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Pisetskiy Yuriy Valerevich, Tashkent University of Information Technologies Tashkent, Uzbekistan, E-mail: yuriy.pisetskiy@mail.ru
THE DESIGN CONFIGURATION OF RADIO MONITORING SYSTEM AIMED AT ENVIRONMENTAL MONITORING
Abstract: This article proposes the design configuration of the radio monitoring system for environmental monitoring at production facilities. The configuration of the radio monitoring system and the block diagram of the central control panel are presented. The work of the radio monitoring system is described.
Keywords: Ecology, environment, radio monitoring, sensors, radio channel, transmitter, receiver, controlled objects, protection system, frequency.
Introduction
In science in general, for a long time, the classical definition of ecology as a branch of biology was accepted that was aimed at studying the interaction of organisms with the environment in which they live, including all living and non-living components. The environment is made up of physico-chemical and biological components. Physicochemical components are light, heat coming from the sun, humidity, wind, oxygen, carbon dioxide, nutrients in soil, water, atmosphere. Biological components are organisms of the same variety, plants and animals [1].
The problem of ecology and environmental pollution is currently at the core of all issues. The environment is the medium wherein people do live. The environment is constantly polluted with various exhaust gases from cars, emissions from industrial plants, thermal stations, combustion products, etc. Therefore, in order to preserve the biosphere, it is necessary to monitor negative impacts [2].
The most effective methods of control is the use of monitoring systems. There are many modern systems of environmental monitoring. Different systems are used in different conditions, depending on the goal. To develop a methodology and create an environmental monitoring system, it is necessary to know the conditions in which it will work. And also the requirements to developed method and system should be clearly defined [3].
Technique of experiments
Currently, there are many methods and monitoring systems. But it is difficult to choose the optimal one for specific conditions and requirements. This is due to the fact that existing methods can be too expensive, or too complicated, either not satisfying the goal. Therefore, new methods and monitoring systems are being developed for certain sites where monitoring is needed. The designed systems should have all necessary functionality and be optimized for price and quality.
In accordance with the requirements, the developed monitoring system should be adapted to the real conditions for working in desert conditions. The system should include a central console, data transmission channels and actuators. Monitoring will be carried out at gas production and refineries. Such enterprises have a complex infrastructure and considerable distance from each other major technological nodes around which monitoring is to be carried out. Therefore, when choosing a data transmission channel, we will stop
at the radio links. This will greatly reduce the cost of the purchase of cables and their installation. And there is no risk of damage [4].
To create a monitoring system, we also need executive devices that determine the components of the environment. To determine the physicochemical components of the environment, sensors suitable for a given composition of the medium are widely used. A sensor is a device that generates a signal under the influence of external irritating factors. The classification of sensors is based on the principle of their operation. The principle of action can be based on physical or chemical phenomena and properties.
For the required conditions, the choice of a thermocatalytic sensor is optimal, since it has all the necessary parameters for our monitoring system. These devices are used in monitoring devices for mines, mines, oil storages, gas pipelines. Such sensors are able to determine the content of gases: ammonia, methane, hydrogen, oxygen, carbon monoxide and the sum of hydrocarbons.
Experimental results and discussion
Since the monitored objects in most cases have a complex infrastructure, the proposed design uses a radio channel to transmit information from the sensors to the control center for the parameters. To increase the noise immunity of the radio channel, the signals are transmitted in digital form. The configuration of the developed radio monitoring system is shown in Fig. 1 [5].
The system consists of four transceivers located in the necessary areas for monitoring the environmental parameters and a central control unit (CCU), where information is received. In the central control panel, a transmitter and a receiver are installed, as well as an emergency alarm device from each one entering the transmitter system. Assess the current state of the environment allows the monitor to which the information received from the sensors is output.
Simultaneous operation of 4 transceivers is possible only at different frequencies, which complicates the circuit design of the system being developed. Therefore, the system was found to work at the same frequency. The frequency was chosen at 27 MHz. 27MHz (civil band), with the authorized output power ofthe transmitter up to 10W. At the same time, the communication range ofthe developed device is about one kilometer, with a transmitter power of up to 1W [5].
According to the development requirements, peripheral transmitters are located in places that can only be powered by batteries. Then assess the state of the environment better discretely, i. e.
within the certain time interval. In our case, the interval was chosen for 10 seconds, thereby achieving economical energy consumption 20 minutes, and during these 20 minutes the transmitters operate of the batteries.
Figure 1. System configuration of the radio monitoring equipment
The operation of the transmitters is synchronized by a synchronization pulse, which is emitted every 20 minutes by a transmitter located in the CCU. The timers of the peripheral transmitters are triggered by this signal. Seconds of time are formed, 10 seconds the transmitter operates in the battery voltage monitoring mode, the next 10 seconds is the transfer of information from the sensor and 10 seconds - the guard interval. After 20 seconds of operation, the transmitters are turned off. Then the cycle of work is repeated.
Peripheral receivers serve to receive the synchronization signal and after the timer starts the synchronization signal, the receiver automatically turns off. This is necessary so that there are no false positives, since the receiver receives all signals at 27 MHz. The algorithm of the system is set by means of timers.
In Fig. 2 a block diagram of the CCU is presented. When the CCU is turned on, the timer starts. The signal from the timer goes to the clock driver, to the device controlling the operation of the transmitter and receiver. From the control unit, the signal is sent to the receiver, transmitter and antenna switch. The receiver is turned off. The transmitter is switched on by the timer only for the time of the timing output, which is received by the peripheral receivers simultaneously. After passing the clock, the transmitter turns off and the receiver turns on. At the same time, a control signal is sent to the antenna switch. The signal from the receiver is fed to the eight-channel receiver via a time slot generator. From an eight-channel receiver, the signal, divided by channels, passes through a digital-to-analog converter and is sent to an eight-channel monitoring device, which indicates the states of the sensors and the battery. In this way, the status of sensors located at a remote distance is controlled [6; 7].
The radio channel of the CPU is designed in accordance with the standard scheme, which includes: a transmitter, a receiver, an antenna switch. The control unit of the system includes a time interval
generator, a timer, a sync signal generator, a radio channel control device. The receiver-control unit contains an eight-channel receiver with a serial to serial converter, digital-to-analog converters, and an eight-channel monitoring device [8].
The radio transmitter device used in the system includes: a transmitter, a modulator, an electronic key, including a command transmitter and an adjustable voltage regulator, which serves to adjust the transmitter output power from 0.5 W to 5 W, depending on the supply voltage. To adjust the output power, there is also an attenuator connected between the antenna and the transmitter output. The manufacture and use of such radio transmitting devices throughout the world is regulated by the relevant legal norms [5]:
A) The maximum power is 1 kW.
B) Operating frequency 27, 12 MHz.
C) Type of radiation: manipulated unmodulated carrier frequency.
D) The level of radio interference from harmonic and spurious emissions at a distance of 30 m from the transmitter should not exceed 30 ^V/m.
As the master oscillator in the transmitter a generator with quartz frequency stabilization, with a quartz resonator in the base circuit and modulation of the generator along the emitter circuit was used. Three-point circuits with resonators, respectively, and the collector of the transistor are distinguished from the point of inclusion of the resonator. A circuit with a quartz resonator connected between the base and the collector of the transistor is called a capacitive three-point circuit. With the inductive character of the reactance connected in series with the resonator, the latter can be excited at a frequency below or above the frequency of the series resonance. At a certain value of this reactance, the resonator is excited at a frequency of successive resonance.
Figure 2. Block diagram of the central control unit
As mentioned above, all the transmitters and receivers of the system operate at one fixed frequency. Therefore, in order to improve the reliability and simplification of the circuit, as well as the tuning of the system, the receiver was based on a direct amplification amplifier with amplifying elements on the microcircuits.
Results and discussion
The developed radio monitoring system was successfully tested at gas stations and demonstrated very good results. With continuous monitoring for a month, several alarm triggers were detected. At the same time, the engineers took the appropriate measures in due time. All data from the online monitoring system was sent to server storage for further processing and diagnostics [9].
The developed radio monitoring system has its positive features, in comparison with analogues. First of all, this is a wireless connection of peripheral sensors, convenient in conditions of a complex in-
frastructure of industrial facilities. Secondly, it is the use of low power transmission, and in turn, the range of one kilometer, which largely solves the problem of electromagnetic compatibility. Thirdly, economical expenditure of battery energy is achieved by means of a discrete assessment of the state of the environment, since peripheral transmitters are often located in places where their power can only be supplied from batteries [5; 9].
Conclusion
The developed monitoring system can be used in the systems of protection of the gas processing, mining industry, shops and warehouses where toxic, explosive substances are stored. Also in emergency situations with possible accidents or malicious acts. Experiments have shown that the advantage of the developed system is the ease of maintenance, the accuracy of measurements and almost complete automation at a relatively low cost.
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