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epeaters overshooting into subsequent paths. In this way the signal level isrelatively maintained. At the distant end, the receiver detects the signal, whicha multiplexer delivers to the end users if required.3.6 SUMMARYEarth stations form a vital part of the overall satellite system. This chapterdiscusses many types of earth stations. In some applications, earth stationsoperate in a transponding mode, in which received satellite signals are used toinitiate a retransmission from the station to another station or to the satellite.For digital transmission, one of the most important performance criteriais the bit error rate. This rate depends, in part, on the type of modulationscheme used for transmission. This chapter also examines the M-PSKmodulation scheme and develops some useful expressions for calculatingthe bit error rate, the transmission bandwidth, and the absolute limit tocommunicate with an errorfree performance.System noise temperature is one of the important variables required inevaluating the performance of an earth station. The text describes a methodthat calculates this variable. In order to prevent antenna pointing loss, the mainlobe of the earth station’s antenna must be pointed automatically or manuallyat the satellite with the greatest possible accuracy. The commonly usedmethods for achieving pointing accuracy are monopulse, step track, andprogrammable steering. Finally, system capacity requirements, as well as theprimary terrestrial links to and from the earth station, which facilitate datatransmissions are discussed.REFERENCES1. Gargliardi, R.M. (1991). Satellite Communications. Van Nostrand Reinhold.2. Tomasi, W. (1987). Advanced Electronic Communications Systems. Prentice-Hall.3. Ziemer, R.E. and Tranter, W.H. (1988). Principles of Communications: Systems,Modulation, and Noise. John Wiley.4. Shannon, C.E. (1948). A mathematical theory of communication, Bell System TechJ., vol. 27.5. Rektorys, K. (1969). Survey of Applicable Mathematics. Iliffe Books.6. Holzmann, G.J. (1991). Design and Validation of Computer Protocols. Prentice-Hall.7. Held, G. (1991). The Complete Modem Reference. John Wiley.8. Qureshi, S. (1982). Adaptive equalization, IEEE Communications, vol. 20.9. Afshar, A. (1995). Principles of Semiconductor Network Testing. Butterworth-Heinemann.Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
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SatelliteCommunicationEngineeringMi
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This book is dedicated to my famili
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Because of the immense importance o
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means of a combination of applicati
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about my promise to my students, an
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2.3 Coverage Area and Satellite Net
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1Basic Principles of SatelliteCommu
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and voice (telephone) communication
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FIGURE 1.2Communication between two
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interpreting or uncovering the deci
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cryptographic keys K ti (where i ¼
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FIGURE 1.6Block ciphering technique
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FIGURE 1.7Part of block ciphering w
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Based on the ordering sequence of (
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TABLE 1.1 (continued )S612 1 10 15
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For an uncoded message x and the fe
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2. Your task is to develop a commun
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FIGURE 2.1Geometry of a satellite.
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Future trends in satellite antennas
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In the United States, the three sat
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TABLE 2.3Typical Links Frequency Ba
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FIGURE 2.4Satellite period and orbi
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FIGURE 2.6An illustration of covera
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FIGURE 2.7constellation.A sketch of
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width of 1:73 with reduced coverag
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y ¼ elevation angle of satellite f
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We can conclude that the antenna mu
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FIGURE 2.9Design flowchart of a sat
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Risk control and monitoring measure
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TABLE 2.4Antenna Selection Criteria
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Then the system availability can be
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In fact, MTBF is the reciprocal of
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2.7 ANTENNASBased on function, sate
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Two kinds of horns in common use ar
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FIGURE 2.13Geometry of a parabolic
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FIGURE 2.14 Axisymmetric reflector
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A transceiver antenna is a single a
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The gain, in the axial mode, of a h
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angles, spacecraft may shadow the s
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3. The probability of both parallel
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the baseband signal (more details a
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matrix in the communications subsys
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FIGURE 2.24Typical transfer charact
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4. Iridium LCC (1997). Iridium Syst
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3Earth StationsIn Chap. 2 we discus
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The most popular forms of modulatio
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Small earth stations are antennas w
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FIGURE 3.2BPSK space diagram.Instea
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OQPSKOffset QPSK (OQPSK) is a modif
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FIGURE 3.7An 8-PSK space diagram.an
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aud. The word ‘‘baud’’ hono
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Noise power density N 0bandwidth:N
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We observe in (3.11) that E b =N 0
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to (3.23) shows that a margin of 11
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FIGURE 3.12 Principle of scrambling
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Equalization FilterAn equalization
Page 226: that is, N zeros at the top and bot
Page 230: Example 3.2: Consider a transmissio
Page 234: which can be written as89>=R xy ðt
Page 238: ecause a voice signal is usually hi
Page 242: systems is discussed in Sec. 4.2. O
Page 246: where T e is the equivalent tempera
Page 250: operating principle of all directio
Page 254: performance of the satellite commun
Page 258: 3. For two independent sources, wit
Page 262: FIGURE 3.21 A representation of mut
Page 266: In practice, Eqs. (3.78) and (3.76)
Page 270: This condition is always satisfied
Page 274: Copyright © 2002 by Marcel Dekker,
Page 280: 10. Kantor, L. Y. (ed). (1987). Han
Page 284: 142. Simulate the probability of bi
Page 288: FIGURE 4.1A simplex link.baseband c
Page 292: Chapter 2, Sec. 2.7, discusses that
Page 296: From (4.6), the received power P r
Page 300: FIGURE 4.3A model of the combined-l
Page 304: 4.1.2 Rain AttenuationRain attenuat
Page 308: FIGURE 4.5rates.Average rainstorm p
Page 312: FIGURE 4.6Adjacent satellite interf
Page 316: FIGURE 4.8Satellite separation dist
Page 320: inability of satellite A to accurat
Page 324: FIGURE 4.10 Cross-link E b =N 0 vs.
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Then using (4.41), the overall C=N
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(iv)(v)(vi)(vii)Calculate the recei
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5Communication Networks andSystemsC
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discriminate among carriers by temp
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FIGURE 5.2 Principle of FDMA system
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FIGURE 5.3 Operational concept of T
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FIGURE 5.5TDMA: bit rate r b for 1
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Copyright © 2002 by Marcel Dekker,
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5.2 CAPACITY COMPARISON OFMULTIPLE-
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Rearranging (5.11) in terms of ener
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The transmission bit rate isR r ¼
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6Error Detection and CorrectionCodi
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the channel and reconstruct the sou
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message sequence X . Thus, a system
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If we consider a message X ¼ð1010
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can be seen in Table 6.1 that the m
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FIGURE 6.1A (7, 4) cyclic code gene
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FIGURE 6.2Convolutional codes encod
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Alternative methods of describing a
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FIGURE 6.5 Code tree diagram of Fig
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FIGURE 6.8 Code tree diagram of rat
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consistent with the constraint leng
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trellis depth is approximated to 5L
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FIGURE P.1A convolutional coder.the
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7Regulatory Agencies andProceduresT
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of the radiofrequency spectrum, and
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The CCIR works through the medium o
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7.1.3 IFRBThe International Frequen
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The national or regional spectrum m
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3. The need to expand or enhance th
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The DSP will be responsible for res
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2. Provide a convenient framework w
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FIGURE 8.3Types of user-to-network
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H1-channels are designed to carry v
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information. The transfer cell prov
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The OSI layers are divided into two
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plane is denoted by U, the control
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interfacing, maintenance, and conne
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adjoining base station to scan the
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FIGURE 8.9Geometry of a polygon.The
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FIGURE 8.11Splitting cells into sma
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causes signal fading. Of course, th
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FIGURE 8.14TCP=IP suite and its rel
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access to an Internet point of pres
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message security via satellite is d
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REFERENCES1. Wu, W.W. (1989). Eleme
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Appendix ANotationsThe symbols have
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N sPP rP sP TRRðtÞR cR eR rR vSS
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g Central anglez Channel gainZ Ante
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AttenuationBandwidthBearer serviceB
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Frequency divisionmultiple accessFr
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MultiplexingNetworkOmnidirectionala
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UplinkUser-to-networkinterfaceThe e
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