MULTIFUNCTIONAL SYSTEM FOR DISPATCHING AND MONITORING MOBILE AND STATIONARY OBJECTS “ALMAZ”
INTRODUCTION
The basis of any complex of technical means for determining the location of moving objects is, first of all, the actual system for determining the location of moving objects.
There are many different methods and systems for determining the location.
A fairly complete classification of known systems and methods is given in the article “Systems and complexes of technical means for determining the location of moving objects” (“Special Equipment”, No. 3, 1998)
Among the well-known systems for determining the location of mobile objects, the most interesting is the American global positioning system (GPS) “Navstar” because it is fully deployed, has been functioning for many years and is currently supported in full.
GPS receivers for civilian use are sold all over the world in a variety of forms, in the form of navigators for individual use, in the form of watches, etc.
The Russian analogue of this system is the “GLONAS” system.
Both systems are designed for military use.
However, if the American GPS system has been deployed for a long time and has been properly maintained for a number of years, the Russian GLONASS system was fully deployed relatively recently.
Thanks to the reforms carried out in the country, and most importantly in the Russian armed forces, the fate of the system is constantly in question, its operation requires significant costs.
However, at present, GLONASS receivers for civil use have been mastered in serial production and are presented on the Russian market, although they are approximately twice as large in size and cost as GPS receivers.
The systems are similar in design.
Both Navstar and Glonas are a system of 24 satellites launched into near-earth orbit, each satellite determines its location in space with high accuracy using the stars and every second, in a high-precision system of time common to all satellites, transmits its coordinates over the air.
The receiver located on the ground receives information from several satellites and measures the delay in receiving the signal.
The receiver includes a computer that solves the spatial problem of determining the location of the receiver itself in space.
It is necessary to note two main differences between the systems.
If the Navstar system uses code division of signals, then the GLONASS system uses frequency division, which leads to more complex processing of received signals and, as a consequence, to an increase in the dimensions, energy consumption and cost of receivers.
The second difference is the following. that the satellites of the GLONASS system have a period of revolution around the earth slightly longer than 24 hours, while in the Navstar system the period of revolution of satellites around the earth is exactly 24 hours.
Thus, for an observer on Earth, the position of the Navstar satellite constellation for each moment of time during the day is known in advance and is repeated on subsequent days.
This means that it is possible to select the best and most accurate observation periods for each observation point during the day.
In the GLONASS system, the period of satellite revolution around the Earth is slightly longer than a day, so the repetition of the position of the satellite constellation is significantly longer than a day, which allows for greater average accuracy in determining coordinates.
The idea of creating a system
Positioning systems are widely used for navigation of sea vessels, land vehicles, during survey work, etc.
The overwhelming majority of positioning systems do not have channels for transmitting coordinate information to the center and are used as navigation systems.
The idea of building a multifunctional monitoring system “Almaz” with a central dispatch center for collecting information arose due to the rapid development of cellular communication systems in recent years.
Since the receiver of the global positioning system, receiving information from satellites, calculates the coordinates of its location in space, when building dispatch systems, the task of delivering information about the location of an object equipped with such a receiver to the dispatch center arises.
In other words, the essence of the problem is in choosing a transport network for delivering this information to the control center.
Information about the location of a remote object can be transmitted via radio channels of a trunking communication system, via VHF radio communication channels, using a network of receiving devices located throughout the city united by an information collection subsystem, etc.
When selecting information transmission channels, it is important to ensure the continuity of information delivery throughout the serviced area, while the selected channel must be sufficiently inexpensive.
In our opinion, the use of inexpensive short message channels of the GSM 900/DCS 1800 cellular communication system meets this criterion to the greatest extent.
Our studies prove the correctness of the choice made.
Tests on data transmission via analog channels of the Moscow Cellular Communications Company showed low reliability of data transmission, which leads to frequent disconnections between modems due to exceeding the permissible error threshold.
Restoring the communication channel requires time to dial, so continuity of data delivery is not achieved.
Similar tests conducted on AMS and DAMS communication channels of the Beeline Company yielded approximately the same results.
The reliability of information transmission via these channels is somewhat higher, but this did not change the situation significantly; interruptions in communication remained unacceptably frequent.
The reliability of information transmission during tests on voice channels and short message channels of digital cellular communication of the GSM 900/DCS 1800 standard of MTS turned out to be approximately two orders of magnitude higher compared to analog channels.
During the tests, there were practically no interruptions in information transmission.
In addition, the use of analog cellular communication systems involves the transmission of information via voice communication channels that are more expensive than short message channels of GSM 900/DCS 1800 cellular communication systems.
Structural diagram of the Almaz system
The Almaz system is a network of remote terminal devices located on mobile and stationary objects and a dispatching and monitoring center.
Information from remote terminals is received via short message channels or via GSM 900/DCS 1800 voice communication channels to the dispatching and monitoring center for accumulation and subsequent processing. The structural diagram of the system is shown in Figure 1.
The terminal devices installed on mobile objects include a GPS receiver, which is used to determine its location.
Information about the location of the object is transmitted to the center in the form of short messages using a GSM modem.
The terminal device processes signals from the object's security system via 8 or 16 inputs and, in the event of a threat, transmits a pre-programmed short message to the center or to a telephone number also pre-programmed.
The terminal device can process an analog value (voltage) coming from any sensor via two inputs and transmit information about reaching a preset threshold value or about this value going beyond a specified interval.
Terminal devices for stationary objects differ from terminal devices for mobile objects mainly only by the absence of GPS receivers in their composition and perform all the other functions listed above.
The center receives information from a number of sensors located on mobile and stationary objects and accumulates it in the corresponding databases from its mathematical software. Data on the location of mobile objects is displayed on an electronic map as a point or a trajectory of the route of movement.
The remaining data is archived and subject to statistical processing. The routes of movement of mobile objects are also accumulated in the corresponding databases of the center.
The center can transmit commands to the terminal device. In accordance with the received commands, the terminal device can control the actuators of the vehicle systems or utility networks of a stationary object.
For example, close the central lock of the car, turn on the heating in a country house, etc.
The terminal device can control the actuators via 8 or 16 lines.
Terminal equipment
The functional diagram of the terminal device is shown in Figure 2.
— the dashed line shows the software and hardware units that can be additionally included in the terminal
The terminal device includes a dual-mode GSM modem to provide two-way communication between the terminal and the center, a GPS receiver to determine the current coordinates of a moving object, a device for interfacing with security sensors to monitor the facility's security system, and a unit for interfacing with actuators.
The terminal controller operates according to the program recorded in its memory and controls all devices, processes commands received from the center, generates control actions on actuators, and generates short messages for transmission to the center.
In the minimum basic package, the terminal can process up to 8 dry contact inputs from the security system and generate a corresponding alarm message for each of its activations, the text of which is determined by the customer.
Alarm messages can be transmitted to several (up to 8) mobile phone numbers in addition to the center. The sequence of alarm message transmission to addresses is programmed during installation and can be changed remotely by command from the center.
The terminal processes analog voltages via two inputs. The terminal can transmit a message about excess or decrease of voltage at this input relative to the programmed value.
The range of permissible voltages can be programmed, and the terminal will transmit a message about the value of the controlled voltage leaving the specified range.
The threshold values and limits of permissible voltage ranges on the analog inputs of the terminal are programmed before its installation and can be changed by remote command.
Having received the corresponding command from the center or from a mobile phone, the terminal can generate an effect on the corresponding actuator of any object system, for example, lock the car doors using the central lock or turn on the heating in a country house.
When installed on a car, the terminal is powered from the on-board network; when installed on a stationary object, power is supplied from the AC network.
The terminal can be equipped with additional hardware and software units that expand its capabilities. Additional interface units allow increasing the number of inputs for processing security sensors and outputs for controlling executive devices of the systems of the controlled object.
The speech terminal allows organizing voice communication between the center and the object. Using a hidden microphone, you can monitor the acoustic environment at the object. The backup power supply unit ensures the terminal continues to function when the network or on-board power supply fails.
The terminal kit includes two remote antennas for cellular communications and a GPS receiver.
Central equipment
The software and hardware complex of the Monitoring and Control Center (PTK CMC) is a complex of information, software, hardware and technological means that ensure the collection, analysis and accumulation of information on changes in the state of monitored objects, the development and transmission of control actions corresponding to the situation that has arisen.
During the design of the PTC TsUP, the following provisions were selected as basic ones.
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- The need for maximum use of the advantages that provide the means implemented by the company «MTS» in its network based on the introduction of equipment and software implementing the service «transmission of short messages» in GSM systems.
Communication with mobile objects in combination with the ability to simultaneously transmit data and voice information, increase the speed and probability of data delivery, and the reliability of their transmission allows for increased efficiency and quality of control in a rapidly changing environment.
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- The PTC CMU must ensure support for the operability of systems of various functional purposes, providing control and management of objects (both mobile and stationary), which are based on the use of mobile communications.
In addition to the main tasks — monitoring the location of moving objects, processing data from sensors and controlling the actuators of a moving object — the PTC MCC can also solve other tasks, such as providing objects with various types of reference information, notifying about the need to change the route, organizing interaction between objects in a group, monitoring the state of the environment, etc.
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- The PTC MCC must have the property of scalability, i.e. represent a single model range of unified functionally complete complexes of various capacities (number of simultaneously serviced objects), cost, differing in the set of functions performed and other characteristics associated with the specific application.
The software and hardware of the PTC CMU is a set of automated workstations (AWP), means of organizing and maintaining arrays of information, means of displaying information for collective and individual use, combined as part of a local or distributed computing network.
The technical base of the automated workplaces are IBM PC-type personal computers equipped with peripheral equipment and, if necessary, means of collecting and transmitting information.
SIMENS GSM Module M20 Terminal cellular modems are used to receive and transmit messages.
The software base is ready-made (purchased) application software packages and developed software for functioning in the Windows-98/NT environment.
Borland C++ Builder 4.0, MS Visual FoxPro 6.0/6.3, MapBasic 4.5/5.0 were used for software development. MapInfo Professional 4.5/5.0 package is used for displaying and processing geoinformation.
The following subsystems are included in the PTK CMU:
The subsystem for exchanging information with control objects via radio channel and via the CKS ensures the reception of data packets from control objects and users, decoding and verification, as well as transmission to control objects and users.
Data packets or voice messages
The data analysis, accumulation and processing subsystem stores data packets in an archive, performs semantic analysis of received messages and ensures the implementation of actions specified for a given situation.
The display subsystem provides output of information about the location, routes of movement of objects on the electronic map (detailed and overview) and in text form, as well as voice and (or) text notification of changes in the state of an object (group of objects).
Figure 3 shows screen forms that display the location of objects on the electronic map (“Overview Map”, “Additional Window”, main window) and in text form (“Location of Objects”).
The information retrieval subsystem determines the location area of objects and provides the user, in text form or on the EC, with information (references) on the movement and state of the OK based on the data accumulated in the “Archive” database.
The route planning subsystem generates a route description for each of the control objects, which includes the coordinates of the zones or route sections, a description of the territories (zones) on the route that require a special response, as well as a time schedule for movement along the route.
The information and reference subsystem provides information on objects (groups of objects) under control, users, situations, routes of movement and location for the required period of time, system operation, user access to procedures and data, etc.
The subsystem for setting operating parameters provides the ability to set the configuration of the SVT, the placement of program and information files, parameters for information interaction with objects and users via communication channels, control parameters for system procedures, etc.
The control and diagnostics subsystem detects equipment failures and malfunctions, records events of this type in the corresponding files, and implements the necessary actions to eliminate the consequences of malfunctions.
The technological support subsystem is designed to implement measures to ensure information security, perform technological operations to update, configure, copy, and restore the TsUP PTC database.
The system uses electronic maps (EM) of the city at a scale of 1:10,000, prepared for visual perception and containing toponymic and address information, as well as overview EM that match the geographic or metric coordinates of geo-objects with the main EM.
The EM includes layers containing object routes, critical zones for determining special situations, and information identifying city territories.