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adiators. An antenna array is a family of individual radiators whose characteristicsare determined by the geometric position of the radiators and theamplitude and phase of their excitation. A phased-array antenna has a numberof advantages over a lens or reflector antenna. This is due to the distribution ofpower amplification at the elementary radiation level, higher aperture efficiency,no spillover loss, no aperture (feed) blockage, and better reliability.The helical antenna has inherent broadband properties, possessingdesirable pattern, polarization, and impedance characteristics over a relativelywide frequency range and may radiate in several modes.Each of these antennas is a major study area alone. However, each isbriefly described in the next subsections.2.7.1 HornA horn is a slightly flared end of a piece of waveguide. Instead of electricalcurrents, the waveguide carries a tightly focused electromagnetic wave withthe electric components extending between the parallel walls. Horns can besquare in section (called pyramidal horns) but rectangular in two orthogonalplanes (called E-plane and H-plane horns), as in Fig. 2.12(a), or circular incross-section, as in Fig. 2.12(b).In the figure, A and B are the aperture length in the H- and E-planerespectively; a and b are the length and breadth of the matching waveguide ifthe horn’s shortest length, L 1 , possible is required; D is the aperture diameterof the conical horn; and L is the axial length to apex to the aperture of theconical horn.FIGURE 2.12Horns: (a) pyramidal; (b) conical.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
Page 82: TABLE 2.3Typical Links Frequency Ba
Page 86: FIGURE 2.4Satellite period and orbi
Page 90: FIGURE 2.6An illustration of covera
Page 94: FIGURE 2.7constellation.A sketch of
Page 98: width of 1:73 with reduced coverag
Page 102: y ¼ elevation angle of satellite f
Page 106: We can conclude that the antenna mu
Page 110: FIGURE 2.9Design flowchart of a sat
Page 114: Risk control and monitoring measure
Page 118: TABLE 2.4Antenna Selection Criteria
Page 122: Then the system availability can be
Page 126: In fact, MTBF is the reciprocal of
Page 130: 2.7 ANTENNASBased on function, sate
Page 136: Example 2.3: The earth subtends an
Page 140: eam is assumed symmetrical (i.e., y
Page 144: FIGURE 2.15Feed array elements ðy
Page 148: If the steering is in the direction
Page 152: 2.8 SATELLITE POWER SYSTEMSA key co
Page 156: Calculate (1) the probability that
Page 160: FIGURE 2.20Carrier processing.infor
Page 164: FIGURE 2.22(d) elliptic.Types of ba
Page 168: FIGURE 2.23A klystron. (Courtesy of
Page 172: FIGURE 2.25A simple block diagram o
Page 176: tional protection is required to en
Page 180: 3.1 BASIC PRINCIPLE OF EARTH STATIO
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3.1.1 Technical and Operational Req
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excellent protection against noise
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FIGURE 3.3QPSK modulator.FIGURE 3.4
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TABLE 3.28-PSK Truth TableInput bit
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FIGURE 3.8An M-ary PSK demodulator
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where B is the allocated channel ba
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A frequently used function is the Q
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In view of (3.11), Eq. (3.18) can b
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Encoder and DecoderAn encoder is an
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Modulator and DemodulatorA modulato
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Zero Forcing Technique. Suppose the
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The adjoint of matrix A is obtained
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FIGURE 3.14The three-tap equalizer
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First, in the case of digital signa
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than 1=A. Whichever law is used, th
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FIGURE 3.16Block diagram for estima
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3.4.2 Antenna TrackingAn earth stat
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controlling antenna pointing. The m
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FIGURE 3.19A generalized model of a
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FIGURE 3.20Entropy of a binary sour
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whereHðYÞ¼output entropy, the av
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To have a feel for this expression,
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2. The system’s overall condition
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transmitted down the fiber as digit
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10. Kantor, L. Y. (ed). (1987). Han
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142. Simulate the probability of bi
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FIGURE 4.1A simplex link.baseband c
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Chapter 2, Sec. 2.7, discusses that
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From (4.6), the received power P r
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FIGURE 4.3A model of the combined-l
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4.1.2 Rain AttenuationRain attenuat
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FIGURE 4.5rates.Average rainstorm p
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FIGURE 4.6Adjacent satellite interf
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FIGURE 4.8Satellite separation dist
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inability of satellite A to accurat
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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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