pick up the signal, transmitting it along a network of masts until they reach the closest one to the phone receiving the call. Once there, the radio waves are finally beamed to the target phone and converted back into electronic signals and then into sound waves that enter the recipient’s ear. Mobile phone masts are placed several kilometres apart in rural areas but can be just a few hundred metres from each other in cities. There will be one mast per ‘cell’, which is the maximum area in which the mast can pick up a mobile signal. Hence the further away you are from a mast, the weaker the signal, so if you cannot get a signal at all, that means you aren’t within range of a mast. As well as the large main masts, there are also a number of micro and picocells that are much smaller and have less coverage. However, these can pick up the radio waves and transmit them to the larger main masts, increasing the coverage without being an eyesore. This network allows people to call wherever and whenever they want, only having to be within range of a tower. Even though satellites are required for long-distance calls that can’t be transmitted from tower to tower, the process of making a phone call by relay is an amazing technological victory.
Sending mixed signals How your calls get from A to B while on the move
028 | How It Works
Roaming charges are made when a user heads out of their service provider’s reach and uses another’s mast instead.
The switch The switch has a database of all the mobile phones that are turned on and their cell site locations. It locates the position of the recipient and sends an electrical signal to the nearest mast.
Call ended
Dialling
If you are talking on the move and travel out of range of a phone mast, the phone call will cut off.
When the number is dialled, the antenna at the local cell site identifies the caller and the recipient. A cell site is where antennas and communications equipment are placed inside a mast or tower.
Motorola StarTAC First clamshell cell phone – design reaches the cell phone at last.
First smartphones Most of you reading this will have a smartphone in your pocket or within arm’s reach. The world’s first smartphone is generally considered to be IBM’s Simon Personal Communicator from the 1990s. It surpassed any other mobile at the time, as it sent and received emails, had a calculator, calendar, games and even a touchscreen, which was a revolutionary concept back then. It even had a basic predictive text function. But it was not a commercial success, so the first smartphone to really take off was the Kyocera 6035, launched in 2001. It had an attached modem that wirelessly to the internet to send and receive emails and had 8GB of memory. It made work on the go a real possibility without the need for cables or heavy laptops.
Roaming
Samsung SPH-M2100 The first MP3 cell phone.
2000
1996 1983
1994
Simon Personal Motorola Communicator DynaTAC 8000X First PDA/cell phone -
Widely regarded as the included applications such first-ever commercial as a calculator, calendar, cellular phone. address book, etc.
1999
1999
Nokia 7110
Sharp J-SH04
One of the first to use Wireless Application Protocol (WAP).
One of the first camera phone (released only in Japan).
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