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Appendix A: Useful Data

Earth gravitational parameter (GM) = 398600.5km3/S

2

Earth mass (M) = 5.9733 x lO24kg

Earth gravitational constant = 6.673 x 1O-20km3/kgs2

Earth equatorial radius = 6378.14kmEarth polar radius = 6356.785kmEarth eccentricity = 0.08182Velocity of light = 299792.458km/sAverage radius of geostationary orbit = 42164.57kmVelocity of geostationary satellite = 3.074689km1sAngular velocity of geostationary satellites = 72.92115 x 1O-6 rad/sGeostationary satellite orbital period = 86164.09s (23 hours, 56

minutes, 4.09 seconds)Boltzmann constant = 1.3803 x lO- 23W/KHz or

-228.6dBW/KMaximum range of geostationary satellite

(00 elevation) =Minimum range of geostationary satellite

(900 elevation) =Half-angle subtended at the satellite by

Earth =Coverage limit on Earth (00 elevation) =One nautical mile =

429

41680km

35786km

8.690

81.30

1.852km

Appendix B:

(1) Doppler effect

Useful Orbit-relatedFormulas

The equation set included here is general enough to provide Doppler shifts innon-geostationary orbits.

The Doppler shift did observed at a given point on the Earth at a frequencyIt is given by

v, It+-- t

C(B.l)

where v, = relative radial velocity between the observer and the satellitetransmitter

c = velocity of lightIt = transmission frequency.

The sign of the Doppler shift is positive when the satellite is approaching theobserver.

The relative velocity can be approximated as

(B.2)

where PI(tl) and Pz(t2) are satellite ranges at times tl and t2 respectively;(t2 - t l , ) is arbitrarily small.

pet) at any instant t can be obtained from the orbital parameters by using thetechnique given in a following section ('(9) Satellite position from orbital parameters'). Range rate can then be obtained by using equation (B.2), at twosuccessive instants.

The following equation set may be used for approximate estimation of therange rate of a geostationary satellite. We note that range rate is a function oforbital eccentricity, inclination and satellite drift rate. The range rate for each ofthese components is given as (Morgan and Gordon, 1989):

(a) Eccentricity

(B.3)Pm

430

Appendix B: Useful Orbit-related Formulas

where Pc = range rate due to eccentricitye = eccentricitya = semi-major axisw•= angular velocity

2'7T where To = orbital periodTo

Pm = mean range from observation pointtp = time from perigee .

(b) Inclination

. iaRw . (J (.)Pi = ---sin cos tot,Pm

where Pi = range rate due to inclinationi = inclinationR = Earth radius(J = latitude of earth stationt, = time from ascending node.

(c) Drift

DaR . AA,Pd = --cos(Jsm~'I'

Pm

431

(B.4)

(B.5)

where D = drift rate in radians/sPd = range rate due to satellite driftaljJ = 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 ofthe above components.

CCIR Report 214 gives the followingapproximate relationship for estimatingthe maximum Doppler shift:

-6afdm = ±3.0(1O) Its (B.6)

where It = operating frequencys = 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 theliterature (e.g. Slabinski, 1974).

(2) Near geostationary satellites

On various occasions, communication satellites are in near geostationary orbits.~xamples are: (a) when orbit inclination is intentionally left uncorrected to

432 Appendix B: Useful Orbit-related Formulas

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 launchedsatellite is being moved to the operational location (such a drifting satellite issometimes used for communication provided the transmissions do not interferewith other systems).

When the satellite orbit is lower than the geostationary orbit altitude, theangular velocity of the satellite is greater than the angular velocity of the Earth.Consequently the satellite drifts in an eastward direction with respect to anearth station. When the satellite altitude is higher than the geostationary height,the satellite drifts westward.

The following relationships apply (Morgan and Gordon, 1989):

M'

P

Aw

w(B.7)

where M' = change in orbital periodP = orbital periodAw = change in angular velocityw = angular velocity

and

~r = _(~)A: (B.8)

where r = orbital radiusAr = change in orbital radius .

For example, a change in radius of +1krn from the nominal causes a westward drift of O.0128°/day.

The required change in satellite velocity AVe to correct the drift is given by

1 AwAv = -v

c 3 w

or

1Av = -at:.w

e 3

where a = semi-major axis.

Effect of inclination

(B.9a)

(B.9b)

The main effect of inclination i on a geostationary satellite is to cause northsouth 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), themotion can be approximated as a sinusoid in a right ascension-declinationcoordinate system.

An associated relatively minor effect is an east-west oscillation with a periodof half a day. This is caused by the change in rate of variation of the rightascension relative to the average rate. The satellite appears to drift west for thefirst 3 hours and then east for the next half quarter. The satellite continues tomove eastward during the next half quarter and then westward, completing thecycle in half a day. The maximum amplitude of such east-west oscillation for acircular orbit is given by

1 .2=-1

229

(B.1Oa)

(B.1Ob)

where i is in degrees.Usually the east-west oscillation is very small (e.g. for i = 2.5°,LlEJ.V; = 0.027°).

The net effect of these two motions is the often-quoted figure-of-eight motion of the sub-satellite point.

Effectofeccentricity

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

~EJ¥. = 2e radians (B.ll)

For example, an eccentricity of 0.001 produces an east-west oscillation of±0.1l45° about the satellite's nominal position.

(3) Coverage contours

It is often necessary to plot the coverage contours of geostationary satelliteson the surface of the Earth. The satellite antenna boresight (the centre OFcoverage area) and a specified antenna power beamwidth (usually, balf-powerbeamwidth) are known. In the case of an elliptical antenna beam shape, thesizes of the major and minor axes together with the orientation of the major axisare known. The coverage contour on the Earth is obtained by calculating thelatitude/longitude of n points on the periphery of the coverage (Siocos, 1973).


Let us first define the following angles:

I'B' I'n :::: tilt angles of antenna boresight and the nth point on the coveragecontour, respectively

En :::: angular antenna beamwidth ofthe specified power (e.g. half-power) inthe direction of the nth point. For a circular beam, En is a constant.

To specify the nth coverage point we further define r/Jn as the angle ofrotation, the rotation being referenced to the plane containing the sub-satelliteand boresight points (see figure B.l).

The following steps are used to specify the nth coverage point Tn. Obtain I'Busing the following equation set

f3 :::: arccoslcoss, COS4>SB)

I'B :::: arctan[sinf3/(6.6235 - cos(3)]

(B.12a)

(Rl2b)

where 8B :::: latitude of boresight4>SB :::: longitude of boresight with respect to sub-satellite point, taken

positive when to the west of the sub-satellite point.Then

ctn4>n:::: (sinl'B ctn e, - cos'YBcosr/Jn)/sinr/Jn

gn :::: arctan(sin </>sB/tan 8B) + 4>n

Coverage contour

Earth

South

(B.13a)

(B.13b)

(B.13c)

Figure B.l Coverage contours geometry. S = sub-satellite point, B = boresightpoint on Earth, T; = nth point on the coverage contour.


f3n = arcsin{6.6235 sin 'Yn) - 'Yn

cPSn = arctan{ tan f3n sin ~n)

where cPSn = longitude of nth point relative to sub-satellite pointOn = latitude of nth point.

When the beam is elliptical, En depends on r/ln as follows:

435

(B.13d)

(B.13e)

(B.13!)

(B.14)

where a = rotation of E1 away from the direction of the azimuth of theboresight

E1 and E2 are the semi-major and semi-minor axes.r/ln can be varied from 0° to 360° to obtain as many points on the coveragecontour 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 behindthe geostationary orbit and therefore appears within earth stations' antennabeam. Sun transit through an earth station's antenna causes disruption to communication services because of a large increase in system noise temperaturecaused by the Sun. The transit time of the Sun through an antenna is predictable, giving the earth station operator the option to make alternative communication arrangements or at least not be taken by surprise when communication isdisrupted.

The position of astronomical bodies such as the Sun is published in a readilyavailable annual publication called the Nautical Almanac (US GovernmentPrinting Office) . The position is given in the right ascension-declination coordinate system. Sun-caused outage occurs when the ascension and declination ofthe satellite and the Sun become equal at an earth station (or nearly equal sothat the Sun appears in the beamwidth of the earth station antenna). Theposition of the satellite at an earth station is usually given in the celestial horizonsystem, as azimuth and elevation. Therefore it is only necessary to convert thesatellite azimuth and the elevation to the ascension-declination coordinatesystem and determine from the NauticalAlmanac the day and the time when theSun has the same ascension and declination. The equations for this conversionare (Siocos, 1973):Declination D is given by

sinD = sin Osin7] - cos Ocos7] cos ~ (B.15)


where 8 = latitude of earth stationT] = satellite elevation~ = 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 satellitemeridian is obtained from

sina = cOST] sindcosD (B.16)

a is positive when westerly.In the Nautical Almanac, the ascension of the Sun is given with respect to theGreenwich meridian. a is converted to HAG from

(B.17)

where HAG = hour angle with respect to GreenwichcPe = longitude of earth station.

Note that the right ascensions of astronomical objects are expressed in hourangle, where 1 hour = 15°.

(5) Solar eclipse caused by the Moon

The occurrence of solar eclipse on a geostationary satellite caused by the Moonis irregular. It may be recalled that Earth-induced eclipses are predictable,occurring within ±21 days of equinoxes. It is also necessary to predict theduration and the extent of occurrences of MOOD-induced eclipses for spacecraftoperations' planning. The technique given here (Siocos, 1981) makes use of Sunand Moon position data available from the Nautical Almanac.

An eclipse occurs when the azimuth/elevation coordinates of the Sun and theMoon from the satellite position are equal or close enough to cause the Moondisk to mask the Sun partially or completely.

The effective elevation H of the Sun or Moon from the satellite location canbe obtained from the following equation set :

cos~ = cosdcosLHA (B.18a)

(B.18b)

where dLHALHAHAG

= declination of the stellar object (Sun or Moon)= local horizon angle= HAG + 8= hour angle with respect to Greenwich, available from the

Nautical Almanac


8 = longitude of the earth station (OOto 180°, positive when tothe east of Greenwich)

R; = geostationary orbit height from geocentre = 6.62 R(where R is earth radius)

(R; + Rs) = distance of Sun or Moon from geocentreand

Ro = 6.62 sin(HP)e, + s;

(B.19)

where HP = horizontal parallex (the maximum difference in geocentric andsatelli-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 NauticalAlmanac.

The azimuth of the Sun and the Moon observed from the satellite locationsis determined by the equation

tan z = sin LHA/tan d (B.20)

where z = 180° - AzAz = azimuth of the Sun or the Moond = declination of the Sun or the Moonz is ea sterly 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 thesum of their radii (see figure B.2):

where rs and rm are the radii of the Sun and the Moon obtained from

(B.21)

and

r=1 - sin(HP) .

smz,[1 - 5.52sin(HP)]

(B.22)

D = arccos(costlH cosdZ) (B.23)


Eclipse _-,..e:..¥-,~ /lJdepth

Sun

Figure D.2 Solar eclipse on geostationary satellite caused by the Moon - viewfromgeostationary orbit.

where Ml and AZ are the differences between the effective elevations andazimuths, respectively

rc is the semi-diameter of the celestial object, as observed on the surfaceof 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, Ed (see the hatchedportion in figure B.2) can be obtained from the equation

where

E = [2A _ sin(2A)] + (rm/'S )2[2B _ sin(2B)]

d 360 2'7T 360 2'7T

cosrm - cos'S cosDcos A = ---"'-------"----

sinz; sinD

cos'S - cosrm cosDcos B = ---.:.------':::..---

sinz, sinD

(B.24)

(B.25a)

(B.25b)


(6) Satellite-referred coordinates to Earth coordinates

439

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

'Ye = arccoslcoss, coscA]

~e = arctan[sincA/tanOs]

f3e = arcsin(6.617sin 'Ye) - 'Ye

Oe = arcsinlsin S, cos ~e)

cPe = arctan(tan f3e sin ~e) + cPo

(B.26a)

(B.26b)

(B.26c)

(B.26d)

(B.26e)

where cPo = longitude of sub-satellite pointOs, cPs = satelli-centric latitude and longitude respectively0e, cPe = transformed latitude and longitude on Earth respectively.

(7) Map projections

Earth coverage from a satellite is most commonly shown as satellite antennapattern contours (referenced from the beam centre) on a suitable map. Acoverage contour is obtained by plotting the latitude and longitude of thecoverage periphery on a map . The coverage contours appear distorted in manytypes of map projections such as Albers and Mercator, whereas in severalprojections the shape of the coverage is undistorted. In general, the choice ofmap depends on the type of orbit and the users. For example, polar projectionsare popular with radio amateurs because of advantages such as simplicity inplotting ground tracks.

In satellite communications, rectangular projections are often used. Onecommonly used projection represents the X-axis as longitude and the Y-axis aslatitude. However, in such projections the shape of the coverage contoursappears distorted. For planning, it is simpler to use maps which retain the angleinformation of the contours. If a projection is made on a plane which is at rightangles to the satellite-Earth vector, the shape of the beams is retained(Chouinard, 1981; CCIR, 1982). Distances on such a projection are linearlyrelated to the angles. The following set of equations transforms a point Pi onEarth to a satelli-centric sphere:

440

where


l' = arctan[sinl3/(6.617 - cosl3)]

13 = arccos[(cosOiCOS(cPi - cPo)]

g= arctan[sin(cPi - cPo)/tanO;]

(B.27)

(B.28a)

(B.28b)

Here OJand c/>; are the latitude and longitude of point PicPo is the longitude of the sub-satellite point.

Finally, the transformed latitude 0:and cP: on a satelli-centric unit sphere aregiven by

0: = arcsin(sin I'cosg)

4>-: = arctan(tan ysin g)

(B.29)

(B.30)

(B.31)

Because 0: and cP :are less than 8°41' (-+ of the angular diameter of Earthfrom a geostationary orbit), mapping them in Cartesian coordinates is quiteadequate. On such a map, if the two scales are equal, angles are almostpreserved.

(8) Off-axis angles

To facilitate interference calculations between satellite networks, it becomesnecessary to develop expressions for off-axis angles. An off-axis angle is definedhere as the angle between the wanted direction and the undesired directionwhich gives rise to interference. Figure B.3 shows two modes of interferenceencountered in practice. Figure B.3(a) shows the interference mode, whereinterference is either received at the satellite (the 'wanted' satellite) serving thedesired network from an earth station of another network, or caused at an earthstation of another network by the desired satellite. Figure B.3(b) shows theinterference mode where interference is either received by an earth station (a'wanted' earth station) in the desired network from a satellite serving anothernetwork (the 'external' satellite) or caused by a wanted earth station to theexternal satellite.

Referring to figure B.3(a), the off-axis angle is given as (Siocos, 1973)

P~ + P~ - 2(1 - COSl3di)cosOT =

2PdPi

where Pd = range between the satellite and desired point E on EarthPi = range between the satellite and the interfered pointI3di = great circle arc between desired point and interfered point.Range is given in terms of Earth radius (equation 2.20b).


S

441

Desiredpath

Desiredpath

S

lat

(b)

Interferingpath

Si

Interferingpath

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

(B.32)

where (Jd' (Ji = latitude of points d and i respectivelyticPi = longitude of point i with respect to the sub-satellite point.tic/J; and ticPd are positive when the point is to the west of the sub

satellite point.ticPd = longitude of point d with respect to the sub-satellite point.

The off-axis angle (JR' figure B.3(b), is given by (Radio Regulations, AP-29,Annex 1)

pJ + pi - [84332Sin(~n2PdPi

(B.33)


where ficPsi = geocentric angular separation of interfering satellite fromwanted satellite (degrees of longitude).

Here ranges Pd 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 centremeasures satellite positions regularly. There are a number of techniques forestimating orbital parameters from such measurements (e.g. see Morgan andGordon, 1989). Orbital parameters are made available to earth station operators and used to estimate useful system parameters such as look angles andDoppler shifts. The method for estimating satellite position, velocity and lookangle from any specified location presented here is suitable for computer solution (Morgan and Gordon, 1989).

There are three broad steps involved in the process. In the first step, satelliteposition is estimated in the orbital plane; the second step involves transformingthe satellite coordinates to the three-dimensional earth-centred coordinate system; finally, the earth-centred coordinates of the satellite are transformed to anearth-station-centred coordinate system for obtain ing the look angle of thesatellite from the earth station.

The following orbital parameters are assumed known: eccentricity, ascendingnode, inclination, mean anomaly at a reference time called epoch (meananomaly = 0 if epoch is taken at perigee pass), and argument of perigee.

Some useful relationships involvingeccentric anomaly E, true anomaly v andmean anomaly Mare:

cosE =

cosv =

cosv + e

1 + ecos v

cosE - e

1 - ecosE

(B.34)

(B.35)

where e is the orbit eccentricity.The mean anomaly M at time t is given by

M = Mo+ w(t - to) (B.36)

where Mo is the mean anomaly at a reference time to (epoch) and w is theangular velocity of the satellite.

Step 1

(a) The mean anomaly at the specified time is determined from equation(B.36) .


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

M = E - esinE

443

(B.37)

For eccentricity <O.DOI the eccentric anomaly can be approximated as

E "'" M + esinM + .!..e2 sin(2M)2

(B.38)

For larger values, equation (B.37) must be solved. The equation, being nonlinear, requires a numerical solution technique. The Newton-Raphsonmethod provides a quick and accurate estimate . The following steps areinvolved:

• 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 tiE* is obtained from

tiE *M-M*

1 - ecosE*(B.39)

where (1 - ecos E*) is the slope of the curve M* = E* - esin E*.The process is repeated until the difference M - M* is as small asdesirable . Note that M and E in the above equations are in radians. Whenthe true anomaly and eccentricity are known, the eccentric anomaly canbe determined by using equation (B.34). Steps (a) and (b) are then notnecessary.

(c) The position of the satellite in the orbital plane is given by

Step 2

X o = a(cosE - e)

1

Yo = a(1 - e2)2sinE

I

radius, r = (x~ + y~)2

(BAOa)

(BAOb)

(BAOc)

The inclination of the satellite, the right ascension of the ascending node andthe argument of perigee are used to transform the perifocal coordinate systemto the geocentric equatorial coordinate system. The following equation set canbe used for this transformation:


P, = cos ta coso. - sin w sinf] cosi

P, = cos w sinf] + sin w coso. cosi

P, = sin w sini

Qx = -sinw coso. - cosw sinf] cosi

Qy = - sin wsinn + cos w coso. cosi

Qz = cos w sini

(B.4la)

(B.4lb)

(B.4lc)

(B.4ld)

(B.4le)

(B.4lf)

Satellite position in the geocentric coordinate system is given by

Step 3

(B.42a)

(B.42b)

(B.42c)

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

Right ascension, a = arctan (y/ x)

Declination, 5 = arctan (~ z )x

2 + l

(

. RSIn1/s - -

Elevation, 1/ = arctan rcosn,

where

1/s = arcsin [sin5 sins, + coss coss, coscPse]

and R = Earth radiusr = satellite distance from Earth centre (use equation BAOc)0. = earth station latitudecPse = cPs - cP.cPs = satellite longitudecP. = earth station longitude.

(B.43)

(B.44)

(BAS)

(B.46)


. [sincPse ]Azimuth, A = arctan -----.;...;;:.----coss, tan S - sin s, coscPse

445

(B.47)

Use the convention given in chapter 2, section 2.6 to obtain the azimuthquadrant.

The equations given above assume no perturbation in satellite orbit. Theaccuracy in these equations can be improved by including the effects ofperturbations. 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 (t2 - tl ) can be made assmall as necessary .

Range

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

p = ~r2- R 2 cos? 17 - R sin 17

(10) Look angle from earth station

(B.48)

Because of the combined effects of inclination and eccentricity, a neargeostationary satellite appears to traverse an ellipse in the sky when viewedfrom the ground. From basic electronics it is well known that this type of shape(Lissajous' figure) consists of two sinusoidal components orthogonal to eachother.

As mentioned, in addition to the effect of inclination and eccentricity, thenon-uniform gravitational force caused by the oblate shape of the Earth causesa geosynchronous satellite to drift towards one of the two stable locations on thegeostationary arc -79°E and 252.4°E. The acceleration caused by this forcedepends 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 inthe satellite position.

The most accurate estimate of satellite look angles from an earth station isobtained by using the orbital parameters. For most practical applications theazimuth and elevation components of the satellite motion viewed from theground may be approximated as (Richharia, 1984):

Oa{t) = 0ai + Am cos[~ (t - Ta)] + Al + tl

Oe{t) = 0e; + Em cos[~ (t - Te)] + Ejt + t2

(B.49)

(B.50)


where Oa(t) = satellite azimuth from an earth station at time t (in hours)0ai = initial azimuth of the satelliteOc(t) = satellite elevation from the earth station at time t0c; = initial elevation of the satellite .Ai and E;are the linear components of the azimuth and elevation angles

respectivelyAm and Em are the maximum excursions in the azimuth and the

elevation respectivelygl and gzare 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.50) can be expanded in a seriesform to facilitate development of the model from real-time position dataobtained from a tracking system (Richharia, 1984). T; and T; are the times thesatellite is at the maximum azimuth and elevation angles respectively.

(11) Stationary bound

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

(B.51)

where I/J = great circle range for which the stationary bound is required; theterm 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 thecoverage is distributed most uniformly around the world.(ii) Compare the above to the stationary bound used by Beste (1978):

N =:; 2.42/{1 - cosl/J) (B.52)

The reader should note that an approximation of (B.52) has been used in figure2.14.

Both equations give similar results, although their methods of derivation aredifferent.

(12) Dynamic bound

Dynamic bound takes consideration of the fact that spatial uniformity of thecoverage in a real constellation degrades at times (Mozhaev, 1972, 1973):


N ~ 5 + 4/3({tan-1(cosl/l) + tan " [cosl/l/(.J2 - 1)]

- 67.5°}/[60° - tan-1(.J3cOSl/l)))

(13) Rosette constellation (Ballard, 1980)

447

(B.53)

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

sin2(rij /2) = {cos4(13/2)sin2(m + 1)(r- i)(7T/p)

+ 2sin2(13/2)cos2(13/2)sin2 m(j - i)(7T/p)

+ sin4(13/2)sin2(m - 1)(j - i)(7T/p)

+ 2sin2(13/2)cos2(13/2)sin! (j - i)(7T/p).

·cos[2x + 2m(j + i)(7T/p)]}

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

Bearing angle l/Iij is defined in figure 2.16 and is given as

Centre of Earth

(B.54)

(B.55)

Figure B.4 Depression angle dq and slant range srq between satellites i andj. H =satellite altitude and RE = Earth radius (Ballard, 1980).


tanl/Jij = [sinOijsin(x + mUj - Tji)]/{sin2(Oij /2)sin[2x + m(uj + u i )

- (T ji + T ij)] - cos2(Oj2)sin[m(uj - ui ) - hi - T ij)]}

(B.56)

where sin 'Tji = sin Tij = cos[(~ - a;)/2]/cos( 0/2)sin(0/2) = sin{3sin[(~ - a;)/2]also COS'Tji = - cos Tij = cos {3 sin[(~ - a;)/2]/cos( 0/2) .

(14) Multi-beam spot beam coverage

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

Figure B.5 Geometry of a multi-beam satellite (Maral et aI., 1991).


Figure B.6 Satellite cell representation. Centre of cell 1 represents the sub-satellitepoint (Maral et al., 1991).

where R = Earth's radius11 = minimum elevation angle (radians)h = satellite altitude (krn) .

Coverage angle of each cell, f3 = Z'IJ.f/(Zn + 1)' (see figure B.5)

where n, termed 'crown', determines the number of hexagonal cells, i.e. spotbeams, N c, within the coverage area (see figure B.6).

N; = 1 + [6n(n + 1)]/Z

Oo/Z = tan-I[Rsin(f3/Z)/{h + R - Rcos(f3/Z)}]

On = tan-I[Rsin{(Zn + 1)f3/Z}/{h + R - Rcos{(Zn + 1)f3/Z}}]n-I

- LOk - 00

k=1 Z

where 00 = beamwidth of central cellOn = beamwidth of the nth crown.


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

Pr0l:ram IREM This Qbasic program calcul ates the azimuth. elevationREM range of a geostationary satellite from a given location on theREM Earth and signal transmission time . Output is saved in a file called PROG 3.DAT : Alternatively.REM Ihc output may be printed to the screen.REM by removing line 25(REMming it) and deleting #1 from allREM print statements.REM Satellite longi tude is set on line 30:REM Earth station longitude (in Deg E) is set on line 35;REM Earth station latitude (+ Northt- South) is set on line 40.REM [Satellite Communication Systems : Design Principles by M.Richharia:REM :Solution to problem 3. Ch 2.1REM Program developed by M.Richharia : 11/9/965 CLSto LET pi = 3.14 1592654#15 LET rad = pi 1 ISO20 LET sigma = 637S.14 142164.57REM Note pi! ISo converts degrees to radiansREM . Set elev. to desired elevation angle25 OPEN "PROG3.DAT" FOR OUTPUT AS #1REM Set satellite location in Degree East30 satlou = 350 • radREM Set earth stat ion longitude in Degree East.15 LET eslon = .5 • radREM Set earth station latitude (Southern latitude -ve)

40 LET cslat = 76.1 • radREM Print satellite locat ion and elevation angle45 PRINT # I. "Satellite longitude (Dcg E)= ": salloni rad50 PRINT # I. "Earth station longitude (Deg E)=' : eslon 1 rad55 PRINT # I. "Earth station latitude (Deg)=": eslat 1 rad : PRINT611 LET dlon = eslon - satlonREM Calcu late Elevation65 LET cosbet= COS(eslat) • COS(dlon)70 LET sinbet = SQIW - cosbet A 2)75 eta = A'FNtfcosbet - sigma) 1sinbet)lIll IF eta 1 rad < o! THEN PRINT #1. "!!! Note : Satellite below horizon !!!"lI5 IF eta 1 rad < O! THEN GOTO 1651)0PRINT # I. "Elevation (Deg) =": eta 1 radREM Calculate Azimuth1)5 az = ABS(ATN«TAN(dlon) 1SIN(eslat))))100 x = ad (2 · pi)REM Determine quadrant115 IF satlon 1 rad > 270 AND eslon 1rad > 0 AND eslon 1 rad <= 90 THENsatlont = satIon • (2 • pi) ELSE sallont = satlon120 IF eslon 1 rad > 270 AND satlon 1rad > 0 AND sallon 1 rad <= 90 THENeslont =eslon - (2 • pi) ELSE eslont =eslon125 LET dlont = sallont - eslont130 IF SGN(eslat 1rad) > O! AND SGN(dlont 1rad) > O! THEN AZIMlITH =ISO -az /rad135 IF SGN (eslat 1rad) >= 0 AND SGN(dlont 1rad) <= 0 THEN AZIMlITH =ISO+ az/rad140 IF SGN(eslat 1rad) < O! AND SGN(dlont 1rad) > O! THEN AZIMlITH = az1 radl45 IF SGN (eslat 1 rad) < 0 AND SGN(dlont 1 rad) <= 0 THEN AZIMlITH =360 - az 1 rad

Appendix E: Useful Orbit-related Formulas

150 PRINT # I, "Azimuth (Deg)=" ; AZIMUTHREM Calculate Range155 range = 35786 * SQR(I + .4199 * (I - cosbetj) : time = range 1(3 * 100)160 PRINT #1, "Range (Km)=" ; range: PRINT #1, "Transmission time (rns)=";time : PRINT165 PRINT, "End of computation"170 END

ProgrlUD :zREM This Qbasie program calculates the latitudellongitude ofREM 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 screenREM by removing line 20 (REMming it) and deleting #1 from allREM print statements.REM Elevation accuracy is set on line 30; satellite longitude is set onREM line 45; longitude step is set on line 85; latitude step is setREM on line 105; Care should be exercised in selecting step sizes.REM The program run time is several minutes, depending on the stepREM size and the accuracy.REM M.Ricbbaria:7/9/96;Solution to problem 4(a), ch 25 CLS10 LET rad = 3.141592654#1 18015 LET sigma = 6378 .14/42164.57REM Note pi/ISO converts degrees to radiansREM Set elev to desired elevation angle20 OPEN "PROG I.DAT" FOR OtITPUT AS #125 LET elev = 5 * radREM Set accuracy required for elevation angleREM Program is easier to run with lower accuracy30 aceur = I * rad35 LET test I = elev • aeeur40 LET test2 = elev + accurREM Set satellite longitude in Deg E45 LET satlon = 345 * radREM Print satellite location and elevation angle50 PRINT # I. "Satellite position (Deg E)=", satlon i rad55 PRINT # I. "Elevation angle contour (Deg)= "; elev 1 rail, "Accuracy(Deg) =";accur 1 rad60 PRINT #1.65 PRINT # I, "Longitude", "Latitude", "Elevation"70 PRINT # I.."(Deg)", "(Deg)" , "(Deg)"75 LET dlonst = -SO.03 * radSOLET dlonen = SO.03 * radREM Select longitude step size ; choose an odd number to avoid 'divide by zero'.error.85 LET stpln = 9.S3 * rad90 FOR dlon = dlonst TO dlonen STEP stpln95 LET lats = -SO.OO I * rad100 LET late = SO.OOI * radREM Select latitude step size; choose an odd number to avoid 'divide by zero'error.105 LET stplt = .073 * radI 10 FOR lat = lats TO late STEP stplt115 LET cosbet = COS(1at) * COS(dlon)120 LET sinbet = SQR(I - cosbet " 2)125 eta = ATN«cosbet· sigma) 1sinbet)126 eslon = (satlon + dlon) 1rad127 IF eslon > 360! TIffiN eslon = eslon - 360130 IF eta > testl AND eta < test2 TIffiN

451


PRINT # I. eslon , lat / rad, eta / radEND IF135 NEXT lat1~0 NEXT dlonI~5 PRINT # I . "End of computation"150 END

PrUl:rOlm JREM This Qbasic program calculates the geostationary arc visible fromREM 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 screenREM by removing line 20 (REMming it) and deleting #1 from allREM print statements.REM Minimum elevation angle is set on line 25; Earth station longitude isREM set on line 30; Earth station latitude is set on line 35;REM The program run time and minimum visibility elevationREM angle accuracy depends on the step size, set on line 75.REM M.Richharia :919/96;Solution to problem 4(b), ch 2.5 CLSIII LET rad ; .1 .141592654# / Ill()15 LET sigma; ('37l!.14/42164.57REM Note pi/lSO converts degrees to radiansREM Set elev to desired elevation angle20 OPEN "PROG2.DAT" FOR OUTPUT AS #125 LET elev ; 5 • radREM Set earth station longitude in Deg E.10 LET eslon ; O! • radREM Set earth station latitude (Southern latitude -ve).15LET eslat ; 51.5 • radREM Print satellite location and elevation angle40 PRINT # I. "Earth station longitude (Deg E);"; eslon / Tad45 PRINT # I. "Ean h station latitude (Deg);" ; eslat / rad50 PRINT # I. "Visibility (Elevation angle);"; elev / rad.55 PRINT #1. "Longitude (Deg E)". "Elevation (Deg)"REM 60 PRINT #1. "(Deg) ", "(Deg)"65 LET dlonst ; -SO.03 • rad70 LET dlonen ; SO.03 • radREM Select step size ; A 'divide by zero' error may occurREM if step size is not proper.75 LET stpln ; .5 • radso FOR dlon ; dlonst TO dlonen STEP stplnK5 LET cosbet ; COS(eslat) • COS(dlon)I}" LET sinbet > SQR(I - cosbet o 2)95 eta; ATN(cosbet - sigma) / sinbet)100 satlon ; (eslon - dlon) / rad1lI5 IF eta > elev THEN·PRINT #J. satlon . . eta / radEND IF110 NEXT dlon115 PRINT #1. "End of computation"120 END

References

Ballard, A.H. (1980). 'Rosette constellations of earth satellites', IEEE Trans. Aerosp.Electr. Systems, Vol. AES-16, No.5, September, pp 65~73.

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 .


CCIR (1982).Report ofInterim Working Party, PLEN/3, CCIR, XVth Plenary Assembley,Geneva.

Chouinard, G. (1981). 'Satel1ite beam optimization for the broadcasting satel1iteservice',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 orbitsatellite systems for communications', International Journal of Satellite Communications, 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 kinematical1yregular satellite networks, I,' Cosmic Res., Vol. 10(UDC 629.191), November-December, 1972, translation in CSCRA7 (Consultants Bureau, New York), Vol. 10, No.6, pp729-882.

Mozhaev, G.V. (1973). 'The problem of continuous earth coverage and kinematical1yregular satel1itenetworks, II,' Cosmic Res., Vol. 11 (UDC 629.191),January-February,1973, translation in CSCRA7 (Consultants Bureau, New York) , Vol. 11, No.1, pp 1152.

Nautical Almanac (yearly). Superintendent of Documents, US Government PrintingOffice, Washington DC, 20402.

Richharia, M. (1984). 'An optimal strategy for tracking geosychronous satel1ites',JIETE(India), Vol. 30, No.5, pp 103-108.

Siocos, CA. (1973). 'Broadcasting satel1ite coverage - geometrical considerations',IEEE Trans. Broadcasting, Vol. BC-19, No.4, December, pp 84-87.

Siocos, CA. (1981). 'Broadcasting satellites power blackouts from solar eclipses due tomoon', IEEE Trans. Broadcasting, Vol. BC-27, No.2, June, pp 25-28.

Slabinski, V.J. (1974). 'Variations in range, range-rate, propagation time delay andDoppler shift in a nearly geostationary satel1ite', Prog. Astronaut. Aeronaut., Vol. 33,No.3.

Index

absorption 72absorption band 72

oxygen 72water vapour 72

absorption cross-section 74absorptivity 310acceptance 321access protocol

ALOHA schemes 261-3channel reservation 260choice of 265contention protocols 261-5data traffic 258-65evaluation criteria 259packet reservations 263-5

accessingschemes 9acoustic environment 217ACSSB 138ACTS 418ACTS payload 424ACTS programme 423adaptive delta modulation 214adaptive differential PCM (adaptive

DPCM, ADPCM) 210, 213, 214adjacent channel interference 235adjacent transponder 235advanced concepts 418Aeronautical and Space Administration

423aeronautical channel

fade duration 91link margin 91link reliability 91multipath 91Rice factor 91shadowing 91

aeronautical environment 91aeronautical terminal 7APC 232Afro-Asian Satellite Communications

Ltd 402air conditioning 355albedo 308Albers 439ALC 122,287algebraic code

BCH code 184examples 184generation 180Hamming code 184parity check 184Reed-Solomon code 184

algebraic coding 180ALOHA 261

frame 263limitations 263pure 267reservation 263slotted 262, 263throughput 261

AM 134detection 135generation 135limitation 135side bands 135spectral characteristics 134

ambient temperature 104, 105amplifier, noise-free 105amplitude companded single side band

(ACSSB) 138amplitude modulation (see also AM)

134-5amplitude non-linearity 111AM-PM conversion 111,112analog telephony 208analog-to-digital conversion 201, 209angle modulation 138antenna 101, 119

aircraft 91aperture 96, 97asymmetric configuration 332axes 95axi-symmetric configuration 330, 332blockage 97boresight 95copolar pattern 96cross-polar coupling 99cross-polar discrimination 96directivity 97dual polarized 99earth station 95effective aperture 98

454

Index 455

efficiency 97f/D 97focallengthldiameter (lID) 97gain 98gain function 97half-power beamwidth 97quantitative relationships 98radiation intensity 97, 98radiation intensity, average 97radiation pattern 95, 96satellite 95single-axis 96

antenna basics 95-100antenna boresight 100antenna characteristics 95antenna efficiency 98antenna gain 102, 103, 121antenna gain function 89antenna mount 333

fixed 334mobile earth station 334

antenna noiseelevation angle dependence 108galaxy noise 108oxygen 108water 108

antenna noise temperature 349Sun 41

antenna radiation patternhalf-power beamwidth 96main lobe 96shaped 96side lobe 96

antenna size, receiver 94antenna temperature

estimated 109oxygen 109rain 109satellite 109water vapour 109

AOCS 282, 291, 296aperture, field pattern distribution 97aperture plane 331apogee 60apogee-kick motor 61,299,311

firing 61application specific integrated circuit

(ASIC) 416Arabian Satellite Communication

Organisation see ARABSATARABSAT 3Archimedes project 373argument of perigee, rate of change 30ARQ 193-5, 199

error probability 193-4performance evaluation 193-4performance measures 193throughput 193, 194

ARQ schemes 194-5ASC system

characteristics 402example 403space segment 402

ascending node 24precession 30

ASIC 416ASK 151aspect ratio 218, 220ASTRA satellites 413asymmetric configuration 332asynchronous transfer mode 270, 396

bit error rate 270cell dropping 270circuit mode 269packet mode 269propagation delay 270satellite network 270

ATM (see also asynchronous transfermode) 270

atmospheric absorption 119atmospheric drag 33, 278, 378atmospheric multipath 79attenuation

cloud 78cloud and fog 78cross-section 74depolarization, relationship with 84fog 78hydrometers 72rain 73theoretical 73

attenuation distribution 75attitude and control system

orbit-raising phase 295orientation determination 295

attitude and orbit control 291on-station control 296

attitude control 296.gravity controlled 293passive 292sensors for 293

attitude-control system 292, 313auto-correlation 248automatic frequency control (AFC) 232automatic level control (ALC) 122, 287automatic repeat request (see also ARQ)

170, 176automatic tracking 337

456 Index

auto-track receivers 338auto-track system 338

comparison 343autumn equinox 39average orbital angular velocity 28axial ratio 100azimuth 21, 29, 38, 445azimuth-elevation mount 333

bandwidth 228bandwidth power, trade-off 144base station 388baseband bit rate 152baseband filter 143baseband signals 201-7

demultiplexing 220multiplexing of 220-3

baseband spectral characteristics 201basic satellite system 4-8battery

charging 307depth of discharge 306figure of merit 306lifetime 45, 46, 306mass 306reconditioning 306, 307voltage regulation 306

bauds 152BCH codes 184beacon 301beam waveguide feeds 336beam-forming technique 414Bessel function 139Bessel zero 139BFSK 165

bandwidth 166big LEO mobile system 397

example 395, 397binary frequency shift keying (BFSK)

165bandwidth 156

binary phase shift keying (see also BPSK)126, 152, 153

bi-phase transmission 204bi-propellant fuel 318bi-propellant system 299bit

high 202low 202

bit energy-to-noise power density 118bit error

due to thermal noise 159sources 159

bit error probability 159

bit error rate 126M-ary PSK 161relationship with symbol error 161

bit ratebandwidth-limited link 245power-limited link 245

bit synchronization 197,204bit-synchronizer circuit 156block code 178, 179-87

orthogonal 180body stabilization 296

momentum wheel 297station-keeping 297

body-stabilized mode 61Boltzmann constant 120, 429Boolean algebra 180boresight 95Bose, Chaudhari and Hocquenghem code

(see also cyclic code) 184BPSK 152, 153

bit error 162bit error rate 160bit-synchronization error, due to 162comparison with QPSK 161phase error, due to 162power spectral density 163probability of error 160symbol error rate 160

bread-board model 321brightness temperature 108, 109British Geological Society 38broadband interactive services 396broadband LEO system 367broadband personal services 12broadband system 395broadbeam antenna 86broadcast

sound 11television 11

broadcast channel 232, 267broadcast quality 210broadcast satellite service (BSS) 3, 68,

325growth trends 413

broadcast satellite systems 406BSS 3, 151

categories 70BSS frequency bands 70bus, requirements 291

cable television 8call congestion 202Calling Network 395canting angle 80

Index 457

capacity management 245carrier and bit time recovery 241carrier power, received 101carrier power spread 204carrier recovery 136, 156, 158, 197

M-ary PSK 157carrier recovery circuit 157carrier regeneration, error in 161carr ier suppression 239carrier to intermodulation noise 126carrier to multipath noise 87carrier to noise power spectral

density 244carrier-to-noise ratio 116

demodulator imput 117downlink 121in transparent repeater 117optimal 208regenerative transponder - total link

118satellite path 121-2total 126total in regenerative transponder 118transparent transponder - total link

117-18uplink 120-1

Carson 's bandwidth 140Carson 's formula 140Carson 's rule 147Cassegrain antenna systems 347Cassegrain feed system 331,332

advantages 332Cassiopeia A 108CCIR 78, 82, 115, 126, 141, 142, 145,

218CCIR Green Books 78CCIR study groups 77CCITI 208, 217, 219, 220, 225CCITI FOM plan 221CCITI multiplexing 223CCITI multiplexing plan 220

group 220super-group 221super-mastergroup 221

COMA 171, 229, 248-58advantages 248capacity 257carrier-to-interference ratio 248degradation in 258grade of service 257implementation 248implementation loss 254interference margin 254multipath noise resistance 248

power spectral density 253processing gain 254receiver carrier-to-noise ratio 254traffic growth, accommodation of 257

celestial equator 19celestial horizon coord inate system 21,

29celestial sphere 19,43,47, 51,57cell delay 270

variation 270cell loss 270cells, geographically fixed 396cellular mobile communication

system 209cellular radio 11channel

impulse noise 186noise characteristics 186sources of impairments 168with error bursts 185

channel coding 125, 176channel congestion 224channel connection, set-up time 260channel interference, adjacent 127channel loading 146channel quality 126channel reservation 260channel reservation schemes 258circuit mode calls 384circular orbit 27circular polarization

left-hand circular 99right-hand circular 99

clock, synchronized 203clock jitter 207clock signal 203close user environments 210clustered satellite 420coaxial and optical fibre cables 10code

classification 178concatenation 187detection and correction 180for channels with error bursts 185-7linear 178maximum length 249

code division multiple access (see alsoCOMA) 167, 229

code generation 180code generator matrix 181code rate

code detection and correction 179reduction 13

code tree 189

458

code words 180coded orthogonal frequency division

multiplexing (COFDM) 167-8code-generating polynomial 184coder 210codes

algebraic 180classification of 178-92linear 180low cross-correlation property 251

coding 9, 76, 133, 169, 170, 173-200,327

adaptive 125background 176-8block code 199channel influence 195comparison of 198concatenated code 199concept 177convolution code 199detection and correction 177hard/soft decision 199performance comparison 196performance in gaussian noise 196selection of 195-9summary 198-9

coding advantage 183coding gain 192-3 , 195, 197

gaussian channel 192theoretical values in gaussian

channel 198using BPSK 197using QPSK 197

coding improvement 178coding overhead 178coding performance comparison

block and convolution codes 197general conclusions 197hard and soft decision 197

coding scheme, adaptive 174COFDM 167-8coherent demodulation 156, 158cold sky 108co-located satellites 420command, verification 302command decoder 302command sub-system 301command system, block diagram

301common TDMA terminal

equipment 352communication equipment 349communication link 101

design 94

Index

design issues 94-131noise considerations 103-13

communication quality 210communication satellite 6, 274-324

antenna 288-90atmospheric pressure and temperature

276attitude and control system 291-7attitude control 292-4attitude control, sensors for 293-4bus 291-313communication considerations 275-6control systems 294-7design considerations 275-7dry mass 317-18environmental conditions 276-7lifetime 278magnetic fields 277mass, payload 316-17mass, primary power sub-system 314-

16mass and power estimations 313-19payload 283-90platform, mass of 317power sub-system 304-8propulsion system 298-9reliability 278-82repeater 283-7space particles 276structure 312-13sub-systems 282-313telemetry, tracking and

command 299-304thermal control 308-11thermal control techn iques 311-12transfer orbit, mass in 319transparent repeater 284-7wet mass 318-19

community reception 70companding 147

improvement 217instantaneous 217syllabic 217

companding range 217compandor 137, 212

attack time 218instantaneous 212recovery time 218signal-to-noise ratio advantage 218syllabic 212

comparative analysis 123complementary error function 160composite television signal 145compression ratio 217

Index 459

compressor 212computer program, source code 450-3concatenated codes 199conical horns 334conical scan 338, 339, 343constellation

Ballard optimization 53, ~4cellular distribution 59combination of various types 58deployment 57Ellipsat 59global coverage 47harmonic factor 52hybrid 58-9ideal 55inclined orbit 51-6inter-orbital separation 49Loopus 57optimization 46, 49orbital period selection 56partial deployment 59phase relationship 47phased 47polar 47random 47reconfiguration 395regional coverage 51,59selection of 373single coverage 47spot beam 59spot beam coverage 59theoretical bound: stationary and

dynamic 58trade-off 59triple coverage 50type 1 47type 2 47Walker 46,51,52worldwide coverage 51

constellation capacity 369, 391altitude dependence 369

constellation deployment 45constellation design

coverage 367store and forward system 59traffic distribution 367

constellation geometry 370, 390, 392constellation optimization,

rationale 396constellation parameter, example 56constellation size

dynamic bound 446-7stationary bound 446

constraint length 188

constraints, sharing 114, 115contention protocols 258,261control algorithm 295control bits 241control law 295control station 64control system, active 292, 293convolution, decoder 190convolution code 178, 187-92

code tree 189constraint length 188, 190decoding 189free distance 189minimum distance 189node 189span 188

convolution encoder 188convolution noise 235coordinate systems 18-21coordinate transformation 29coordination

frequency 114process 115

copolar attenuationcross-polar discrimination, -relationship

with 82outage probability 82

copolar link margin 83copolar signal 100correlation bandwidth 167corrugated horn 335cosec correction 72cosmic noise 107coverage

between pole and a latitude 49efficiency 49,50examples 289global 47high latitude 57regional 57,59single 47triple 50types 289unbiased 55

coverage angle 50,51coverage area 96

optimization 121, 290satellite antenna gain 121

coverage circle 48coverage contour geometry 434coverage efficiency 49coverage region 4critical design review 321cross-correlation 248

460

cross-luminance 219cross-polar component loocross-polar coupling 99, 127

total 127typical value 127

cross-polar discrimination 79, 80, 81,83, 99, 100, 114

calculated 81circularly polarized wave 82copolar attenuation, relationship

with 82frequency, relationship with 82horizontally polarized wave 81measured results 83measurements 82, 83outage probability 82vertically polarized wave 81

cross-polar isolation 79, 80, 127cross-polar pattern 99CITE 352

functions 354customers' premises, terminal mounted

on 124cyclic code 183

BCH 183Golay 183Reed-Solomon 183

Cygnus A 108

DASS 233DASS unit 234data access protocol, selection of 265data codec 350data signals 202-8data traffic 229

access protocol 258asynchronous 178bursty factor 259categorization 258characteristics 258environment model 259examples 258inter-arrival time 259synchronous 178

DBS 8decentralized regulation, disadvantages

308declination 19,444decoding 182

look-up table 180sequential 126Viterbi 126

decoding table 181de-emphasis 141

Index

CCIR recommendation 141filter characteristics 141

de-emphasis advantageFDM telephony 145television 145

de-encryption 361delta modulation 210, 213

detection 213digital conversion 213feedback loop gain 214idle noise 214limitations 213

delta patterns 52demand assignment 225

advantages 232signalling and switching 233

demand-assigned data channel,throughput, upper bound 260

demand-assigned FDMA 229improvement factor 238versus pre-assigned 238

demand-assigned SCPCcapacity 237SPADE 237

demand-assigned time division multipleaccess 232

demodulation 133demodulator

realization 133threshold extension 349

demultiplexing 220de-orbiting satellites 395deployable antennas 416depolarization

attenuation, relationship with 84ice 80,83mechanism 80rain 80

DEPSK 157,158descending node 24descrambling 361design defects 280difference pattern 340differential attenuation 83differential PCM 210, 212, 213differential phase 83differential phase shift keying

(DPSK) 157, 158, 160differentially encoded phase shift keying

(DEPSK) 157, 158digital compression 12digital data without interpolation 352digital modulation 151-{j5

amplitude shift keying 151

Index 461

frequency shift keying 151higher order 154phase shift keying 151

digital modulation schemes 151digital multiplexing 221-3digital signals

characteristics 203-8examples 202

digital speech interpolation 245, 246,268,352

digital systems, advantages 202digital telephony 209digital television 219,414

advantages 219digital word 211digital-to-analog converter 209direct broadcast receiver

antenna 361baseband processing 361cost 417descrambling 361design optimization 361encryption 361receiver 361

direct broadcast satellite 287Indian programme 413

direct broadcast satellite receiver 329direct digital interface 355direct orbit 25direct sequence spread spectrum 251-4

narrow-band interferer 252occupied channel width 252principle 251processing gain 252receive power spectrum 252receiver 251, 252spreading function 251synchronization technique 252transmit power spectrum 252transmitter 251

direct sound broadcast 12,414directivity, antenna 97direct-to-home broadcasting 12distress alert facility 407distributed architecture 44distributed frequency management

233advantages 233

distributed telemetry systems 301disturbing torques 293DNI 352domestic networks 3domestic satellite systems 3domestic systems 124

Doppler effect 34-5, 44, 45, 89, 232,430

Doppler frequency shift 5, 34, 35due to environment 89due to satellite motion 89

double side band suppressed carrier(DSB-SC) 134, 135-6

downlink margin, main components 119DPSK 157, 158, 160DPSK demodulator 157drag 25,61drift phase 61drop distribution, Marshall-Palmer 78drop size distribution 74DSB-SC 134-6

demodulation 135DSI 246,352

freeze-out fraction 248gain 248

DSI gain 248dual mode terminal 388, 421dual spin satellites 296dual-polarized antenna 289dual-polarized system 79, 82, 99, 127

bandwidth utilization 99interference in 114

duplex circuit 224duplex TDMA 400

EJNo 118EarlyBird 2Earth, infra-red emissions 293Earth acquisition 63Earth coordinates, sateIIi-centricsystem,

conversion 440Earth eccentricity 429Earth equatorial radius 429Earth gravitational constant 429Earth gravitational field 30, 293Earth gravitational parameter 429Earth magnetic field 33, 293Earth mass 30, 429Earth observations 31Earth orbit 304

eccentricity 277Earth polar axis 333Earth polar radius 429Earth sensors 293Earth shape 25earth station 4, 9, 101, 120, 325-63

antenna pattern 96, 115antenna system 329-34categories 325, ;326characteristics 347-62

462

configuration 328constraints 169design considerations 325-8design trade-off 326direct broadcast service 169, 327feed system 328, 334-6fixed satellite service 169, 347-56functions 325general configuration 328-47G/T 325group delay 235high-power amplifier 345-7IF system 350interface 6international regulations 327look angle 445-6low-noise amplifier 344mobile satellite service 327, 356-60optimization 328out-of-band transmissions 111power control 112power spectral dens ity 115RF sub-system 329satellite television 360--2size reduction 328specification 328support services 355support sub-system 329technical constraints 327-8tracking source 300tracking system 336-44user 's premises, located in 327

earth station antenna 95CCIR reference patterns 330side lobe characteristics 330

earth station antenna system 418earth station cost

factors 327optimization 327

earth station designconstraints, international regulation,

technical 327optimization 327

earth station equipmentcommunication 349receive 349transmit 349

earth station operator 29earth station technology 405, 417

growth trend 417earth station tracking systems 29eccentric anomaly 28, 442eccentricity 24echo control 421

Index

echo control technology 418eclipse ·45, 46, 308, 379

geostationary satellite 306economies of scale 396edge , of service area 120effective isotropic radiated power (EIRP)

100,123,326effective length , rain 77eight-phase PSK 153EIRP 100, 123, 326

satellite 170EIRP of user terminals 390electric generation

nuclear power 304solar cells 304

electrical propulsion 416electromagnetic interference 377electromagnetic wave, polarization 98electronic beam squinting 344elevation 21,29,444elevation angle 54ellipsoid 30elliptic orbit 27elliptical beam 290elliptical polarization, inclination 99elliptically polarized wave 100EMI 377emissivity 310encryption 176, 361energy dispersal 151

analog signal 151digital signal 151

engineering model 321engineering service circuits 355entropy 174

maximum 174envelope delay 151envelope detector 143equator 49equatorial cross-section 31equipotential field 60erf 160erfc 160Erlang 224error function 160error matrix 182error probability 118ESA 423Euler number 249European Space Agency 391,418,423European Telecommunication Satellite

Organisation (EUTELSAT) 3EUTELSAT 3excitation analyser 216

Index 463

expandor 212expansion ratio 217Explorer-I 2

fadecumulative distribution 373frequency dependence 373.

fade duration 89measured results 91

fade margin 87fade rate 89fade threshold 91failure mode

early 279random 279wear-out 279

fairing 312Faraday effect 84-5

compensation 85frequency dependence 85

FDM (frequency division multiplexing)142, 144,220-1

time-frequency plot 220FDM signal, occupied bandwidth 147FDM system

channel loading 146pre-emphasis/de-emphasis

network 142FDM telephony channel 145FDMIFM/FDMA 231FDMA 1n, 229-39, 260, 397

advantages 239bandwidth channel 236bandwidth utilization 236carrier extraction 231categorization 231channel utilization 237definition 229demand versus pre-assigned 238design considerations 234-9disadvantages 239impairments 234salient features 239spectrum utilization efficiency 236transponder capacity 237transponder utilization 235-8

FDMNfDMA, multiple beamenvironment 245-6

FEe code (forward error correctioncode) 176, 195

feed system 334, 347functions 334

feeder links 70fibre optic cables 10

fibre optic systems 45, 408final stage burnout of the launcher 26finite element method 313fixed ground terminal 85fixed satellite service (FSS) 3, 12, 68,

70,124,151,212,268,325,408impact of optical fibres 408

fixed terminals 124fleet management 412flexible antenna 416flight model 321floating base stations 423flux density 102FM

channel loading with voice 146-8group delay effects 150-1threshold effect 148--50threshold extension 150

FM demodulator 349input/output relationship 143noise characteristics 141threshold 143threshold effect 143using feedback 150

FM discriminator 150FM equation 142-6

approximation 144FM improvement 144FM signal (see also frequency

modulation)effective bandwidth 150group delay, effect of 150

FMIFDM telephony 349forward error correction code 176, 195forward link 393frame 218frame efficiency 243frame length 243frame rate 218free space path loss 101, 119frequency

coordination 69errors 34operational, selection of 67selection, existing system 69selection, new system 69selection of 103uncertainties 34

frequency aIlocationfootnote 68plan 115primary 68secondary 68

frequency discriminator 143

464 Index

frequency division multiple access (seealso FDMA) 111,229-39,260,397

number of accesses 235frequency division multiplexed telephony

145weighting advantage 145

frequency division multiplexing (FDM)142,144,220-1

time-frequency plot 220frequency domain coder 210,214-16frequency hopped spread spectrum

254-6code rate 256hopping rate 256interference mechanism 256processing gain 256transmitter spectrum 255

frequency hopping 254frequency modulated signal,

bandwidth 140frequency modulation (see also

FM) 138-51, 219applications 138arbitrary signal 140bandwidth 140carrier power 139demodulator 149deviation adjustment 141frequency deviation 139, 140generation 138improvement 149input/output signal-to-noise ratio

142modulation index 139noise effects 141phase lock loop 149side band magnitude 139sinusoidal 140spike generation mechanism 149subjective estimation of

threshold 149threshold 149threshold effect 148using feedback 149

frequency modulation demodulatornoise characteristics 141power spectral density of noise 141

frequency multiplexed telephony 142frequency planning, constraints 113frequency pool management

advantage 232centralized 232distributed 232

frequency reuse 290

frequency shift keying (FSK) 151, 1657

frequency translator 349dual conversion 349single conversion 349

frequency uncertainties 34frequency window 71FSK 151, 165-7,FSS 3,12,68,70,124,151,212,268,

325,408earth stations 347

FSS allocations 125FSS frequency bands, main 70fuel

bi-propellant 298impulse 298mono-propellant 298specific 298total impulse 298

fuel requirements 314future public land mobile

telecommunication systems 421future trends 12-13, 405

influencing factors 405, 407

G7 nations' Global InformationBroadband Initiative (GIl) 424

G/T 108,123G/T specifications 126galaxy noise 109gallium arsenide field-effect

transistors 344gallitrrn arsenide technology 415gaseous absorption 72gaussian noise 137generator matrix 180, 181GEO 365GEO system 392geocentre 18, 19geocentric coordinate system 444geocentric latitude 21geocentric-equatorial coordinate system

19geodetic latitude 21geometric visibility 367geostationary orbit 31, 32, 35, 96

advantages 5, 35angular velocity 429average radius 429azimuth 38coverage angle 36coverage limit 429disadvantages 5, 35drift 31

Index 465

eclipse by Moon 436-8eclipse by Moon, eclipse depth 438effective utilization 330elevation 36geometric solution 36geometry 36-8half-angle 429interference model 440,441maximum range 429minimum range 429Moon eclipse 41off-axis angle 440-2perturbations 277primary power 38propagation delays 35range 38satellite spacing 330slot selection 42-3solar eclipse 38solar eclipse, by Moon 436Sun eclipse, by Moon, eclipse depth

438Sun transit time 435-6tilt angle 36velocity 429

geostationary satellite 22, 35, 39, 275,288

azimuth 38coverage contours 433-5Earth eclipse 39,40east-west oscillations 433eclipse due to Earth 39-40eclipse due to Moon 41effect of eccentricity 433effect of inclination 432elevation 36-7external perturbations 292launch 60launch, expendable launcher 61-3launch, space shuttle 63-4perturbations 296range 38range rate, eccentricity 430range rate , inclination, drift 431solar eclipses 38-41

geostationary satellite systemlimitation 12transmission delay 12

geosynchronous orbit 35GIBN 424GIl 424global coverage

minimum satellites 56true 45

global information infrastructure 424role of satellites 424

Global Mobile System 387Global Positioning System 416GLOBALSTAR 387GMPCS 13go-back N ARQ 194GOS 225GPS 412GPS receiver 400grade of service (GOS) 225gradient tracking algorithm 344gravitational effects 32

heavenly bodies 32gravitational force (gravitational

pull) 30Moon 25,32Sun 25,32

gravity gradient 32great circle 21great circle range 54

elevation and orbital period 55Gregorian configuration (system) 331,

332Grey coding 161ground segment 4, 6

characteristics 6ground station 4

tracking beacon 301ground track 59group delay 151

effect on SCPC 235group delay distortions 235group delay equalizers 151GSM 387guard band 114, 127, 148,221,231,235,

242Gunn oscillators 344gyroscope 294

Hamming code 181, 184Hamming distance 179, 183, 184, 185,

189hand set, rad iation issues 377hand-held communicators 8hand-held satellite service 398hand -held telephones 411hand-held terminals 418hand-held unit, radiation risk 370handover 44,45,385,387

beam to beam 45satellite to satellite 45

handover procedures 6hard decision decoding 191

466 Index

hardware constraints 170harmonic factor 52HDTV 219,220heat fluctuations, body-stabilized

spacecraft 312heliocentric-ecliptic coordinate

system 25HEO system 392hexagonal cells 449high definition television 219, 220, 408,

414high latitude locations 30

communication 90. service 6high latitude regions 44high power amplifier (HPA) 111, 122,

287,288 ,345,346,349configuration 345multi-amplifier configuration 346single-amplifier configuration 345

higher-order modulation schemes410

high-frequency bands 418high-power satellites 417Hilbert transform 136HLR 388Hohmann transfer 60home location register 388hopping beam system 415,419hopping spot beams 397horizontal parallex 437horn antenna 334hot sky 108hour angle 436HPA 111,122,287,288

transfer characteristics 111HPA rating 349HPA redundancy 346hub 355human cognitive process 209hybrid coder 210, 211hybrid constellation 43, 392hybrid frequency management

scheme 234hydrazine 298, 299, 318hydrometers, attenuation due to 72-8

ice, depolarization, caused by 83lCO

constellation capacity 401main elements 401satellite lifetime 401terminal types 401

lCO Global Communication Ltd 400

lCO system 366,400idle channel noise 213implementation issues 290implementation loss 161implementation margin 159, 161impulse noise 150, 235impulse response, rectangular filter

206lMT-2000 421,424inclination 24inclination change 32inclined elliptical orbit 6individual reception 70information 173information bits 180information rate , average 174information signal 152information theory 173

basics 173-6infra-red detectors 293lnmarsat 3, 124lnmarsat network 266lnmarsat-A 267lnmarsat-Aero 267lnmarsat-B 267, 356lnmarsat-B terminal

above deck unit 357antenna system 358below deck unit 358control functions 358specifications 357

lnmarsat-C 267,356lnmarsat-C system 195lnmarsat-C terminal 358lnmarsat-M 267lnmarsat-P 400in-orbit tests 63lNSAT 413insulation blanket 311,312integrate and dump circuit 156integrated stages 63integrated switched digital network

202integrated terrestrial-satellite mobile

communication 420intelligent track(ing) 343, 344intelligible cross-talk 234lNTELSAT 3, 124, 246, 313lNTELSAT network 347lNTELSAT SCPC system 349lNTELSAT standard-A 329,343 ,347lNTELSAT standard-B 343lNTELSATTDMA 352

characteristics 352

Index 467

INTELSAT VII 289, 290interactive multi-media service 424inter-fade interval 89interference 96, 114-16, 126

adjacent channel 127adjacent transponder 127cross-polar coupling 127in dual-polarized system 114intentional 116inter-system 114intra-system 114Radio Regulations 114-16solar 41-2terrestrial systems 128

interference effects 44interference management

fixed satellite service 115mobile satellite service 115

interference margin 257interference sources, adjacent satellite

126interleaving 185interleaving depth 185, 186inte rmodulation noise 111-13,121,

122, 126, 236, 238, 239, 245, 287,345

adjacent transponders 235intermodulation product 112, 256

estimation 113odd order 113order 113satellite 113third order 113

International MobileTelecommunications 2000 424

international regulations 327international switching centres 10International Telecommunication

Union (ITU) 3, 9, 67,.68, 114, 327,360

Internet 219, 407Internet access 395Internet model 423inter-orbital separation 50inter-satellite link 44, 45, 135, 370, 383,

399,417,419advantages 420bearing angle 447great circle range 447slant range 447system architecture 420

INTER-SPUTNIK 3inte r-symbol interference (lSI) 164,

204, 205

inter-symbol noise 206inter-system interference

allowable 114various types 114

inter-system noise 107, 119intra-system interference 99, 114

link margin 114intra-system noise 119inverse parabolic filter 141investment 123, 423ionosphere 71,84

effects on radio wave 84electron content 84Faraday effect 84F-region 85frequency dependencies 84polarization rotation 84scintillation 84total electron content 85

ionospheric conditions 33ionospheric effects 84-5ionospheric scintillation 85

diurnal variation 85influencing factors 85link margin 85peak levels 85

I-Q plane 153, 154Iridium 14,397Iridium constellation/system 51, 398

network architecture 399ISDN 410lSI 164, 204, 205isotropic antenna 100isotropic radiator 98, 100ITU 3,9,67,68,327,360

procedures 114region 1 68region 2 68region 3 68

jamming 256

«,band 71advantages 418shortcomings 418

K, band payloads 417«; band 125Kennedy Space Center 63Kepler's equation 443Kepler's laws 16Kepler's second law 28Kepler's third law 26kinetic energy 27klystron 345, 349

468

land mobile channelelevation angle dependence 90environment dependence 89, 90limitations 89link margin 89link quality 90measurement results 90problems 89propagation characteristics 89

land mobile communication 30terrestrial 87

land portable terminal 89propagation environment 89

land terminal 7large earth stations 347lasers 135last mile 408, 409latitude 21, 23

high 59launch

polar orbit 63space shuttle 63

launch cost 44, 379launch errors 318launch phase 308launch sequence, geostationary satellite

62launch site, effect on orbital

inclination 61launch vehicle, reusable 63launch window 64launcher

expendable 61, 62reliability 11

LEC> 6,45,293,309,364,365,367,378

LEC> system 46,395,412lifetime extension 415lightweight materials 416line of apsides 60line of nodes 24line rate 218linear algebraic codes 182linear modulation 134linear modulation schemes 134-8linear polarization 99linearizer 287,345link

design methods 94opt imization 94satellite component 121

link availability 125VSAT system 125

link budget, service link 393

Index

link calculations, operational satellite122

link design 116-29example 124numerical example 128-9planning 123-4VSAT 123,124-9

link margin 75, 76, 85, 118, 119, 159elevation angle dependence 76worst-case 118

link parameters, channel related 117link partition

downlink 94satellite path 94uplink 94

link reliability 44, 75, 83, 85, 118system cost 119

Lissajous' figure 445little LEC> system 366, 401

example 401LNB 361location registration 387log-normal distribution 87longitude 21, 23look angle 29Loopus 44loss factor 106low earth orbit (LEC» 6, 45, 293, 309,

364,365,367,378advantage 6altitude 378disadvantage 6

low earth orbit constellation 393messaging system 195

low earth orbit satellite system 12coverage snap shot 369

low noise amplifier 415characteristics 344

low noise block down-converter 361low noise window 108

M level frequency shift keying 165MAC 361magnetic declination 38magnetic deviation 38magnetic variation 38man-made space debris 276manual track 337map projection 439-40

Albers 439Mercator 439polar 439rectangular 439

maritime channel 90-1

Index 469

antenna dependence 90elevation dependence 90frequency characterization 91link margin 91measured data 91multipath 90Ricean model 90sea condition dependence 91shadowing 90signal fade 90signal impairments 90time characterization 91

M-ary frequency shift keying, bandwidth166-7

M-ary FSK 165bandwidth 166, 167generation 165orthogonal frequencies 167

M-aryFSK receiver 166M-ary orthogonal FSK 175M-ary PSK 152, 157, 159

bandwidth compared with BPSK165

demodulator 159spectral occupancy 164

MASER 344mass estimate model, accuracy 314mass of the Earth 25matched filter 175maximum fade length 91maximum likelihood technique 192MCPC (multiple channel per

carrier) 231mean anomaly 24, 28, 442mean deviation 147mean equatorial radius 30mean fade length 91mean speech level 208mean time between failures 279medium earth orbit (MEa) 6, 364, 365,

367advantage 6altitude 378disadvantage 6

medium earth orbit constellation 393medium earth orbit system,

example 400melting layer 83MEa 6, 364, 365, 367

satellite lifetime in 45MEa system 45,366,412Mercator 439meridian 21mesh network 268

hybrid schemes 268maximum interconnections 268

messageaverage delay 259delay in delivery 258inter-arrival time 259loss through collision 258quality 94quantity 94total information 174

message delay, inter-arrival time 260message interception 176message quality 100, 116meteorites 33meteoroids 276'micro' satellites 402microwave integrated circuits 415microwave radio 123Mie theory 74military communication 116, 210minimum elevation angle 56minimum shift keying (MSK) 165mobile channel

amplitude probability distribution 88environment dependence 88low earth orbit 88medium earth orbit 88time-dependent characteristics 89

mobile communication channel,propagation effects 85-91

mobile communication system 159mobile communications 12

high latitudes 35propagation less 35

mobile earth stationdesign optimization 356large 357small 358

mobile environment 86mobile ground terminal 86mobile propagation channel

diffused path 87direct path 87environment dependence 87phase 87shadowing 87specular path 87time characterization 87

mobile satellite channelaeronautical 86land 86maritime 86

mobile satellite communication 11applications 11

470

mobile satellite service (MSS) 3,.7,68,70,71,136,170,209,266,325,411

categories 7ground segment 7growth trends 411spectrum allocation 412spectrum sharing 412

mobile satellite system 406VSAT 410

mobile switchingcentre 387mobile telephony 58mobile terminal 71, 94, 391

EIRP 371hand-held 124orbital altitude 371satellite GlT 371specification 391

mobile-satellite path 86mobility management 387mode extraction 341mode extractor 335model of satellite motion 29modulation 9, 132-72,209

amplitude 133channel dependence 168-9continuous 133definition of 132direct broadcast service 169-70earth station constraints 169-70fixed satellite service 169hardware complexity 133hardware constraints 170-1mobile satellite service 168necessity for 132phase 133selection for mobile satellite service

170selection of 168-71sensitivity to 133signal impairment 133sinusoidal 133spectral occupancy 133system consideration 13~

system level consideration 133modulation index 149

compression 150modulation scheme, spectrally efficient

245modulo-2 adders 178Molniya orbit 30, 35.277, 377momentum dumping 295momentum wheels 294, 297monitoring stations 34

Index

monolithic microwave integrated circuit416

monopulse 338, 343monopulse system 340, 342

difference pattern 341feed system 341performance trade-off 342sum pattern 341

monopulse technique 302Moon, reflection 2MPEG-2 219M-QAM 153MSC 387,388MSK 165

bandwidth occupancy 165definition 165

MSS 3,7,68,70,71,136,170,209,266,325,411

optimal frequency range 71propagation consideration 72

MSS architecture 386multichannel

bandwidth 147mean deviation 147peak deviation 147rms deviation telephony 147signal-to-noise ratio 147

multichannel peak factor 147multichannel rms deviation 147multichannel telephony

occupied bandwidth 148peak deviation 148rms deviation 148

multi-media terminals 8multipath 86, 119

power spectral density 86multipath noise 86

elevation dependence 87probability distribution 87

multipath spectrum 89multiple access

asynchronous transfer mode 269-70data traffic 258examples 266-8fixed satellite service 268future trends 268-70influencingparameters 228Inmarsat network 266mobile satellite service 266-8optimization criteria 228throughput 258, 259

multiple access examples 266multiple access protocols 259multiple access scheme 406

Index 471

future trends 268INTELSAT network 268

multiple access techniques 209, 2~73multiple amplifier configuration 346multiple beam 290

FDMA operation 245TDMA operation 245

multiple channel per carrier 231categorization 231definition 231

multiple spot beam system 419multiple spot beams 288multiple stage rockets 60multiplexed analog components 361multiplexed telephonic signals 201multiplexer

high bit rate 223low bit rate 223

multiplexing 201multiplexing plan

Bell Systems 223CCITT 223time division multiplexing 223

multiplexingstandards 220multi-tone ranging system 302

NASA 418,423National Aeronautical and Space

Administration (NASA) 418,423natural resources 329Nautical Almanac 41,435,436,437navigation system 396

communication system, combinationwith 412 .

nobody problem 29NCS (network control station) 232,267near geostationary satellites 431network, coexistence 115network architecture 44, 45, 382network control station 232, 267

assignment rules 232network issues 390network management 385network synchronization 203new technology 410Newton's laws 26

of gravitation 17of motion 17

Newton-Raphson method 443Ni-Cd batteries 306Ni-H cells 306NLR 147noise 115

budget 115

cosmic 71downlink 117effects of 94in resistor 104interference 117intermodulation 111,117intra-system 103link total 117man-made 71, 103mean square voltage 104natural 103propagation media 108radio stars 108rain 108satellite system 115single entry 115sources of 94thermal 103uplink 117

noise burst 185noise figure 104

active device 105attenuator 106cascaded amplifiers 107definition 105lossy network 105, 106series network 106

noise generator 104maximum power transfer 104

noise loading ratio (NLR) 147noise power 104noise power spectral density 104noise source 126

external 107man-made 107natural 107VSAT 126-8

noise temperature 104, 105, 120active device 105amplifier 105antenna 107-10attenuation 106cascaded amplifiers 107effective 110equivalent 108lossy network 106lossy network definition 105rain 108receiver 110satellite 110series network 106Sun 41system 110

non-furlable-type antennas 312

472 Index

non-geostationary constellation 43-59altitude dependence 43constellation issues 377eccentricity dependence 43health issues 377inclination dependence 43orbital considerations 377spectrum allocation 375spectrum availability 375

non-geostationary orbit satellite system270, 364-404

advantages 364case study 389-94communication requirement 370-2constellation optimization 367constellation size 377-9design considerations 367-89disadvantages 364electromagnetic interference 377examples 394-404financial issues 380-1health considerations 377launch considerations 379network issues 381-9operation considerations 380orbital considerations 377-9orbital debris 379-80quality of service 373-5reasons for interest 364regulatory issues 380-1satellite capacity 369spacecraft technology 370spectrum availability 375-6terminal characteristics 370-2traffic distribution and coverage 367

9non-geostationary satellite system

call charge 380case study 389choice of orbit 392communication requirement 370disadvantages 365diversity improvements 373examples 394financial issues 380launch considerations 379maintenance 380message delivery delay 382monitoring 380network architecture 382network issues 381operational considerations 380path loss 365propagation delay 365

propagation issue 373quality of service 373reasons for interest 365regulatory considerations 380spares policy 380specifications , inputs 389synthesis 391terminal characteristics 370terminal cost 380

non-geostationary systemarchitecture 385, 386connectivity 385,386mobility management 386real time 383routing 383

non-linearityamplitude 111phase 111

non-real-time services 382non-return to zero 203non-systematic codes 181NRZ 204NRZ signal, power spectral density 204NTSC 218, 361nutation 295nutation sensors 295Nyquist rate 205Nyquist sampling rate 211Nyquist's sampling theorem 211

observer position, estimation 34occupied bandwidth 148off-axis angles 440offset antenna 347offset QPSK 158offset reflector 290OLYMPUS 418OMJ 335OMT 335on-board processing 246,399,411,423open satellite communication systems

standard 423open-loop control systems 337operating licence 381operational phase 63, 291optical fibre 123optical fibre system 1, 395

advantages 408cost 409

optimum receiver 190O-QPSK 158ORBCOM 14,366,382,401orbit(s) 5, 277

altitude 46

Index 473

comparison of 43, 44coverage 44elliptical 59formulas 43G-49geostationary 35-43highly elliptical 90hybrid 46inclined 90parking 60,61,62satellite 16-66transfer 61, 62types 46useful formulas 430

orbit and control system 277orbit control 298orbit normal 32orbital altitude 54orbital debris 45

radio regulation 379removal 46

orbital eccentricity 33orbital inclination 60orbital mechanics 16,314orbital parameters 24-5, 300, 302, 442orbital perturbations 52orbital plane 50

rotation 30orbital position, efficient use of 115orbital separation 42orbital slot

available 42number of 42overcrowding 42selection 42

orbit-control system 291orbiter 63orbit-raising 277orbit-raising phase 291orderwire 232orthogonal mode junction 335orthogonal mode transducer 335orthogonal polarization feed

assembly 335orthogonal port 99orthogonal signals 180orthogonality 168

packet 258, 259vulnerable period 262

packet access schemes 229packet loss, collision 261packet reservation 263

mechanisms 264queue management 264

recovery 264reservation requests 263

packet reservation protocols 258packet switching technology 396paging system 138PAL 218, 361PAM-D 64parabolic noise 141, 145parallel redundancy 280parameter of the conic 26parametric amplifiers 344parking orbit 64path loss 44, 45, 46, 102, 103payload 63payload complexity 380payload cost 320payload repeater

regenerative 283transparent 283

peM 212, 213, 217decoding 211

peak deviation 148peak-to-peak luminance 145Peltier effect 344perifocal coordinate system 19, 20, 27perigee 19, 24perigee stages 63period of a satellite 26personal communication services 360,

400personal communication systems 402

main features 360terminals 360

personal communications 365,411,424perturbations 29, 32, 63phase angle 152phase detector 149, 150phase lock loop/phase locked loop 34,

149phase modulation

demodulator complexity 153generation 138mitigation of noise 153RF bandwidth 153spectral efficiency 153

phase noise 159phase non-linearity 235phase shift keying (PSK) 151-65

bandwidth 163-5demodulation 156-62demodulation, effect of thermal noise

159-61demodulation, effects of noise 159

62

474

error in bit synchronization 162error in carrier regeneration 161-2modulators 155spectral efficiency 154-5

phase state 155phased array 290phased array antennas 416phased array technique 344pilot 137

recovery 137pitch 215, 292pitch axes 297pixel 218planet 16

mass 17planetary motion 16plans, pre-assigned 114p-n junction 304pocket-sized telephones 400point-to-point communications 3Poisson process 261polar constellation 47-58, 398

optimum 47, 51worldwide single coverage 47-50worldwide triple coverage 50

polar mounts 333polar orbits 377Polaris 293, 294polarization

circular 98coupling 81horizontal 98linear 98orthogonal 99vertical 98

polarizer 98, 335polarization compensation 335

portable radios 407position 29position determination 45potential energy 27power control, uplink 245power estimate model, accuracy 314power fluxdensity 100, 101power generation 304power spectral density 115power sub-system 291, 304power-bandwidth trade-off 170, 175power-limited link 244preamble 241pre-assigned data channel, throughput

upper bound 260pre-assigned FDMA, versus demand

assigned 238

Index

pre-detection bandpass filter 156pre-detection bandwidth 120pre-detection filter 143prediction coefficients 213pre-emphasis

CCIR recommendation 141cross-over frequency 141filter characteristics 141

pre-emphasis advantageFDM telephony 145telephony 145television 145

pre-emphasis/de-emphasis 219preliminary design review 321primary feed 331prime-focus feed 331

limitations 331user 331

processing gain 252program track 337propagation

degradation due to 67tropospheric effects 72-84

propagation considerations 71propagation delay 44, 45, 375, 395propagation environments 176propagation loss 35propellant tank 299propulsion system 298protocols 229, 259prototype model 321pseudo-random bit sequence 151pseudo-random code

auto-correlation function 250power spectral density 250

pseudo-random data 304pseudo-random sequence(s) 204,249-

51auto-correlation function 249"power spectral density 249properties 249

pseudo-random spreading signal 248PSK 151--65PSK demodulator, effects of noise

159PSK modem 350PSK schemes

efficiency factor 154RF spectrum 154spectral efficiency 154, 155

psophometric weighting 144public switched network 10pulse, band-limiting 204pulse code modulation 210

QAM 151,153QPSK 152, 153, 167

bandwidth comparison, BPSK 164bit error rate 160coherent demodulation 158power spectral density 164probability of error 160symbol error rate 160

quadrature amplitude modulation(QAM) 151, 153

susceptibility to noise 153quadrature phase shift keying (see also

QPSK) 152, 153, 167quality of service 270,373, 392quantization, step size 212quantization noise 212quantization process 211quantizer 210

one-bit 213quasi-stationary constellation 57quasi-stationary footprints 416

RADAR 339radiation pattern 95radiation safety standards 356, 401radiator, lossless 98radio amateurs 34radio channel, degradation 71radio detection and ranging 339radio frequency 392radio link 94, 102

end-to-end 95frequency dependence 103reliability 56

radio link parametersearth station related 116satellite related 116

radio regulations 9,67,96, 114Article 8 68, 71, 115Article 29 115

radio relays 10radio services,categorization 68radio signal

attenuation 86multipath 86reflection 86scattering 86specular component 86

radio spectrum 96equitable use 67-71

radio stars 108rain

attenuation 73-8attenuation prediction 76-8

Index

depolarization, caused by 8{}-3physical temperature 108

rain attenuationCCIR recommendations 77prediction 76prediction technique 77

rain attenuation measurements 75rain attenuation prediction

Crane model 78Lin's model 77

rain dropattenuation cross-section 74drop size distribution 74scattering cross-section 74specificattenuation 74

rain fade 125rain rate, 5-minute advantage 77raised cosine filter 206, 207range 119range estimate, error 303range rate 445ranging tone 302Rayleigh distribution 87Rayleigh fading 159reaction wheels 294real-time interactive services 382real-time tracking 29received carrier power 118-20received power fluxdensity 100received signal level 102received signal quality 117receiver filter bandwidth 34receiver sensitivity

figure of merit 120G/T 120

recent tracking techniques 342reciprocal device 95rectangular waveguide 334redundancy 177, 280

optimization 281redundant bits 180Reed-Solomon code 184, 186, 187

characteristics 186reference meridian 21reflector antenna 290;329, 331regenerative repeater 13,419

advantages 419regenerative transponder 118, 125regional mobile satellite systems 12regional networks 3regional system 402regulations, affecting design!

planning 115relative humidity 72

475

476 Index

reliabilityparallel 280satellite 281satellite, figure of merit, redundancy

282series 279

reliability bound 280reliability model 280

communication satellite 281communication sub-system 281

repeater 282comparison of 284dual-conversion isolation, transmit-

receive sections 287multiple-stage conversion 286multiplexer 287regenerative 285single-stage conversion 286transparent 284, 285

repeater gain 284request for proposals 320rescue coordination centre 8retrograde orbit 25return link 393return link budget 394revenue 123RF carrier spikes 204RF sensing method 294RF signal

load 151power spectral density 151

RF visibility 367Rice (Ricean) factor 87,91Ricean amplitude distribution 87Ricean distribution 86, 87Ricean fading 159Ricean model 91right ascension 24, 444right ascension angle 19, 52right ascension-declination coordinate

system 19, 20right-hand circularly polarized wave 99risk 45rms deviation 148rocket

first-stage 61second-stage {i1V-2 2

roll 292roll axes 297roll-off factor 206, 7..07

filter implementation complexity 207rosette constellation 52, 393, 447-9rotary joint 336

rotation of perigee 31routing protocols

centralized routing 385distributed routing 385flooding 385

routing table 386Royal Greenwich Observatory 21RS code (Reed-Solomon code) 184,

186, 187

sampler 210sampling, timing accuracy 205satelli-centric coordinates, conversion to

earth coordinates 439satellite 9, 101, 275

access 9active 2advanced technique 415altitude 291antenna gain 119antenna pattern 119,274antenna pointing 115available EIRP 122capacity 275configuration 275coverage 275coverage area 288design 274disturbing torques 293EIRP limit 124electrical power 274environment conditions 274environment effects 276equipment life 33fuel capacity 33gain 122global coverage 288heat sources 308integration with terrestrial

lifetime 278, 296, 318lifetime extension 415maximum antenna diameter 327maximum primary power 327multiple bus 308multiple path 114operational 122, 278operators 115optical fibre 395other applications 3'paper' 43passive 2path in space 25-6period 26-7position 27-9

Index 477

power supply 308range 302, 445range-rate 302redundancy 11reliability 11, 274reliability, definition, failure

mode 278reliability-cost trade-off 282replacement 46requirements 274RF transmitter power 313search 57secondary power source 39service area 274service type 275spin-stabilized 276stabilization of 63stabilized 276station-keeping 115storage battery 39sub-systems 282surface area 33telecommunications 275temperature change 306temperature variations 276thermal control 308thermal design 39thermal environment 308thermal model 310three-axis 276track 57tracking 302translation frequency 232velocity 27zero delay 397

satellite access 238satellite access nodes 401satellite accessing technique 170satellite acquisition 337satellite altitude, lower limit 33satellite antenna, horizon, direction of

98satellite antenna beamwidth 292satellite antenna gain, coverage area

121satellite attitude

pitch 292roll 292yaw 292

satell ite azimuth and elevation 444satellite capacity 239, 369, 372satellite cell representation 449satellite clusters 422satellite communication(s) 1

advanced concept 418-26advantages 1advantages, vis-a-vis optical fibres 408applications 1, 10-12background 2-3benefits 1business plan 123competition 1economics 10future applications 407-14future applications, broadcast satellite

services 413-14future applications, fixed satellite

services 408-11future applications, mobile satellites

411-13future trends 12,405-28growth 1growth trend 405important milestones 13-14initial years 405last mile 409limitations 10, 11network 1, 94planning 123restoration time 408risk 123technology growth 405technology trends 414-26technology trends, earth station

technology 417-18technology trends, spacecraft

technology 414-17vis-a-vis optical fibre system 409

satellite communication growthemerging growth area 407future applications 407influencing factors 407

satellite communication systemcapacity re-allocation 410comparative analysis 123optical fibre 410

satellite communication technique,investments 423

satellite communication technology,growth trends 406

satellite constellation, deployment 365satellite control centre 301, 302satellite control facility/system 294, 321satellite drift 432satellite eclipse 42satellite EIRP 372

mobile C/T 372orbital height 372

478 Index

satellite footprint 288satellite gain, selection of 122satellite high power amplifier

back-off 234impairments 234

satellite lifetime 396functional 33operational 33orbital 33

satellite lifetime extension 422satellite mobile communications 3satellite motion, laws governing 16-18satellite orbits 16satellite period 26satellite platform 291satellite position 27

from orbital parameters 442-5satellite production techniques 416satellite range 29satellite receiver, noise temperature 121satellite redundancy 44satellite resources 242satellite switched TDMA 268satellite system

basic 4fibre optic 364fibre optic-like 366integration with terrestrial system 388interface with terrestrial system 388planning 365

satellite system cost 409satellite telephones 365satellite television receivers 360satellite transmitter 122satellite velocity 27, 29

circular orbit 27elliptic orbit 27

satellite visibility 45, 387multiple 58

satellite-optical fibre synergy 409satellite-referred coordinates 439sawtooth waveform 151SCADA 395scanning sensor scheme 294scattering cross-section 74scintillation 84, 119, 185, 342

fading rate 79magnitude 79tropospheric 79

SCPC (single channel per carrier) 144,146,231-4,246,349

demand-assigned 232earth station 350effects of frequency drift 232

IF system 350pre-assigned 232SPADE 238

SCPC channels 202SCPC receiver

APC 352automatic frequency correction 352DASS 352demand-assigned signalling and

switchingunit 352timing and frequency control unit 352

SCPC system 268demand-assigned 171pre-assigned 171

SCPC terminal 351fixed-assigned 350fixed-assigned scrambling 350

SEACAM 218, 361secondary power source 40selective repeat request, throughput

efficiency 195selective request ARQ 194

mean time for transmission 194throughput efficiency 195

semi-major axis 24, 26semi-stable points 31sequential decoding 191service area 42, 390SES (ship earth station) 267shadowing 119Shannon's theorem 175Shannon-Hartley theorem 175shaped beam 288

synthesis 290shaped spot beam 274sharing constraints 125shift register 178, 185, 187, 189, 249

maximum length linear sequences249

ship earth station (SES) 267ship terminal 7sidereal day 21, 22, 23, 35signal fidelity 94signal quality, figure of merit 116signalling channel 232, 233signal-to-noise ratio 126signal-to-quantization ratio 212simplex signal 196simultaneous lobing 340sine' function 163single channel per carrier (SCPC) 144,

146, 231-4, 246, 249companding 146companding advantage 146

Index 479

demand-assigned 246FM equation 146pre-emphasis advantage 146weighting advantage 146

single event failures 377single parity check 184single side band (SSB) 134, 136-8single side band modulation (SSB

modulation) 136-8detection 137occupied bandwidth 138

single side band suppressed carrier (SSB-SC) 136

single visibility 56single visibility coverage 47,51site diversity 76sixteen-QAM 153sky noise 107

Moon 108Sun 108

slope overload 213slotted ALOHA

channel capacity 262throughput 262

soft decision decoding 191soft handover 387solar activity 276solar array 304

average temperature 305cell interconnection 305degradation 315deployment 63effective temperature 315primary power 315single point failure 305size, spin-stabilized 315size, three-axis stabilized 315

solar array sizebody-stabilized spacecraft 305dependence on attitude and orbit

control system 305spin-stabilized spacecraft 305surface area 305

solar cell 276, 277, 304, 305, 306conversion efficiency 304effects of space environment 304long-term voltage variation 304silicon 304voltage variation 306

solar cell efficiency 315,316solar constant 315solar day 21solar flares 84solar interference 41

maximum duration 42maximum number of days 42

solar radiation 277variation in intensity 306

solar rad iation pressure 33, 296solar temperature 108solar-array Sun tracking 297solid-state amplifiers 287solid-state power amplifiers 345sound broadcasts 8, 70sound channels 70source coder 209, 214-16South Atlantic anomaly 378space

atmospheric pressure 276environment 276space particles 276temperature 276

space debris 44space environment 377

magnetic fields 277space hardened computers 416space platforms 422space segment 4, 5, 400

cost estimates 319-21cost model 319,320non-recurring cost 320planning 319recurring cost 320

space segment cost 380circular orbit 320elliptical orbit 320

space shuttle 61Space Transportation System 61spacecraft 275, 390, 392

antenna 282antenna, unfurling 288array 316attitude and orbit control system 282batteries 379battery 316bus 282cost 287critical components 278design considerations 275development programme 321development stages 321-2electric power supply 283failure analysis 280in-orbit 319mass, beginning of life 319mass estimate 316mass estimation model 313mechan ical environment 312

480 Index

payload 282,283,316power control 316power estimation model 313primary power 316primary power, equinox/solstice 315primary power sub-system 314propulsion 282repeater 282structure 282,312sub-system 283telemetry, tracking and command 283thermal 282transfer orbit 319

spacecraft antenna 393cross-polar discrimination 290feed, excitation coefficient, beam

forming network 290implementation issues 290signal routing 290

spacecraft development programme 321conceptual design 321definition phase 321development phase 321

spacecraft development stages 321spacecraft mass

beginning of life 318dry 317platform 317reflector/feed 317wet 318

spacecraft power 228, 414spacecraft power system 277spacecraft structure , material 313spacecraft technology 370,405 ,414

growth trend 414spacecraft temperature 310space-qualified electronics 2SPAJ)E 233,268,352SPAJ)E terminal- demand-

assigned 352specific attenuation 74specific mechanical energy 27spectrum 390

equitable use 67expansion in operational system 67

spectrum allocationexclusive 68planned 68shared 68

spectrum efficiency 44, 45spectrum regulation 9spectrum reuse 402spectrum shortage 414spectrum utilization efficiency 236

speechredundancy 209synthetic quality 210unvoiced 215vocal tract response 215voice excitation analyser 215voice pitch generator 215voiced 215

speech energyamplitude 208bandwidth 208

speech generating model 214source 214system 214

speech interpolation 24fr8speech model 211speech pause 248speech signal

reference point 208statistical analysis 213

spherical Earth 30spin axis 294spin mode 63spin rate, decay 296spin stabilization 291, 296

solar arrays 296station-keeping 297

spot beam 76,274, 288, 402, 413, 414,419

advantages 76connectivity 245frequency to beam mapping 246traffic in 246

spot beam coveragemulti-beam 448

spot beam technology 44spread spectrum 248

direct sequence 249frequency hopped 249RF bandwidth 251

spread spectrum modulation 125, 167,171

spread spectrum system 266applications 256capacity of 257-8

spring equinox 39Sputnik-I 2SSB 134

generat ion 136satellite communication 137-8spectral occupancy 136

SSB modulation 13fr8effects of noise 137satellite communication 137

Index 481

signal-to-noise ratio 137synchronous detection 137use of compandors 137

SSB-SC 136SSPA 415stabilization system 334stable points of the orbit 31standby generators 355star sensor 294static Earth sensors 297static sensing technique 293stationary platform system 422station-keeping 52, 115

fuel 301, 318fuel requirement 319specific impulse 318

Stefan-Boltzmann law 309step-track 338, 343step-track system 342step-track technique 358stop and wait ARQ 194store and forward

architecture 382asynchronous schemes 383capacity 383earth station based, capacity, routing

schemes 383inter-satellite link 383satellite-based 382

store-and-forward service 358store-and-forward system 195, 382stratospheric air platform 368stratospheric balloons 422stratospheric systems 422structural model 321structure design 313STS/Centaur 64sub-band coder 210sub-band coding 214sub-satellite point 37sum pattern 340Sun 16, 17, 18

movement relative to equator 39Sun acquisition 63Sun eclipses 44, 378Sun inclination 39Sun radiation

average power 304variation in intensity 304

Sun spot numbers 85Sun transit 125

earth station 108occurrence of 42occurrence prediction 42

Sun-synchronous orbit 31,379orbital altitude 377

supercells 396supervisory control and data acquisition

(SCADA) 395syllabic compandors 217-18symbol 152symbol duration 152symbol rate 152, 155synchronization pulse 145synchronized digital network 203synchronous detection 135, 137Syncom III 2syndrome 182syndrome decoding 183synthetic quality 211system constraints 8system design

frequency considerations 67-71propagation considerations 71-91

system design considerations 8-10system design tools 94system planning

evolutionary 124risk 124

systematic codes 181

TASI 246Taurus A 108TOM 202, 220

composite bit rate 222statistical variations 222timing plan 222

TDM/PSKlFDMA 231TDMA 112, 170,202,203,229,240-8,

260,268,269,397advantages 245burst synchronization 242capacity 240capacity alteration 241closed-loop burst synchronization 242closed-loop synchronization 242-3demand-assigned 267demodulator performance 244disadvantages 245earth station 244effect of satellite motion 241frame efficiency 243~

frame time 242guard time 240network synchronization 240,241open-loop burst synchronization 242open-loop synchronization 242reception 240

482 Index

reservation 264salient features 245satellite switched 246, 247switch matrix 247synchronization 243time slot 240, 241transmission 240transponder utilization 244-5voice capacity 243

TDMA burst 354TDMA terminal 352

demodulator 354multiplexing baseband 354receive section 354terrestrial interface 354

TDMA traffic terminal 353TDMAlDNI 352TDMNDSI 352TDRSS 419technology 46technology trends 414tele-command receiver 302telecommunications research and

development 424Teledesic 395

services 395system architecture 395terminals 395

telemetred parameters 300telemetry, modulation 300telemetry carrier 302telemetry data rates 300telemetry sub-system 300telemetry tracking and command system

(TT&C) 5,291,299,300,301,308main blocks 300main functions 300

telephone channels, analog 209telephone signals 208telephony 208-18

analog 208digital 209-18FMIFDM 349

television 144,349audio 349direct broadcast to ships 219luminance signal ,144peak-to-peak amplitude 144sound transmission 219standards 219, 361

television picture, degradation 219television receive only 360television signal 218-20

chrominance 218

colour saturation 218hue 218luminance 218

television standard 145, 218television transmissions 201terrestrial access circuits 238terrestrial transmissions 8test tone deviation, multichannel

deviation, conversion of 146tethered satellites 421theoretical channel limit 197thermal control

active 311electric heaters 311factors influencing 308heat pipes 311hinged pipes 311passive 311principles 308system design 309

thermal control techniques 311thermal design

body-stabilized 311spin-stabilized 311

thermal environment 309low earth orbit 309transfer orbit 309

thermal equilibrium 309,310thermal gradients 39thermal model 321thermal noise 103-5 , 126, 159thermal noise power 120thermal sub-systems 291thermal-vacuum simulation tests 311three-axis stabilization 291, 296, 297three-axis stabilized satellite 298threshold effect 143throughput 194thruster 298

force applied 298time division multiple access (seealso

TDMA) 112, 202satellite switched 246

time division multiplexing (TDM) 202,220,222

time domain coders 210-14time slots 232time-assigned speech interpolation 246time-shared bus 301timing recovery circuit 156tolI quality 210tone level, relationship to speech level

146tracking 338

Index 483

manual mode 338program track 338

tracking and data relay satellite system419

tracking antennas for mobiles 71tracking loss 119tracking receiver 340

conical scan 340tracking stations 61tracking systems 5, 336

comparisons 342main elements 337

traffic 390call congestion 202channels required 202

traffic carried 224traffic channels 114traffic considerations 202, 223-6traffic engineering 223traffic forecast 123traffic growth trends 411traffic matrix 224traffic model

Erlang-B model 225Poisson model 225

traffic patternchangesin 246spot beams 246

traffic theory 223traffic variation

diurnal behaviour 224peak traffic 224

transfer orbit 291,309,319elliptical 60

transmission coefficients 80transmission delay 12, 421transmission efficiency 193transmission equation 100-3, 118,

244transmission plans 245transmissions, out-of-band 111transmitted power 67transmitter technology 415trans-multiplexer 355transparent repeater 117transponder 246

access 246advantages 286bandwidth requirement 246definition 286gain control 286hopping 246leasing 123numbers in spot beams 246

routing 246sharing 122single carrier access 240

transponder bandwidth 245transponder interference, adjacent 127transponder utilization 235travelling wave tube amplifier

(TWT) 111, 112, 113, 234, 235,287,345 ,349,415

troposphere 5, 71troposphere effects 72tropospheric scintillation 85true anomaly 28, 29, 442true global coverage 44true north 21, 38trunk 238trunk routes 10, 209IT&C 5, 291, 299, 300, 301, 308tundra orbit 30TYRO terminals 360two-body problem 26, 29

corrections to 29-33two-body system 60TWT 111,112,113,234,235,287,345,

349, 415amplitude-frequency response 234AM-PM conversion 235input back-off 111output back-off 111transfer characteristics 111

TWTA technology 417

UMTS 360, 424uniformity index

spatial 55temporal 55

unique word 241universal gravitational constant 17universal mobile telecommunication

service 360Universal Mobile Telecommunications

Systems 424uplink carrier-to-noise ratio 120uplink power control 239US standard atmosphere 72useful data 429utopian global village 426

Van Allen radiation belts 44, 277,377

variable bit rate services 270VCO 149velocity

Earth's rotational 61

-484 Index

exhaust 60increment 60

velocity of light 429vernal equinox 18, 19, 24, 32very large scale integration (VLSI) 183,

202,217,418very lightweight satellites 421very small aperture terminal

(VSAT) 10, 11, 123,347,355video

blending with computing 219on demand 219

video compression 418video conferencing 395virtual connection 270visitor location register 388Viterbi algorithm 192, 197Viterbi decoding algorithm 189VLR 388VLSI 183, 217, 418VLSI technology 202vocal response 216vocoder (alsosee source coder) 209,

211,214main blocks 215

vocoder implementation 216voice, excitat ion analyser 216voice activation 238voice baseband 146voice coder

main characteristics 211requirement 209selection criteria 217

voice coding 201,209-17,418comparison 216

voice coding techniques 410comparison of 216-17

voice detection 350voice pitch generator 216voice-activated loading 238voltage axial ratio 99voltage controlled oscillator (VeO) 149voltage regulation

centralized 306, 307decentralized 306, 307

VSAT 10,11,123,347,355antenna size 125coding 356frequency band 125, 355frequency selection 125inbound link 124modulating scheme 355modulation 356numerical example 128outbound link 124personal 12portable 58sensitivity 125system architecture 124typical parameters 128

VSAT link 169VSAT network 268

Walker constellations 370waveform coder 209,210-14waveguide, mode 334,335,341weighting advantage 144, 219word, definition of 202worldwide coverage

minimum number of satellites 43-7multiple visibility 43single visibility 43

worldwide plan 70worldwide voice services 389wrist watch size radios 407

xenon Jon engines 416XPD (cross-polar discrimination) 79,

80,81XPI (cross-polar isolation) 79,80, 127X-polar pattern 99X-Ymount 333

yaw 292yaw axis 297

zero crossings 207zero delay satellites 422zero gravity 276zero momentum 294