Navigation equipment is of various types and modifications. There are systems designed for use in the open sea, others are adapted for the general public, using navigators in many respects for entertainment purposes. What are navigation systems?
What is navigation?
The term "navigation" is of Latin origin. The word navigo means "I am sailing on a ship". That is, initially it was actually a synonym for shipping or navigation. But with the development of technologies that make it easier for ships to navigate 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 directly control, as well as a miscalculation of the optimal path of the object.
Navigation types
The classification of navigation types is very extensive. Modern experts distinguish the following main varieties:
- automotive;
- astronomical;
- bionavigation;
- air;
- space;
- maritime;
- 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 satellite-specific tools.
There are mixed types, within which several technological resources are simultaneously used, such as, for example, navigation and information systems. As such, satellite communication resources can be key in them. However, the ultimate goal of their involvement will be to provide the target user groups with the necessary information.
Navigation systems
The corresponding type of navigation forms, as a rule, a system of the same name. There is, therefore, a car navigation system, marine, space, etc. The definition of this term is also present in the expert community. The navigation system, in accordance with the common interpretation, is a combination of various types of equipment (and, if applicable, software) that allow you to determine the position of an object, as well as 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 andother aggregates for calculating coordinates;
- non-system objects that provide information about the geographic location of the target;
- hardware-software analytical unit that provides data input and output, as well as linking the first three components.
As a rule, the structure of certain systems is adapted to the needs of end users. Certain types of solutions can be accentuated towards the software part, or, conversely, the hardware part. For example, the Navitel navigation system, which is 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.
Navigation via satellite
Any navigation system involves, first of all, the determination of the coordinates of an object - usually geographical. Historically, human tools in this regard have been constantly improved. Today, the most advanced navigation systems are satellite. Their structure is represented by a set of high-precision equipment, part of which is located on Earth, while the other part rotates in orbit. Modern satellite navigation systems are able to calculate not only geographic coordinates, but also the speed of an object, as well as the direction of its movement.
Satellite navigation elements
The corresponding systems include the following main elements: constellation of satellites, ground-based units for measuring the coordination of orbital objects and exchanging information with them, devices for the end user(navigators) equipped with the necessary software, in some cases - additional equipment for specifying geographic coordinates (GSM towers, Internet channels, radio beacons, etc.).
How satellite navigation works
How does a satellite navigation system work? At the heart of its work is 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 laid down. Finding a satellite and connecting to it (or to several at once), the device determines, in turn, its geographical position. The main method here is to calculate the distance to the satellites based on the speed of the radio waves. An orbiting object sends a request to Earth with exceptional time accuracy - atomic clocks are used for this. Having received a response from the navigator, the satellite (or a group of them) determines how far the radio wave has traveled in such and such a time period. The speed of movement of 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. What, for example? First of all, this is the inhomogeneity of the distribution of the gravitational field of the planet - this affects the position of the satellite relative to the Earth. The same property is also characterized byatmosphere. Its inhomogeneity may affect the speed of radio waves, due to which there may be inaccuracies in the corresponding measurements.
Another technical difficulty - the signal sent from the satellite to the navigator is often blocked by other ground objects. As a result, the full use of the system in cities with high buildings is difficult.
Practical use of satellites
Satellite navigation systems find the widest range of applications. In many ways - as an element of various commercial solutions of a civil orientation. It can be both household devices and, for example, a multifunctional navigation media system. Apart from civilian use, satellite resources are used by surveyors, cartographers, transport companies, and various government services. Satellites are actively used 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, which includes geopositioning methods, companies conduct research on their customer base, and also, 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 navigationsystems
Which navigation systems are currently in operation or being deployed? Let's start with the one that appeared on the global public market before 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.
GLONASS is actively gaining popularity. 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 only recently, in 2011. More and more manufacturers of hardware solutions for navigation implement GLONASS support in their devices.
It is assumed that the global navigation system "Beidou", developed in China, can seriously compete with GLONASS and GPS. True, at the moment it functions only as a national one. According to some analysts, it can receive global status by 2020, when a sufficient number of satellites will be launched into orbit - about 35. The Beidou system development program is relatively young - it began only in 2000, and the first satellite was developed by Chinese developerslaunched in 2007.
Europeans are also trying to keep up. The GLONASS navigation system and its American counterpart may well compete with GALILEO in the foreseeable future. The Europeans plan to deploy a constellation of satellites in the required number of units of orbital objects by 2020.
Among other promising projects for the development of navigation systems, one can note 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 is not yet available. It is assumed that IRNSS will serve only the territory of India. The program is also quite young - the first satellite was put 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 functioning of satellite navigation systems. Among the main ones that we have named - the location of satellites in orbit, or their movement along a given trajectory, is not always characterized by absolute stability due to a number of reasons. This predetermines inaccuracies in the calculation of geographical coordinates in navigators. However, this is not the only factor affecting the correctness of positioning using a satellite. What else affects the accuracy of the coordinate calculation?
First of all, it is worth noting that the very atomic clocks that are installed on satellites are not always absolutely accurate. They are possible, although quitesmall, but still affecting the quality of the navigation systems errors. For example, if an error is made at the level of tens of nanoseconds when calculating the time during which a 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 would be useful to supplement this fact with other information concerning 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 open space - the ionosphere - consists of a layer of particles that have a certain charge. They, colliding with radio waves sent by the satellite, 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 are also working with this kind of source of communication problems: the algorithms for the operation of orbital equipment, as a rule, include various kinds of corrective scenarios that take into account the peculiarities of the passage of radio waves through the ionosphere in the calculations.
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, just like particles in the ionosphere, affect the speedradio waves.
Of course, with regard to the domestic use of GLONASS or GPS as part of such units as, for example, a navigation media system, the functions of which are largely entertaining, then small inaccuracies in the calculation of coordinates are not critical. But in the military use of satellites, the corresponding calculations should ideally correspond to the real geographical location of objects.
Features of marine navigation
After talking about the most modern type of navigation, let's take a short digression into history. As you know, the very term in question first appeared among navigators. What are the characteristics of maritime navigation systems?
Speaking of the historical aspect, one can note the evolution of the tools at the disposal of seafarers. One of the first "hardware solutions" was the compass, which, according to some experts, was invented in the 11th century. The process of mapping, as a key navigational tool, has also been improved. In the 16th century, Gerard Mercator began to draw maps based on the principle of using a cylindrical projection with equal angles. In the 19th century, a log was invented - a mechanical unit capable of measuring the speed of ships. In the twentieth century, radars appeared in the arsenal of sailors, and then space communications satellites. The most advanced maritime navigation systems function today, thus reaping the benefits of human space exploration. What is the nature of their work?
Some experts believe thatThe main feature that characterizes a modern marine navigation system is that the standard equipment installed on the ship has a very high resistance to wear and water. This is quite understandable - it is impossible for a ship that went on open voyage thousands of kilometers from land to find itself in a situation where the equipment suddenly fails. On land, where the resources of civilization are available, everything can be repaired, but at sea it is problematic.
What other notable features does a maritime navigation system have? Standard equipment, in addition to the mandatory requirement - wear resistance, as a rule, contains modules adapted to fixing 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.
