View File - University of Engineering and Technology, Taxila

More documents

Recommendations

Info

3.4.2 Antenna TrackingAn earth station antenna may be required to work to satellites in differentorbital positions during its lifetime. A recent example is the tracking of theRussian Mir Space Station (Fig. 3.17) as it orbited and guided back to earth onFriday, March 23, 2001. The Mir’s progress was charted up to the point ofentry. Fragments from the massive complex splashed down in the SouthPacific just as ground controllers had planned. It was a technological feat inthe history of space tracking and research and demonstrated the criticalimportance of precise direction finding.Some earth station antennas may need to switch between satellitesfrequently. For example, the antenna may be required to relay programsfrom a number of different satellite systems to a local broadcasting stationor a number of broadcasting stations (like major events, such as militaryconflicts, the Olympics, or World Cup soccer), or cable-TV network. In suchcases, it is important to point and repoint the antenna swiftly, simply, andaccurately, whether or not it has a tracking system.Recently deployed satellite communications antennas operate in the11=14- and 20=30-GHz ranges and have narrower radiation patterns than olderantennas. In order to point the earth station’s antenna beam within thesenarrow sectors of the satellite antenna beam, it is essential to direction-find thesatellite with significantly greater precision.With these examples, how do we track any satellites orbiting the earthand by what method(s)? Three commonly used direction-finding systems inearth stations are monopulse, step track, and programmable steering. TheFIGURE 3.17The Mir space station. (Courtesy of NASA.)Copyright © 2002 by Marcel Dekker, Inc. All Rights Reserved.
Page 2:
SatelliteCommunicationEngineeringMi
Page 6:
This book is dedicated to my famili
Page 10:
Because of the immense importance o
Page 14:
means of a combination of applicati
Page 18:
about my promise to my students, an
Page 22:
2.3 Coverage Area and Satellite Net
Page 26:
1Basic Principles of SatelliteCommu
Page 30:
and voice (telephone) communication
Page 34:
FIGURE 1.2Communication between two
Page 38:
interpreting or uncovering the deci
Page 42:
cryptographic keys K ti (where i ¼
Page 46:
FIGURE 1.6Block ciphering technique
Page 50:
FIGURE 1.7Part of block ciphering w
Page 54:
Based on the ordering sequence of (
Page 58:
TABLE 1.1 (continued )S612 1 10 15
Page 62:
For an uncoded message x and the fe
Page 66:
2. Your task is to develop a commun
Page 70:
FIGURE 2.1Geometry of a satellite.
Page 74:
Future trends in satellite antennas
Page 78:
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 134:
Two kinds of horns in common use ar
Page 138:
FIGURE 2.13Geometry of a parabolic
Page 142:
FIGURE 2.14 Axisymmetric reflector
Page 146:
A transceiver antenna is a single a
Page 150:
The gain, in the axial mode, of a h
Page 154:
angles, spacecraft may shadow the s
Page 158:
3. The probability of both parallel
Page 162:
the baseband signal (more details a
Page 166:
matrix in the communications subsys
Page 170:
FIGURE 2.24Typical transfer charact
Page 174:
4. Iridium LCC (1997). Iridium Syst
Page 178:
3Earth StationsIn Chap. 2 we discus
Page 182:
The most popular forms of modulatio
Page 186:
Small earth stations are antennas w
Page 190:
FIGURE 3.2BPSK space diagram.Instea
Page 194:
OQPSKOffset QPSK (OQPSK) is a modif
Page 198: FIGURE 3.7An 8-PSK space diagram.an
Page 202: aud. The word ‘‘baud’’ hono
Page 206: Noise power density N 0bandwidth:N
Page 210: We observe in (3.11) that E b =N 0
Page 214: to (3.23) shows that a margin of 11
Page 218: FIGURE 3.12 Principle of scrambling
Page 222: 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 252: controlling antenna pointing. The m
Page 256: FIGURE 3.19A generalized model of a
Page 260: FIGURE 3.20Entropy of a binary sour
Page 264: whereHðYÞ¼output entropy, the av
Page 268: To have a feel for this expression,
Page 272: 2. The system’s overall condition
Page 276: transmitted down the fiber as digit
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.
Page 328:
Then using (4.41), the overall C=N
Page 332:
(iv)(v)(vi)(vii)Calculate the recei
Page 336:
5Communication Networks andSystemsC
Page 340:
discriminate among carriers by temp
Page 344:
FIGURE 5.2 Principle of FDMA system
Page 348:
FIGURE 5.3 Operational concept of T
Page 352:
FIGURE 5.5TDMA: bit rate r b for 1
Page 356:
Copyright © 2002 by Marcel Dekker,
Page 360:
5.2 CAPACITY COMPARISON OFMULTIPLE-
Page 364:
Rearranging (5.11) in terms of ener
Page 368:
The transmission bit rate isR r ¼
Page 372:
6Error Detection and CorrectionCodi
Page 376:
the channel and reconstruct the sou
Page 380:
message sequence X . Thus, a system
Page 384:
If we consider a message X ¼ð1010
Page 388:
can be seen in Table 6.1 that the m
Page 392:
FIGURE 6.1A (7, 4) cyclic code gene
Page 396:
FIGURE 6.2Convolutional codes encod
Page 400:
Alternative methods of describing a
Page 404:
FIGURE 6.5 Code tree diagram of Fig
Page 408:
FIGURE 6.8 Code tree diagram of rat
Page 412:
consistent with the constraint leng
Page 416:
trellis depth is approximated to 5L
Page 420:
FIGURE P.1A convolutional coder.the
Page 424:
7Regulatory Agencies andProceduresT
Page 428:
of the radiofrequency spectrum, and
Page 432:
The CCIR works through the medium o
Page 436:
7.1.3 IFRBThe International Frequen
Page 440:
The national or regional spectrum m
Page 444:
3. The need to expand or enhance th
Page 448:
The DSP will be responsible for res
Page 452:
2. Provide a convenient framework w
Page 456:
FIGURE 8.3Types of user-to-network
Page 460:
H1-channels are designed to carry v
Page 464:
information. The transfer cell prov
Page 468:
The OSI layers are divided into two
Page 472:
plane is denoted by U, the control
Page 476:
interfacing, maintenance, and conne
Page 480:
adjoining base station to scan the
Page 484:
FIGURE 8.9Geometry of a polygon.The
Page 488:
FIGURE 8.11Splitting cells into sma
Page 492:
causes signal fading. Of course, th
Page 496:
FIGURE 8.14TCP=IP suite and its rel
Page 500:
access to an Internet point of pres
Page 504:
message security via satellite is d
Page 508:
REFERENCES1. Wu, W.W. (1989). Eleme
Page 512:
Appendix ANotationsThe symbols have
Page 516:
N sPP rP sP TRRðtÞR cR eR rR vSS
Page 520:
g Central anglez Channel gainZ Ante
Page 524:
AttenuationBandwidthBearer serviceB
Page 528:
Frequency divisionmultiple accessFr
Page 532:
MultiplexingNetworkOmnidirectionala
Page 536:
UplinkUser-to-networkinterfaceThe e
show all

View File - University of Engineering and Technology, Taxila

Create successful ePaper yourself

Delete template?

Save as template?