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SOME PECULIARITIES OF THE ORGANIZATION OF THE DIGITAL RADIO BROADCASTING NETWORK OF THE LONG-WAVE RANGE
Belyansky Vladimir Borisovich,
PhD, Associate Professor, Moscow Technical University of Communications and Informatics, Moscow, Russia, [email protected]
Pronina Evgenia Dmitrievna,
graduate student, Moscow Technical University of Communications and Informatics, Moscow, Russia, [email protected]
Batuhug Uguumur,
master student, Moscow Technical University of Communications and Informatics, Moscow, Russia, [email protected]
ABSTRACT
When designing a digital broadcasting network for medium-wave and long-wave bands, considering the sufficiently large service areas and the features of servicing these areas in width and longitude, it is advisable to use a trapezoidal zone limited by longitude and latitude lines as a cell of the broadcasting network. Elementary cells of the network will have a clearly defined trapezoidal shape only for very high latitudes (the Arctic is for the territory of Russia), and at lower latitudes the trapezium will practically have the shape of a rectangle. In these cells, the transmitters should be placed at points providing the maximum area utilization rate, which refers to the ratio of the cell area to the actual area covered by the transmitter for a given signal level exceeding the level of interference. The principle of calculating the parameters of a unit cell, taking into account the latitudinal dependence of atmospheric radio interference, is considered. With frequency-territorial planning, an important issue is the development of the principle of sending programs to radio transmitting stations. At high latitudes, the possibility of using geostationary satellites and cable lines is excluded. In this case, the cheapest way to apply the program is to use repeaters that allow you to receive the program from a neighboring radio station located in the right time zone. The receiving antennas of such repeaters should have a significant directivity factor providing a given signal-to-interference ratio. The directive of such receiving antennas can be in the range of 3-12 dB. The receiving array is of the lattice type in the lattice. External interference on the northern and southern latitudes differs not only in their level, but also in statistical parameters. For northern latitudes, it is important to use radio receivers with a low thermal noise factor at the input, and for radio-frequency receivers with impulse-noise compensators, radio receivers can be effective. An important aspect of organizing a digital LW broadcasting network is the development of fairly compact transmission antennas of the LW band and matching devices for these antennas, taking into account the features of modern radio transmitting devices with high efficiency. With the help of these matching device , in principle, it is possible to eliminate the quadratic dependence of the input resistance of the antenna on the frequency due to a very small decrease in the efficiency of the antenna-feeder device.
Keywords: long-wave range; unit cell of network; frequency-territorial planning; repeater; antenna efficiency; matching device; working frequency band.
For citation: Belyansky V. B., Pronina E.D., Batuhug U. Some peculiarities of the organization of the digital radio broadcasting network of the long-wave range. H&ES Research. 2017. Vol. 9. No. 3. Pp. 71-76.
In Moscow Technical University of Communications and Informatics (MTUCI) for several years study was carried out on the design of digital broadcasting networks for MW and LW range [1-5]. According to the published results of these studies, the following conclusions can be drawn:
1. The service area ofthe LW station ofthe range has a diameter in the range of 300-1200 km, depending on the latitude and center frequency ofthe transmitter.
2. At high latitudes, the level of atmospheric interference is significantly lower than at low latitudes.
3. For territories with a low population density, it is advisable to use the lowest frequencies ofthe considered range.
4. Given the high uneven density ofthe population ofthe Russian Federation and a limited number of operating frequencies, the broadcast network of the LW band is best implemented using a "cluster" method.
From the foregoing it follows that, taking into account sufficiently large areas of service areas and taking into account the specifics of servicing these areas in width and longitude, it is expedient to use a trapezoidal zone limited by longitude and latitude lines as a cell of the broadcasting network (fig. 1). A grid of this type is self-adjoint, potentially reducing the number of radio stations covering the served territory. Obviously, the unit cells ofthe network will have a clearly defined trapezoidal shape only for very high latitudes (the Arctic is for the territory of Russia), and at lower latitudes the trapezium will practically have the shape of a rectangle. Consider the features ofthe partition of the territory served by digital broadcasting of the LW range into unit cells. In these cells, the transmitters should be placed at points providing the maximum area utilization coefficient "n, which refers to the ratio ofthe cell area to the actual area covered by the transmitter for a given excess of the signal level above the interference level (1). As a rule, when planning a broadcasting network, the transmission pattern of the transmitting antenna is assumed to be non-directional, and the level of interference is the same throughout the entire territory under consideration. In this case, the transmitter is placed
in the center of the unit cell. If the interference level is sufficiently strong from the latitude or longitude coordinates, this is certainly a suboptimal solution, and the transmitter coordinates should be shifted from the center of the serviced territory in such a way as to optimize the area utilization factor. In addition, such a correction of the coordinates of the transmitter is suitable, for example, in the case of the cost of a microwave link delivering the program to a broadcast transmitter. Let us consider here the principle of calculating the parameters of an elementary cell, taking into account the latitudinal dependence ofatmospheric radio interference.
Let R1 be the radius of a circle in which the signal-to-noise ratio exceeds a given level if the noise level is set at the latitude ofthe trapezoid vertex (the vertex of this trapezoid is assumed to be al). In fig. 1, the angle a is determined by the latitude of the apex ofthe trapezium. When calculating, it is necessary to determine the length of the trapezoid base a2, the trapezium height h = h\ + hi, and the components of this height hi (2) and h2 (3), which determine the coordinates ofthe transmitting radio station. Let the coefficient k determine the ratio of the interference level at the latitude of the vertex of the trapezium and on its basis. Then, the utilization coefficient ^ is a function ofthe length ofthe vertex of trapezium al and this coefficient k
1, k )
(a
. k )
n(ai>k )
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(2)
From the geometric relations for the unit cell in fig. 1 it follows that in the first approximation with a sufficiently high accuracy, hl(al, k) will be equal to
h2 (ai,k) :
" 2 aia(ai
R2 (k)"Op + f 22aia(ai) | -aih1 (ai)a(ai)
(3)
Fig.l. The geometry of the unit cell ofbroadcasting
Assuming that the antenna pattern is isotropic and taking into account the values of hi and hi, it is easy to calculate the area utilization coefficient ^ for a number of values of the utilization factor k asa function ofthe length ofthe vertex al.
Fig. 2 shows the dependence ofthe utilization coefficient ^ as a function of al and k for the case when the trapezium vertices are at the latitude 9 = 78 It follows from the calculations that the maximum of-q (al, k) depends weakly on the coefficient k, so the calculation for several values of k makes it possible to determine with high accuracy the coordinates ofthe radio transmitting center.
An important issue in frequency-territorial planning is the development of the principle of sending programs to radio transmitting stations. At high latitudes, the possibility of using geostationary satellites and cable lines is excluded. In this
2
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Fig. 2. Dependence of the coverage ratio on the length of the upper base of the trapezium
case, the cheapest way to apply the program is to use repeaters that allow you to receive the program from a neighboring radio station located in the right frequency zone. The use of repeaters is also possible for the supply of programs from the territory of the Russian Federation to adjacent territories. At the same time, the receiving antennas of such repeaters should have a significant gain that ensures a given signal-to-interference ratio. It is determined that the gain of such receiving antennas can be in the range of 3-12 dB. It is believed that it is theoretically possible to create antennas of arbitrarily small dimensions with arbitrarily large amplification [13]. However, antennas with "over-amplification" have high instability of their characteristics. Therefore, in the case under consideration, the antennas of the LW transponder should be provided with a tuning system that automatically turns on at specified intervals. The authors of the article propose a receiving array of lattice type lattice. Such an antenna array provides a high gain factor and a convenient tuning algorithm.
The question of the nature of the interference in the LW range deserves a separate consideration. Obviously, external noise on the northern and southern latitudes differ not only in their level, but also in the statistical parameters (fig. 3). And if the use of radio receivers with a low coefficient of thermal
noise at the input is relevant for northern latitudes, then radio receivers with impulse-noise compensators can be effective for southern latitudes, which have now been developed quite well [7-10]. In the technical literature, there are many publications on the nature of atmospheric radio interference, but to date they have not been fully analyzed in relation to the problems of digital broadcasting LW [14,15]. The authors believe that noise immunity of mass radio receivers for digital LW broadcasting should be considered from both a technical and an economic point of view. In principle, the domestic industry has great experience in creating radio receivers with high noise immunity and noise immunity. Apparently, the best solution to the problem of creating efficient radio receivers for mass use is the development of a basic receiver with various options. Such a radio receiver is interfaced with the basic version of the design, giving the consumer the opportunity to choose the most acceptable option for him. For territories directly adjacent to radio transmission centers, it is possible to develop very cheap radio receivers that do not need power supplies.
An important aspect of organizing a digital LW broadcasting network is the development of sufficiently compact transmission antennas ofthe LW range and matching devices for these antennas, taking into account the features of modern radio transmitting
70
al
F., SO
50
\ \
40
60
SO
Fig. 3. Dependence of the external noise factor Fa on the longitude 9 (for given latitudes yl = 180 y2 = 75 °)
antennas with high efficiency [11-12]. At present, the possibility of overcoming the Chu-Harrington-Fano limit is proved, which creates the basis for the development of antennas of this type [6]. Reduce the cost of antennas and increase the level of radiated power is also possible when using the principle ofadding power in the air. The matching devices, when making small losses, can ensure the implementation of radio transmission systems with a high operating frequency band and a high level of agreement.
So, for example, when using the corrected SS in fig. 4. the working band of the antenna (determined by the efficiency of the antenna-feeder device) is doubled if the efficiency is allowed to decrease by 18% (fig. 5). It is obvious that in this case the matching of the antenna with the transmitter remains equal to unity in an unlimitedly wide frequency range. With an efficiency AFD of 10%, the bandwidth is increased by a factor of 1.5. In addition to this correction of the SS principle, it is possible to eliminate
Fig. 4. Correction of the matching device (corrected MD).
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60
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10
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j j \
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165
170
175
ISO
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Fig. 5. Working band of the antenna with the initial and corrected MD.
the quadratic dependence of the antenna input resistance due to a very small decrease in the efficiency ofthe AFD.
In conclusion, the authors consider it a pleasant duty to express gratitude to Oleg Varlamov for a number of useful comments.
Literature
1. Varlamov O.V. A way to organize a global network of digital broadcasting in the range of LW. T-Comm. 2015. Vol. 9. No. 5. Pp. 63-68. (InRussian)
2. VarlamovO.V. Features of frequency-spatial planning of broadcasting networks DRM bands LW and MW. T-Comm. 2013. No. 9. Pp. 43-46. (InRussian)
3. Varlamov O.V. Correctly planning of drm broadcasting networks. Elektrosvyaz'. 2014. No. 6. Pp. 26-34. (InRussian)
4. VarlamovO.V. Development of requirements for receiving equipment of digital broadcasting networks of the DRM standard. T-Comm. 2013. No. 9. Pp. 39-42. (In Russian)
5. Varlamov O.V. Development of the national regulatory framework for digital broadcasting of the DRM standard. T-Comm. 2013. No. 9. Pp. 47-50. (In Russian)
6. Belyanskiy V. B.Is it possible to overcome the Chu-Har-rington limit? T-Comm. 2013. No. 8. Pp. 24-27. (InRussian)
7. Bykhovsky M.A. Single-channel compensators ofradio interference in communication systems. Radiotekhnika [Radioengineering]. 1981.No. 11. (InRussian)
8. Bykhovsky M.A., PavlyukA.P. Approach to the development of a unified methodology for analyzing EMC radio systems. Telecommunication Jornal. 1993. Vol. 60-11. (InRussian)
9. Bykhovsky M.A. Management of the use of the radio-frequency spectrum and the development ofradio communications and broadcasting in Russia. Elektrosvyaz'. 1997. No. 12. Pp. 17-23. (InRussian)
10. Bykhovskiy M.A. Method of perspective planning of the use of frequency bands by radio stations of fixed and mobile services. Elektrosvyaz'. 1994. No. 7. (InRussian)
11. Belyanskiy V.B., ProninaE.D. Miniature transmitting antennas long wavelength digital broadcasting standard. Trudy Severo-Kavkazskogofiliala Moskovskogo tekhnicheskogo uni-versiteta svyazi i informatiki [Proceedings ofthe North Caucasian Branch ofthe Moscow Technical University of Communication and Informatics], 2015. Pt. 1. Pp. 226-229. (InRussian)
12. ProninaE. D.Modernization ofthe broadcasting stations of the LW of the range, taking into account the DRM standard. Trudy Severo-Kavkazskogo filíala Moskovskogo tekhnicheskogo universiteta svyazi i informatiki [Proceedings ofthe North-Caucasian Branch ofthe Moscow Technical University of Communications and Informatics], 2014. No. 1. Pp. 307-311. (InRussian)
13. Belyanskiy V.B., ProshinA.B., Khudyakov K.N. Antennas LW, MW, and SW bands of digital audio broadcasting of reduced dimensions. T-Comm. 2013. No. 8. Pp. 28-29. (In Russian)
14. Recommendation ITU-R P. 372-11 (09/2013). Radio noise. Geneva: ITU, 2013. 78p.
15. Handbook on "National Spectrum Management". Geneva: Radiocommunication Bureau, ITU, 1995. 340 p.
НЕКОТОРЫЕ ОСОБЕННОСТИ ОРГАНИЗАЦИИ СЕТИ
ЦИФРОВОГО РАДИОВЕЩАНИЯ ДЛИННОВОЛНОВОГО ДИАПАЗОНА
Белянский Владимир Борисович,
к.т.н., доцент Московского технического университета связи и информатики, Москва, Россия, [email protected]
Пронина Евгения Дмитриевна,
аспирант Московского технического университета связи и информатики, Москва, Россия, [email protected]
Батхуяг Угуумур,
магистрант Московского технического университета связи и информатики, Москва, Россия, [email protected]
АННОТАЦИЯ
При проектировании сети цифрового радиовещания средневолнового и длинноволнового диапазонов с учетом достаточно больших площадей территорий обслуживания и, учитывая особенности обслуживания этих площадей по ширине и долготе, в качестве ячейки сети радиовещания целесообразно использовать трапецеидальную зону, ограниченную линиями долгот и широт. Элементарные ячейки сети будут иметь четко выраженную трапецеидальную формы только для очень высоких широт (Арктика - для территории России), а на более низких широтах трапеция практически будет иметь форму прямоугольника. В этих ячейках передатчики следует размещать в точках, обеспечивающих максимальный коэффициент использования площади, под которым понимается отношения площади ячейки к фактической площади, покрываемой передатчиком при заданном превышении уровня сигнала над уровнем помех. Рассматривается принцип расчета параметров элементарной ячейки, учитывающей широтную зависимость атмосферных радиопомех. При частотно-территориальном планировании важным вопросом является разработка принципа подачи программ на радиопередающие станции. На высоких широтах исключается возможность использования геостационарных спутников и кабельных линий. В этом случае наиболее дешевым способом подачи программы является применение ретрансляторов, которые позволяют принимать программу от соседней радиостанции, находящейся в нужном частотном поясе. При этом приемные антенны таких ретрансляторов должны иметь существенный коэффициент усиления, обеспечивающий заданное соотношение «сигнал-помеха». Коэффициент усиления таких приемных антенн может находиться в пределах 3-12 дБ. Авторами работы предлагается приемная антенная решетка типа «решетка в решетке». Внешние помехи на северных и южных широтах отличаются не только своим уровнем, но и статистическими параметрами. Для северных широт актуальным является использование радиоприемников с низким коэффициентом теплового шума по входу, а для южных широт эффективными могут оказаться радиоприемники с компенсаторами импульсных помех. Важным аспектом организации сети цифрового длинноволнового радиовещания является разработка достаточно компактных передающих антенн длинноволнового диапазона и согласующих устройств для этих антенн с учетом особенностей современных радиопередающих антенн с высоким коэффициентом полезного действия. Кроме такой коррекции согласующего устройства в принципе возможно устранить квадратичную зависимость входного сопротивления антенны за счет весьма небольшого понижения коэффициента полезного действия антенно-фидерного устройства.
Ключевые слова: длинноволнового диапазон; элементарная ячейка сети; частотно-территориальное планирование; ретрансляторы; коэффициент полезного действия антенны; согласующее устройство; рабочая полоса частот.
Для цитирования: Белянский В. Б., Пронина Е. Д., Батхуяг У. Некоторые особенности организации сети цифрового радиовещания длинноволнового диапазона // Наукоемкие технологии в космических исследованиях Земли. 2017. Т. 9. № 3. С. 71-76.
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