There are some great worldwide gps navigation systems available today by companies such as garmin and tomtom. Almost all gps systems are worldwide today due to the large network of global positioning system satellites.

Gone are the days when the only option you had while traversing unfamiliar roads and terrain was to ask the locals for directions. For you can now use a (global positioning system) GPS-based navigation unit to accomplish the same task without the need to ask local people the directions. A navigation unit for most laymen is a wonder gizmo that will help you to know your position and direct you towards your selected destination.

How does such a navigation unit work?

Well, first simply thank the long and rapid strides technology has taken in many diverse areas. These areas include (i3 conducted) Earth imagery mapping, satellites, GPS-enabled cellphones, and dedicated in-car GPS navigation units.

They also include software (mapping, database, and control), hardware (inertial navigation unit, memory, pocketPCs, and the plethora), database systems, and micro-electronics. You need to also mainly thank the US Department of Defense (DoD) and erstwhile late US President Ronald Reagan.

Coming back, a navigation unit is simply an electronic device that helps you track your route, know your current position, reach a destination, or find how far you are from a specific well-known location. The circuitry in it helps it to locate its position at all times. It works by receiving microwave signals transmitted at certain preset frequencies by a cluster of 32 Navstar-GPS medium Earth orbit US-launched satellites up in the sky.

The signals tell you the coordinates of your (actually that of the navigation unit available with you) current location, wherever in the world you might be, in the air, over the seas, or on land. Moreover, you also have available with your navigation unit a database (in memory) that has already been developed through a process known as mapping.

Using mapping, the database stores the coordinates of all well known locations in nearby areas. Using software to compare your coordinates with those of nearby well known locations, you can also know exactly where your current location is with respect to these well-known landmarks.

Now, a navigation unit (such as the Garmin 2610) is something that you can have built-in into your Lincoln Continental SUV/car dashboard. Alternatively, you can have a navigation unit packaged smartly in your new GPS-enabled Nokia cellphone or simply use a dedicated Garmin etrex navigation unit.

Since everyone carries their cellphone wherever they go it becomes easy for government agencies to locate them. In this way terrorists can be discovered and caught or a criminal's movements traced, or a person in an emergency can be located and reached in hospital in time. Privacy laws are infringed anyway, but see the advantages of a navigation unit. Its advantages far outweigh the small issue of privacy.

The US DoD it was that launched those 24 GNSS (global navigational satellite system) satellites for military purposes, but President Reagan ordered them later to be also used for civilian use. So, next time you hear the word navigation unit, I am sure you would not bat your eyelid.