A Short History of Navigation
In the Age of Discovery of the 15th to 18th centuries, explorers employed latitude for north-south measurements, taking the equator (0 degrees) as its base point. With the angle measured from the center of the Earth, plus 90 degrees took you to the North Pole, and minus 90 degrees the South Pole. Longitude, for east-west, was more complicated – as centuries of seafarers will attest. The 0 degrees reference point has been set at the Greenwich Meridian in London, with longitude measured as up to 180 degrees east or minus 180 degrees west of this point.
As the Earth moves 360 degrees a day, or 15 degrees an hour, there is a direct relationship between longitude and time. If you are three hours ahead of UTC (Coordinated Universal Time, formerly GMT), for example in Mogadishu, you will have a longitude of 45 degrees east. For this reason, having a reliable clock was essential.
GPS coordinates rely on latitude and longitude. The Empire State Building has a latitude of north 40º 44’54.388”, while the longitude is west 73º 59’8.39”. Global Satellite Positioning, however, wasn’t developed until the 1970s, when the US Department of Defense took inspiration from the way radio signals were being transmitted by Russian satellite Sputnik. When Korean Air flight 007 was shot down after accidentally entering Soviet airspace in 1983, the US government extended the technology to civilian airlines, but it wasn’t until 2000 that it became available to everyone.
GPS continues to be owned by the US government. So far, just over 70 satellites have been put in Space although not all are in service – the minimum number required for a“full constellation”is 24. While a few early attempts at producing in-car GPS and handheld receivers had entered the market in the nineties, it wasn’t until the early 2000s that the technology became accurate enough to be really useful.
The first successful personal navigation device (PND) was released by TomTom in 2004, with Garmin and Magellan quickly getting in on the act. By 2008, more than 18 million units had been sold in the US, but sales went into decline with the emergence of built-in GPS on smartphones. Google Maps Navigation with turn-by-turn directions entered the scene in 2009, with Apple Maps following in 2012.