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muior, MDR ryp &U nier up Io ud includins TI
would bc rcquirrd
Syuhrmiratim is me of the ty arcam of plential
vulnerability in Ihe design ud oprratim of a
MIUATCOM ystan. In R& tn met operational
raquirancnh an MDR EllF MIUATCOM syslcm mu.%
pvide a syrwhmnixalirm upability hat is 11 ICul U
robust U Ihe uxnmunicatimr capability it sup-
Synchmniruim cmsism ot hxh rquiritim d %ti%
pmrcssm Thc~ p~reu~i involve adjwling the critical
puuncim or spatial pointing. rmuency ud timing. It the
g m d cemirul. It vnll k umwd that be payload is Ihe
spem rcfmmr vi& rcgud to trcquency utd timing. md
that UK gmund terminal must match iu timing uul
rrcqumy to che DL roccivcd signals. Similuly it lnus
cnwrc Ihal the UL signals urivc at the paylimd matched
in tim uxl frcquency IO thau of Ihe paylord This papa
cimimn chc systcm &sign consideration* for
rynchmni7atim of EHF MDR systems u~iliring Tactical
Satcllitcs (TACSATS). Thc anphmis of thr discussion
will hr im pvformance capahilltics lo nrcl thcatrc
rmand qummcnu.
Thc paw is organi7ml as follows. Sccthm II ciamincs
d
rimc of the syricni chuacterirtics and asrumpli~ms which
imp8ct Ihc dcsign or Ihe r)nchroni7alion pmfcsr. Srction
111. 1V. mi V rraminc the hign or spatial. iimc a
frcqumcy syicl~nimim aIpnithm.. mrpstivcly. Srrtim
VI eranlines paramr~m ~d pcrlammcc mcuurrq kn UI
ovrrall .ynrhnmiialam aI$irithn. Sccticm VI1 pr~ividcr a
CorTIUslon to lhc papcl.
2 MDR EllF SYSTEM CHARACTERISTICS
2.1 Wavrtorm and Opmllonal Cnnsldrrallunr
The rmmcd kcy wavcfnrm .nd opcralional characicristics
thai are peninml io Ihe
>
discussion in this papr arc
outlid in Tahle I. These characteristics were conridcrcd
hy the Canadian Dcpuune I of National Dcfcnce tor the
currint MDR EHF MILSAT CM system design (21. As
dmcusscd ahrve. the uplink h dwidth is 2 GI11 ceiitcrcd
about 44.5 GHr. whrxas c dcrmlink hanlwdih is I
GH7 ccntcrcd ahut 21 CIO. hquency lwpping is
cmploycd to comhat jamming. with the hopping rate king
on thc dcr of kllz. A typical systcm conliguration is
illustratcd in Lgure I. in which L grixrnd lcnninal (CT) in
I given hatrr of operation communicaics with a GT in
the same or dilfcrcnt Ihcam. A tlravc of opcratim is
dcfinal by Ihr salclliic antema hcam patton coverage.
The salcllitc antenna CUI e i h h a fixed w slccrahlc 'put
beam. or a multihcam antenna that can be dynamically
slccrcd from one theme to another m a hop to 1 op or
kame to Cram basis. In order to accommc&tc multiuscm
and variable data rata. a hybid FDMA/TDMA frame
svUcturc is employed on Ihe uplink as illur~rated in FsRure
2. Usen arc rsw~ad capcity in terns or M ~CVSI whlch
CUI be one or more m)nconcuncnt subtruncr in OK or
mm uscr channels. The downlink employs a singlc
channel TDMA wucture. The modulation assumed for
r -
UL frequency
budwidth
budwidth
modulation I DPSK -1
liopping ntc slow frequency hqrpina
Diu Rates 32 kbm IO TI
I
Rocasing fwtim - coding: Mat or
cmvolutiaul
- divmily
. inlcrleaving
- timc oermutation
I 11
satellite abiu ~
&lbibiuuy
payload UItCnN 1 T-5'bcamwidIh
26-34 dRi
payload amplifier 5 W SSPA
nnwnd terminal mcnm I un to 1.R m I
ground tam;nrl up to 20 w
bmplifia
.\
Figu:c I: Syslcm Configuraum
purposcs ol his discussiim is DPSK. No pulx shaping has
hcn as*umed. although Wmt studies idicalc lhal lhis
may be useful for MDR applicatim 131. M-uy FSK could
also he considend however given hat slow frequency
I