Appendix A: Useful Data

Home , Eutelsat 117 West A, Inclined orbit, Medium Earth orbit, Tundra orbit

Earth gravitational parameter (GM) = 398 600.5 km3/s2 Earth mass (M) = 5.9733 x 1024 kg Earth gravitational constant = 6.673 X 10-20 km3/kgs2 Earth equatorial radius = 6378.14km Earth polar radius = 6356.785km Earth eccentricity = 0.08182 Velocity of light = 299 792.458 km/s Average radius of geostationary orbit = 42164.57km Velocity of geostationary satellite = 3.074689km/s Angular velocity of geostationary satellites = 72.92115 X 10-6 rad/s Geostationary satellite orbital period = 86164.09 s (23 hours, 56 minutes, 4.09 seconds) Boltzmann constant = 1.3803 X 10-23 W/KHz or - 228.6 dB W/K Maximum range of geostationary satellite (0° elevation) = 41680km Minimum range of geostationary satellite (90° elevation) = 35786km Half-angle subtended at the satellite by Earth= 8.69° Coverage limit on Earth (0° elevation) = 81.3° One nautical mile = 1.852km

429 Appendix B: Useful Orbit-related Formulas

(1) Doppler effect

The equation set included here is general enough to provide Doppler shifts in non-geostationary orbits. The Doppler shift /lfct observed at a given point on the Earth at a frequency ft is given by

vr -F ilfct=±-Jt (B.l) c where vr = relative radial velocity between the observer and the satellite transmitter c = velocity of light ft = transmission frequency. The sign of the Doppler shift is positive when the satellite is approaching the observer. The relative velocity can be approximated as

(B.2)

where p1(t1) and p2(t 2) are satellite ranges at times t1 and t2 respectively; (t2 - t1,) is arbitrarily small. p(t) at any instant t can be obtained from the orbital parameters by using the technique given in a following section ('(9) Satellite position from orbital pa• rameters'). Range rate can then be obtained by using equation (B.2), at two successive instants. The following equation set may be used for approximate estimation of the range rate of a geostationary satellite. We note that range rate is a function of orbital eccentricity, inclination and satellite drift rate. The range rate for each of these components is given as (Morgan and Gordon, 1989):

(a) Eccentricity

(B.3) Pm

430 Appendix B: Useful Orbit-related Formulas 431 where Pe = range rate due to eccentricity e = eccentricity a = semi-major axis w• = angular velocity

2'7T where To = orbital period To Pm = mean range from observation point tp = time from perigee.

(b) Inclination

iaRw . (. ) Pi = ---smOcos wti (B.4) Pm where Pi = range rate due to inclination i = inclination R = Earth radius 0 = latitude of earth station ti = time from ascending node.

DaR . A.-I,. Pct = --cosOsm~'+' (B.S) Pm where D = drift rate in radians/s Pct = range rate due to satellite drift Ll¢ = difference in longitude between satellite and earth station. The total range rate at any given time is the sum of range rates due to each of the above components. CCIR Report 214 gives the following approximate relationship for estimating the maximum Doppler shift: -6 Llfctm = ± 3.0(10) fts (B.6) where ft = operating frequency s = number of revolutions/24 hours of the satellite with respect to a fixed point on the Earth. For a more precise treatment of the subject the reader is referred to the literature (e.g. Slabinski, 1974).

(2) Near geostationary satellites

On various occasions, communication satellites are in near geostationary orbits. Examples are: (a) when orbit inclination is intentionally left uncorrected to 432 Appendix B: Useful Orbit-related Fonnulas conserve on-board fuel and thereby prolong the satellite's useful lifetime and (b) when a satellite is being relocated to another position or a newly launched satellite is being moved to the operational location (such a drifting satellite is sometimes used for communication provided the transmissions do not interfere with other systems). When the satellite orbit is lower than the geostationary orbit altitude, the angular velocity of the satellite is greater than the angular velocity of the Earth. Consequently the satellite drifts in an eastward direction with respect to an earth station. When the satellite altitude is higher than the geostationary height, the satellite drifts westward. The following relationships apply (Morgan and Gordon, 1989):

AP Aw (B.7) p w where AP = change in orbital period P = orbital period Aw = change in angular velocity w = angular velocity and

~r = -(~)A: (B.8) where r = orbital radius Ar = change in orbital radius. For example, a change in radius of + 1 km from the nominal causes a west• ward drift of 0.0128°/day. The required change in satellite velocity Ave to correct the drift is given by

1 Aw Ave= -v- (B.9a) 3 w or

1 -aAw (B.9b) 3 where a = semi-major axis.

Effect of inclination

The main effect of inclination i on a geostationary satellite is to cause north• south oscillation of the sub-satellite point, with an amplitude of i and period of Appendix B: Useful Orbit-related Formulas 433 a day. When the inclination is small (the condition is, tan (i) = i in radians), the motion can be approximated as a sinusoid in a right ascension-declination coordinate system. An associated relatively minor effect is an east-west oscillation with a period of half a day. This is caused by the change in rate of variation of the right ascension relative to the average rate. The satellite appears to drift west for the first 3 hours and then east for the next half quarter. The satellite continues to move eastward during the next half quarter and then westward, completing the cycle in half a day. The maximum amplitude of such east-west oscillation for a circular orbit is given by

(B.10a)

1 ·2 = -l (B.10b) 229 where i is in degrees. Usually the east-west oscillation is very small (e.g. fori = 2.5°, LlliW; = 0.027°). The net effect of these two motions is the often-quoted figure-of-eight mo• tion of the sub-satellite point.

Effect of eccentricity

The effect of eccentricity in a geostationary orbit is to cause east-west oscilla• tion with a period of a day. The satellite is to the east of its nominal position between perigee and apogee and to the west between apogee and perigee. The amplitude of the oscillation is given by

L1EW., = 2e radians (B.ll)

For example, an eccentricity of 0.001 produces an east-west oscillation of ±0.1145° about the satellite's nominal position.

(3) Coverage contours

It is often necessary to plot the coverage contours of geostationary satellites on the surface of the Earth. The satellite antenna boresight (the centre of coverage area) and a specified antenna power beamwidth (usually, half-power beamwidth) are known. In the case of an elliptical antenna beam shape, the sizes of the major and minor axes together with the orientation of the major axis are known. The coverage contour on the Earth is obtained by calculating the latitude/longitude of n points on the periphery of the coverage (Siocos, 1973). 434 Appendix B: Useful Orbit-related Formulas

Let us first define the following angles:

'YB, 'Yn = tilt angles of antenna boresight and the nth point on the coverage contour, respectively En = angular antenna beamwidth of the specified power (e.g. half-power) in the direction of the nth point. For a circular beam, En is a constant.

To specify the nth coverage point we further define 1/Jn as the angle of rotation, the rotation being referenced to the plane containing the sub-satellite and boresight points (see figure B.l). The following steps are used to specify the nth coverage point Tn. Obtain 'YB using the following equation set

{3 = arccos( cos 8B cos cf>sB) (B.l2a)

'YB = arctan[ sinf3/ (6.6235 - cosf3)] (B.l2b) where 8B = latitude of boresight cf>sB = longitude of boresight with respect to sub-satellite point, taken positive when to the west of the sub-satellite point. Then

(B.13a)

(B.13b)

gn = arctan(sincf>sB/tan8B) + c/>n (B.13c)

Coverage contour

Earth

South

Figure B.l Coverage contours geometry. S = sub-satellite point, B = boresight point on Earth, Tn = nth point on the coverage contour. Appendix B: Useful Orbit-related Formulas 435

f3n = arcsin(6.6235sinrn)- 'Yn (B.13d)

(B.13e)

(B.13f) where

(B.14) where a = rotation of t:1 away from the direction of the azimuth of the bore sight t:1 and t:2 are the semi-major and semi-minor axes. 1/Jn can be varied from 0° to 360° to obtain as many points on the coverage contour as desired. For a multiple beam satellite the above steps are repeated for each beam.

(4) Sun transit time

Around the equinox periods (March and September), the Sun is directly behind the geostationary orbit and therefore appears within earth stations' antenna beam. Sun transit through an earth station's antenna causes disruption to com• munication services because of a large increase in system noise temperature caused by the Sun. The transit time of the Sun through an antenna is predict• able, giving the earth station operator the option to make alternative communi• cation arrangements or at least not be taken by surprise when communication is disrupted. The position of astronomical bodies such as the Sun is published in a readily available annual publication called the Nautical Almanac (US Government Printing Office). The position is given in the right ascension-declination coordi• nate system. Sun-caused outage occurs when the ascension and declination of the satellite and the Sun become equal at an earth station (or nearly equal so that the Sun appears in the beamwidth of the earth station antenna). The position of the satellite at an earth station is usually given in the celestial horizon system, as azimuth and elevation. Therefore it is only necessary to convert the satellite azimuth and the elevation to the ascension-declination coordinate system and determine from the Nautical Almanac the day and the time when the Sun has the same ascension and declination. The equations for this conversion are (Siocos, 1973): Declination D is given by

sinD = sin fJsin '17 - cos (Jcos '17 cos g (B.15) 436 Appendix B: Useful Orbit-related Fonnulas where 8 = latitude of earth station TJ = satellite elevation g = satellite azimuth (positive when the denomination is west) D is positive when denomination is north. The ascension a of the earth station in hour angle relative to the satellite meridian is obtained from

sin a = COSTJ sing/cosD (B.16) a is positive when westerly. In the Nautical Almanac, the ascension of the Sun is given with respect to the Greenwich meridian. a is converted to HAG from

(B.17) where HAG = hour angle with respect to Greenwich tPe = longitude of earth station. Note that the right ascensions of astronomical objects are expressed in hour angle, where 1 hour = 15°.

(5) Solar eclipse caused by the Moon

The occurrence of solar eclipse on a geostationary satellite caused by the Moon is irregular. It may be recalled that Earth-induced eclipses are predictable, occurring within ±21 days of equinoxes. It is also necessary to predict the duration and the extent of occurrences of Moon-induced eclipses for spacecraft operations' planning. The technique given here (Siocos, 1981) makes use of Sun and Moon position data available from the Nautical Almanac. An eclipse occurs when the azimuth/elevation coordinates of the Sun and the Moon from the satellite position are equal or close enough to cause the Moon disk to mask the Sun partially or completely. The effective elevation H of the Sun or Moon from the satellite location can be obtained from the following equation set:

cos~= cosdcosLHA (B.18a)

(B.18b) where d = declination of the stellar object (Sun or Moon) LHA = local horizon angle LHA = HA 0 + 8 HAG = hour angle with respect to Greenwich, available from the Nautical Almanac Appendix B: Useful Orbit-related Formulas 437

(J = longitude of the earth station (0° to 180°, positive when to the east of Greenwich) Ro = geostationary orbit height from geocentre = 6.62 R (where R is earth radius) (Ro + R,) = distance of Sun or Moon from geocentre and

Ro = 6.62sin(HP) (B.19) R0 +R, where HP = horizontal parallex (the maximum difference in geocentric and satelli-centric altitude of the stellar object). For the Sun:

HP = 8.85 seconds

For the Moon, the hourly horizontal parallex can be obtained from the Nautical Almanac. The azimuth of the Sun and the Moon observed from the satellite locations is determined by the equation

tanz = sinLHA/tand (B.20) where z = 180° - Az Az = azimuth of the Sun or the Moon d = declination of the Sun or the Moon z is easterly when LHA > 180° z is westerly when LHA <180° and when d is negative, (B.20) gives the value z + 180° rather than z. An eclipse occurs whenever the centre-to-centre distance between the Sun disk and the Moon disk, as viewed from the geostationary orbit, is less than the sum of their radii (see figure B.2):

(B.21) where r, and rm are the radii of the Sun and the Moon obtained from

1- sin(HP) . r= smrc (B.22) [1 - 5.52sin{HP)] and

D = arccos{cosLl/l cosd.Z) (B.23) 438 Appendix B: Useful Orbit-related Formulas

Figure B.2 Solar eclipse on geostationary satellite caused by the Moon - view from geostationary orbit.

where t:J{ and az are the differences between the effective elevations and azimuths, respectively rc is the semi-diameter of the celestial object, as observed on the surface of the Earth, available from the Nautical Almanac HP is obtained from the Nautical Almanac.

Eclipse depth

The covered area of Sun's disk or the depth of eclipse, Ect (see the hatched portion in figure B.2) can be obtained from the equation

Ect = [ 2A _ sin(2A)l + (rm/ r.)z[ 2B _ sin(2B)l (B.24) 360 2'1T 360 2'1T where

cosrm - cosr, cosD cosA = (B.25a) sinr, sinD

cosr, - cosrm cosD casE= (B.25b) sinrm sinD Appendix B: Useful Orbit-related Formulas 439

(6) Satellite-referred coordinates to Earth coordinates

Sometimes the antenna pattern of a satellite is referred to the satellite centred coordinate system. In such a coordinate system the satellite location is taken as the origin. The latitude and longitude are referred to an imaginary sphere around the satellite. The following equation set is used to transform the satellite-centred coordinate system to Earth coordinates:

'Ye = arccos( cosO, coscA] (B.26a)

ge = arctan[ sincA/ tan8,] (B.26b)

f3e = arcsin( 6.617 sin y e) - y e (B.26c)

8e = arcsin( sin f3e cos ge) (B.26d)

(7) Map projections

Earth coverage from a satellite is most commonly shown as satellite antenna pattern contours (referenced from the beam centre) on a suitable map. A coverage contour is obtained by plotting the latitude and longitude of the coverage periphery on a map. The coverage contours appear distorted in many types of map projections such as Albers and Mercator, whereas in several projections the shape of the coverage is undistorted. In general, the choice of map depends on the type of orbit and the users. For example, polar projections are popular with radio amateurs because of advantages such as simplicity in plotting ground tracks. In satellite communications, rectangular projections are often used. One commonly used projection represents the X-axis as longitude and the Y-axis as latitude. However, in such projections the shape of the coverage contours appears distorted. For planning, it is simpler to use maps which retain the angle information of the contours. If a projection is made on a plane which is at right• angles to the satellite-Earth vector, the shape of the beams is retained (Chouinard, 1981; CCIR, 1982). Distances on such a projection are linearly related to the angles. The following set of equations transforms a point Pi on Earth to a satelli-centric sphere: 440 Appendix B: Useful Orbit-related Formulas

y = arctan[sinf3/(6.617 - cosf3)] (B.27) where

f3 = arccos((cos8i cos(

g = arctan[sin(

Here Oi and

o; = arcsin( sin ycosg) (B.29)

{ = arctan( tan y sing) (B.30)

Because o; and¢; are less than 8°41' (~+of the angular diameter of Earth from a geostationary orbit), mapping them in Cartesian coordinates is quite adequate. On such a map, if the two scales are equal, angles are almost preserved.

(8) Off-axis angles

To facilitate interference calculations between satellite networks, it becomes necessary to develop expressions for off-axis angles. An off-axis angle is defined here as the angle between the wanted direction and the undesired direction which gives rise to interference. Figure B.3 shows two modes of interference encountered in practice. Figure B.3(a) shows the interference mode, where interference is either received at the satellite (the 'wanted' satellite) serving the desired network from an earth station of another network, or caused at an earth station of another network by the desired satellite. Figure B.3(b) shows the interference mode where interference is either received by an earth station (a 'wanted' earth station) in the desired network from a satellite serving another network (the 'external' satellite) or caused by a wanted earth station to the external satellite. Referring to figure B.3(a), the off-axis angle is given as (Siocos, 1973)

p~ + p~ - 2(1 - cosf3cti) COS8T = (B.31) 2PctPi where Pct = range between the satellite and desired point E on Earth Pi = range between the satellite and the interfered point f3cti = great circle arc between desired point and interfered point. Range is given in terms of Earth radius (equation 2.20b ). Appendix B: Useful Orbit-related Formulas 441 s

Interfering /path Desired path

(a)

s S,

Desired Interfering path path

(b)

Figure B.3 (a) Interference received or caused by a satellite; (b) interference received or caused by an earth station. (S = wanted satellite, E = wanted earth station, Si = satellite causing or susceptible to interference, Ei = earth station causing or susceptible to interference.)

(B.32) where ed, ei = latitude of points d and i respectively tlcpi = longitude of point i with respect to the sub-satellite point. tlcpi and tlc/Jct are positive when the point is to the west of the sub• satellite point. tlc/Jct = longitude of point d with respect to the sub-satellite point. The off-axis angle eR, figure B.3(b ), is given by (Radio Regulations, AP-29, Annex 1)

p; + Pi _ [84 332sin(Ll~)'] (B.33) 2PctPi 442 Appendix B: Useful Orbit-related Formulas where flt/>si = geocentric angular separation of interfering satellite from wanted satellite (degrees of longitude). Here ranges Pct and Pi are in km (equation 2.20a).

(9) Satellite position from orbital parameters

To estimate the orbital parameter of a satellite, the satellite control centre measures satellite positions regularly. There are a number of techniques for estimating orbital parameters from such measurements (e.g. see Morgan and Gordon, 1989). Orbital parameters are made available to earth station opera• tors and used to estimate useful system parameters such as look angles and Doppler shifts. The method for estimating satellite position, velocity and look angle from any specified location presented here is suitable for computer solu• tion (Morgan and Gordon, 1989). There are three broad steps involved in the process. In the first step, satellite position is estimated in the orbital plane; the second step involves transforming the satellite coordinates to the three-dimensional earth-centred coordinate sys• tem; finally, the earth-centred coordinates of the satellite are transformed to an earth-station-centred coordinate system for obtaining the look angle of the satellite from the earth station. The following orbital parameters are assumed known: eccentricity, ascending node, inclination, mean anomaly at a reference time called epoch (mean anomaly = 0 if epoch is taken at perigee pass), and argument of perigee. Some useful relationships involving eccentric anomaly E, true anomaly v and mean anomaly M are:

cosv + e cos£= (B.34) 1 + ecosv

cos£- e cosv = (B.35) 1 - ecosE where e is the orbit eccentricity. The mean anomaly M at time t is given by

M = M 0 + w(t - t0 ) (B.36) where M 0 is the mean anomaly at a reference time t0 (epoch) and w is the angular velocity of the satellite.

Step 1

(a) The mean anomaly at the specified time is determined from equation (B.36). Appendix B: Useful Orbit-related Formulas 443

(b) The eccentric anomaly is determined by solving Kepler's equation

M = E- esinE (B.37)

For eccentricity <0.001 the eccentric anomaly can be approximated as

E z M + esinM + ..!..e2 sin( 2M) (B.38) 2

For larger values, equation (B.37) must be solved. The equation, being non• linear, requires a numerical solution technique. The Newton-Raphson method provides a quick and accurate estimate. The following steps are involved:

• Obtain an initial estimate of E using equation (B.38) • Obtain the mean anomaly M* using equation (B.37) • The difference M - M* must be made -0 by trial and error.

The increment :lE* is obtained from

M-M* :lE* (B.39) 1 - ecosE*

where (1 - ecosE*) is the slope of the curve M* = E* - esinE*. The process is repeated until the difference M - M* is as small as desirable. Note that M and E in the above equations are in radians. When the true anomaly and eccentricity are known, the eccentric anomaly can be determined by using equation (B.34). Steps (a) and (b) are then not necessary. (c) The position of the satellite in the orbital plane is given by

X0 = a(cosE - e) (B.40a)

1 Yo = a(l - e2 )2 sinE (B.40b)

1 radius, r = (xg + yg)2 (B.40c)

Step 2

The inclination of the satellite, the right ascension of the ascending node and the argument of perigee are used to transform the perifocal coordinate system to the geocentric equatorial coordinate system. The following equation set can be used for this transformation: 444 Appendix B: Useful Orbit-related Formulas

Px = cosw cosO - sinw sinO cosi (B.41a)

py = cos w sin 0 + sin w cos 0 cos i (B.41b)

Pz = sin w sini (B.41c)

Qx = - sin w cos 0 - cos w sin 0 cos i (B.41d)

QY = -sinwsinO + coswcosOcosi (B.41e)

Qz = cos w sini (B.41f)

Satellite position in the geocentric coordinate system is given by

(B.42a)

(B.42b)

(B.42c)

Step 3

Finally, the following set of equations can be used to obtain satellite azimuth and elevation from a specified earth station:

Right ascension, a = arctan (y / x) (B.43)

Declination, o = arctan ( ~ z ) (B.44) X 2 + l

R sin TJs - Elevation, TJ = arctan r (B.45) COST], where

TJs = arcsin [sino sin8e + coso cos8e cos,e] (B.46) and R = Earth radius r = satellite distance from Earth centre (use equation B.40c) oe = earth station latitude s - e ¢, = satellite longitude

Azimuth,. A = arctan [ _____sin c..::::.se ____ ] (B.47) cos8e tan8 - sin8e cosse

Use the convention given in chapter 2, section 2.6 to obtain the azimuth quadrant. The equations given above assume no perturbation in satellite orbit. The accuracy in these equations can be improved by including the effects of perturbations. Equations (2.13) and (2.14) can be used as a first approximation. As a corollary, the range rate at a given location can be obtained from (B.2) and the Doppler shift from (B.1). The time increment (t 2 - t1) can be made as small as necessary.

Range

The distance p of a satellite from a given point on the Earth is given as

p = ~ r 2 - R 2 cos2 'Y/ - R sin TJ (B.48)

(10) Look angle from earth station

Because of the combined effects of inclination and eccentricity, a near geostationary satellite appears to traverse an ellipse in the sky when viewed from the ground. From basic electronics it is well known that this type of shape (Lissajous' figure) consists of two sinusoidal components orthogonal to each other. As mentioned, in addition to the effect of inclination and eccentricity, the non-uniform gravitational force caused by the oblate shape of the Earth causes a geosynchronous satellite to drift towards one of the two stable locations on the geostationary arc -79°E and 252.4°E. The acceleration caused by this force depends on the longitude of the satellite, the maximum value being -0.0018°/ day. To an earth station antenna, the drift appears as a linear displacement in the satellite position. The most accurate estimate of satellite look angles from an earth station is obtained by using the orbital parameters. For most practical applications the azimuth and elevation components of the satellite motion viewed from the ground may be approximated as (Richharia, 1984):

e.(t) = 8ai +Am cos[~ (t- T.)] + AJ + g1 (B.49)

8e(t) = 8ei +Em cos[~ (t- Te)] + EJ + g2 (B.50) 446 Appendix B: Useful Orbit-related Fonnulas where o.(t) = satellite azimuth from an earth station at timet (in hours) (Jai = initial azimuth of the satellite

00 (t) = satellite elevation from the earth station at time t (Jei = initial elevation of the satellite. Ai and Ei are the linear components of the azimuth and elevation angles respectively Am and Em are the maximum excursions in the azimuth and the elevation respectively t1 and t2 are the uncertainties in the position estimates of the satellite for the two axes respectively. The period of the sinusoid is 24 hours. The cosine terms in equations (B.49) and (B.SO) can be expanded in a series form to facilitate development of the model from real-time position data obtained from a tracking system (Richharia, 1984). T. and Teare the times the satellite is at the maximum azimuth and elevation angles respectively.

(11) Stationary bound

(i) The minimum number of stationary satellites required to cover the Earth is obtained by the use of the following equation (Ballard, 1980):

(B.51) where 1/J = great circle range for which the stationary bound is required; the term within the brackets is in degrees N = number of stationary satellites. The equation is derived by dividing the Earth into non-overlapping equilat• eral spherical triangles and determining the sides of the triangle; in this way the coverage is distributed most uniformly around the world. (ii) Compare the above to the stationary bound used by Beste (1978):

N z 2.42/ (1 - cosl/f) (B.52)

The reader should note that an approximation of (B.52) has been used in figure 2.14. Both equations give similar results, although their methods of derivation are different.

(12) Dynamic bound

Dynamic bound takes consideration of the fact that spatial uniformity of the coverage in a real constellation degrades at times (Mozhaev, 1972, 1973): Appendix B: Useful Orbit-related Fonnulas 447

N ~ 5 + 4/3({tan-1 (cosl/l) + tan- 1[cosl/I/(-J2- 1)] (B.53) - 67.5°}/[60°- tan- 1 (-f3cosl/l)])

(13) Rosette constellation (Ballard, 1980)

This section includes some formulas which may be used for the analysis of inter• satellite links in rosette constellation. Referring to figure B.4 and figure 2.17, the inter-satellite great circle range r;j is given as:

sin 2 (r;j2) = {cos 4 (,B/2)sin2 (m + 1)(j- i)(7r/P) + 2sin2 (,B/2)cos2 (,B/2)sin2 m(j - i)('TI"/ P) + sin4 (,B/2)sin2 (m - 1)(j - i)('TI"/ P) (B.54) + 2sin2 (,B/2)cos2 (,B/2)sin2 (j - i)('TI"/ P)· ·cos[2x + 2m(j + i)('TI"/ P))}

The slant range, figure B.4 (Ballard, 1980), is given as:

sr;j = 2(H + RE )sin(r;j /2) (B.55)

Bearing angle 1/!;j is defined in figure 2.16 and is given as

Centre of Earth

Figure B.4 Depression angle d9 and slant range srij between satellites i andj. H = satellite altitude andRE = Earth radius (Ballard, 1980). 448 Appendix B: Useful Orbit-related Fonnulas

tanlh = (sin09 sin(x + mai - TJ;)]/{sin2 (0;)2)sin[2x + m(ai + a;) - h; + riJ)] - cos2 (0,)2)sin[m(ai -a;) - h; - r;J]} (B.56)

where sin '7j; = sin riJ = cos[ ( Gj - a;)/2]/cos( Oj2) sin(0;/2) = sin,Bsin[(Gj - a;)/2] also COS1j; = -cOS7fJ = cos,Bsin[(Gj - a;)/2]/cos(0;/2).

(14) Multi-beam spot beam coverage

The following equations apply (Maral et al., 1991):

Coverage angle, 'I' = 2R{7T/2 - TJ- sin- 1(R: h · COSTJ )}

Figure B.S Geometry of a multi-beam satellite (Maral et al., 1991). Appendix B: Useful Orbit-related Formulas 449

Figure B.6 Satellite cell representation. Centre of cell 1 represents the sub-satellite point (Mara! et al., 1991).

where R = Earth's radius 71 = minimum elevation angle (radians) h = satellite altitude (km).

Coverage angle of each cell, {3 = 2W/(2n + 1) (see figure B.5) where n, termed 'crown', determines the number of hexagonal cells, i.e. spot beams, Nc, within the coverage area (see figure B.6).

Nc = 1 + [6n(n + 1)]/2

1 00 /2 = tan- [Rsin(f3/2)/{h + R- Rcos(f3/2)}]

(Jn = tan- 1[Rsin{(2n + l)f3/2}/{h + R- Rcos{(2n + l)f3/2}}] n-1 - 2:ek - Oo k=l 2 where 00 = beamwidth of central cell ()n = beamwidth of the nth crown. 450 Appendix B: Useful Orbit-related Formulas

(15) Listing of computer programs used for solving some chapter 2 problems

Pnlgnam 1 REM This Qbasic program calculates the azimuth. elevation REM range of a geostationary satellite from a given location on the REM Earth and signal transmission time. Output is saved in a file called PROG3.DAT: Alternatively, REM the output may be printed to the screen. REM by removing line 25(REMming it) and deleting #I from all REM pnnt statements REM Satellite longitude is set on line 30: REM Earth station longitude (in Deg E) is set on line 35: REM Earth station latitude(+ North:- South) is set online 40. REM l Sa tell lie Communication Systems: Destgn Principles by M.Richharia: REM .Solution to problem 3, Ch 2.] REM Program developed by M.Richhana: ll/9/96 5 CLS Ill LET pt = 3. 141592654# 15 LET rad =pi I 180 20 LET sigma= 6378.14 I 42164.57 REM Note pi/ HW converts degrees to radians REM Set elev. to desired elevation angle 25 OPEN "PROG3 OAT" FOR OUTPUT AS#! REM Set satellite location in Degree East :10 satlon = 350 * rad REM Set earth station longitude in Degree East 15 LET eslon = .5 * rad REM Set earth station latitude (Southern latitude -ve) 40 LET eslat = 76 1 * rad REM Pnnt satellite location and elevation angle 45 PRINT #L "Satellite longitude (Dcg E)=": satlon I rad 511 PRINT# l. "Earth station longitud~(Deg E)=": eslon I rad 55 PRINT# L "Earth station latitude (Deg)=": eslat/ rad: PRINT 611 LET dlon = eslon - satlon REM Calculate Elevation 65 LET cosbet = COS(eslat) * COS(dlon) 70 LET smbet = SQR(l - cosbet" 2) 75 eta= ATN((cosbet- sigma) I smbet) XO IF eta I rad < 0! THEN PRINT #L "!!!Note: Satellite below honzon !!!" X5 IF eta I rad < 01 THEN GOTO 165 'JO PRINT# I. "Elevation (Deg) =":eta I rad REM Calculate Anmuth '!5 az = ABS(ATN({TAN(dlon) I SIN(eslat)))) I 110 x = aL I (2 * pi) REM Determine quadrant 115 IF satlon I rad > 270 AND eslon I rad > 0 AND eslon I rad <= 90 THEN sat1ont = satlon - (2 • pi) ELSE sat1ont = satlon 120 IF eslon I rad > 270 AND satlon I rad > 0 AND sat1on I rad <= 90 THEN eslont = eslon - (2 * pi) ELSE es1ont = es1on 125 LET dlont = satlont - es1ont 130 IF SGN(es1at I rad) > O! AND SGN(d1ont I rad) > 0! THEN AZIMUTII = 180- az I rad 135 IF SGN(eslat I rad) >= 0 AND SGN(d1ont I rad) <= 0 THEN AZIMUTH= 180 + az I rad 140 IF SGN(eslat I rad) < 0! AND SGN(d1ont I rad) > 0! THEN AZIMUTH= az I rad 145 IF SGN(es1at I rad) < 0 AND SGN(dlont I rad) <= 0 THEN AZIMUTII = 360- az I rad Appendix B: Useful Orbit-related Formulas 451

!50 PRINT #I, "Azimuth (Deg)="; AZIMUTH REM Calculate Range 155 range= 35786 * SQR(l + .4199 *(I- cosbet)): time= range I (3 * 100) 160 PRINT #I, "Range (Km)="; range: PRINT #1, "Transmission time (ms)="; time: PRINT 165 PRINT, "End of computation" 170 END

Program 2 REM This Qbasic program calculates the latitude/longitude of REM a given elevation angle contour for a given satellite location. REM Output is saved in a file called PROGI.DAT.; Alternatively, REM output may be printed to the screen REM by removing line 20 (REMming it) and deleting #1 from all REM print statements. REM Elevation accuracy is set on line 30; Satellite longitude is set on REM line 45; longitude step is set on line 85; latitude step is set REM on line 105; Care should be exercised in selecting step sizes. REM The program run time is several minutes, depending on the step REM size and the accuracy. REM M.Rlchharia:719196;Solution to problem 4(a), ch 2 5 CLS 10 LET rad = 3.141592654# 1180 15 LET sigma= 6378.14142164.57 REM Note pil180 converts degrees to radians REM Set elev to desired elevation angle 20 OPEN "PROGI.DAT" FOR OUTPUT AS #1 25 LET elev = 5 * rad REM Set accuracy required for elevation angle REM Program is easier to run with lower accuracy 30 accur = .I * rad 3 5 LET test! = elev - accur 40 LET test2 = elev + accur REM Set satellite longttude in Deg E 45 LET satlon = 345 * rad REM Print satellite location and elevation angle 50 PRINT #I. "Satellite position (Deg E)=", satlon I rad 55 PRINT #L "Elevation angle contour (Deg)="; e1ev I rad, "Accuracy(Deg) ="; accur I rad 60 PRINT #I. 65 PRINT #I. "Longitude", "Latitude", "Elevation" 70 PRINT #I. "(Deg)", "(Deg)", "(Deg)" 75 LET dlonst = -80.03 * rad 80 LET dlonen = 80.03 * rad REM Select longitude step size; choose an odd number to avoid 'divide by zero' error. 85 LET stpln = 9.83 * rad 90 FOR dlon = dlonst TO dlonen STEP stpln 95 LET lats = -80.001 * rad 100 LET late= 80.001 * rad REM Select latitude step size; choose an odd number to avoid 'divide by zero' error. 105 LET stplt = .073 * rad 110 FOR !at = lats TO late STEP stplt 115 LET cosbet = COS(lat) * COS(dlon) 120 LET sinbet = SQR(l - cosbet" 2) 125 eta= ATN((cosbet- sigma) I sinbet) 126 eslon = (satlon + dlon) I rad 127 IF eslon > 360! THEN eslon = eslon- 360 130 IF eta> test! AND eta < test2 THEN 452 Appendix B: Useful Orbit-related Formulas

PRINT # l, eslon, !at I rad, eta I rad END IF 135 NEXT !at 140 NEXT dlon 145 PRINT #I, "End of computation" 150END

Program 3 REM This Qbasic program calculates the geostationary arc visible from REM a given earth location for a given minimum elevation angle. REM Output is saved in a file called PROG2.DAT; Alternatively, REM the output may be printed to the screen REM by removing line 20 (REMming it) and deleting #I from all REM print statements. REM Minimum elevation angle is set on line 25; Earth station longitude is REM set on line 30; Earth station latitude is set online 35; REM The program run time and minimum visibility elevation REM angle accuracy depends on the step size, set on line 7 5. REM M.Richharia:9/9/96;Solution to problem 4(b), ch 2. 5 CLS 10 LET rad = 3.141592654# I 180 15 LET sigma= 6378.14 I 42164.57 REM Note pi/ 180 converts degrees to radians REM Set elev to desired elevation angle 20 OPEN "PROG2.DAT" FOR OUTPUT AS #I 25 LET elev = 5 * rad REM Set earth station longitude in Deg E 30 LET eslon = 0! * rad REM Set earth station latitude (Southern latitnde -ve) 35 LET eslat = 51.5 * rad REM Print satellite location and elevation angle 40 PRINT# I, "Earth station longitnde (Deg E)="; eslon I rad 45 PRINT# I, "Earth station latitude (Deg)="; eslat I rad 50 PRINT #L "Visibility (Elevation angle)=": elev I rad 55 PRINT #L "Longitnde (Deg E)", "Elevation (Deg)" REM 60 PRINT #I, "(Deg) ", "(Deg)" 65 LET dlonst = -80.03 * rad 70 LET dlonen = 80.()3 * rad REM Select step size: A 'divide by zero' error may occur REM if step size is not proper. 75 LET stpln = .5 * rad 80 FOR dlon = dlonst TO dlonen STEP stpln 85 LET cosbet = COS(eslat) * COS(dlon) 90 LET sinbet = SQR(l - cosbet" 2) 9 5 eta = A TN ( (cosbet - sigma) I sinbet) 100 sat! on= (eslon- dlon) I rad 105 IF eta > elev THEN· PRINT # L sat! on, , eta I rad END IF 110 NEXT dlon 115 PRINT #1, "End of computation" 120END

References

Ballard, AH. (1980). 'Rosette constellations of earth satellites', IEEE Trans. Aerosp. Electr. Systems, Vol. AES-16, No.5, September, pp 656-673. Beste, D.C. (1978). 'Design of satellite constellation for optimal continuous coverage', IEEE Trans. Aerosp. Electr. Systems, Vol. AES-14, No.3, May, pp 466-473. Appendix B: Useful Orbit-related Formulas 453

CCIR (1982). Report ofInterim Working Party, PLEN/3, CCIR, XVth Plenary Assembley, Geneva. Chouinard, G. (1981). 'Satellite beam optimization for the broadcasting satellite service', IEEE Trans. Broadcasting, Vol. BC-27, No. 1, pp 7-20. Maral, G., Ridder, J-J. D., Evans, B.G. and Richharia, M. (1991). 'Low earth orbit satellite systems for communications', International Journal of Satellite Communica• tions, Vol. 9, pp 209-225. Morgan, W.L. and Gordon, G.D. (1989). Communications Satellite Handbook, Wiley, New York. Mozhaev, G.V. (1972). 'The problem of continuous earth coverage and kinematically regular satellite networks, 1,' Cosmic Res., Vol.10 (UDC 629.191), November-Decem• ber, 1972, translation in CSCRA7 (Consultants Bureau, New York), Vol. 10, No.6, pp 729-882. Mozhaev, G.V. (1973). 'The problem of continuous earth coverage and kinematically regular satellite networks, II,' Cosmic Res., Vol. 11 (UDC 629.191 ), January-February, 1973, translation in CSCRA7 (Consultants Bureau, New York), Vol. 11, No. 1, pp 1- 152. Nautical Almanac (yearly). Superintendent of Documents, US Government Printing Office, Washington DC, 20402. Richharia, M. (1984). 'An optimal strategy for tracking geosychronous satellites', !JETE (India), Vol. 30, No.5, pp 103-108. Siocos, C.A. (1973). 'Broadcasting satellite coverage - geometrical considerations', IEEE Trans. Broadcasting, Vol. BC-19, No.4, December, pp 84-87. Siocos, C.A. (1981). 'Broadcasting satellites power blackouts from solar eclipses due to moon', IEEE Trans. Broadcasting, Vol. BC-27, No. 2, June, pp 25-28. Slabinski, V.J. (1974). 'Variations in range, range-rate, propagation time delay and Doppler shift in a nearly geostationary satellite', Prog. Astronaut. Aeronaut., Vol. 33, No.3. Index

absorption 72 BCH code 184 absorption band 72 examples 184 oxygen 72 generation 180 water vapour 72 Hamming code 184 absorption cross-section 74 parity check 184 absorptivity 310 Reed-Solomon code 184 acceptance 321 algebraic coding 180 access protocol ALOHA 261 ALOHA schemes 261-3 frame 263 channel reservation 260 limitations 263 choice of 265 pure 267 contention protocols 261-5 reservation 263 data traffic 258-65 slotted 262, 263 evaluation criteria 259 throughput 261 packet reservations 263-5 AM 134 accessing schemes 9 detection 135 acoustic environment 217 generation 135 ACSSB 138 limitation 135 ACTS 418 side bands 135 ACTS payload 424 spectral characteristics 134 ACTS programme 423 ambient temperature 104, 105 adaptive delta modulation 214 amplifier, noise-free 105 adaptive differential PCM (adaptive amplitude companded single side band DPCM, ADPCM) 210, 213, 214 (ACSSB) 138 adjacent channel interference 235 amplitude modulation (see also AM) adjacent transponder 235 134-5 advanced concepts 418 amplitude non-linearity 111 Aeronautical and Space Administration AM-PM conversion 111, 112 423 analog telephony 208 aeronautical channel analog-to-digital conversion 201, 209 fade duration 91 angle modulation 138 link margin 91 antenna 101, 119 link reliability 91 aircraft 91 multipath 91 aperture 96, 97 Rice factor 91 asymmetric configuration 332 shadowing 91 axes 95 aeronautical environment 91 axi-symmetric configuration 330, 332 aeronautical terminal 7 blockage 97 AFC 232 boresight 95 Afro-Asian Satellite Communications copolar pattern 96 Ltd 402 cross-polar coupling 99 air conditioning 355 cross-polar discrimination 96 albedo 308 directivity 97 Albers 439 dual polarized 99 ALC 122,287 earth station 95 algebraic code effective aperture 98

454 Index 455

efficiency 97 error probability 193-4 f!D 97 performance evaluation 193-4 focal length/diameter (f!D) 97 performance measures 193 gain 98 throughput 193, 194 gain function 97 ARQ schemes 194-5 half-power beamwidth 97 ASC system quantitative relationships 98 characteristics 402 radiation intensity 97, 98 example 403 radiation intensity, average 97 space segment 402 radiation pattern 95, 96 ascending node 24 satellite 95 precession 30 single-axis 96 ASIC 416 antenna basics 95-100 ASK 151 antenna boresight 100 aspect ratio 218, 220 antenna characteristics 95 ASTRA satellites 413 antenna efficiency 98 asymmetric configuration 332 antenna gain 102, 103, 121 asynchronous transfer mode 270, 396 antenna gain function 89 bit error rate 270 · antenna mount 333 cell dropping 270 fixed 334 circuit mode 269 mobile earth station 334 packet mode 269 antenna noise propagation delay 270 elevation angle dependence 108 satellite network 270 galaxy noise 108 ATM (see also asynchronous transfer oxygen 108 mode) 270 water 108 atmospheric absorption 119 antenna noise temperature 349 atmospheric drag 33, 278, 378 Sun 41 atmospheric multipath 79 antenna radiation pattern attenuation half-power beamwidth 96 cloud 78 main lobe 96 cloud and fog 78 shaped 96 cross-section 74 side lobe 96 depolarization, relationship with 84 antenna size, receiver 94 fog 78 antenna temperature hydrometers 72 estimated 109 rain 73 oxygen 109 theoretical 73 rain 109 attenuation distribution 75 satellite 109 attitude and control system water vapour 109 orbit-raising phase 295 AOCS 282, 291, 296 orientation determination 295 aperture, field pattern distribution 97 attitude and orbit control 291 aperture plane 331 on-station control 296 apogee 60 attitude control 296 apogee-kick motor 61, 299, 311 gravity controlled 293 firing 61 passive 292 application specific integrated circuit sensors for 293 (ASIC) 416 attitude-control system 292, 313 Arabian Satellite Communication auto-correlation 248 Organisation see ARABSAT automatic frequency control (AFC) 232 ARABSAT 3 automatic level control (ALC) 122, 287 Archimedes project 373 automatic repeat request (see also ARQ) argument of perigee, rate of change 30 170, 176 ARQ 193-5, 199 automatic tracking 337 456 Index auto-track receivers 338 bit error rate 126 auto-track system 338 M-ary PSK 161 comparison 343 relationship with symbol error 161 autumn equinox 39 bit rate average orbital angular velocity 28 bandwidth-limited link 245 axial ratio 100 power-limited link 245 azimuth 21, 29, 38, 445 bit synchronization 197, 204 azimuth-elevation mount 333 bit-synchronizer circuit 156 block code 178, 179-87 bandwidth 228 orthogonal 180 bandwidth power, trade-off 144 body stabilization 296 base station 388 momentum wheel 297 baseband bit rate 152 station-keeping 297 baseband filter 143 body-stabilized mode 61 baseband signals 201-7 Boltzmann constant 120, 429 demultiplexing 220 Boolean algebra 180 multiplexing of 220-3 boresight 95 baseband spectral characteristics 201 Bose, Chaudhari and Hocquenghem code basic satellite system 4-8 (see also cyclic code) 184 battery BPSK 152, 153 charging 307 bit error 162 depth of discharge 306 bit error rate 160 figure of merit 306 bit-synchronization error, due to 162 lifetime 45, 46, 306 comparison with QPSK 161 mass 306 phase error, due to 162 reconditioning 306, 307 power spectral density 163 voltage regulation 306 probability of error 160 bauds 152 symbol error rate 160 BCH codes 184 bread-board model 321 beacon 301 brightness temperature 108, 109 beam waveguide feeds 336 British Geological Society 38 beam-forming technique 414 broadband interactive services 396 Bessel function 139 broadband LEO system 367 Bessel zero 139 broadband personal services 12 BFSK 165 broadband system 395 bandwidth 166 broadbeam antenna 86 big LEO mobile system 397 broadcast example 395, 397 sound 11 binary frequency shift keying (BFSK) television 11 165 broadcast channel 232, 267 bandwidth 156 broadcast quality 210 binary phase shift keying (see also BPSK) broadcast satellite service (BSS) 3, 68, 126, 152, 153 325 hi-phase transmission 204 growth trends 413 hi-propellant fuel 318 broadcast satellite systems 406 hi-propellant system 299 BSS 3, 151 bit categories 70 high 202 BSS frequency bands 70 low 202 bus, requirements 291 bit energy-to-noise power density 118 bit error cable television 8 due to thermal noise 159 call congestion 202 sources 159 Calling Network 395 bit error probability 159 canting angle 80 Index 457 capacity management 245 power spectral density 253 carrier and bit time recovery 241 processing gain 254 carrier power, received 101 receiver carrier-to-noise ratio 254 carrier power spread 204 traffic growth, accommodation of 257 carrier recovery 136, 156, 158, 197 celestial equator 19 M-ary PSK 157 celestial horizon coordinate system 21, carrier recovery circuit 157 29 carrier regeneration, error in 161 celestial sphere 19, 43, 47, 51, 57 carrier suppression 239 cell delay 270 carrier to intermodulation noise 126 variation 270 carrier to multipath noise 87 cellloss 270 carrier to noise power spectral cells, geographically fixed 396 density 244 cellular mobile communication carrier-to-noise ratio 116 system 209 demodulator imput 117 cellular radio 11 downlink 121 channel in transparent repeater 117 impulse noise 186 optimal 208 noise characteristics 186 regenerative transponder - total link sources of impairments 168 118 with error bursts 185 satellite path 121-2 channel coding 125,176 total 126 channel congestion 224 total in regenerative transponder 118 channel connection, set-up time 260 transparent transponder - total link channel interference, adjacent 127 117-18 channelloading 146 uplink 120-1 channel quality 126 Carson's bandwidth 140 channel reservation 260 Carson's formula 140 channel reservation schemes 258 Carson's rule 147 circuit mode calls 384 Cassegrain antenna systems 347 circular orbit 27 Cassegrain feed system 331, 332 circular polarization advantages 332 left-hand circular 99 Cassiopeia A 108 right-hand circular 99 CCIR 78, 82, 115, 126, 141, 142, 145, clock, synchronized 203 218 clock jitter 207 CCIR Green Books 18 clock signal 203 CCIR study groups 77 close user environments 210 cenT 208, 211, 219, 220, 225 clustered satellite 420 CCITI FDM plan 221 coaxial and optical fibre cables 10 CCITI multiplexing 223 code CCITI multiplexing plan 220 classification 178 group 220 concatenation 187 super-group 221 detection and correction 180 super-mastergroup 221 for channels with error bursts 185-7 CDMA 171, 229, 248-58 linear 178 advantages 248 maximum length 249 capacity 257 code division multiple access (see also carrier-to-interference ratio 248 CDMA) 167, 229 degradation in 258 code generation 180 grade of service 257 code generator matrix 181 implementation 248 code rate implementation loss 254 code detection and correction 179 interference margin 254 reduction 13 multipath noise resistance 248 code tree 189 458 Index

code words 180 design issues 94-131 coded orthogonal frequency division noise considerations 103-13 multiplexing (COFDM) 167-8 communication quality 210 code-generating polynomial 184 communication satellite 6, 274-324 coder 210 antenna 288-90 codes atmospheric pressure and temperature algebraic 180 276 classification of 178-92 attitude and control system 291-7 linear 180 attitude control 292-4 low cross-correlation property 251 attitude control, sensors for 293-4 coding 9, 76, 133, 169, 170, 173-200, bus 291-313 327 communication considerations 275-Q adaptive 125 control systems 294-7 background 176-8 design considerations 275-7 block code 199 dry mass 317-18 channelinfluence 195 environmental conditions 276-7 comparison of 198 lifetime 278 concatenated code 199 magnetic fields 277 concept 177 mass, payload 316-17 convolution code 199 mass, primary power sub-system 314- detection and correction 177 16 hard/soft decision 199 mass and power estimations 313-19 performance comparison 196 payload 283-90 performance in gaussian noise 196 platform, mass of 317 selection of 195-9 power sub-system 304-8 summary 198-9 propulsion system 298-9 coding advantage 183 reliability 278-82 coding gain 192-3, 195, 197 repeater 283-7 gaussian channel 192 space particles 276 theoretical values in gaussian structure 312-13 channel 198 sub-systems 282-313 using BPSK 197 telemetry, tracking and using QPSK 197 command 299-304 coding improvement 178 thermal control 308-11 coding overhead 178 thermal control techniques 311-12 coding performance comparison transfer orbit, mass in 319 block and convolution codes 197 transparent repeater 284-7 general conclusions 197 wet mass 318-19 hard and soft decision 197 community reception 70 coding scheme, adaptive 174 companding 147 COFDM 167-8 improvement 217 coherent demodulation 156, 158 instantaneous 217 cold sky 108 syllabic 217 co-located satellites 420 companding range 217 command, verification 302 compandor 137,212 command decoder 302 attack time 218 command sub-system 301 instantaneous 212 command system, block diagram recovery time 218 301 signal-to-noise ratio advantage 218 common TDMA terminal syllabic 212 equipment 352 comparative analysis 123 communication equipment 349 complementary error function 160 communication link 101 composite television signal 145 design 94 compression ratio 217 Index 459 compressor 212 constraints, sharing 114, 115 computer program, source code 450-3 contention protocols 258, 261 concatenated codes 199 control algorithm 295 conical horns 334 control bits 241 conical scan 338, 339, 343 controllaw 295 constellation control station 64 Ballard optimization 53, 54 control system, active 292, 293 cellular distribution 59 convolution, decoder 190 combination of various types 58 convolution code 178, 187-92 deployment 57 code tree 189 Ellipsat 59 constraint length 188, 190 global coverage 47 decoding 189 harmonic factor 52 free distance 189 hybrid 58-9 minimum distance 189 ideal 55 node 189 inclined orbit 51-6 span 188 inter-orbital separation 49 convolution encoder 188 Loopus 57 convolution noise 235 optimization 46, 49 coordinate systems 18-21 orbital period selection 56 coordinate transformation 29 partial deployment 59 coordination phase relationship 4 7 frequency 114 phased 47 process 115 polar 47 copolar attenuation random 47 cross-polar discrimination, relationship reconfiguration 395 with 82 regional coverage 51, 59 outage probability 82 selection of 373 copolar link margin 83 single coverage 4 7 copolar signal 100 spot beam 59 correlation bandwidth 167 spot beam coverage 59 corrugated horn 335 theoretical bound: stationary and cosec correction 72 dynamic 58 cosmic noise 107 trade-off 59 coverage triple coverage 50 between pole and a latitude 49 type 1 47 efficiency 49, 50 type 2 47 examples 289 Walker 46, 51, 52 global 47 worldwide coverage 51 high latitude 57 constellation capacity 369, 391 regional 57, 59 altitude dependence 369 single 47 constellation deployment 45 triple 50 constellation design types 289 coverage 367 unbiased 55 store and forward system 59 coverage angle 50, 51 traffic distribution 367 coverage area 96 constellation geometry 370, 390, 392 optimization 121, 290 constellation optimization, satellite antenna gain 121 rationale 396 coverage circle 48 constellation parameter, example 56 coverage contour geometry 434 constellation size coverage efficiency 49 dynamic bound 446-7 coverage region 4 stationary bound 446 critical design review 321 constraint length 188 cross-correlation 248 460 Index cross-luminance 219 CCIR recommendation 141 cross-polar component 100 filter characteristics 141 cross-polar coupling 99, 127 de-emphasis advantage total 127 FDM telephony 145 typical value 127 television 145 cross-polar discrimination 79, 80, 81, de-encryption 361 83, 99, 100, 114 delta modulation 210, 213 calculated 81 detection 213 circularly polarized wave 82 digital conversion 213 copolar attenuation, relationship feedback loop gain 214 with 82 idle noise 214 frequency, relationship with 82 limitations 213 horizontally polarized wave 81 delta patterns 52 measured results 83 demand assignment 225 measurements 82, 83 advantages 232 outage probability 82 signalling and switching 233 vertically polarized wave 81 demand-assigned data channel, cross-polar isolation 79, 80, 127 throughput, upper bound 260 cross-polar pattern 99 demand-assigned FDMA 229 CTIE 352 improvement factor 238 functions 354 versus pre-assigned 238 customers' premises, terminal mounted demand-assigned SCPC on 124 capacity 237 cyclic code 183 SPADE 237 BCH 183 demand-assigned time division multiple Golay 183 access 232 Reed-Solomon 183 demodulation 133 Cygnus A 108 demodulator realization 133 DASS 233 threshold extension 349 DASS unit 234 demultiplexing 220 data access protocol, selection of 265 de-orbiting satellites 395 data codec 350 deployable antennas 416 data signals 202-8 depolarization data traffic 229 attenuation, relationship with 84 access protocol 258 ice 80, 83 asynchronous 178 mechanism 80 bursty factor 259 rain 80 categorization 258 DEPSK 157, 158 characteristics 258 descending node 24 environment model 259 descrambling 361 examples 258 design defects 280 inter-arrival time 259 difference pattern 340 synchronous 178 differential attenuation 83 DBS 8 differential PCM 210, 212, 213 decentralized regulation, disadvantages differential phase 83 308 differential phase shift keying declination 19, 444 (DPSK) 157, 158, 160 decoding 182 differentially encoded phase shift keying look-up table 180 (DEPSK) 157, 158 sequential 126 digital compression 12 Viterbi 126 digital data without interpolation 352 decoding table 181 digital modulation 151-65 de-emphasis 141 amplitude shift keying 151 Index 461

frequency shift keying 151 Doppler effect 34-5, 44, 45, 89, 232, higher order 154 430 phase shift keying 151 Doppler frequency shift 5, 34, 35 digital modulation schemes 151 due to environment 89 digital multiplexing 221-3 due to satellite motion 89 digital signals double side band suppressed carrier characteristics 203-8 (DSB-SC) 134, 135-6 examples 202 downlink margin, main components 119 digital speech interpolation 245, 246, DPSK 157, 158, 160 268, 352 DPSK demodulator 157 digital systems, advantages 202 drag 25, 61 digital telephony 209 drift phase 61 digital television 219, 414 drop distribution, Marshall-Palmer 78 advantages 219 drop size distribution 74 digital word 211 DSB-SC 134-6 digital-to-analog converter 209 demodulation 135 direct broadcast receiver DSI 246,352 antenna 361 freeze-out fraction 248 baseband processing 361 gain 248 cost 417 DSI gain 248 descrambling 361 dual mode _terminal 388, 421 design optimization 361 dual spin satellites 296 encryption 361 dual-polarized antenna 289 receiver 361 dual-polarized system 79, 82, 99, 127 direct broadcast satellite 287 bandwidth utilization 99 Indian programme 413 interference in 114 direct broadcast satellite receiver 329 duplex circuit 224 direct digital interface 355 duplex TDMA 400 direct orbit 25 direct sequence spread spectrum 251-4 Eb!No 118 narrow-band interferer 252 Early Bird 2 occupied channel width 252 Earth, infra-red emissions 293 principle 251 Earth acquisition 63 processing gain 252 Earth coordinates, satelli-centric system, receive power spectrum 252 conversion 440 receiver 251, 252 Earth eccentricity 429 spreading function 251 Earth equatorial radius 429 synchronization technique 252 Earth gravitational constant 429 transmit power spectrum 252 Earth gravitational field 30, 293 transmitter 251 Earth gravitational parameter 429 direct sound broadcast 12, 414 Earth magnetic field 33, 293 directivity, antenna 97 Earth mass 30, 429 direct-to-home broadcasting 12 Earth observations 31 distress alert facility 407 Earth orbit 304 distributed architecture 44 eccentricity 277 distributed frequency management Earth polar axis 333 233 Earth polar radius 429 advantages 233 Earth sensors 293 distributed telemetry systems 301 Earth shape 25 disturbing torques 293 earth station 4, 9, 101, 120, 325-63 DNI 352 antenna pattern 96, 115 domestic networks 3 antenna system 329-34 domestic satellite systems 3 categories 325, 326 domestic systems 124 characteristics 347-62 462 Index

configuration 328 echo control technology 418 constraints 169 eclipse 45, 46, 308, 379 design considerations 325-8 geostationary satellite 306 design trade-off 326 economies of scale 396 direct broadcast service 169, 327 edge, of service area 120 feed system 328, 334-6 effective isotropic radiated power (EIRP) fixed satellite service 169, 347-56 100, 123, 326 functions 325 effective length, rain 77 general configuration 328-47 eight-phase PSK 153 G/T 325 EIRP 100, 123, 326 group delay 235 satellite 170 high-power amplifier 345-7 EIRP of user terminals 390 IF system 350 electric generation interface 6 nuclear power 304 international regulations 327 solar cells 304 look angle 445-6 electrical propulsion 416 low-noise amplifier 344 electromagnetic interference 377 mobile satellite service 327, 356-60 electromagnetic wave, polarization 98 optimization 328 electronic beam squinting 344 out-of-band transmissions 111 elevation 21, 29, 444 power control 112 elevation angle 54 power spectral density 115 ellipsoid 30 RF sub-system 329 elliptic orbit 27 satellite television 360-2 elliptical beam 290 size reduction 328 elliptical polarization, inclination 99 specification 328 elliptically polarized wave 100 support services 355 EMI 377 support sub-system 329 emissivity 310 technical constraints 327-8 encryption 176, 361 tracking source 300 energy dispersal 151 tracking system 336-44 analog signal 151 user's premises, located in 327 digital signal 151 earth station antenna 95 engineering model 321 CCIR reference patterns 330 engineering service circuits 355 side lobe characteristics 330 entropy 174 earth station antenna system 418 maximum 174 earth station cost envelope delay 151 factors 327 envelope detector 143 optimization 327 equator 49 earth station design equatorial cross-section 31 constraints, international regulation, equipotential field 60 technical 327 erf 160 optimization 327 erfc 160 earth station equipment Erlang 224 · communication 349 error function 160 receive 349 error matrix 182 transmit 349 error probability 118 earth station operator 29 ESA 423 earth station technology 405, 417 Euler number 249 growth trend 417 European Space Agency 391, 418, 423 earth station tracking systems 29 European Telecommunication Satellite eccentric anomaly 28, 442 Organisation (EUTELSAT) 3 eccentricity 24 EUTELSAT 3 echo control 421 excitation analyser 216 Index 463

expandor 212 fibre optic systems 45, 408 expansion ratio 217 final stage burnout of the launcher 26 Explorer-] 2 finite element method 313 fixed ground terminal 85 fade fixed satellite service (FSS) 3, 12, 68, cumulative distribution 373 70,124,151,212,268,325,408 frequency dependence 373 impact of optical fibres 408 fade duration 89 fixed terminals 124 measured results 91 fleet management 412 fade margin 87 flexible antenna 416 fade rate 89 flight model 321 fade threshold 91 floating base stations 423 failure mode flux density 102 early 279 FM random 279 channel loading with voice 146-8 wear-out 279 group delay effects 150-1 fairing 312 threshold effect 148-50 Faraday effect 84-5 threshold extension 150 compensation 85 FM demodulator 349 frequency dependence 85 input/output relationship 143 FDM (frequency division multiplexing) noise characteristics 141 142, 144, 220-1 threshold 143 time-frequency plot 220 threshold effect 143 FDM signal, occupied bandwidth 147 using feedback 150 FDM system FM discriminator 150 channelloading 146 FM equation 142-6 pre-emphasis/de-emphasis approximation 144 network 142 FM improvement 144 FDM telephony channel 145 FM signal (see also frequency FDM/FM/FDMA 231 modulation) FDMA 111, 229-39, 260, 397 effective bandwidth 150 advantages 239 group delay, effect of 150 bandwidth channel 236 FM/FDM telephony 349 bandwidth utilization 236 forward error correction code 176, 195 carrier extraction 231 forward link 393 categorization 231 frame 218 channel utilization 237 frame efficiency 243 definition 229 frame length 243 demand versus pre-assigned 238 frame rate 218 design considerations 234-9 free space path loss 101, 119 disadvantages 239 frequency impairments 234 coordination 69 salient features 239 errors 34 spectrum utilization efficiency 236 operational, selection of 67 transponder capacity 237 selection, existing system 69 transponder utilization 235-8 selection, new system 69 FDMAJTDMA, multiple beam selection of 103 environment 245-6 uncertainties 34 FEC code (forward error correction frequency allocation code) 176, 195 footnote 68 feed system 334, 347 plan 115 functions 334 primary 68 feeder links 70 secondary 68 fibre optic cables 10 frequency discriminator 143 464 Index frequency division multiple access (see frequency shift keying (FSK) 151, 165- also FDMA) 111, 229-39, 260, 397 7 number of accesses 235 frequency translator 349 frequency division multiplexed telephony dual conversion 349 145 single conversion 349 weighting advantage 145 frequency uncertainties 34 frequency division multiplexing (FDM) frequency window 71 142, 144, 220-1 FSK 151, 165-7, time-frequency plot 220 FSS 3, 12,68, 70,124,151,212,268, frequency domain coder 210, 214-16 325, 408 frequency hopped spread spectrum earth stations 347 254-6 FSS allocations 125 code rate 256 FSS frequency bands, main 70 hopping rate 256 fuel interference mechanism 256 hi-propellant 298 processing gain 256 impulse 298 transmitter spectrum 255 mono-propellant 298 frequency hopping 254 specific 298 frequency modulated signal, total impulse 298 bandwidth 140 fuel requirements 314 frequency modulation (see also future public land mobile FM) 138-51, 219 telecommunication systems 421 applications 138 future trends 12-13, 405 arbitrary signal 140 influencing factors 405, 407 bandwidth 140 carrier power 139 G7 nations' Global Information demodulator 149 Broadband Initiative (Gil) 424 deviation adjustment 141 G/T 108, 123 frequency deviation 139, 140 G/T specifications 126 generation 138 galaxy noise 109 improvement 149 gallium arsenide field-effect input/output signal-to-noise ratio transistors 344 142 gallium arsenide technology 415 modulation index 139 gaseous absorption 72 noise effects 141 gaussian noise 137 phaselockloop 149 generator matrix 180, 181 side band magnitude 139 GEO 365 sinusoidal 140 GEO system 392 spike generation mechanism 149 geocentre 18, 19 subjective estimation of geocentric coordinate system 444 threshold 149 geocentric latitude 21 threshold 149 geocentric-equatorial coordinate system threshold effect 148 19 using feedback 149 geodetic latitude 21 frequency modulation demodulator geometric visibility 367 noise characteristics 141 geostationary orbit 31, 32, 35, 96 power spectral density of noise 141 advantages 5, 35 frequency multiplexed telephony 142 angular velocity 429 frequency planning, constraints 113 average radius 429 frequency pool management azimuth 38 advantage 232 coverage angle 36 centralized 232 coverage limit 429 distributed 232 disadvantages 5, 35 frequency reuse 290 drift 31 Index 465

eclipse by Moon 436-8 global information infrastructure 424 eclipse by Moon, eclipse depth 438 role of satellites 424 effective utilization 330 Global Mobile System 387 elevation 36 Global Positioning System 416 geometric solution 36 GLOBALSTAR 387 geometry 36-8 GMPCS 13 half-angle 429 go-back N ARQ 194 interference model 440, 441 GOS 225 maximum range 429 GPS 412 minimum range 429 GPS receiver 400 Moon eclipse 41 grade of service (GOS) 225 off-axis angle 440-2 gradient tracking algorithm 344 perturbations 277 gravitational effects 32 primary power 38 heavenly bodies 32 propagation delays 35 gravitational force (gravitational range 38 pull) 30 satellite spacing 330 Moon 25,32 slot selection 42-3 Sun 25,32 solar eclipse 38 gravity gradient 32 solar eclipse, by Moon 436 great circle 21 Sun eclipse, by Moon, eclipse depth great circle range 54 438 elevation and orbital period 55 Sun transit time 435-6 Gregorian configuration (system) 331, tilt angle 36 332 velocity 429 Grey coding 161 geostationary satellite 22, 35, 39, 275, ground segment 4, 6 288 characteristics 6 azimuth 38 ground station 4 coverage contours 433-5 tracking beacon 301 Earth eclipse 39, 40 ground track 59 east-west oscillations 433 group delay 151 eclipse due to Earth 39-40 effect on SCPC 235 eclipse due to Moon 41 group delay distortions 235 effect of eccentricity 433 group delay equalizers 151 effect of inclination 432 GSM 387 elevation 36-7 guard band 114, 127, 148, 221, 231, 235, external perturbations 292 242 launch 60 Gunn oscillators 344 launch, expendable launcher 61-3 gyroscope 294 launch, space shuttle 63-4 perturbations 296 Hamming code 181, 184 range 38 Hamming distance 179, 183, 184, 185, range rate, eccentricity 430 189 range rate, inclination, drift 431 hand set, radiation issues 377 solar eclipses 38-41 hand-held communicators 8 geostationary satellite system hand-held satellite service 398 limitation 12 hand-held telephones 411 transmission delay 12 hand-held terminals 418 geosynchronous orbit 35 hand-held unit, radiation risk 370 GIBN 424 handover 44, 45, 385, 387 Gil 424 beam to beam 45 global coverage satellite to satellite 45 minimum satellites 56 handover procedures 6 true 45 hard decision decoding 191 466 Index

hardware constraints 170 ICO system 366, 400 harmonic factor 52 idle channel noise 213 HDTV 219,220 implementation issues 290 heat fluctuations, body-stabilized implementation loss 161 spacecraft 312 implementation margin 159, 161 heliocentric-ecliptic coordinate impulse noise 150, 235 system 25 impulse response, rectangular filter HEO system 392 206 hexagonal cells 449 I~T-2000 421, 424 high definition television 219, 220, 408, inclination 24 414 inclination change 32 high latitude locations 30 inclined elliptical orbit 6 communication 90 individual reception 70 service 6 information 173 high latitude regions 44 information bits 180 high power amplifier (HPA) 111, 122, information rate, average 174 287,288,345,346,349 information signal 152 configuration 345 information theory 173 multi-amplifier configuration 346 basics 173-6 single-amplifier configuration 345 infra-red detectors 293 higher-order modulation schemes Inmarsat 3, 124 410 Inmarsat network 266 high-frequency bands 418 Inmarsat-A 267 high-power satellites 417 Inmarsat-Aero 267 Hilbert transform 136 Inmarsat-B 267, 356 HLR 388 Inmarsat-B terminal Hohmann transfer 60 above deck unit 357 home location register 388 antenna system 358 hopping beam system 415, 419 below deck unit 358 hopping spot beams 397 control functions 358 horizontal parallex 437 specifications 357 horn antenna 334 Inmarsat-C 267, 356 hot sky 108 Inmarsat-C system 195 hour angle 436 Inmarsat-C terminal 358 HPA 111, 122, 287, 288 Inmarsat-~ 267 transfer characteristics 111 Inmarsat-P 400 HPA rating 349 in-orbit tests 63 HPA redundancy 346 INSAT 413 hub 355 insulation blanket 311, 312 human cognitive process 209 integrate and dump circuit 156 hybrid coder 210, 211 integrated stages 63 hybrid constellation 43, 392 integrated switched digital network hybrid frequency management 202 scheme 234 integrated terrestrial-satellite mobile hydrazine 298, 299, 318 communication 420 hydrometers, attenuation due to 72-8 intelligent track(ing) 343, 344 intelligible cross-talk 234 ice, depolarization, caused by 83 INTELSAT 3, 124, 246, 313 ICO INTELSAT network 347 constellation capacity 401 INTELSAT SCPC system 349 main elements 401 INTELSAT standard-A 329, 343, 347 satellite lifetime 401 INTELSAT standard-B 343 terminal types 401 INTELSAT TD~ 352 ICO Global Communication Ltd 400 characteristics 352 Index 467

INTELSAT VII 289,290 inter-symbol noise 206 interactive multi-media service 424 inter-system interference inter-fade interval 89 allowable 114 interference 96, 114-16, 126 various types 114 adjacent channel 127 inter-system noise 107, 119 adjacent transponder 127 intra-system interference 99, 114 cross-polar coupling 127 link margin 114 in dual-polarized system 114 intra-system noise 119 intentional 116 inverse parabolic filter 141 inter-system 114 investment 123, 423 intra-system 114 ionosphere 71, 84 Radio Regulations 114-16 effects on radio wave 84 solar 41-2 electron content 84 terrestrial systems 128 Faraday effect 84 interference effects 44 F-region 85 interference management frequency dependencies 84 fixed satellite service 115 polarization rotation 84 mobile satellite service 115 scintillation 84 interference margin 257 total electron content 85 interference sources, adjacent satellite ionospheric conditions 33 126 ionospheric effects 84-5 interleaving 185 ionospheric scintillation 85 interleaving depth 185, 186 diurnal variation 85 intermodulation noise 111-13, 121, influencing factors 85 122,126,236,238,239,245,287, link margin 85 345 peak levels 85 adjacent transponders 235 1-Q plane 153, 154 intermodulation product 112, 256 Iridium 14, 397 estimation 113 Iridium constellation/system 51, 398 odd order 113 network architecture 399 order 113 ISDN 410 satellite 113 lSI 164, 204, 205 third order 113 isotropic antenna 100 International Mobile isotropic radiator 98, 100 Telecommunications 2000 424 ITU 3, 9, 67, 68, 327, 360 international regulations 327 procedures 114 international switching centres 10 region 1 68 International Telecommunication region 2 68 Union (ITU) 3, 9, 67, 68, 114, 327, region 3 68 360 Internet 219, 407 jamming 256 Internet access 395 Internet model 423 K. band 71 inter-orbital separation 50 advantages 418 inter-satellite link 44, 45, 135, 370, 383, shortcomings 418 399,417,419 K. band payloads 417 advantages 420 K" band 125 bearing angle 447 Kennedy Space Center 63 great circle range 447 Kepler's equation 443 slant range 447 Kepler's laws 16 system architecture 420 Kepler's second law 28 INTER-SPUTNIK 3 Kepler's third law 26 inter-symbol interference (lSI) 164, kinetic energy 27 204, 205 klystron 345, 349 468 Index land mobile channel link calculations, operational satellite elevation angle dependence 90 122 environment dependence 89, 90 link design 116-29 limitations 89 example 124 link margin 89 numerical example 128-9 link quality 90 planning 123-4 measurement results 90 VSAT 123, 124-9 problems 89 link margin 75, 76, 85, 118, 119, 159 propagation characteristics 89 elevation angle dependence 76 land mobile communication 30 worst-case 118 terrestrial 87 link parameters, channel related 117 land portable terminal 89 link partition propagation environment 89 downlink 94 land terminal 7 satellite path 94 large earth stations 347 uplink 94 lasers 135 link reliability 44, 75, 83, 85, 118 last mile 408, 409 system cost 119 latitude 21, 23 Lissajous' figure 445 high 59 little LEO system 366, 401 launch example 401 polar orbit 63 LNB 361 space shuttle 63 location registration 387 launch cost 44, 379 log-normal distribution 87 launch errors 318 longitude 21, 23 launch phase 308 look angle 29 launch sequence, geostationary satellite Loopus 44 62 loss factor 106 launch site, effect on orbital low earth orbit (LEO) 6, 45, 293, 309, inclination 61 364,365,367,378 launch vehicle, reusable 63 advantage 6 launch window 64 altitude 378 launcher disadvantage 6 expendable 61, 62 low earth orbit constellation 393 reliability 11 messaging system 195 LEO 6, 45, 293, 309, 364, 365, 367, low earth orbit satellite system 12 378 coverage snap shot 369 LEO system 46, 395, 412 low noise amplifier 415 lifetime extension 415 characteristics 344 lightweight materials 416 low noise block down-converter 361 line of apsides 60 low noise window 108 line of nodes 24 line rate 218 M level frequency shift keying 165 linear algebraic codes 182 MAC 361 linear modulation 134 magnetic declination 38 linear modulation schemes 134-8 magnetic deviation 38 linear polarization 99 magnetic variation 38 linearizer 287, 345 man-made space debris 276 link manual track 337 design methods 94 map projection 439-40 optimization 94 Albers 439 satellite component 121 Mercator 439 link availability 125 polar 439 VSAT system 125 rectangular 439 link budget, service link 393 maritime channel 90-1 Index 469

antenna dependence 90 hybrid schemes 268 elevation dependence 90 maximum interconnections 268 frequency characterization 91 message link margin 91 average delay 259 measured data 91 delay in delivery 258 multipath 90 inter-arrival time 259 Ricean model 90 loss through collision 258 sea condition dependence 91 quality 94 shadowing 90 quantity 94 signal fade 90 total information 174 signal impairments 90 message delay, inter-arrival time 260 time characterization 91 message interception 176 M-ary frequency shift keying, bandwidth message quality 100, 116 166-7 meteorites 33 M-ary FSK 165 meteoroids 276 bandwidth 166, 167 'micro' satellites 402 generation 165 microwave integrated circuits 415 orthogonal frequencies 167 microwave radio 123 M-ary FSK receiver 166 Mie theory 74 M-ary orthogonal FSK 175 military communication 116, 210 M-ary PSK 152, 157, 159 minimum elevation angle 56 bandwidth compared with BPSK minimum shift keying (MSK) 165 165 mobile channel demodulator 159 amplitude probability distribution 88 spectral occupancy 164 environment dependence 88 MASER 344 low earth orbit 88 mass estimate model, accuracy 314 medium earth orbit 88 mass of the Earth 25 time-dependent characteristics 89 matched filter 175 mobile communication channel, maximum fade length 91 propagation effects 85-91 maximum likelihood technique 192 mobile communication system 159 MCPC (multiple channel per mobile communications 12 carrier) 231 high latitudes 35 mean anomaly 24, 28, 442 propagation loss 35 mean deviation 147 mobile earth station mean equatorial radius 30 design optimization 356 mean fade length 91 large 357 mean speech level 208 small 358 mean time between failures 279 mobile environment 86 medium earth orbit (MEO) 6, 364, 365, mobile ground terminal 86 367 mobile propagation channel advantage 6 diffused path 87 altitude 378 direct path 87 disadvantage 6 environment dependence 87 medium earth orbit constellation 393 phase 87 medium earth orbit system, shadowing 87 example 400 specular path 87 melting layer 83 time characterization 87 MEO 6, 364, 365, 367 mobile satellite channel satellite lifetime in 45 aeronautical 86 MEO system 45, 366,412 land 86 Mercator 439 maritime 86 meridian 21 mobile satellite communication 11 mesh network 268 applications 11 470 Index mobile satellite service (MSS) 3, 7, monolithic microwave integrated circuit 68, 70, 71,136,170,209,266,325, 416 411 monopulse 338, 343 categories 7 monopulse system 340, 342 ground segment 7 difference pattern 341 growth trends 411 feed system 341 spectrum allocation 412 performance trade-off 342 spectrum sharing 412 sum pattern 341 mobile satellite system 406 monopulse technique 302 VSAT 410 Moon, reflection 2 mobile switching centre 387 MPEG-2 219 mobile telephony 58 M-QAM 153 mobile terminal 71, 94, 391 MSC 387,388 EIRP 371 MSK 165 hand-held 124 bandwidth occupancy 165 orbital altitude 371 definition 165 satellite G/T 371 MSS 3, 7, 68, 70, 71,136,170,209,266, specification 391 325, 411 mobile-satellite path 86 optimal frequency range 71 mobility management 387 propagation consideration 72 mode extraction 341 MSS architecture 386 mode extractor 335 multichannel model of satellite motion 29 bandwidth 147 modulation 9, 132-72, 209 mean deviation 147 amplitude 133 peak deviation 147 channeldependence 168-9 rms deviation telephony 147 continuous 133 signal-to-noise ratio 147 definition of 132 multichannel peak factor 147 direct broadcast service 169-70 multichannel rms deviation 147 earth station constraints 169-70 multichannel telephony fixed satellite service 169 occupied bandwidth 148 hardware complexity 133 peak deviation 148 hardware constraints 170-1 rms deviation 148 mobile satellite service 168 multi-media terminals 8 necessity for 132 multipath 86, 119 phase 133 power spectral density 86 selection for mobile satellite service multipath noise 86 170 elevation dependence 87 selection of 168-71 probability distribution 87 sensitivity to 133 multipath spectrum 89 signal impairment 133 multiple access sinusoidal 133 asynchronous transfer mode 269-70 spectral occupancy 133 data traffic 258 system consideration 133-4 examples 266-8 system level consideration 133 fixed satellite service 268 modulation index 149 future trends 268-70 compression 150 influencing parameters 228 modulation scheme, spectrally efficient Inmarsat network 266 245 mobile satellite service 266-8 modulo-2 adders 178 optimization criteria 228 Molniya orbit 30, 35, 277, 377 throughput 258, 259 momentum dumping 295 multiple access examples 266 momentum wheels 294, 297 multiple access protocols 259 monitoring stations 34 multiple access scheme 406 Index 471

future trends 268 cosmic 71 INTELSAT network 268 downlink 117 multiple access techniques 209, 228-73 effects of 94 multiple amplifier configuration 346 in resistor 104 multiple beam 290 interference 117 FDMA operation 245 intermodulation 111, 117 TDMA operation 245 intra-system 103 multiple channel per carrier 231 link total 117 categorization 231 man-made 71, 103 definition 231 mean square voltage 104 multiple spot beam system 419 natural 103 multiple spot beams 288 propagation media 108 multiple stage rockets 60 radio stars 108 multiplexed analog components 361 rain 108 multiplexed telephonic signals 201 satellite system 115 multiplexer single entry 115 high bit rate 223 sources of 94 low bit rate 223 thermal 103 multiplexing 201 uplink 117 multiplexing plan noise burst 185 Bell Systems 223 noise figure 104 CCITT 223 active device 105 time division multiplexing 223 attenuator 106 multiplexing standards 220 cascaded amplifiers 107 multi-tone ranging system 302 definition 105 lossy network 105, 106 NASA 418,423 series network 106 National Aeronautical and Space noise generator 104 Administration (NASA) 418, 423 maximum power transfer 104 natural resources 329 noise loading ratio (NLR) 147 Nautical Almanac 41, 435, 436, 437 noise power 104 navigation system 396 noise power spectral density 104 communication system, combination noise source 126 with 412 external 107 n-body problem 29 man-made 107 NCS (network control station) 232, 267 natural 107 near geostationary satellites 431 VSAT 126-8 network, coexistence 115 noise temperature 104, 105, 120 network architecture 44, 45, 382 active device 105 network control station 232, 267 amplifier 105 assignment rules 232 antenna 107-10 network issues 390 attenuation 106 network management 385 cascaded amplifiers 107 network synchronization 203 effective 110 new technology 410 equivalent 108 Newton's laws 26 lossy network 106 of gravitation 17 lossy network definition 105 of motion 17 rain 108 Newton-Raphson method 443 receiver 110 Ni-Cd batteries 306 satellite 110 Ni-H cells 306 series network 106 NLR 147 Sun 41 noise 115 system 110 budget 115 non-furlable-type antennas 312 472 Index non-geostationary constellation 43-59 propagation issue 373 altitude dependence 43 quality of service 373 constellation issues 377 reasons for interest 365 eccentricity dependence 43 regulatory considerations 380 health issues 377 spares policy 380 inclination dependence 43 specifications, inputs 389 orbital considerations 377 synthesis 391 spectrum allocation 375 terminal characteristics 370 spectrum availability 375 terminal cost 380 non-geostationary orbit satellite system non-geostationary system 270, 364-404 architecture 385, 386 advantages 364 connectivity 385, 386 case study 389-94 mobility management 386 communication requirement 370-2 real time 383 constellation optimization 367 routing 383 constellation size 377-9 non-linearity design considerations 367-89 amplitude 111 disadvantages 364 phase 111 electromagnetic interference 377 non-real-time services 382 examples 394-404 non-return to zero 203 financial issues 380-1 non-systematic codes 181 health considerations 377 NRZ 204 launch considerations 379 NRZ signal, power spectral density 204 network issues 381-9 NTSC 218, 361 operation considerations 380 nutation 295 orbital considerations 377-9 nutation sensors 295 orbital debris 379-80 Nyquist rate 205 quality of service 373-5 Nyquist sampling rate 211 reasons for interest 364 Nyquist's sampling theorem 211 regulatory issues 380-1 satellite capacity 369 observer position, estimation 34 spacecraft technology 370 occupied bandwidth 148 spectrum availability 375-6 off-axis angles 440 terminal characteristics 370-2 offset antenna 347 traffic distribution and coverage 367- offset QPSK 158 9 offset reflector 290 non-geostationary satellite system OLYMPUS 418 call charge 380 OMJ 335 case study 389 OMT 335 choice of orbit 392 on-board processing 246, 399, 411, 423 communication requirement 370 open satellite communication systems disadvantages 365 standard 423 diversity improvements 373 open-loop control systems 337 examples 394 operating licence 381 financial issues 380 operational phase 63, 291 launch considerations 379 optical fibre 123 maintenance 380 optical fibre system 1, 395 message delivery delay 382 advantages 408 monitoring 380 cost 409 network architecture 382 optimum receiver 190 network issues 381 0-QPSK 158 operational considerations 380 ORBCOM 14, 366, 382, 401 path loss 365 orbit(s) 5, 277 propagation delay 365 altitude 46 Index 473

comparison of 43, 44 recovery 264 coverage 44 reservation requests 263 elliptical 59 packet reservation protocols 258 formulas 430-49 packet switching technology 396 geostationary 35-43 paging system 138 highly elliptical 90 PAL 218,361 hybrid 46 PAM-D 64 inclined 90 parabolic noise 141, 145 parking 60, 61, 62 parallel redundancy 280 satellite 16-66 parameter of the conic 26 transfer 61, 62 parametric amplifiers 344 types 46 parking orbit 64 useful formulas 430 path loss 44, 45, 46, 102, 103 orbit and control system 277 payload 63 orbit control 298 payload complexity 380 orbit normal 32 payload cost 320 orbital altitude 54 payload repeater orbital debris 45 regenerative 283 radio regulation 379 transparent 283 removal 46 PCM 212, 213, 217 orbital eccentricity 33 decoding 211 orbital inclination 60 peak deviation 148 orbital mechanics 16, 314 peak-to-peak luminance 145 orbital parameters 24-5, 300, 302, 442 Peltier effect 344 orbital perturbations 52 perifocal coordinate system 19, 20, 27 orbital plane 50 perigee 19, 24 rotation 30 perigee stages 63 orbital position, efficient use of 115 period of a satellite 26 orbital separation 42 personal communication services 360, orbital slot 400 available 42 personal communication systems 402 number of 42 main features 360 overcrowding 42 terminals 360 selection 42 personal communications 365, 411, 424 orbit-control system 291 perturbations 29, 32, 63 orbiter 63 phase angle 152 orbit-raising 277 phase detector 149, 150 orbit-raising phase 291 phase lock loop/phase locked loop 34, orderwire 232 149 orthogonal mode junction 335 phase modulation orthogonal mode transducer 335 demodulator complexity 153 orthogonal polarization feed generation 138 assembly 335 mitigation of noise 153 orthogonal port 99 RF bandwidth 153 orthogonal signals 180 spectral efficiency 153 orthogonality 168 phase noise 159 phase non-linearity 235 packet 258, 259 phase shift keying (PSK) 151-65 vulnerable period 262 bandwidth 163-5 packet access schemes 229 demodulation 156-62 packet loss, collision 261 demodulation, effect of thermal noise packet reservation 263 159-61 mechanisms 264 demodulation, effects of noise 159- queue management 264 62 474 Index

error in bit synchronization 162 pre-detection bandpass filter 156 error in carrier regeneration 161-2 pre-detection bandwidth 120 modulators 155 pre-detection filter 143 spectral efficiency 154--5 prediction coefficients 213 phase state 155 pre-emphasis phased array 290 CCIR recommendation 141 phased array antennas 416 cross-over frequency 141 phased array technique 344 filter characteristics 141 pilot 137 pre-emphasis advantage recovery 137 FDM telephony 145 pitch 215, 292 telephony 145 pitch axes 297 television 145 pixel 218 pre-emphasis/de-emphasis 219 planet 16 preliminary design review 321 mass 17 primary feed 331 planetary motion 16 prime-focus feed 331 plans, pre-assigned 114 limitations 331 p-n junction 304 user 331 pocket-sized telephones 400 processing gain 252 point-to-point communications 3 program track 337 Poisson process 261 propagation polar constellation 47-58, 398 degradation due to 67 optimum 47, 51 tropospheric effects 72-84 worldwide single coverage 47-50 propagation considerations 71 worldwide triple coverage 50 propagation delay 44, 45, 375, 395 polar mounts 333 propagation environments 176 polar orbits 377 propagation loss 35 Polaris 293, 294 propellant tank 299 polarization propulsion system 298 circular 98 protocols 229, 259 coupling 81 prototype model 321 horizontal 98 pseudo-random bit sequence 151 linear 98 pseudo-random code orthogonal 99 auto-correlation function 250 vertical 98 power spectral density 250 polarizer 98, 335 pseudo-random data 304 polarization compensation 335 pseudo-random sequence(s) 204, 249- portable radios 407 51 position 29 auto-correlation function 249 position determination 45 power spectral density 249 potential energy 27 properties 249 power control, uplink 245 pseudo-random spreading signal 248 power estimate model, accuracy 314 PSK 151-65 power flux density 100, 101 PSK demodulator, effects of noise power generation 304 159 power spectral density 115 PSK modem 350 power sub-system 291, 304 PSK schemes power-bandwidth trade-off 170, 175 efficiency factor 154 power-limited link 244 RF spectrum 154 preamble 241 spectral efficiency 154, 155 pre-assigned data channel, throughput psophometric weighting 144 upper bound 260 public switched network 10 pre-assigned FDMA, versus demand pulse, band-limiting 204 assigned 238 pulse code modulation 210 Index 475

QAM 151,153 depolarization, caused by 80-3 QPSK 152, 153, 167 physical temperature 108 bandwidth comparison, BPSK 164 rain attenuation bit error rate 160 CCIR recommendations 77 coherent demodulation 158 prediction 76 power spectral density 164 prediction technique 77 probability of error 160 rain attenuation measurements 75 symbol error rate 160 rain attenuation prediction quadrature amplitude modulation Crane model 78 (QAM) 151, 153 Lin's model 77 susceptibility to noise 153 rain drop quadrature phase shift keying (see also attenuation cross-section 74 QPSK) 152, 153, 167 drop size distribution 74 quality of seiVice 270, 373, 392 scattering cross-section 74 quantization, step size 212 specific attenuation 74 quantization noise 212 rain fade 125 quantization process 211 rain rate, 5-minute advantage 77 quantizer 210 raised cosine filter 206, 207 one-bit 213 range 119 quasi-stationary constellation 57 range estimate, error 303 quasi-stationary footprints 416 range rate 445 ranging tone 302 RADAR 339 Rayleigh distribution 87 radiation pattern 95 Rayleigh fading 159 radiation safety standards 356, 401 reaction wheels 294 radiator, lossless 98 real-time interactive seiVices 382 radio amateurs 34 real-time tracking 29 radio channel, degradation 71 received carrier power 118-20 radio detection and ranging 339 received power flux density 100 radio frequency 392 received signal level 102 radio link 94, 102 received signal quality 117 end-to-end 95 receiver filter bandwidth 34 frequency dependence 103 receiver sensitivity reliability 56 figure of merit 120 radio link parameters G/T 120 earth station related 116 recent tracking techniques 342 satellite related 116 reciprocal device 95 radio regulations 9, 67, 96, 114 rectangular waveguide 334 Article 8 68, 71, 115 redundancy 177, 280 Article 29 115 optimization 281 radio relays 10 redundant bits 180 radio seiVices, categorization 68 Reed-Solomon code 184, 186, 187 radio signal characteristics 186 attenuation 86 reference meridian 21 multipath 86 reflector antenna 290, 329, 331 reflection 86 regenerative repeater 13, 419 scattering 86 advantages 419 specular component 86 regenerative transponder 118, 125 radio spectrum 96 regional mobile satellite systems 12 equitable use 67-71 regional networks 3 radio stars 108 regional system 402 rain regulations, affecting design/ attenuation 73-8 planning 115 attenuation prediction 76-8 relative humidity 72 476 Index reliability rotation of perigee 31 parallel 280 routing protocols satellite 281 centralized routing 385 satellite, figure of merit, redundancy distributed routing 385 282 flooding 385 series 279 routing table 386 reliability bound 280 Royal Greenwich Observatory 21 reliability model 280 RS code (Reed-Solomon code) 184, communication satellite 281 186, 187 communication sub-system 281 repeater 282 sampler 210 comparison of 284 sampling, timing accuracy 205 dual-conversion isolation, transmit- satelli-centric coordinates, conversion to receive sections 287 earth coordinates 439 multiple-stage conversion 286 satellite 9, 101, 275 multiplexer 287 access 9 regenerative 285 active 2 single-stage conversion 286 advanced technique 415 transparent 284, 285 altitude 291 repeater gain 284 antenna gain 119 request for proposals 320 antenna pattern 119, 274 rescue coordination centre 8 antenna pointing 115 retrograde orbit 25 available EIRP 122 return link 393 capacity 275 return link budget 394 configuration 275 revenue 123 coverage 275 RF carrier spikes 204 coverage area 288 RF sensing method 294 design 274 RF signal disturbing torques 293 load 151 EIRP limit 124 power spectral density 151 electrical power 274 RF visibility 367 environment conditions 274 Rice (Ricean) factor 87, 91 environment effects 276 Ricean amplitude distribution 87 equipment life 33 Ricean distribution 86, 87 fuel capacity 33 Ricean fading 159 gain 122 Ricean model 91 global coverage 288 right ascension 24, 444 heatsources 308 right ascension angle 19, 52 integration with terrestrial right ascension-declination coordinate lifetime 278, 296, 318 system 19, 20 lifetime extension 415 right-hand circularly polarized wave 99 maximum antenna diameter 327 risk 45 maximum primary power 327 rms deviation 148 multiple bus 308 rocket multiple path 114 first -stage 61 operational 122, 278 second-stage 61 operators 115 V-2 2 optical fibre 395 roll 292 other applications 3 roll axes 297 'paper' 43 roll-off factor 206, 207 passive 2 filter implementation complexity 207 path in space 25-6 rosette constellation 52, 393, 447-9 period 26-7 rotary joint 336 position 27-9 Index 477

power supply 308 advanced concept 418-26 range 302,445 advantages 1 range-rate 302 advantages, vis-a-vis optical fibres 408 redundancy 11 applications 1, 10-12 reliability 11, 274 background 2-3 reliability, definition, failure benefits 1 mode 278 business plan 123 reliability-cost trade-off 282 competition 1 replacement 46 economics 10 requirements 274 future applications 407-14 RF transmitter power 313 future applications, broadcast satellite search 57 services 413-14 secondary power source 39 future applications, fixed satellite service area 274 services 408-11 service type 275 future applications, mobile satellites spin-stabilized 276 411-13 stabilization of 63 future trends 12, 405-28 stabilized 276 growth 1 station-keeping 115 growth trend 405 storage battery 39 important milestones 13-14 sub-systems 282 initial years 405 surface area 33 last mile 409 telecommunications 275 limitations 10, 11 temperature change 306 network 1, 94 temperature variations 276 planning 123 thermal control 308 restoration time 408 thermal design 39 risk 123 thermal environment 308 technology growth 405 thermal model 310 technology trends 414-26 three-axis 276 technology trends, earth station track 57 technology 417-18 tracking 302 technology trends, spacecraft translation frequency 232 technology 414-17 velocity 27 vis-a-vis optical fibre system 409 zero delay 397 satellite communication growth satellite access 238 emerging growth area 407 satellite access nodes 401 future applications 407 satellite accessing technique 170 influencing factors 407 satellite acquisition 337 satellite communication system satellite altitude, lower limit 33 capacity re-allocation 410 satellite antenna, horizon, direction of comparative analysis 123 98 optical fibre 410 satellite antenna beamwidth 292 satellite communication technique, satellite antenna gain, coverage area investments 423 121 satellite communication technology, satellite attitude growth trends 406 pitch 292 satellite constellation, deployment 365 roll 292 satellite control centre 301, 302 yaw 292 satellite control facility/system 294, 321 satellite azimuth and elevation 444 satellite drift 432 satellite capacity 239, 369, 372 satellite eclipse 42 satellite cell representation 449 satellite EIRP 372 satellite clusters 422 mobile G!T 372 satellite communication(s) 1 orbital height 372 478 Index satellite footprint 288 IF system 350 satellite gain, selection of 122 pre-assigned 232 satellite high power amplifier SPADE 238 back-off 234 SCPC channels 202 impairments 234 SCPC receiver satellite lifetime 396 AFC 352 functional 33 automatic frequency correction 352 operational 33 DASS 352 orbital 33 demand-assigned signalling and satellite lifetime extension 422 switching unit 352 satellite mobile communications 3 timing and frequency control unit 352 satellite motion, laws governing 16-18 SCPC system 268 satellite orbits 16 demand-assigned 171 satellite period 26 pre-assigned 171 satellite platform 291 SCPC terminal 351 satellite position 27 fixed-assigned 350 from orbital parameters 442-5 fixed-assigned scrambling 350 satellite production techniques 416 SEACAM 218, 361 satellite range 29 secondary power source 40 satellite receiver, noise temperature 121 selective repeat request, throughput satellite redundancy 44 efficiency 195 satellite resources 242 selective request ARQ 194 satellite switched TDMA 268 mean time for transmission 194 satellite system throughput efficiency 195 basic 4 semi-major axis 24, 26 fibre optic 364 semi-stable points 31 fibre optic-like 366 sequential decoding 191 integration with terrestrial system 388 service area 42, 390 interface with terrestrial system 388 SES (ship earth station) 267 planning 365 shadowing 119 satellite system cost 409 Shannon's theorem 175 satellite telephones 365 Shannon-Hartley theorem 175 satellite television receivers 360 shaped beam 288 satellite transmitter 122 synthesis 290 satellite velocity 27, 29 shaped spot beam 274 circular orbit 27 sharing constraints 125 elliptic orbit 27 shift register 178, 185, 187, 189, 249 satellite visibility 45, 387 maximum length linear sequences multiple 58 249 satellite-optical fibre synergy 409 ship earth station (SES) 267 satellite-referred coordinates 439 ship terminal 7 sawtooth waveform 151 sidereal day 21, 22, 23, 35 SCADA 395 signal fidelity 94 scanning sensor scheme 294 signal quality, figure of merit 116 scattering cross-section 74 signalling channel 232, 233 scintillation 84, 119, 185, 342 signal-to-noise ratio 126 fading rate 79 signal-to-quantization ratio 212 magnitude 79 simplex signal 196 tropospheric 79 simultaneous lobing 340 SCPC (single channel per carrier) 144, sinc2 function 163 146, 231-4, 246, 349 single channel per carrier (SCPC) 144, demand-assigned 232 146,231-4,246,249 earth station 350 companding 146 effects of frequency drift 232 companding advantage 146 Index 479

demand-assigned 246 maximum duration 42 FM equation 146 maximum number of days 42 pre-emphasis advantage 146 solar radiation 277 weighting advantage 146 variation in intensity 306 single event failures 377 solar radiation pressure 33, 296 single parity check 184 solar temperature 108 single side band (SSB) 134, 136-8 solar-array Sun tracking 297 single side band modulation (SSB solid-state amplifiers 287 modulation) 136-8 solid-state power amplifiers 345 detection 137 sound broadcasts 8, 70 occupied bandwidth 138 sound channels 70 single side band suppressed carrier (SSB- source coder 209, 214-16 SC) 136 South Atlantic anomaly 378 single visibility 56 space single visibility coverage 47, 51 atmospheric pressure 276 site diversity 76 environment 276 sixteen-QAM 153 space particles 276 sky noise 107 temperature 276 Moon 108 space debris 44 Sun 108 space environment 377 slope overload 213 magnetic fields 277 slotted ALOHA space hardened computers 416 channel capacity 262 space platforms 422 throughput 262 space segment 4, 5, 400 soft decision decoding 191 cost estimates 319-21 soft handover 387 cost model 319, 320 solar activity 276 non-recurring cost 320 solar array 304 planning 319 average temperature 305 recurring cost 320 cell interconnection 305 space segment cost 380 degradation 315 circular orbit 320 deployment 63 elliptical orbit 320 effective temperature 315 space shuttle 61 primary power 315 Space Transportation System 61 single point failure 305 spacecraft 275, 390, 392 size, spin-stabilized 315 antenna 282 size, three-axis stabilized 315 antenna, unfurling 288 solar array size array 316 body-stabilized spacecraft 305 attitude and orbit control system 282 dependence on attitude and orbit batteries 379 control system 305 battery 316 spin-stabilized spacecraft 305 bus 282 surface area 305 cost 287 solar cell 276, 277, 304, 305, 306 critical components 278 conversion efficiency 304 design considerations 275 effects of space environment 304 development programme 321 long-term voltage variation 304 development stages 321-2 silicon 304 electric power supply 283 voltage variation 306 failure analysis 280 solar cell efficiency 315, 316 in-orbit 319 solar constant 315 mass, beginning of life 319 solar day 21 mass estimate 316 solar flares 84 mass estimation model 313 solar interference 41 mechanical environment 312 480 Index

payload 282, 283, 316 speech power control 316 redundancy 209 power estimation model 313 synthetic quality 210 primary power 316 unvoiced 215 primary power, equinox/solstice 315 vocal tract response 215 primary power sub-system 314 voice excitation analyser 215 propulsion 282 voice pitch generator 215 repeater 282 voiced 215 structure 282, 312 speech energy sub-system 283 amplitude 208 telemetry, tracking and command 283 bandwidth 208 thermal 282 speech generating model 214 transfer orbit 319 source 214 spacecraft antenna 393 system 214 cross-polar discrimination 290 speech interpolation 246-8 feed, excitation coefficient, beam• speech model 211 forming network 290 speech pause 248 implementation issues 290 speech signal signal routing 290 reference point 208 spacecraft development programme 321 statistical analysis 213 conceptual design 321 spherical Earth 30 definition phase 321 spin axis 294 development phase 321 spin mode 63 spacecraft development stages 321 spin rate, decay 296 spacecraft mass spin stabilization 291, 296 beginning of life 318 solar arrays 296 dry 317 station-keeping 297 platform 317 spot beam 76, 274, 288, 402, 413, 414, reflector/feed 317 419 wet 318 advantages 76 spacecraft power 228, 414 connectivity 245 spacecraft power system 277 frequency to beam mapping 246 spacecraft structure, material 313 traffic in 246 spacecraft technology 370, 405, 414 spot beam coverage growth trend 414 multi-beam 448 spacecraft temperature 310 spot beam technology 44 space-qualified electronics 2 spread spectrum 248 SPAJJE 233,268,352 direct sequence 249 SPAJJE terminal- demand- frequency hopped 249 assigned 352 RF bandwidth 251 specific attenuation 74 spread spectrum modulation 125, 167, specific mechanical energy 27 171 spectrum 390 spread spectrum system 266 equitable use 67 applications 256 expansion in operational system 67 capacity of 257-8 spectrum allocation spring equinox 39 exclusive 68 Sputnik-1 2 planned 68 SSB 134 shared 68 generation 136 spectrum efficiency 44, 45 satellite communication 137-8 spectrum regulation 9 spectral occupancy 136 spectrum reuse 402 SSB modulation 136-8 spectrum shortage 414 effects of noise 137 spectrum utilization efficiency 236 satellite communication 137 Index 481

signal-to-noise ratio 137 Sun-synchronous orbit 31, 379 synchronous detection 137 orbital altitude 377 use of compandors 137 supercells 396 SSB-SC 136 supetvisory control and data acquisition SSPA 415 (SCADA) 395 stabilization system 334 syllabic compandors 217-18 stable points of the orbit 31 symbol 152 standby generators 355 symbol duration 152 star sensor 294 symbol rate 152, 155 static Earth sensors 297 synchronization pulse 145 static sensing technique 293 synchronized digital network 203 stationary platform system 422 synchronous detection 135, 137 station-keeping 52, 115 Syncom III 2 fuel 301, 318 syndrome 182 fuel requirement 319 syndrome decoding 183 specific impulse 318 synthetic quality 211 Stefan-Boltzmann law 309 system constraints 8 step-track 338, 343 system design step-track system 342 frequency considerations 67-71 step-track technique 358 propagation considerations 71-91 stop and wait ARQ 194 system design considerations 8-10 store and forward system design tools 94 architecture 382 system planning asynchronous schemes 383 evolutionary 124 capacity 383 risk 124 earth station based, capacity, routing systematic codes 181 schemes 383 inter-satellite link 383 TASI 246 satellite-based 382 Taurus A 108 store-and-forward setvice 358 TDM 202,220 store-and-forward system 195, 382 composite bit rate 222 stratospheric air platform 368 statistical variations 222 stratospheric balloons 422 timing plan 222 stratospheric systems 422 TDM/PSK/FDMA 231 structural model 321 TDMA 112, 170, 202, 203, 229, 240-8, structure design 313 260,268,269,397 STS/Centaur 64 advantages 245 sub-band coder 210 burst synchronization 242 sub-band coding 214 capacity 240 sub-satellite point 37 capacity alteration 241 sum pattern 340 closed-loop burst synchronization 242 Sun 16, 17, 18 closed-loop synchronization 242-3 movement relative to equator 39 demand-assigned 267 Sun acquisition 63 demodulator performance 244 Sun eclipses 44, 378 disadvantages 245 Sun inclination 39 earth station 244 Sun radiation effect of satellite motion 241 average power 304 frame efficiency 243-4 variation in intensity 304 frame time 242 Sun spot numbers 85 guard time 240 Sun transit 125 network synchronization 240, 241 earth station 108 open-loop burst synchronization 242 occurrence of 42 open-loop synchronization 242 occurrence prediction 42 reception 240 482 Index

reservation 264 colour saturation 218 salient features 245 hue 218 satellite switched 246, 247 luminance 218 switch matrix 247 television standard 145, 218 synchronization 243 television transmissions 201 time slot 240, 241 terrestrial access circuits 238 transmission 240 terrestrial transmissions 8 transponder utilization 244-5 test tone deviation, multichannel voice capacity 243 deviation, conversion of 146 TDMA burst 354 tethered satellites 421 TDMA terminal 352 theoretical channel limit 197 demodulator 354 thermal control multiplexing baseband 354 active 311 receive section 354 electric heaters 311 terrestrial interface 354 factors influencing 308 TDMA traffic terminal 353 heat pipes 311 TDMA/DNI 352 hinged pipes 311 TDMA/DSI 352 passive 311 TDRSS 419 principles 308 technology 46 system design 309 technology trends 414 thermal control techniques 311 tele-command receiver 302 thermal design telecommunications research and body-stabilized 311 development 424 spin-stabilized 311 Teledesic 395 thermal environment 309 services 395 low earth orbit 309 system architecture 395 transfer orbit 309 terminals 395 thermal equilibrium 309, 310 telemetred parameters 300 thermal gradients 39 telemetry, modulation 300 thermal model 321 telemetry carrier 302 thermal noise 103-5, 126, 159 telemetry data rates 300 thermal noise power 120 telemetry sub-system 300 thermal sub-systems 291 telemetry tracking and command system thermal-vacuum simulation tests 311 (TT&C) 5, 291, 299, 300, 301, 308 three-axis stabilization 291, 296, 297 main blocks 300 three-axis stabilized satellite 298 main functions 300 threshold effect 143 telephone channels, analog 209 throughput 194 telephone signals 208 thruster 298 telephony 208-18 force applied 298 analog 208 time division multiple access (see also digital 209-18 TDMA) 112,202 FM/FDM 349 satellite switched 246 television 144, 349 time division multiplexing (TDM) 202, audio 349 220, 222 direct broadcast to ships 219 time domain coders 210-14 luminance signal 144 time slots 232 peak-to-peak amplitude 144 time-assigned speech interpolation 246 sound transmission 219 time-shared bus 301 standards 219, 361 timing recovery circuit 156 television picture, degradation 219 toll quality 210 television receive only 360 tone level, relationship to speech level television signal 218-20 146 .chrominance 218 tracking 338 Index 483

manual mode 338 routing 246 program track 338 sharing 122 tracking and data relay satellite system single carrier access 240 419 transponder bandwidth 245 tracking antennas for mobiles 71 transponder interference, adjacent 127 tracking loss 119 transponder utilization 235 tracking receiver 340 travelling wave tube amplifier conical scan 340 (TWT) 111, 112, 113, 234, 235, tracking stations 61 287,345,349,415 tracking systems 5, 336 troposphere 5, 71 comparisons 342 troposphere effects 72 main elements 337 tropospheric scintillation 85 traffic 390 true anomaly 28, 29, 442 call congestion 202 true global coverage 44 channels required 202 true north 21, 38 traffic carried 224 trunk 238 traffic channels 114 trunk routes 10, 209 traffic considerations 202, 223-6 TT&C 5, 291, 299, 300, 301, 308 traffic engineering 223 tundra orbit 30 traffic forecast 123 TYRO terminals 360 traffic growth trends 411 two-body problem 26, 29 traffic matrix 224 corrections to 29-33 traffic model two-body system 60 Erlang-B model 225 TWT 111,112,113,234,235,287,345, Poisson model 225 349, 415 traffic pattern amplitude-frequency response 234 changesin 246 AM-PM conversion 235 spot beams 246 input back-off 111 traffic theory 223 output back-off 111 traffic variation transfer characteristics 111 diurnal behaviour 224 TWTA technology 417 peak traffic 224 transfer orbit 291, 309, 319 UMTS 360, 424 elliptical 60 uniformity index transmission coefficients 80 spatial 55 transmission delay 12, 421 temporal 55 transmission efficiency 193 unique word 241 transmission equation 100-3, 118, universal gravitational constant 17 244 universal mobile telecommunication transmission plans 245 service 360 transmissions, out-of-band 111 Universal Mobile Telecommunications transmitted power 67 Systems 424 transmitter technology 415 uplink carrier-to-noise ratio 120 trans-multiplexer 355 uplink power control 239 transparent repeater 117 US standard atmosphere 72 transponder 246 useful data 429 access 246 utopian global village 426 advantages 286 bandwidth requirement 246 Van Allen radiation belts 44, 277, definition 286 377 gain control 286 variable bit rate services 270 hopping 246 vco 149 leasing 123 velocity numbers in spot beams 246 Earth's rotational 61 484 Index

exhaust 60 VSAT 10, 11, 123, 347, 355 increment 60 antenna size 125 velocity of light 429 coding 356 vernal equinox 18, 19, 24,32 frequency band 125, 355 very large scale integration (VLSI) 183, frequency selection 125 202, 217, 418 inbound link 124 very lightweight satellites 421 modulating scheme 355 very small aperture terminal modulation 356 (VSAT) 10, 11, 123, 347, 355 numerical example 128 video outbound link 124 blending with computing 219 personal 12 on demand 219 portable 58 video compression 418 sensitivity 125 video conferencing 395 system architecture 124 virtual connection 270 typical parameters 128 visitor location register 388 VSAT link 169 Viterbi algorithm 192, 197 VSAT network 268 Viterbi decoding algorithm 189 VLR 388 Walker constellations 370 VLSI 183, 217, 418 waveform coder 209, 210-14 VLSI technology 202 waveguide, mode 334, 335, 341 vocal response 216 weighting advantage 144, 219 vocoder (also see source coder) 209, word, definition of 202 211, 214 worldwide coverage main blocks 215 minimum number of satellites 43-7 vocoder implementation 216 multiple visibility 43 voice, excitation analyser 216 single visibility 43 voice activation 238 worldwide plan 70 voice baseband 146 worldwide voice services 389 voice coder wrist watch size radios 407 main characteristics 211 requirement 209 xenon ion engines 416 selection criteria 217 XPD (cross-polar discrimination) 79, voice coding 201, 209-17,418 80,81 comparison 216 XPI (cross-polar isolation) 79, 80, 127 voice coding techniques 410 X-polar pattern 99 comparison of 216-17 X-Y mount 333 voice detection 350 voice pitch generator 216 yaw 292 voice-activated loading 238 yaw axis 297 voltage axial ratio 99 voltage controlled oscillator (VCO) 149 zero crossings 207 voltage regulation zero delay satellites 422 centralized 306, 307 zero gravity 276 decentralized 306, 307 zero momentum 294