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About GPS systems for sailors, boaters, and cruisers

Satellite positioning systems have been available for many years and are widely used by the general public, mariners, and military. With constant advances in technology boosting the capabilities and heightening the limits of these navigational systems, it comes to no surprise that in the year 2020 the world will see many new systems and satellites orbiting the earth playing a crucial role in positioning technology. Unsurprisingly, however, global positioning systems and satellites have come a long way and are expected to have many advances in our lifetime alone. Their humble roots began during the Cold War for military purposes, but now civilians all across the world see them integrated into their everyday lives. Continue reading below to learn more about the history and technology behind the global positioning systems, and to discover what plans have been set in place for new systems and satellite launches by the year 2020!

GPS Systems

The Navstar global positioning system is commonly referred to just as a GPS system. While many instantly envision a small built in car navigational system when they hear ‘GPS system’, the first GPS started out actually as a military invention. Officially designed and produced in the year 1973 by the US Department of Defense, the first GPS system was nothing like the common devices seen today. They were built specifically for anti-war measures during the Cold War, and weren’t actually authorized for public use until Ronald Reagan declared so after two civilian planes were shot down over Russia in the 1980’s. Four years after the development of the Navstar GPS system, the United States Air Force launched its first GPS satellite into orbit around the Earth. Fast forward to around the year 1994, and you’ll see a total number of twenty-four satellites now launched into space and orbiting around the planet creating a fully operational GPS system. Despite there being twenty-four crucial satellites in the GPS system, the system itself is designed so that even if two of the twenty-four go down, it will remain fully functional. Additionally, these satellites have several fail-safes installed to ensure that they don’t go down. One of which is a dual power source consisting of both solar power and strong NiCad batteries. NiCad batteries are actually nickel-cadmium batteries and are far superior than ordinary alkaline batteries in the fact that they are rechargeable. Additionally, they hold their charge far longer than normal batteries, making them a superior option for the powerful energy needs on the GPS satellites. This strong power supply ensures that these satellites have ample energy to maintain their orbit and continue broadcasting their signals.

GPS Coordinates and Signals

Despite the complex computers, algorithms, and data collection methods that go into computing the various positions and locations, the process that a GPS satellite uses to broadcast the position is quite simple to understand. First, a satellite will maintain its orbit and broadcast its specific location according to atomic clocks, computers, and a radio that it is equipped with. The satellite will analyze its changing orbit and use that, along with the atomic clock, to understand its new location and broadcast this data to the GPS receivers down on earth. These receivers will then use this information to calculate the position of the receiver and display it on the monitor or LCD screen for the viewer. Each GPS satellite is outfitted with four atomic clocks alongside the radio and the computer. These clocks are used only one at a time, but they ensure that the timing on the GPS satellite is impeccable and helps accurately coordinate the satellite. To calculate the exact geographical location of one of the satellites,  the computer uses a triangulating system that will take the position of three other satellites, calculate the difference in time based on one of the four atomic clocks, and then use that to determine its own location. While the method behind finding the position of the satellite may seem like it would take a long time, it is actually a very fast process; this ensures that the positions are constantly being relayed down to the various GPS receivers on Earth for them to use and establish their information. One thing that must be accounted for when it comes to the GPS signal is that there are always slight delays in the signal between the satellite and the receiver. This means that the computer needs to calculate for various differences in the delays caused by the various atmosphere levels the signal has to pass through (i.e ionosphere and troposphere). Once the receiver analyzes this data it can then determine the exact location based off the signal from the satellite and the external data it obtains for the delay in signal. After the signal is calculated, it is broadcast to the GPS receivers down on Earth where the location is displayed. Unfortunately there are a few limitations to the GPS signals. While their signal strength has been improved over the years, it can still be disrupted by metal. Because of the thick metals used in buildings, people often find that they have a harder time receiving a signal inside, or right next to a building. Fortunately plastic, glass, and most other coverings are not enough to impede the signal, but new satellites are being launched within the next year with a signal significantly stronger than the ones currently being used. Once the information is analyzed and an exact location is determined for the GPS satellite, then the location is displayed in two sets of data for the location: longitudinal position and latitudinal position.  A great thing about the satellites is that if all four are used to calculate the position, then the actual altitude can be obtained rather than just its coordinates!

Military and Civilian Codes and Frequencies

As stated earlier, the GPS satellites were initially launched by the US military and were made usable by the public years later. To accommodate the two types of users accessing the data from the satellites, each satellite broadcasts the data in two types of code on the same frequency. The L1 frequency is used for both C/A and P codes. The C/A code is for normal civilian users that are accessing the data with their GPS receivers. The C/A stands for course acquisition and is relatively accurate with a fifteen meter leeway. Since the military are obviously in need of coordinates that are much more precise than a possible fifteen meter difference, they use the P code. This P code stands for precise and is broadcasted on two different frequencies – L1 and L2. Since the military is in need of much more accurate coordinates their code needs to be different and it will also be received by different GPS receivers as well. The frequencies that these GPS satellites use are quite complex, however they are transmitted in a fairly simple manner. For the codes and data to be transmitted successfully from the satellite to the receiver on Earth, they are actually modulated for a frequency. To modulate the data, you actually alter the properties of a frequency signal before sending it. The difference between the L1 and L2 frequencies is actually the strength of their frequency. The first, L1, is 1.023 MHz while the second, L2, is 10.23MHz.

GPS Satellites in 2014

In just a few short decades the uses for GPS satellites and receivers has vastly expanded for both military use and civilian use. Cars are now being made with built in navigation systems, exercise watches have a GPS feature on them, and the military application for GPS devices has been significantly improved. Additionally, mariners are massively using the aid of navigation systems and an entirely new generation of satellites is being set for launch. GPS III – The GPS III satellites are set to launch in 2014 and are going to be a huge improvement from the previous satellites. The vastly improved technology used on these new satellites ensures that the signal is incredibly accurate and is also harder to jam. In fact, it is estimated that the new broadcasting signal on the GPS III are going to be up to eight times more powerful than current GPS satellite signals. To top it off, these new GPS satellites are going to have an improved design, longer life span, and will be able to incorporate their civilian signal in with various global navigation systems. While the benefits of these new GPS III satellites are widespread, marine uses will see a massive improvement. Since vessels are required to have a GPS device on them for simple safety features, the new satellites can significantly improve search and rescue missions for stranded ships, as well as increase the simple tracking for ships when they are out at sea.

Glonass and GPS

While the United States has various satellites orbiting the earth for both military and civilian navigational purposes, Russia also has a similar system called Glonass. Glonass is simply an acronym of the following words: Globalnaya navigatsionnaya sputnikovaya Sistem and simply translates to the global navigation satellite system. Glonass, much like the US GPS system, was created during the Cold War and was intended initially for military purposes only. Sputnik, the primary satellite first launched for the Russian Glonass system, was deployed in 1982. For a while after its first launch, Russia’s Glonass system was stagnant until the government invested a fair amount of money and drastically boosted its production. Since then a multitude of other satellites have been added into the Glonass system until it became a fully operational global navigation system in 1993. Now, there are a total of twenty-four different satellites in the system and more are expected for the future. Twenty-four satellites in the Glonass system are split up into three different sets of orbits around the Earth. Each orbit is comprised of eight satellites and they make their full rotation around the earth at just over eleven hours each. These various orbits are designed to help improve accuracy in their signal and frequencies for both civilian and military use.

Glonass Frequency

GPS satellites use two frequencies, L1 and L2, and transmit two types of codes depending on whether it is for civilian use or military use. The Glonass system also transmits C/A and P code, but each satellite transmits these codes on a different frequency strength based on their location to ensure full accuracy. With twenty-four different frequencies being used, one would think that it would be harder for receivers to obtain the signals and project the locations accurately, but this apparently isn’t so. In fact, many manufacturers of GPS receivers are making devices that incorporate signals from both the GPS system and the Glonass system. This use of dual navigation systems can massively improve the accuracy of the location to just centimeters. Additionally it also helps ensure that the signal is not interrupted or delayed further by the atmosphere, buildings, or other obstructions.

BeiDou

Aside from the US and Russia, there was another country that developed its own navigational system – China. In the year 2000, China launched two satellites and named its system BeiDou, or Compass. This Chinese navigational system was used mainly for forest fires, transportation, weather, and traffic control. Now, just a few years later, there are an additional fourteen different satellites added into their BeiDou system with four more experimental satellites. Fortunately China, like Russia and the US, is still expanding its navigational system. By the year 2020 the BeiDou system is set to have global coverage thanks to the estimated thirty-five satellites that are going to be included in its system. China, ever ambitious, plans on further increasing the number of satellites to forty just a few years after their 2020 deadline ensuring astounding signal accuracy and coverage.

Galileo

To contribute to the navigation system designed for civilians, Europe is going to use the satellite Galileo for the GNSS. The GNSS stands for the Global Navigation Satellite System and it will be a privately funded navigation system that is designed entirely for civilians and will have a much more accurate location. Unfortunately the system won’t be completely operational until around 2020 if all goes to plan, but it will have an astounding number of satellites (thirty in total) that will ensure an accurate position of just one meter! Additionally, when the Galileo is combined with other satellites it can accurately pinpoint a position within just a few centimeters! This system is also expected to feature a great deal more in the way of civilian uses. Applications for mountain rescues, elderly patient monitoring, and even guide devices for the blind are expected to be available! Fortunately it won’t be much longer until these applications are seen in the real world because the satellites for the Galileo system are going to start being launched in 2014 with full operational capabilities being seen in the next few years after that!

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