GNSS (Global Navigation Satellite System)

Today GNSS or Global Navigation Satellite System is widely used as a navigation tool. Some nations have their own GNSS in place as we are already acquainted with the GPS or Global Positioning System. For example, GPS was developed by the United States, GLONASS by Russia, Beidou by China, Gallileo by the EU and Gagan by India. The GPS specifically has become part of our daily lives to help us navigate through the roads, rivers, seas, skies, and unknown outdoor territories. The GPS that we are currently familiar with is a small portable device with LCD screen capable of pinpointing our current position in relation to the global coordinate system and navigate us through the path or road to be taken take ahead assisted with voice navigation. This device is actually called a GPS receiver, where the actual system operates by computing signals beamed by the GPS satellites in space.

GPS was fitted on board a Delta rocket and launched into space reaching an altitude of 680 km. There are currently a total of 26 GPS satellites in space on 26 orbital slots respectively. Orbit is defined as a path for a satellite that revolves around a planet at a certain speed and altitude based on its specific mission. There many types of orbital paths pattern, the commonly used patterns are circular and elliptical.

The GPS was originally designed and developed by a private US military contractor, Global Navstar Inc. The GPS program was initiated by the United States Air Force in the 1990 to assist soldiers, fighter pilots, and naval navigators to operate effectively on the battlefield. The GPS operates by transmitting microwave signals from space onto a GPS receiver of a user, either can be placed in a moving vehicle or handheld. These signals later will be processed by the GPS receiver and compute all the necessary information in current time, those are three dimensional positions in latitude, longitude, and altitude, speed and heading of a particular vehicle or person.

However the accuracy of the GPS data has been reduced for the civilian usage. But it can be improvised by implementing SBAS (Space Based Augmented System) or GBAS (Ground Based Augmented System).