GPS

GPS



GPS

The principle behind GPS position determination is called time of arrival (TOA). TOA is simply the signal travel time from one point to another. TOA ranging involves transmitting a signal at a known time and measuring the arrival (reception of that signal at a later known time) the interval between the known time of broadcast and known time of reception is the TOA value.

Radio signals continuously transmitted from the satellites carry with them, as part of the positioning information, the time of its broadcast. When the radio signal is received by the user's receiver, the time of arrival is compared with the time of broadcast, and the TOA value is calculated. From this it is possible to calculate the distance to the receiver from the satellite. The receiver multiplies this time by the speed of light to determine how far the signal traveled.

Time of arrival - Time of signal's broadcast = TOA Value

TOA value ´ 2.999´ 108 ms-1 = distance to the receiver from the satellite

GPS applications continue to grow in land, sea, air, and space navigation. The ability to enhance safety and to decrease fuel consumption will make GPS an important component of travel in the international airspace system. The GPS system is also extremely accurate, the differential GPS provides a horizontal position accurate to about 3 m.

Main Functions of Vessel Position System

Efficiency

A shipping company must make money to survive. Without effective and efficient processes, too much time and therefore money can be wasted, dribbling away the already all too slim profit margins. Efficiency can be improved only when the management can compare performance to an established base line standard. Ship operators currently rely on the crew to make observations of time, ship position, speed, engine output and other pertinent voyage data, then record them on a sheet of paper or input them into a computer data base. Operations should take place once and only once, and must have a clear purpose. IT technology introduced to a shipping company or vessel must not hinder its efficient operation.

Safety

Working with large machinery inherently carries risks. These risks must be understood and minimised to ensure that staff and crew are protected against accidents. IT technology that provides a more complete or accurate picture of the entire current situation can reduce risks in two ways.

Firstly by the early highlighting of potentially dangerous situations, and secondly by ensuring that those dealing with a dangerous situation can assess the impact of their actions.

Security

With large amounts of cargo and valuable equipment, shipping companies and vessels must be protected against malicious acts, including:

Theft of both cargo and vessels(Piracy)

Smuggling of both goods and people

Terrorism

Value-Added logistics services

A greater emphasis on technology, an increasingly complex and global supply chain, and the ever-present pressure on costs means logistics and supply chain professionals need to have a much broader array of skills today than in the past. The increased costs in the supply chain may be a blessing in disguise, spurring manufacturers to work harder at getting control ...