Difference rangefinder method for determining coordinates. Methods for locating emitter sources
The task of determining the location of a vehicle is to determine its coordinates on the Earth's surface. Positioning systems are divided into local location systems and remote location systems. In the case of local location determination, the object itself determines its position. An example is the GPS system. Remote location determination is carried out from a central point, which determines the location of individual objects. For example, radar systems operate in this mode.
There are mainly four technical methods used for positioning: direct positioning, indirect positioning, satellite systems and terrestrial transmitters. Of these, indirect position determination in combination with satellite systems has become the most common. A significant advantage of the systems is that they do not require the creation of central points or complex communication infrastructure.
It is known that the use of sensors (Fig. 13.4) of only one type does not allow, as a rule, to determine the location of an object with high accuracy and sufficient reliability. Therefore, data from different sensors is often combined using different methods and algorithms.
Figure 13.4 – Sensors used to determine vehicle location
Direct positioning. It would seem that this is the simplest method of determining location, since the location is determined at the moment the vehicle passes through a given section formed, for example, by a radio beacon. In this case, we often talk about a position sensor, the signal of which can be transmitted not only using radio waves, but also using light or infrared rays. An essential condition is the presence in the vehicle of an on-board device capable of communicating with the radio beacon. In addition, a sufficiently dense network of beacons covering a given area must be created.
In the absence of an on-board device, video cameras are used that allow you to read license plates and use them to determine the passage of a vehicle through this network. The main disadvantage of such a system, which is used for electronic tolls, is the high cost of the infrastructure created. It contains not only the price of radio beacons, but also the price of the entire communication network. Therefore, this system is not recommended to be used only for determining the location of the vehicle.
Indirect location determination. This method is one of the simplest, and it is based on the principle by which it is possible to calculate the position of a vehicle moving in two-dimensional space if its initial position is known (Fig. 13.5). This method consists of summing the trajectory increments and direction angles relative to the starting point, i.e., the position relative to the reference point is determined.
Figure 13.5 – Indirect location method
The main disadvantage of the method is the summation of errors for each measurement.
Satellite navigation. The current stage of development of methods for determining coordinates is associated with the creation of satellite navigation systems.
First generation satellite systems are the American Transit system and the Soviet system Cicada. System Transit originally designed to control submarines, it was launched in 1964 and consisted of 7 low-orbit satellites. Since 1967, it has become available to civilian users. In 2000, the system was taken out of service.
System deployment Cicada was started in 1967, when the first navigation satellite was launched into orbit. The system was fully put into operation in 1979, consisting of four spacecraft. Currently, Cicada has limited use in navigation. The Soviet Union and Russia have a military version of the system called "Cyclone".
In both systems, coordinates were determined based on the Doppler frequency shift from each satellite, which determined the position of the observer relative to the satellite. The height of the satellite orbits in both systems is 1000 km, the navigation accuracy is about 100 m. Although these systems covered the basic needs for ship navigation, they also had significant drawbacks - low performance, lack of continuous availability, the ability to position only slowly moving objects and etc.
Second generation satellite systems are those that are already operating or are being put into operation; these are American systems NAVSTAR (GPS), Russian GLONASS, European GALILEO, Chinese BEIDOU, Indian IRNSS.
GPS (Global Positioning System)– a satellite radio navigation system that provides high-precision determination of the coordinates of objects at any point on the earth’s surface at any time of the day. Today, in scientific and other specialized literature, as well as in many official documents, the abbreviation GPS refers exclusively to the American NAVSTAR system, although it was initially assumed that all global satellite positioning systems would be called this way.
NAVSTAR (NAVigation Sattelite providing Time And Range)– a navigation system that provides time and distance measurement.
GPS was developed in the USA and is managed by the Department of Defense. The deployment of the system began in 1977, when the first satellite was launched, and was fully implemented in 1993. Initially, the main purpose of GPS was high-precision navigation of military facilities, but already in 1983 the system became open for civilian use, and in 1991 Restrictions on the sale of GPS equipment to the countries of the former USSR have been lifted.
Currently, the orbital constellation includes 32 satellites.
GLONASS (Global Navigation Satellite System). The first satellite was launched in 1982, in 1995 the deployment of the system was completed, 24 satellites were launched, but many of them failed, and until recently the system was not fully operational. Launch of new satellites in 2009–2011. changed the situation significantly. As of November 14, 2011, the orbital constellation included 30 satellites, of which 23 were used for their intended purpose. Thus, at the end of 2011, GLONASS began to provide navigation throughout almost the entire globe.
Galileo– European satellite navigation system. The first experimental satellites were launched in 2005 and 2008. In October 2011 The first two working satellites were launched, two more are expected to be launched in 2012. A total of 30 satellites are expected to be launched. 27 workers and 3 spares.
Beidou(Chinese name for the constellation Ursa Major) is a Chinese satellite navigation system. July 27, 2011 The 9th satellite was launched. It is expected that within the Asia-Pacific region the system will begin to provide navigation services as early as 2012. The full deployment of the 35-satellite system is scheduled to be completed in 2020.
IRNSS– Indian navigation satellite system, currently under development. Intended for use in this country only. The first satellite was launched in 2008.
Depending on the class of ground equipment used, the accuracy of determining the coordinates of objects using GPS and GLONASS lies in the range from 10 m to a few millimeters (the accuracy of determining absolute coordinates on Earth), and the measurement time in most cases ranges from seconds to a few minutes. Today, satellite navigation methods are the most accurate of all existing ones for determining the coordinates of terrestrial and near-Earth objects.
Purpose of satellite systems. Navigation satellite systems are designed to determine the location, speed of movement, as well as the exact time of sea, air, land and other types of consumers. NAVSTAR and GLONASS are dual-use systems, originally developed by order and under the control of the military for the needs of the Ministries of Defense and therefore the first and main purpose of the systems is strategic, the second purpose of these systems is civilian. Based on this, all satellites currently in operation transmit two types of signals: standard accuracy for civilian users and high accuracy for military users (this signal is encrypted and is available only with the appropriate level of access from the Ministry of Defense).
General composition of the system. The global positioning system (GPS) includes 3 segments (Fig. 13.6):
Space segment (all working satellites).
Control segment (all ground stations of the system: main control and additional for control).
User segment (all civilian and military GPS users).
Space segment. Satellites, divided into groups, rotate in their orbital planes in a constant medium-altitude orbit, at a constant distance from the Earth's surface. To receive a signal at any time, anywhere in the world and 100 kilometers from the surface of the earth, 24 satellites are required. If we divide it roughly, then there are 12 satellites for each hemisphere. The orbits of these satellites form a "grid" over the earth's surface, so that at least four satellites are always guaranteed to be above the horizon, and the constellation is built so that, as a rule, at least six are available at the same time.
Figure 13.6 – General composition of the GNSS system
A fully deployed satellite system (Fig. 13.7) also has backup satellites, one in each plane, for “hot” replacement (in the event of failure of the main satellite, they can be promptly introduced). Reserve satellites are not idle and also participate in the operation of the system, improving positioning accuracy. They can also be used to increase the coverage of a particular region. Satellites, to a limited extent, can be regrouped upon command from a ground control station, but due to the limited fuel supply on board the satellite, this is done only in exceptional cases. If necessary, only minor movement corrections occur during the service life. On board the satellite there are several time and frequency standards “high-precision atomic clocks”. One standard always works, and there are several of them (from three to four) located in the satellite.
Satellite navigation systems are designed in such a way that at least 4 satellites are visible from any point on Earth (Fig. 13.8).
a) GPS satellite orbits in 6 different planes; b) satellite positions on the map
Figure 13.7 – Space segment of the system
Thus, despite the receiver clock and time errors, the position is calculated with an accuracy of approximately 5–10 m.
Figure 13.8 – Four satellites for determining position in 3-D space
Sources of errors during signal propagation are shown in Fig. 13.9.
Figure 13.9 – Sources of errors during signal propagation
Satellite ranging. Satellite navigation systems use high-mounted satellites that are placed in such a way that from any point n on the ground it was possible to draw a line to at least four satellites.
Determining the location of a moving object using ground transmitters.
Determining the subscriber's location in GSM networks. Theoretically, location determination systems (PLS) make it possible to determine the subscriber’s coordinates with an accuracy of several tens of meters and are a real alternative to global satellite positioning systems, but only in the service territory of cellular networks.
The task of positioning mobile phones involves automatically determining their location within cellular networks. Moreover, under the term “ location“We should not understand the finding of geographic coordinates - latitude and longitude, which is also possible in principle, but the unambiguous identification of the position of the owner of the mobile phone on the ground (electronic map).
According to the accepted classification, SMPs are divided into two main types: systems, the functioning of which requires modification or replacement of subscriber devices, and those working with conventional mobile terminals (positioning systems within a cellular network).
In the first case, you will need either a new SIM card or a new device, or possibly both. In the second case, no changes are required in the hardware of the mobile terminal, but only changes in the software are required, thus, all costs for deploying the system are borne by the network operator.
To determine the position of a mobile device, three main parameters of radio signals can be used: direction of arrival, amplitude and delay time.
Amplitude of received signals is able to characterize the distance between the transmitter and the receiver. However, in practice, the level of mobile phone signals at the receiving location depends on so many reasons that in most cases it cannot provide the required accuracy in determining the location and is used as an auxiliary parameter.
Direction of arrival of signals can be automatically determined by the difference in phases of the signals on the antenna elements. You can also use multiple base stations located nearby. Using sector antennas instead of omnidirectional ones allows you to determine the direction of arrival of signals with greater accuracy. The intersection of bearings from two or more places provides a certain accuracy for determining the position of the mobile phone.
When implementing goniometric method– method of direction of arrival of signals – Angle of Arrival – AOA the measured parameters are the angles of direction of arrival of radiotelephone radiation α1 and α2 (deg) (Fig. 13.10) relative to the base line connecting two cell stations of the network.
Figure 13.10 – Principle of implementation of the goniometric method
When implementing rangefinder method the measured parameters are the time delays Dt1 [s] and Dt2 (sec) (Fig. 13.11) of the propagation of the subscriber's radiotelephone signal to at least two cell stations of the network relative to their time scales, which must be synchronized with each other, and the calculated parameters are the distance from cellular stations to the subscriber's location.
Figure 13.11 – Schematic diagram of the implementation of the rangefinder method.
When implementing difference-range-measuring method The measured parameters are the time delays Dt1[c], Dt2[c] and Dt3[c] of the propagation of the subscriber's radiotelephone signal to at least three base stations of the network relative to their synchronized time scales, and the calculated parameters are the distances from the cellular stations to the subscriber's location.
The disadvantages of such a positioning system include:
· Low accuracy in location determination (compared to satellite systems);
· Linking to a specific cellular operator (GPS – global system);
· Uneven quality of service (depending on the signal coverage area).
Determining the location of a moving object using a system of control points. With the help of a sufficiently large number of road signs or control points (CP), the exact location of which is known in the system, a network of control zones is created throughout the city. The location of the vehicle is determined as it passes the checkpoint. The individual CP code is transmitted to the on-board equipment, which, through the data transmission subsystem, transmits this information, as well as its identification code, to the control and data processing subsystem. Thus, the direct approximation method is implemented. However, in practice, the inverse approach method is more often used - detection and identification of vehicles is carried out using active, passive or semi-active low-power radio beacons installed on them, transmitting their individual code to the CP receiver, or using optical equipment for reading and recognizing the characteristic features of an object, for example , license plates. Information from the CP is further transmitted to the control and data processing subsystem.
Obviously, for zonal systems, the accuracy of location and the frequency of data updating directly depends on the density of the location of control points throughout the territory of the system. Approximation methods require a developed communication infrastructure to organize a data transmission subsystem from a large number of control points to a command and control center, and in the case of using optical reading methods, they also require complex equipment at the control point, and therefore are very expensive when building systems covering large areas. At the same time, inverse approximation methods make it possible to minimize the volume of on-board equipment - a radio beacon, or completely do without equipment installed on the vehicle. The main application of these systems is comprehensive provision of vehicle security and search for vehicles in case of theft. An example of such a system is the KORZ-GAI system, which provides recording of the approach of a stolen equipped vehicle to a traffic police post.
The most developed network of road signs, with the help of which both direct and inverse approach systems are implemented, is in Japan. Road signs in Japan form a nationwide network. In Europe in the 70-80s. systems for selective detection, identification and location of vehicles developed by Philips and Cotag International Ltd (Great Britain) were actively introduced. Road signs in the form of electromagnetic loops are placed directly in the road surface. A semi-active pulse radio transponder is installed on the vehicle, which is turned on when it is exposed to the electromagnetic field of the loop. Currently, ANANDA Holding AG is active in European countries. Since 1992 In France, and then in 12 European countries and Mexico, INMED/VOLBACK systems are being deployed to detect the location of stolen vehicles. Receiving antennas of control points are built into the road surface, poles and other design elements of roadways. The transmitter on the vehicle measures about 5x4x2 cm. The control points are connected into a single pan-European network. In France, 1,500 control points form 400 zones. According to French experts, the efficiency of returning stolen cars equipped with INMED/VOLBACK system transmitters is more than 85% versus 60% for unequipped cars. According to ANANDA Holding AG, the total number of equipped vehicles in Europe should be at least 500 thousand vehicles.
Security questions
1. Special automatic devices for monitoring the operation of vehicles. Brief description.
2. Types of chip cards for digital tachographs.
3. Vehicle location systems.
4. Methods for determining the location of vehicles.
5. Satellite navigation systems for determining the location of the vehicle.
6. Determining the location of a moving object using ground transmitters.
7. Determining the location of a moving object using a system of control points.
The position of an object in space is determined by three coordinates x i, i=1,2,3, in one or another coordinate system. The position of an object on the Earth's surface is specified by two coordinates. Location methods are divided into the following groups:
§ overview and comparative;
§ dead reckoning methods;
§ positional line methods.
Survey and comparative methods are based on comparing the observed map of the area with a reference map stored in the system’s memory. The observed map shows the position of the object. Combining the reference map with the observed one allows you to determine its coordinates.
The cards used may have different physical natures. This can be an image of the earth's surface in the optical or radar range, a map of the starry sky in the optical or radio range, a map of radio thermal radiation of the earth's surface, etc.
Map matching is usually done by finding their cross-correlation function. For 2D maps
where is the cross-correlation function (MCF); – observed image; 
– reference image; x, y – coordinates of the point on the observed map; x 0, y 0 – coordinates of the origin.
The maximum of the cross-correlation function occurs when x 0 +Dx=x, y 0 +Dy=y. The values of Dх, Dу at this point correspond to the displacement of the reference map relative to the real one. Complete alignment of maps is fixed at the maximum VCF, which is why the method is sometimes called correlation-extremal.
The survey-comparative method is used in navigation.
Dead reckoning is also used in navigation. The essence of the dead reckoning method is that on an object (ship, car, armored personnel carrier, etc.) starting from a point with known coordinates x 0, y 0, the accelerations a x (t), a y ( t) or speed v x (t), v y (t) no of each of the coordinates. The ground speed is determined by integrating the acceleration.
For example:
.
,
and then the coordinate itself x(t) = x 0 + Dx(t).
Devices for measuring acceleration (accelerometers) are based on the use of Newton's second law
where m is body weight; F – force applied to it; a is the acceleration received by the body as a result of the application of force F to it.
A load of mass m is placed in a spring suspension. Under the influence
acceleration, the load moves, and the movement, which is measured, is proportional to the acceleration.
Systems based on measuring acceleration are called inertial. There are navigation systems in which it is not the acceleration a(t) that is measured, but the speed v(t) itself. The Doppler effect is used for this purpose.
The most widely used method in radar and radio navigation is the position line method. The position line method is based on the concept of a position surface - a surface in space on which the measured radio quantity is constant.
Distance, distance difference and direction can be measured directly by radio engineering methods. Let us consider the corresponding position surfaces.
1. Surface of equal ranges, R = const. Obviously this is a sphere. The intersection of a sphere with a plane (for example, with the plane of the Earth) gives a line of position - a circle (Fig. 3.50). Its equation is in polar coordinates.
2. Surface of equal bearings (directions), a = const. If the bearing is measured in the horizontal plane from the geographic meridian (north-south direction - N-S), it is called true bearing or azimuth. The intersection of a plane of equal azimuths with the surface of the earth gives a straight line - a line of equal bearings (Fig. 3.51).
3. Surface of equal distance differences - a surface on which the difference in distances to two fixed points in space remains constant. In space it is a hyperboloid, and on the surface of the earth it is a hyperbola. In Fig. 3.52 points A and B are points with known coordinates, R A – R B = R AB = const – equation of a line of equal distance differences:
R AB = cDt AB,
where Dt AB is the difference in signal propagation time from point O to points A and B.
It is fundamentally important that in this method the distances R A and R B are not measured, but their difference R AB is measured.
In radar and radio navigation, the following methods of target location are used, based on the use of the listed position surfaces.
Rangefinder method. From three points in space, the distances to the object are determined. The intersection of two position surfaces (spheres) produces a position line. The intersection of this line with the third sphere gives the location of the object in space.
In Fig. Figure 3.53 shows the interpretation of the method as applied to a plane. As can be seen from the figure, the two position lines intersect at two points. To identify the one that corresponds to the true position of the object, you must have approximate information about it or use the third line of position. The method is widely used in navigation: from the ship, the distances R A and R B to points A and B with known coordinates are determined, then its location is calculated.
Direction finding (goniometer) method, also called triangulation. Let's consider it in relation to a plane. From two points P 1 and P 2, the position of which on the plane is known, the directions to the object O are determined (Fig. 3.54). Then the position of the object relative to these points is determined by solving the triangle P 1 P 2 O:
(3.24)
where L is the rangefinder base.
Range R 1 and bearing a 1 are the coordinates of the object in the polar coordinate system with the center at point P 1.
The direction finding method is used in various variants. In one of them, point O is a radiating object, the coordinates of which should be determined. This is done by direction finding it using non-emitting devices located at points P 1 and P 2 with known coordinates. To calculate the range R, the bearing from one direction finding point, say P 2, is transmitted to another, for example, via a radio channel. This location determination method has become widespread in electronic warfare systems.
In radio navigation systems, the values of angles a 1 and a 2 measured by radio direction finders are transmitted via radio channels to the object O, where calculations are carried out.
In another version of the method used in radio navigation, at point O there is a consumer of radio navigation information with a radio receiver on board. At points P 1 and P 2 with known coordinates, transmitting radio navigation devices are located.
An on-board radio receiver may have directional reception, that is, direction-finding capability. Such devices are called radio compasses. By determining the directions to the omnidirectional radiation sources P 1 and P 2 (drive stations), they then calculate the location of the navigation object. The on-board radio receiver may be omnidirectional. In this case, bearing beacons are installed at points P 1 and P 2 - radio transmitting devices, the signals of which depend on the direction of radiation within 0 - 2p in azimuth. Bearings are determined from received beacon signals.
Rangefinder-direction-finding method. From one point in space, the distance to the object R and the direction (bearing) to it are measured (Fig. 3.55). This method is most often used in radar. The range R is determined by the delay of the received signal relative to the emitted one:
The angular position of the target in the horizontal and vertical planes: a – azimuth, b – elevation angle (elevation angle), are determined by amplitude or phase methods.
Difference-rangefinder (hyperbolic) method. Let's consider it in relation to a plane (Fig. 3.56).
Let the observation object (point O) emit signals. The differences in the arrival times of these signals Dt AB, Dt BC at spatially separated points A and B, B and C are measured. The distance differences are calculated from them and position lines (hyperbolas) are constructed, the intersection of which determines the position of the object. To synchronize the operation of receiving points A, B and C, there must be communication lines between them. The following relations hold:
In this embodiment, the method is used in electronic warfare systems, when it is necessary to determine the coordinates of the radiation source of the opposing side.
The difference-range location method is widely used in radio navigation. In this option, at point O (see Fig. 3.56) the navigation information consumer is located. At points A, B and C there are transmitting devices with known coordinates emitting synchronous signals. The structure of signals contains elements that make it possible to determine their belonging to a particular emitter. The consumer is equipped with a radio receiver that allows you to simultaneously receive signals from transmitting points and measure the difference in their reception time Dt AB, Dt BC. The difference in distances DR AB, DR BC is calculated using the formulas; the location of point O is determined from the difference in distances.
Radar systems
In the context of the increased combat capabilities of aerospace attack weapons, the volume of tasks solved by the country's air defense has increased significantly. First of all, this concerns conducting all types of reconnaissance, ensuring air defense of the most important state and military facilities, and covering strategic directions. Carrying out coordinated actions on air defense is possible only as a result of the use of radio technical formations, units and subunits equipped with modern radars for various purposes and deployments. Conducting combat operations by fighter aircraft and anti-aircraft missile forces without analyzing the air situation in real time is not only ineffective, but also doomed to defeat. To solve the problems of ensuring the country's security in aerospace, it is necessary to create a unified reconnaissance and warning system about aerospace attacks, which will ensure the timeliness, completeness and orderliness of the receipt of information.
The invention relates to the field of control systems and can be used to quickly assess and minimize information about the geographic area where mobile small-sized radio receiving systems are located. The achieved technical result is a reduction in the time for determining locations on the ground for different types of technical equipment of the radio receiving complex. The method for assessing the terrain for the placement of radio receiving equipment includes entering initial conditions and data for a given geographic area, loading a digital terrain map (DTM), initial assessment of the area according to the physical and geographical conditions recorded on the DTM, excluding areas that are unsuitable for the placement of radio receiving complexes based on capabilities, inherent in the deployed radio receiving equipment when performing control tasks, optimization of the central digital computer according to specific and general criteria. 1 ill.
The invention relates to the field of military equipment and can be implemented in the form of a program for electronic computers (computers) of an automated control system (ACS) for troops for assessing the terrain and quickly minimizing information about the geographical area of \u200b\u200blocation of mobile small-sized radio receiving systems, in which the best conditions for their functioning and rational location of radio receiving equipment on the ground.
Modern forms and methods of armed struggle are inextricably linked with the use of information technologies, which today determine both the degree of reliability of the analysis of the terrain and the situation, and the speed of making quality decisions by officials. Correct assessment of the properties of the terrain and the situation has a significant impact on the effectiveness of solving issues in the military sphere related to the use of radio receiving systems. Temporary indicators of the combat capabilities of troops are becoming more and more dependent on the level of information technologies used and the quality of the information used in them. These dependencies form the basis of the claimed invention.
The essence of the invention lies in the preliminary analysis, study and assessment of the terrain area intended for the deployment of radio receiving complexes using an optimization method, for example, a dynamic programming method using an additive quality criterion (objective function), while, for example, mathematical, information or geometric primitives are introduced as components of the criterion characterizing, for example, the unsuitability of zones for the placement of radio receiving systems and the exclusion of these zones from the calculation.
At the initial stage of implementing the method for assessing terrain by optimization, the geographic area of possible placement of radio receiving complexes is minimized, taking into account the exclusion of administrative and physical (and other) components, forming possible placement areas on a digital terrain map (DTM). Minimization leads to a reduction in the amount of information (without loss of quality), which reduces the size of the sample to be processed on a computer and, as a result, reduces the requirements for hardware resources, which allows, for example, the use of small-sized mobile computers.
At the next stage, a structuring and predictive assessment of the minimized working area is carried out in order to possibly select a certain type of radio receiving complex, which can be most effectively placed and used in a given geographical area to perform special tasks, for which operational and tactical operating conditions and parameters limiting the use are introduced and placement of selected radio receiving facilities in the area. Next, for the selected radio-receiving complex, additional new criteria for the objective function are determined, which, for example, make it possible to assess the electromagnetic accessibility (EMA) of radio emission sources (ERS) of the selected radio-receiving complex to perform monitoring tasks in the geographic area specified on the digital computer.
The result of the forecast will be information-structured forecast geographical zones on the central space station, taking into account the tactical properties of the terrain and the capabilities of radio receiving systems for EMD IRI.
As a toolkit for implementing the method of assessing a terrain, they choose, for example, a specialized software and hardware complex of computer technology and a Geographical Information Systems (GIS) complex with a digital computer (for example, “Panorama”, “Integration”, “Map 2011”, etc. ) .
The technical result of the proposed solution is to reduce the total sampling volume of geographic information by filtering and optimizing the initial data associated with the characteristics of the area where radio receiving equipment is located before the start of the process of their use, which makes it possible to study the areas of operation of technical means and plot routes to them, use mobile hardware computer facilities, as well as preliminary assessment of the capabilities of radio receiving facilities for the electromagnetic accessibility of controlled sources of radio emissions in these areas, which, due to their tactical and technical characteristics, can (or cannot, or may with a decrease in tactical and technical indicators) operate in minimized forecast geographic zones ( to solve the monitoring problem).
The achieved technical result of the invention is to reduce the calculation time spent on determining areas for placing different types of technical equipment by decision-makers, by reducing subjective factors and errors, by reducing the volume of analyzed data in conditions of a priori uncertainty based on the use of information technology, which allows saving hardware computer resources and use small-sized, object-oriented, network mobile systems.
Known methods for assessing terrain are based on the analysis of a priori and a posteriori information stored in databases and data banks about the properties of the terrain using digital digital maps and information using GIS and other sources.
For example, when assessing terrain under various conditions, data obtained from topographic maps and aerial photographs are used. [Nikolaev A.S. and others. Military topography. / M.: Military Publishing House of the USSR Ministry of Defense, 1997; Govorukhin A.M. and others. Handbook of military topography. - M.: Military Publishing House, 1980, p. 111, 3, sheet 12-2.4; SOUTH. Maslak et al. Military topography in the service and combat activities of operational units. - M.: Academic Project, 2005]. This technology, based on the use of paper maps, is classical and generally accepted, of great importance, but the disadvantage of the known method is its practical lack of focus on the use of modern geographic information technologies, in particular, the global navigation satellite system (GLONASS) and geographic information system. This method for solving the problem of quickly selecting a suitable geographic area for placing radio receiving systems is not applicable, since it requires a significant amount of topographic information (digitization, scanning, creating a database of data banks, etc.).
There is a known method for assessing terrain proposed by P.A. Ivankov, G.V. Zakharov. [Terrain and its influence on the combat operations of troops - Publisher: Ministry of Defense of the USSR, 1969]. This methodology does not provide for the use of modern information technologies, GIS and digital computer tools and is focused on a high degree of subjectivity when decision-making by officials.
There is a known method for laying out routes for different types of transport complexes with different traffic areas using geoinformation technologies and digital computers (patent RU No. 2045773, IPC G06F 17/16 dated 10/19/1995), where the main criterion for choosing the optimal route is the saving of fuels and lubricants. The advantage of the known invention is its orientation towards modern geoinformation technologies, however, the specified method solves other problems and uses other optimization criteria, therefore it cannot be a complete prototype of the method proposed by the authors, but certain elements of the known invention, such as the use of GIS and digital computer data, are borrowed in the proposed invention.
There is a known method in which optimization of station location coordinates is proposed, thereby ensuring the most effective coverage, i.e. minimum number of zones with unstable coating (patent RU No. 2460243, IPC H04W 16/18 dated February 17, 2011). This method uses modern information technologies based on digital computers according to the criterion of the minimum acceptable signal level. The disadvantage of this known method is the assessment of the geographic area directly in the process of optimizing the location area, which leads to the need to process large amounts of information.
There is a known method for plotting the optimal movement of mobile objects over rough terrain [Dorogoe A.Yu., Lesnykh V.Yu., Rakov V.I., Titov G.S. Algorithms for optimal movement of mobile objects over rough terrain and transport networks. - St. Petersburg State Electrotechnical University, 2006], including the stages of determining the initial element to optimize the loading of an electronic map of the area, determining the start and finish point, and finding optimal routes. This method does not allow pre-filtering by certain characteristics of the data before the optimization process and, thereby, reducing the sample size to be processed on a computer, which requires the use of powerful resource-intensive computing systems and leads to an increase in information processing time.
It is stated that the closest in essence to the claimed invention is a method for plotting a travel route on rough terrain (patent RU No. 2439, IPC G01C 21/34 dated July 15, 2010), which proposes an assessment of the geographical properties of the area according to geographical criteria and criteria patency without evaluating effectiveness. However, in this prototype, the criteria for laying out a route on the ground are saving the consumption of fuel and lubricants and the ability to overcome geographical zones of the terrain by a mobile vehicle.
The purpose of the present invention is to reduce the time required to determine locations on the ground for various types of technical equipment of a radio receiving complex
The solution to this goal is implemented in the form of a technique represented by the flowchart of the algorithm in Fig. 1.
At stage 1 (Fig. 1), operational and tactical data are entered for a given geographic area, which include initial data on the area (sector, zone) of the area being assessed, time of day (night, morning, evening or day for spring-autumn or summer time) , characteristics of the season (winter, spring-autumn, summer), line of sight capabilities and others, depending on the assigned tasks.
At stage 2, a tool (complex) is determined to implement a method for assessing location on the ground in a given geographical area, taking into account accepted criteria and restrictions with the involvement of GIS, GLONASS, digital computer and other modern technologies.
At stage 3, a digital map of the area is downloaded for the geographic area determined at stage 1.
At stage 4, conditions are set and criteria are determined for minimizing the geographic area determined at stage 1 in order to exclude from this area areas unsuitable for the placement of radio receiving systems, for example, according to administrative, geographical or physical (or other) parameters (features).
At stage 5, to organize a conditional cycle when repeatedly calculating geographical zones according to various private criteria, a counter is installed for the number of the current private criterion for calculating and assessing the properties of the geographical zone.
At stage 6, the next particular criterion used in this calculation cycle to optimize the geographical area is determined (or calculated).
At stage 7, if necessary and if possible, based on the results of the previous calculation in the cycle (if there was one), the geographic zone on the central digital computer is specified. Next, after analyzing this zone, the step of scanning the geographic zone is selected, i.e. a grid at the nodes of which informative terrain features will be calculated according to the current criterion and superimposed on the DCM. It should be remembered that a large scanning step speeds up the solution of the problem, but negatively affects the accuracy of the results and vice versa.
At stage 8, informative features are calculated at the nodal points of the DCM scanning, and an information array of the results of scanning the geographic area is generated according to the current particular criterion.
If at stage 9 the quality of the calculation and the results satisfy the conditions of the problem statement, then at stage 11 the information array is output and visualized with reference to the digital computer. Based on these data, the results are analyzed and a decision is made. If the calculation results are not satisfactory, then at step 10 the scanning algorithm is modified and another scanning step is selected for re-calculation.
At stage 12, the condition for the end of the cycle organized at stage 5 is checked, for which the number of the particular criterion is evaluated, and, if it is the last, then proceed to stage 14, where the generalized geographical criterion is calculated for the optimized geographic zone on the CCM for the area determined at stage 1 and minimized at stage 4, while informative features are determined at the nodal points of the DCM scan, taking into account the generalized criterion, which is additive and is defined as the sum of particular criteria. If the number of the private criterion is not the last, then at step 13 the number of the private criterion is modified and another one is selected for the next calculation.
At stage 15, the output and visualization of the information array is carried out according to a generalized geographical criterion to analyze the results and make the necessary decisions.
Next, after minimizing and optimizing the geographic zones at the central computer, the nomenclature (list) of radio receiving systems that can be used in a given geographic zone to perform the assigned tasks is determined according to geographic criteria, followed by an assessment of their effectiveness.
To do this, at stage 16, tactical and technical restrictions and initial conditions are introduced for the possible use of radio receiving systems in a given geographical area to solve special problems. They include factors that depend on the conditions for using the funds, as well as the basic requirements for placement.
At stage 17, a nomenclature of possible types and the number of radio receiving systems intended for use are introduced in order to solve the problem of their placement in a given minimized geographic area.
At stage 18, in order to organize a conditional cycle when repeatedly calculating the effectiveness of using the entire range of certain radio receiving complexes according to the relevant tactical and technical data (criteria), a counter for the number of the radio receiving complex used is installed.
At stage 19, the next radio receiving complex used in this calculation cycle is determined, and its tactical and technical data are entered (or calculated).
At step 20, the feasibility of placement is assessed and the effectiveness of the possible use of the current radio receiving system in a given geographic area is checked.
At stage 21, the condition for the end of the cycle organized at stage 18 is checked, for which the number of the current radio receiving complex from the nomenclature under consideration is assessed, if it is the last, then proceed to stage 23, where information is generated about the feasibility, possibility and effectiveness of the special application determined at stage 17 radio receiving complex for a minimized geographical area. If the number of the radio receiving complex is not the last, then at step 22 the number of the radio receiving complex is modified to perform the next calculation.
At stage 24, the output, visualization and analysis of the results are carried out to make a decision on the placement of radio receiving systems and compliance with the conditions of their use. At the same time, the geographical area is structured into zones of possible use of specific radio receiving systems from the range under consideration to solve the assigned tasks.
The proposed methodology fits into the modern concept of command and control as follows. There is a great complexity of solving control problems in conditions of extreme shortage of time allocated for planning operations (combat actions) with a shortage of personnel in control bodies, sharply aggravating the global problem of completeness and timeliness of information processing. In order to move to a new qualitative level, it is necessary to jointly use modern tools (GIS, GLONASS, TsKM and others) in automated systems for military purposes. A significant number of combat and regulatory technical documents correspond to the concept of warfare of the 70s - 80s. At the same time, most of the tasks of command and control require for their solution information about the terrain, the preparation and processing of which is currently largely carried out in the traditional way, i.e. manually. Automation of control processes through new information technologies and their use at the system level by troops requires the development and use of special technologies for assessing the situation in areas of special purpose at the preparatory stage, i.e. in peacetime. Therefore, the need to solve the problem of preliminary assessment of the geographic area for the placement of radio receiving systems, taking into account the tactical properties of the area, exists, since it is one of the most important in organizing special operations and will be the main limitation for performing the immediate task of optimizing the placement of radio receiving systems in a given area. This method takes into account:
Concept of integration of geographic information systems and new information technologies;
Operational and tactical operating conditions and tactical and technical characteristics of radio receiving systems intended for deployment in a given area;
Tactical properties of the terrain in combination with seasonal climatic conditions;
Saving hardware resources for a significant amount of input information when using small-sized, object-oriented mobile computing tools.
Thus, the proposed method of assessing the terrain consists in performing new operations and a new sequence of their implementation and has a number of significant advantages that make it possible to minimize and structure the proposed area for placing radio receiving systems, reduce the time for making a decision on the deployment of assets in positional areas, and ensure a high degree of use of information technologies, reduce the subjective factor in decision-making by officials, increase the efficiency of using radio receiving systems, and the use of a geographic information system allows you to reliably, with accuracy and completeness, display the current state of the area, its typical features and characteristic features at the present time.
Thus, the claimed technical solution meets the invention criterion of “novelty”.
Analysis of known technical solutions in the studied and related areas allows us to conclude that the introduced operations are partially known. However, their introduction into the method of assessing the location of radio-receiving complexes, taking into account the tactical properties of the area using a digital computer and a specialized software and hardware complex “Geographic Information Systems” in the specified sequence, gives this method new properties.
Thus, the technical solution meets the criterion of “inventive step”.
The proposed technical solution can be used in an automated troop control system when managing units and subunits when solving optimization problems, which require minimizing the initial information at the preliminary stage.
Sources of information
1. Bellman R. Dynamic programming. - Publishing house of foreign literature. - 1960, 400 p.
2. Gitis V. Fundamentals of spatiotemporal forecasting in geoinformatics. - M.: FIZMATLIT, 2004. - 256 p.
3. “Review of domestic GIS for military purposes, February 2014”, [Electronic resource] - Access mode: - www.gistechnik.ru
4. Bryson A. Applied theory of optimal control: Optimization, evaluation and control. - M.: Mir. - 1972. - 544 p.
5. Reikleitis G. Optimization in technology. - M.: Mir. - 1986 - 347 p.
6. Tikunov V. Modeling in cartography. - Moscow State University Publishing House. - 1997 - 400 p.
A method for assessing terrain for the placement of radio receiving equipment, including entering initial conditions and data for a given geographic area, loading a digital terrain map (DTM), calculating geographic zones according to various particular criteria, generating information about the zones of possible placement of radio receiving equipment according to their tactical and technical characteristics , clarification of the geographical zone on the central station, characterized in that the initial assessment of the area is carried out according to the physical-geographical conditions recorded on the central station, exclusion of areas unsuitable for the placement of radio-receiving complexes due to the operational and technical capabilities inherent in the radio-receiving facilities being placed when performing control tasks, is carried out optimization of the digital computer using dynamic programming methods according to specific and general criteria for the area of possible placement of radio receiving systems on the ground with subsequent assessment of the possibility of radio receiving systems located in a given geographic area.
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The purpose of the module is to describe the principles of determining the location of objects based on the use of position lines.
In navigation in general and in radio navigation in particular, the problem of determining location is solved using the basic concepts of a navigation parameter and a position line.
Navigation parameter (NP) is a measured quantity used to determine location (MP).
NP - angle, range, distance difference, sum of distances.
Each LP corresponds to a line of position (LP) (position surface) - this is the geometric locus of points of equal values of the LP.
To determine the LP when using various direction finding methods, consider diagrams for determining the position line:
Goniometer system:
Figure 1
The angle defines the angular MP, in this case the position line is a straight line.
Technically, the goniometric method can be implemented using a rotating directional antenna system.
Rangefinder system:
Figure 2
When using the rangefinder method, the distance to the object is measured. The antenna used is omnidirectional, but a request-response system may be required.
The position line in the rangefinder method is a circle.
Figure 3
The peculiarity of the difference-rangefinding method is that the objects themselves do not emit anything, but only receive signals, the antennas are non-directional, and the system can serve an unlimited number of consumers.
The position line in the difference-rangefinder method is a hyperbola.
Total rangefinder system:
Figure 4
In a summative rangefinder system, one navigation point emits a signal, the object re-emits it, after which the signal is received by the second navigation point.
The position line in the total rangefinder method is an ellipse.
The position lines corresponding to the considered direction finding methods are given in the following table.
The location of the object is determined by the coordinates (point) of the intersection of lines (surfaces) of position with the same value of the navigation parameter. To solve the navigation problem, i.e. to find the MP, use navigation functions that define the functional relationship between navigation parameters and the object’s MP.
To determine the MP, the intersection of at least two LPs is required, therefore the methods for determining the MP are characterized by a selected pair of methods for determining the LP and can be represented by corresponding diagrams for determining the MP.
Diagrams for determining the location of objects on a plane.
1. Goniometer system:
Figure 5
2. Rangefinder system
Figure 6
DRM - rangefinder radio beacon.
3. Goniometer-rangefinder system:
Figure 7
ARM - azimuth radio beacon.
Difference-rangefinder system:
Figure 8
VM - slave, VSC - master.
This principle works: Laurent - S, Chaika, RSDN.
5. Total rangefinder system
Figure 9
Pseudo-rangefinder system.
An interesting variety of rangefinder methods is pseudo-rangefinder, to explain the essence of which we consider the following auxiliary figure.
Figure 10
In this figure - the distance between objects and, - the speed of light, - the unknown moment of signal emission, - the moment of signal reception, which is known. The problem of the unknown moment in time can be solved if information about this moment is encoded in the transmitted signal itself. But in this case, due to the inevitable divergence of clocks by an amount on objects, it is not the true range that is measured, but the pseudo-range
In the figure, the dotted line shows the displacement of the position line by an amount. However, the task of determining the MP in this case can be solved by using three navigation points, as shown in the following figure, in which solid lines correspond to true ranges, and dotted lines correspond to pseudo-ranges.
In this case, the true position of the object is in the middle of the triangle formed by the dotted pseudo-range lines.
Figure 11
Figure 12
Project assignment
Task. Determine how many intersection points of the LP on the plane there can be if the radio navigation system uses the rangefinder-cumulative-rangefinder method.
The position line for the rangefinder method is a circle, and the position line for the total rangefinder method is an ellipse.
To determine the possible number of intersection points of the LP, it is necessary to depict on the plane the possible mutual positions of the circle and the ellipse. The four below outline the relevant provisions.
Figure 13
Figure 14
Figure 15
Figure 16
From the presented figures it follows that if the radio navigation system uses the rangefinder-total-rangefinder method, then the position lines can intersect at one, two, three and four points.
Didactic tests of midterm control
Test 1. What type of antenna is required to implement the goniometric method? Choose the correct answer from the table below.
Test 2. What type of antenna is required to implement the rangefinder method? Choose the correct answer from the table below.
Test 3. What does the position line look like in the difference-rangefinder system? Choose the correct answer from the table below.
Test 4. What is the shape of the position line in the total rangefinder system? Choose the correct answer from the table below.
Table of keys with correct answers
The table with keys can be given to the student after completing the tests. The test results are converted into a rating on a five-point scale using the following table
Based on the totality of measured geometric parameters, the system for determining the location of EMR sources is divided into:
· triangulation (goniometer, direction finding);
· difference-rangefinders;
· angular-difference-rangefinders.
The type and number of measured geometric quantities determine the spatial structure of the system for determining the location of the EMR source: the number of spatially separated receiving points of EMR source signals and the geometry of their location.
The triangulation (goniometer, direction finding) method is based on determining directions (bearings) to the EMR source at two points in space using radio direction finders spaced at base d (Fig. 18, a).
Rice. 18. Explanation of the triangulation method for determining the location of the EMR source on the plane (a) and in space (b)
If the EMR source is located in a horizontal or vertical plane, then to determine its location it is enough to measure two azimuth angles μ1 and μ2 (or two elevation angles). The location of the EMR source is determined by the intersection point of straight lines O1I and O2I - two position lines.
To determine the location of the source in space, measure the azimuth angles qa1 and qa2 at two spaced points O1 and O2 and the elevation angle qm1 at one of these points or, conversely, the elevation angles qm1 and qm2 at two receiving points and the azimuth angle qa1 at one of them (Fig. 18, b).
By calculation, the distance from one of the receiving points to the source can be determined using the measured angles and the known base value d:
from here we equate two expressions for h:
Thus, the distance to the source
The triangulation method is easy to technically implement. Therefore, it is widely used in radio and RTR systems, in passive radar diversity systems for detecting and determining the coordinates of emitting objects.
A significant disadvantage of the triangulation method is that with an increase in the number of EMR sources located in the coverage area of direction finders, false detections of non-existent sources may occur (Fig. 19). As can be seen from Fig. 19, along with determining the coordinates of three true sources I1, I2 and I3, six false sources LI1, ..., LI6 are also detected. False detections can be eliminated when using the triangulation method by obtaining redundant information about direction-finding sources - by increasing the number of spaced direction finders or by identifying the received information as belonging to a specific source. Identification can be carried out by comparing signals received by direction finders by carrier frequency, repetition period and pulse duration
Rice. 19.
Additional information about sources is also obtained through cross-correlation processing of signals received at spaced points in space.
Elimination of false detections when using the triangulation method is also possible by obtaining data on the difference in distances from the radiation source to receiving points (locations of radio direction finders). If the point of intersection of the bearing lines does not lie on the hyperbola corresponding to the range difference, then it is false.
The difference-range-measuring method of location determination is based on measuring, using RES, the difference in distances from the EMR source to receiving points separated in space by a distance d. The location of the source on the plane is found as the intersection point of two hyperbolas (two range differences measured at three receiving points) belonging to different bases A1A2, A2A3 (Fig. 20). The focal points of the hyperbolas coincide with the locations of the reception points.
Rice. 20.
The spatial position of EMR sources is determined by three range differences, measured at three to four receiving points. The source location is the intersection point of three hyperboloids of revolution.
The goniometer-difference-rangefinder method of location determination involves measuring, using RES, the difference in distances from an EMR source to two spaced receiving points and measuring the direction to the source at one of these points.
To determine the coordinates of the source on the plane, it is enough to measure the azimuth μ and the difference in the ranges of the arterial pressure from the source to the receiving points. The location of the source is determined by the intersection point of the hyperbola and the straight line.
To determine the position of the source in space, it is necessary to additionally measure the elevation angle of the EMR source at one of the receiving points. The source location is found as the intersection point of the two planes and the surface of the hyperboloid.
Errors in determining the location of an EMR source on a plane depend on the errors in measuring two geometric quantities:
· two bearings in triangulation systems;
· two range differences in difference rangefinder systems;
· one bearing and one range difference in angular-difference-rangefinder systems.
With a centered Gaussian law of distribution of errors in determining position lines, the root-mean-square value of the error in determining the location of the source is:
where are the variances of errors in determining position lines; r is the cross-correlation coefficient of random errors in determining the position lines L1 and L2; r - angle of intersection of position lines.
For independent errors in determining position lines, r = 0.
With the triangulation method of determining the location of the source
Root Mean Square Position Error
When using identical direction finders
The greatest accuracy will be when the position lines intersect at right angles (r = 90°).
When assessing errors in determining the location of a source in space, it is necessary to consider measurement errors of three geometric quantities. The location error depends in this case on the relative spatial orientation of the position surfaces. The highest accuracy of position determination will be when the normals to the position surfaces intersect at right angles.