Cell Towers: The Meat In The Mobile Phone Sandwich

Ever since man tried to talk with God at Babel we've been building towers as a way to communicate. While mobile phone makers fall over themselves to make us buy the latest, greatest and most fashionable handsets they are little more than plastic and shiny lights without a tower to talk to.

The first portable telephones communicated to a tower that was connected to the landline phone system. By just after World War Two, AT&T in the USA had come up with a way for a single tower to host multiple conversations, but they needed Federal Communications Commission (FCC) approval to continue development. The FCC, in their infinite wisdom, decided to grant AT&T enough spectrum to host a massive 23 simultaneous conversations. Clearly, a phone system that could only handle 23 calls wasn't worth dropping lots of investment dollars into.

Twenty years later, the FCC reconsidered and research started again. One of the big problems with the previous systems was that calls could only be made and completed from one tower. If a caller moved away from one tower to another the call dropped out. In 1970, Amos Edward Joel, an engineer at Bell Labs, developed the call handoff system that facilitated phone call continuity as a caller moved between towers.

The original towers from the 1940s worked by establishing point to point connections with the portable telephone. Where the AT&T system differed was that their towers could transmit and receive signals in three directions. This way, the towers work together to create a coverage mesh that covers a large area. Each tower in the network has three sets of directional antennas aimed in different directions, sending and receiving into three different cells at different frequencies. In this way, each tower covers a hexagonal area.

Today, cell towers are found all over the place. Providing you're not nervous about the potential effects of the transmitter, having a tower on your property can be a nice revenue source as phone companies pay rent on space for erecting towers.

So, with an established phone system, cell tower technology and all the requisites for working handsets, the time had come for the first mobile phone.

MobileModo is Gizmodo Australia's look at the rise and rise of the mobile phone, from Bell's landline to the ubiquitous mobiles of today.

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