| | | | | GNSS systems require an absolute time source, |
| We are all used to the Sat Nav by now. More and | | | | that is a time source as accurate as humanely |
| more people are installing those little black boxes | | | | possible such as that from an atomic clock. |
| into their cars and throwing away their old paper | | | | Without knowing exactly what the time is a |
| road maps. The advantages of satellite navigation | | | | GNSS satellite would not be able to accurately pin |
| are many fold – from constant updates | | | | point a location (as the Earth, satellites and people |
| keeping the maps current to being able to pin | | | | are all moving about a location can only be defined |
| point your location miles from any landmarks or | | | | by a position and time). Because of the distance |
| road signs. | | | | of the satellites away from the Earth, even an |
| Currently the American Military run the Global | | | | inaccuracy of a second or two could mean a sat |
| Positioning System (GPS) which at present is the | | | | nav’s location could be miles out. |
| world’s only fully operational Global Navigation | | | | As a consequence of having this accurate time |
| Satellite System (GNSS). However, the Europeans | | | | sources, GPS and the new breed of GNSS |
| have started their own GNSS system called | | | | systems can all be used to receive an absolute or |
| Galileo which is expected to be fully operational by | | | | UTC (Universal Coordinated Time) time source. |
| 2013. Russia and China are also working on their | | | | This time source is currently used by computer |
| own systems too. | | | | networks running a NTP server to synchronise all |
| This will mean more accurate direction finding for | | | | machines and devices to the same time. |
| all of us as the differing GNSS are expected to | | | | Having a time signal broadcast all over the world |
| be interoperable. However, there is more to | | | | means the entire globe can synchronise to the |
| GNSS than just direction finding. | | | | exact same time, vital in many computer |
| GNSS systems work by using satellites several | | | | applications. |
| thousand miles above the Earth’s that beam | | | | When the new GNSS systems are fully functional |
| positional information down to a GNSS receiver | | | | timing accuracy will also increase along side |
| (like a sat nav). | | | | accuracy in direction finding. |
| However to accurately pinpoint a location, all | | | | |