Navigation equipment is of various types and modifications. There are systems designed for use in the open sea, others are adapted for the masses of users who use navigators in many ways for entertainment purposes. What are navigation systems?
What is navigation?
The term "navigation" is of Latin origin. The word navigo means "sailing on a ship." That is, initially it was actually a synonym for shipping or navigation. But with the development of technologies that facilitate the navigation of ships on the oceans, with the advent of aviation, space technology, the term has significantly expanded the range of possible interpretations.
Today, navigation means a process in which a person controls an object based on its spatial coordinates. That is, navigation consists of two procedures - this is direct control, as well as miscalculation of the optimal path of the object.
Types of navigation
The classification of navigation types is very extensive. Modern experts distinguish its following main varieties:
- automobile;
- astronomical;
- bioavigation;
- air;
- space;
- sea;
- radio navigation;
- satellite;
- underground;
- informational;
- inertial.
Some of the above types of navigation are closely related - mainly due to the commonality of the technologies involved. For example, car navigation often uses tools specific to satellite.
There are mixed types within which several technological resources are simultaneously used, such as, for example, navigation and information systems. In them, satellite communications resources may be key. However, the ultimate goal of their involvement will be to provide target groups of users with the necessary information.
Navigation systems
The corresponding type of navigation forms, as a rule, the system of the same name. Thus, there is a car navigation system, marine, space, etc. The definition of this term is also present in the expert environment. The navigation system, in accordance with a common interpretation, is a combination of various types of equipment (and, if applicable, software) that allow you to determine the position of an object and also calculate its route. The toolkit here may be different. But in most cases, systems are characterized by the presence of the following basic components, such as:
- cards (usually in electronic form);
- sensors, satellites and other units for calculating coordinates;
- non-systemic objects that provide information about the geographical location of the target;
- a hardware-software analytical unit that provides data input and output, as well as connecting the first three components.
As a rule, the structure of various systems is adapted to the needs of end users. Certain types of solutions can be accentuated in the direction of the software, or, conversely, hardware. For example, the Navitel navigation system, popular in Russia, is mostly software. It is intended for use by a wide range of citizens who own various kinds of mobile devices - laptops, tablets, smartphones.
Satellite navigation
Any navigation system involves, first of all, determining the coordinates of the object - usually geographic. Historically, human tools have been constantly improved in this regard. Today, the most advanced navigation systems are satellite. Their structure is represented by a combination of high-precision equipment, some of which are located on Earth, the other rotates in orbit. Modern satellite navigation systems are able to calculate not only geographical coordinates, but also the speed of the object, as well as the direction of its movement.
Elements of satellite navigation
The composition of the relevant systems includes the following main elements: satellite constellation, ground-based units for measuring coordination of orbital objects and information exchange with them, end-user devices (navigators) equipped with the necessary software, in some cases, additional equipment for updating geographical coordinates (GSM towers) , Internet channels, beacons, etc.).
How does satellite navigation work
How does a satellite navigation system work? Its work is based on an algorithm for measuring the distance from an object to satellites. The latter are located in orbit practically without changing their position, and therefore their coordinates relative to the Earth are always constant. In the navigators, the corresponding numbers are embedded. Finding a satellite and connecting to it (or several at once), the device determines, in turn, its geographical location. The main method here is calculating the distance to satellites based on the speed of the radio waves. The orbiting object sends a request to the Earth with exceptional accuracy in time - atomic clocks are used for this. Having received a response from the navigator, the satellite (or a group of those) determines what distance the radio wave has managed to travel over a certain time period. The speed of moving an object is measured in a similar way - only the measurement here is somewhat more complicated.
Technical difficulties
We have determined that satellite navigation is the most advanced method for determining geographic coordinates today. However, the practical use of this technology is accompanied by a number of technical difficulties. Which, for example? First of all, this is the heterogeneity of the distribution of the planet’s gravitational field - this affects the position of the satellite relative to the Earth. The atmosphere is also characterized by a similar property. Its heterogeneity can affect the speed of radio waves, which may lead to inaccuracies in the corresponding measurements.
Another technical difficulty - the signal sent from the satellite to the navigator is often blocked by other ground-based objects. As a result, full use of the system in cities with tall buildings can be difficult.
Practical use of satellites
Satellite navigation systems find the widest range of applications. In many ways, as an element of various commercial decisions of a civilian orientation. It can be both household devices, and, for example, a multifunctional navigation media system. Apart from civilian applications, satellite resources are used by surveyors, cartography specialists, transport companies, and various government services. Satellites are actively involved by geologists. In particular, they can be used to calculate the dynamics of the movement of tectonic earth plates. Satellite navigators are also used as a marketing tool - with the help of analytics, in which there are location methods, companies conduct research on their client base, and, for example, send targeted advertising. Of course, military structures also use navigators - it was they who, in fact, developed the largest navigation systems today, GPS and GLONASS - for the needs of the US Army and Russia, respectively. And this is not an exhaustive list of areas where satellites can be used.
Modern navigation systems
What navigation systems are currently operational or deployed? Let's start with the one that appeared on the global public market earlier than other navigation systems - GPS. Its developer and owner is the US Department of Defense. Devices that communicate via GPS satellites are the most common in the world. Mainly because, as we said above, this American navigation system was introduced to the market before its modern competitors.
Actively gaining popularity GLONASS. This is a Russian navigation system. It belongs, in turn, to the Ministry of Defense of the Russian Federation. It was developed, according to one version, around the same years as GPS - in the late 80s - early 90s. However, it was introduced to the public market quite recently, in 2011. More and more manufacturers of navigation hardware solutions are implementing GLONASS support in their devices.
It is assumed that serious competition between GLONASS and GPS can be made by the Beidou global navigation system, developed in China. True, at the moment it functions only as a national one. According to some analysts, it can get global status by 2020, when a sufficient number of satellites will be put into orbit - about 35. The Beidou system development program is relatively young - it started only in 2000, and the first satellite Chinese developers launched in 2007 m.
Try to keep up with the Europeans. The GLONASS navigation system and its American counterpart in the foreseeable future may well enter into competition with GALILEO. The Europeans plan to expand the satellite constellation in the required number of units of orbital objects by 2020.
Other promising projects for the development of navigation systems include the Indian IRNSS, as well as the Japanese QZSS. Regarding the first widely advertised public information about the intentions of the developers to create a global system yet. It is assumed that IRNSS will serve only the territory of India. The program is also quite young - the first satellite was launched into orbit in 2008. The Japanese satellite system is also expected to be used primarily within or adjacent to the national territories of the developing country.
Positioning accuracy
Above, we noted a number of difficulties that are relevant for the operation of satellite navigation systems. Among the main ones that we called - the location of satellites in orbit, or their movement along a given path, is not always characterized by absolute stability for several reasons. This determines the inaccuracies in the calculation of geographical coordinates in navigators. However, this is not the only factor affecting the correct positioning by satellite. What else affects the accuracy of the calculation of coordinates?
First of all, it is worth noting that the very atomic clocks that are installed on satellites are not always absolutely accurate. Errors are possible in them, although very small, but still affecting the quality of work of navigation systems. For example, if a mistake is made at the level of tens of nanoseconds when calculating the time for which the radio wave moves, then the inaccuracy in determining the coordinates of a ground object can be several meters. At the same time, modern satellites have equipment that makes it possible to carry out calculations even taking into account possible errors in the operation of atomic clocks.
We noted above that among the factors affecting the accuracy of navigation systems is the heterogeneity of the Earth’s atmosphere. It will be useful to supplement this fact with other information regarding the influence of near-Earth regions on the operation of satellites. The fact is that the atmosphere of our planet is divided into several zones. The one that is actually on the border with outer space - the ionosphere - consists of a layer of particles having a certain charge. When they collide with the radio waves sent by the satellite, they can reduce their speed, as a result of which the distance to the object can be calculated with an error. Note that satellite navigation developers work with this kind of source of communication problems: as a rule, various types of corrective scenarios are incorporated into the algorithms of operation of orbital equipment, taking into account in the calculations the features of the passage of radio waves through the ionosphere.
Clouds and other atmospheric phenomena can also affect the accuracy of navigation systems. Water vapor present in the corresponding layers of the Earth’s air envelope, like particles in the ionosphere, affects the speed of radio waves.
Of course, as for the domestic use of GLONASS or GPS as part of such units, such as, for example, a navigation media system, the functions of which are largely entertaining in nature, small inaccuracies in the miscalculations of coordinates are not critical. But in the military use of satellites, the corresponding calculations should ideally correspond to the real geographical position of objects.
Features of maritime navigation
Having talked about the most modern type of navigation, we will make a short excursion into history. As you know, the term in question first appeared among sailors. What features are characterized by marine navigation systems?
Speaking about the historical aspect, it is possible to note the evolution of the tools at the disposal of sailors. One of the first "hardware solutions" was a compass, which, according to some experts, was invented in the 11th century. The mapping process, as a key navigation tool, has also been improved. In the XVI century, Gerard Mercator began to draw up maps based on the principle of using a cylindrical projection with equal angles. In the 19th century, lag was invented - a mechanical unit capable of measuring the speed of marine vessels. In the twentieth century, radar appeared in the arsenal of seafarers, and then space communications satellites. The most modern marine navigation systems today function, thus reaping the fruits of space exploration by man. What is the specificity of their work?
Some experts believe that the main feature that is characterized by a modern marine navigation system - the standard equipment installed on the vessel, has a very high resistance to wear and water. This is understandable - it is impossible for a ship that went into open voyage thousands of kilometers from land to be in a situation where the equipment unexpectedly fails. On a land where civilization’s resources are available, everything can be repaired; on the sea, it’s problematic.
What other notable features does a marine navigation system have? Regular equipment, in addition to the mandatory requirement of wear resistance, as a rule, contains modules adapted to fix certain environmental parameters (depth, water temperature, etc.). Also, the speed of the ship in marine navigation systems in many cases is still calculated not by satellites, but by standard methods.