Note: Descriptions are shown in the official language in which they were submitted.
WO 95/31070 ~ ) 5 7 PCT/IB95/00313
"Point-to-multipoint cellular television trancmiCcic~n system"
The present invention relates to a point-to-multipoint cellular television
trAncmiccion system inclu-ling at least two cells, each provided with a relatively low-power
l.An~ P~ station for cell-wise tr~ncmiccion of at least one television signal in a cell of the
cellular system in which cells are ~tljArPnt to at least one other cell of the cellular system,
5 and in which the tr~ncmittpr stations tr~ncmit at least in part, the same television signals in a
microwave band, the system further inrlll-ling a plurality of receiver stations comprising a
dire.ctionAl receiving ~ntonnA for receiving a television signal from one of the trAncmittrr
stAti~nS,,
A point-to-mnltiroint cellular television tr~ncmiccion system of this kind is
known from the Eur~ Patent Application No. 0 282 347. Herein, a cellular television
system is ~les-~;hecl ~h~l~;n I~A~I~In;~t~J stations are located in centres of cells of an array of
cells. In order to cover complete cells, the t.An~.";~ are provided with an omnidirectin
15 I~An.~ g An~f nnA~ e.g. i rl m~nted by a small number of quadrant directionAl radiators.
A mllltipl~Y~ signal is modll1Atrd onto a single microwave carrier, so æ to allow for a wide
variety of signal fo~ to be combined effici-o-ntly. Such signals can be FM (I~l~uency
Modulation) video signals with audio ;~llbCA 1 ;e ;~ digital signals, or the like. The system is
arranged for two-way co.. -~.. ;rAtion services inclu-iing television, both for public and
20 private ~ lAIlllll;llg~ digital two way tr~ncmicc;~n, video t~ onr4.c:--cing, radio
~,og.A.. ing, telephon~o services, or the like, cim~ ;.n~ous cGllllllllr~;rAtic)n services being
possible because of the broad bandwidth available in the applied 27.5 to 29.5 GHz
microwave band. The system applies relatively low-power LlAl~ i SO as to allow for
freque Ar reuse in a given geo~l~phical area. In the licclose~ microwave band it is
25 extreme~y rliffirult to mAnllf~rtllre a usable omni-directic-nAl AntrnnA In fact, omnidirectional
bro~dcActing is achieved by applying a small m "-bel of quadrant directional radiators so as
to achieve space dis~ --c-~t of multiple ring locations of the IIAI~ IeI stations, such as
flicrlosrd in Fig. 4A, and on page 6, lines 50-52, page 7, lines 9-10, and page 8, lines 61-63
of said Eur~ean Patent Application No. 0 282 347. The use of quadrant directionAl
WO 95/31070 PCT/IB95/00313
21~6~7 2
r~Ai~rs, however, gives rise to a relatively complex, and herewith relatively expensive
lt'r station, because of the fact that phase coherent radiation by the various radiators
is required. Also, applying multipleYing and Aeml-ltiplexing of a large number of signals is a
complir~ting factor.
It is an object of the present invention to provide a point-to-multipoint
cellular television tr~n~mic~ion system of the above kind not having the drawbacks of said
known system, which can be easily implemPnt~PA and which can be easily PYtenA.~P~A
To this end the point-to-multipoint cellular television tr~ncmiccion system
acco..ling to the present invention is char~rt~ri7pd in that each tr~ncmitter station is located
at a circumference of its cell of the cellular system, and is provided with one directional
tr~ncmitting ~ntPnn~ for ~ubsl~nl;~lly r~ ting at least one television signal into its cell. Due
to the fact that no phase inter-relationship has to exist beLween various ch~nn~lc to be
15 tMncmitted, inter ~_, a very simple system a c~ e is achieved.
In an embo~liment of a point-to-multipoint cellular television tr~ncmiccirJn
system according to the present invention, the tMn~",jll;ng ~ntenn~c generally tldl~lnit along
a main geogl~hical axis of the system. IIel~;wiLh, il~L~;lÇe.~nce b~l~n t.~ ...iL~ g stations
is ~ ced as to the application of omni-directional L~ c."i~ g st~tinnc
In another embo~iim~nt of a point-to-multipoint cellular television
tPncmiccion system according to the present invention, the system comprises two sub-
systems, in each of which the trancmitting ~ geneMlly l.,.n~."il along a g~gla~hica
axis, the axes being non-coinri~iing. IIele~.~iLh, the system can more easily be adapted to
various terrain con-litionc.
In an embodim~nt of a point-to-multipoint cellular television tMn~miccion
system according to the present invention, the tPncmittP.r stations comprise a plurality of
in~ependently o~.,-ling ~ ,"il~ each tr~ncmitting on a different, relatively n~n,wtJand,
ch~nn.o,l, the !.,..~...ill,.~ each being coupled to a radiator. Herewith, there is no logical int~r-
relationship belwe~n the ch~nn~lc of the the system wl.atso~/er. The system can thus be
30 eYr~nde~ very easily, just by adding ~ ."i~ and ~o~ c~ as long as band width is
available.
In an embodiment of a point-to-multipoint cellular television tr~ncmiccion
system according to the present invention, the radiators per tMncmitt~r station are directed
into subst~nti~lly the same direction. Herewith, all receiver stations in a cell receive the same
WO 9S/31070 ~16 ~ PCT/IB95100313
set of ch;~nnelc In the ~ltrrn~tive~ with many chilnnPlc, some program diversity could be
achieved in a cell by directing radiators of groups of ch~nnrlc to difrclcnt sectors of the cell.
Then, the beamwidth of the r~rli~tors should be such that only a part of the cell is covered
hGlGV' i~
S In an embodiment of a point-to-multipoint cellular television tr;~ncmiccion
system according to the present invention, large signal shadows in the system are covered by
auxiliary tr;~n~mitt~AAr st;~tionC, which are coup'^~ to a main tpncmittrr station in a cell. Such
large signal shadows can be caused by terrain con-litionc, such as a hilly terrain. The
auxiliary tr~n~mittfr station can be coupled to the main ~ ;llær station by wire or by
10 wireless link. In given terrain circumct;~nees~ such reflective areas at large objects, such an
auxiliary ~ t-r station can be licI~Pncf-ll with.
In an embo~limPnt of a point-to-multipoint cellular television tr~ncmiccit~n
system according to the present invention, small signal shadows in the system are covered by
cabling from a receiver station, which is shared by a plurality of subscribers. Such small
15 signal shadows can be caused by large b~-iltlingc Then, the receiver station can be put on top
of the large building. Herewith, the overall serviceability of the cellular system is improved.
Further cl~lb~l;~ are c~ im~ in the dc~ -denl claims, and relate to
improved system pc~ro~l"ance. This improved system pclr l",ance can be achieved by
applying signal col"pl~sion methotlc such as MPEG (Moving Picture Expert Group), by
20 applying pol~ri7~tion diversity ll,r~,~gllol,~ the arrdy of cells, by intrrle-~ving ch~nnf--lc groups
~Ccigned to particular rl~U- n~iy sets, or by applying polarization diversity within a cell. For
a good overall coverage of the cells of the system, the cells may partly overlap each other.
The microwave band used by the system may be 40.5 to 42.5 GHz for the so-called CEPT
(ConÇclcnce of Eul~an Posts and Teleco,.. u,~ ti~ ns Atiminict;~tionc) counLlies, may be
25 27.5 to 29.5 GHz for other cO~.n ;es, or may be another microwave band when other
frequencies are made available by the Authorities. The tr~ncmitting ;lntenn;~c can be dilc,~d
in such an angle with respect to a t~ ;,Lial ground level in a propagation direction of a
radiated bearn that in a straight line the beam touches the ground level at a plcdeLcl~ ed
t;~nr~, preferably between S and 6 kilometers from the !-,--c---;ller station, it being
30 achieved tha~ a tr~ncmitting range is limited so that a better frequency re-use is possible. The
tr~ncmittt--r stations can partly be provided with public plo~ "s or with private programs,
i.e. the pl~J~,l`d_n p~r1~g~s and services provided by the tr~ncmitting stations may vary per
cell. The n~r.~ stations may be provided with lJlvgldlns and services via lzln(llinf-c, via
satt-llitf-s, via wireless links, or by any other means. When (two-way) services are provided,
WO 95/31070 21 6 6 ~ 5 7 PCT/IB95/00313
billing of these services can be done at a central site. With two-way services, a return
ch~nnPl to the tr~n~mitting station can be a public telephone line, or can be a Telepoint line
from a cellular radio system, or the like. Apart from television signals, a con~idprable
nu~,bf ~ of audio signals or data signals can be assembled with the television signals on one
S or more auxiliary c~rrif rs. ~er~ldbly, an a~l~u~ angle of the ~ g ~ntf nn~ can be
between 50 and 70 degrees, thus giving rise to a good coverage area. A practical angle of 64
degrees has been proven to be a good choice.
The receiver stations may be fixed st~tion~, or may be mobile stations. In
the latter case, the receiver stations constantly keep their direction~l ~"1~ .~n~ pointing to a
10 tr~n~mitter station.
The present invention will now be described, by way of example, with
reference to the accol"lpanying drawings, wherein
Fig. 1 sçhPm~ti~ ly shows a point-to-multipoint cellular television
tr~n~mi~ion system according to the present invention,
Fig. 2 sc~ ly shows geog,~llical det~uls in a cell of a point-to-
ml-ltiroint cellular television system according to the present invention,
Fig. 3 shows positiQning of ll,.n~ .l stations in a first cell configuration
- 20 accor~lillg to the present invention,
Fig. 4 shows positioning of tr~n~mit~er stations in a second cell
configuration according to the present invention,
Fig. S shows po~itioning of radiators in a tlAn~...;lle~ station casing
according to the present invention,
Fig. 6 shows an electric~l fii~gr~m of a L,i1n~.. ill~ station according to the
present invention,
Fig. 7 shows a part of an IF-exciter according to the present invention,
- Fig. 8 shows an electrical ~ gr~m of a signal combining part in a
~.~~......... ....;llt~ station accol~i"g to the present invention,
Fig. 9 shows an ele~tric~l fli~gr~m of a rec~iver station in a point-to-
multipoint cellular television tr~n~mi~ion system according to the present invention, and
Fig. 10 sc~ l;c~lly shows an in-house receiver station according to the
present invention.
Throughout the figures the same ,~;ference mlmPral~ are used for the same
21~557
WO 95/31070 ` ~ ~ PCT/IB9~/003 13
S
features.
Fig. l schP~ ;rAlly shows a point-to-multipoint cellular television
5 tr~ncmicsion system 1 accoldil~g to the present invention. The cellular system 1 is configured
as a plurality of cells C1, C2, C3, C4, C5, and C6. The cells are arljarpnt to at least one
other cell of the cellular system 1. The cells may have dir~Gnt ~im~oncions. The cell C6 is
also shown in an enlarged view, in~iirAtp~d with C6'. The cellular system 1, in which
television signals, radio signals, t~-lo.phone signals, and data signals are tr~n.cmitt~ inter alia,
10 either in analog or digital form, inrll~des trAn.cmittPr stations T1, T2, T3, T4, T5, and T6
which are located at a circumference of the cells Cl, C2, C3, C4, C5, and C6"es~ ively.
The tr~ncmittPr stations Tl to T6 are each provided one ~-~n~...i~l;n,~ ~ntP.~n~ TAl, TA2,
TA3, TA4, TAS, and TA6, r~s~ ely, which can be a complexity of radiators. For
...ini...i,;.~g inter-station h LelrcIcnce, preferably the trancmittin~ Ant~ennAc TAl to TA6
15 genPr~lly L,dns"~iL along a main geogldphical axis ax, in the given example all generally in
the same direction dl. The trancmittçr stations Tl to T6 l~ relatively low-power
microwave signals, plcr~.bly in the 27.5 to 29.5 GHz range or 40.5 to 42.5 GHz range.
The tr~ncmitter stations Tl to T6 l~ ";~ at least in part, the same television signals, or
other signals. ]:n this respect a cell may cover a community, each cull~ y having its own
20 dem~n~. As w;ll be dP-scribed in the sequel, typically each trAncmittp-r station ~Idns~"ils a
nu~bcr of dirr~l~nt signals. A part of these signals can be be public television signals, and
other signals can be private signals, collc~nding to specific services requested by the
community. The trAncmitter stations may be coupled to public trAncmitt~Pr stations by
landlines or by other means such as wireless links, for getting public television signals, and
25 may be coupled to service providers to get private signals and services. Such a provision of
signals to the tran.cmittPr stations Tl to T6 is known per se, and is not shown in detail here.
Low-power trancmi.c.cion ~ ~ distinguishes the system 1 over eYi.cting public television
broadç~cting systems. For a general desel;~lion of non-cellular prior low-power television
systems, referred is to the article "Low-power television - Short-range, low-cost TV stations
30 are in the offing as the PCC plG~ GS to establish broadcast lG~luilG",ents", IEEE s~ecllulll,
pp. 54-59, June 1982. The system 1 further in~ des a plurality of receiver stations Rl, R2,
R3, R4, and R5, comprising directional ~nte~ AC RAl, RA2, RA3, RA4, and RA5,
~c~ ;Li~ely, for receiving a television signal from one of the tr~ncmitter stations. For a more
det~ilçd desc,i~lion of a co...~ icAtion bG~wGen a L1An~ station and a receiver station,
WO 95/31070 2 ~ 6 6 5 5 7 PCT/IB9S/00313
the enlarged cell C6' is shown, which inrlud~ps receiver stations R6 and R7, having receiving
~ntPnn~c RA6, and RA7, ~ ely. Typically, there may be thousands of receiver stations
in the cell C6', serviced by the tr~ncmitt~Pr station T6. Typically, the tr~nCmittPr station T6
may l.i n~...;l 32 ch~nnPlc in p~r~ P.l, The !~ ntenn~ TA6, which is pocitionPJ at a
S Ci~iu,l,Ç~ ce CF of the cell C6', covers the cell C6', which typically has a ~ mPtPr of a
few tens of kilo",~ ~. To this end the ~ntenn~ TA6 can be a complexity of 64 horn
r~ tors In order to obtain a more co n~ e system coverage, ~e cells Cl to C6 partly
overlap each other. The receiver ~ntenn~c RA6 and RA7, which are ~nl~nn~c with a few
degrees ~ntenn~ d~lUl~, are d~d to the tr~ncmitt~pr station T6, so as to form a line-of-
10 sight tr~ncmiccion link. Antenna apellu-e angles Al and A2 of the ~nl~.nn~c TA6 and RA6,
l~.~;Li~/ely, are shown in Fig. 1. Frequence re-use in the cellular system 1 may be based on
e A~lin~elltal measule,.,ent values in a given geo~;ld~)hical area or may be based on estim~tps
using system mod~Phc, e.g. a model based on protection ratio, a model based on in~lrt;,c;r
below noise, or a model based on a radio horizon, these models not being shown in detail. A
15 simple model is the radio horizon based model in which the radio horizon is simply
determined by the l~ .";l height and the receive height and the curvature of the earth. A
protection ratio based model for analogue FM television may be in accor~ance with a model
~luposed by Harverson etc al., ~Required Protection Ratios for Co-Frequency PAL", Int.
Journal of S~tPllite Co.. ln;r~tion~ Vol. 9, 1991, pp. 381-389, for a 16 MHz/V devition as
20 l~....,-Pn-l~Pci in MPT 1550, a Standard for Analogue MVDS (Multipoint Video Disl.il,uLion
Systems) op~.i.l;ng in the frequency band 40.5 to 42.5 GHz. Harverson et al. give Cl.~nn
to-inlelrc;l~.lce ratios for a desired picture grade. For a better in~lrerellce protection, the
40.5 to 42.5 GHz microwave band may be split in two frequency sets. In addition to
alLell,ali.lg hn~ l and vertical pol~ri7~tion, either on a cell-by-cell basis or on a chalmel
25 by-ch~nn~Pl basis within a cell, inlell~ ing of the two rr~ueil~ sets will then give a better
ill~,Ç~r~.lce ~ lion.
Fig. 2 sC.h~..";.l;r~lly shows geo~ -phi~l details in the cell Cl of the
point-to-multipoint cellular television system 1 according to the present invention. In the cell
1, obstacles may upset line-of-sight co~ ;r~tion beLweell the tr~n~mittrr station Tl and
30 the receiver stations within the cell Cl. In the example given, a hill H upsets line-of-sight
c~-.----nnir~tion bc;l~n the n~ e- station Tl and the receiver stations Rl and R2, the
hill H giving rise to a large signal shadow as to the t-,-.~ station Tl. To cover the
receiver stations Rl and R2 in the large radio shadow, an auxiliary station in the form of a
r~_~eat~ l station RS, which comprises directional antennas RSAl and RSA2, is positioned on
wo ss/3l07~ 2 1 6 6 5 5 7 PCT~395/00313
top of the hill H for relaying signals between the trAncmittPr station Tl and the receiver
stations Rl and R2, and vice versa, as the case may be. ~ltPrnAtively, an A~iAition~
trAncmittPr station TA7 may be provided for covering the large radio shadow. TheI~An~ ;L~ station T7, which covers a sub-cell Cla, IIAI1~ in a direction d2 of the main
S geQglAphirAl axis ax, opposite to the direction dl. Subs~;libela Sl and S2 are positioned in a
- small signal shadow of a high building B. For establishing a comm--nicAtion between the
tr~ncmittPr sta*on Tl and the subscribers Sl and S2, a receiver R8, provided with a
directionAl AntennA RA8 dilGcled to the trAncmit*nP AnlenllA TAl, is placed in the building
B. The radio station R8 is shared by the subscribers Sl and S2 by cabling.
Fig. 3 shows positioning of fr~ncmitt~r sta*ons T8, T9, T10, and Tl1 in
a first cell configuration acco~ing to the present invention. The t~Ar.~ le~ stations T8 to
Tll are located at cil.;u,l,fe.~nces of cells C8, C9, C10, Cll, and Clla, ~ecLi~ely. With
arrows ar8, ar9, arlO, arll, and arlla, lci.l,eeLi~ely, main tr~ncmitting directions of the
tr~ncmittPr st~tions are in-lirAtP~, the trAncmittPr stations T8 and T10 genPr~lly trAncmittinP
15 along a first geogld~hical axis axl of the system 1, and the trAn~ e~ sta*ons T9, Tll, and
Tlla generally l-An~-..iLI;ng along a second geo~;-~hical axis ax2 of the system 1.
T-A.-c.niLIil-g Ant~nllAc of the LlA~ sta*ons T8 to Tll, and Tlla are positioned at
suitable locations along the ci- ;ul"relence of the cells C8 to Cll, i.e. generally on top of
high b~ 1invc so that a clear line of sight is g.~A.Ant~ for the majority of aubs,~;b~a
serviced by tlle LIA~.s~ st~tionC The programs or services offered by the !-Ar~
stations T8 to Tl 1 may vary per tr~ncmittP- station. Such a configuration can be applied in a
hilly terrain ht, in the given example to the right of a coActline cl to the left of which a sea
se eYtPn~lC The pocitionin, of the nAi~C.,.;l~Pr stations T8 to Tll, and Tlla, as de~ ;h
conl~iLuLes to intelrGlGnce free reception by the receiving stations co~,el~ h~lc~illl.
Fig. 4 shows positioning of tr~ncmittPr stations T12 to Tl9 in a second
cell configuration according to the present invention. The 1~ ~ncn~ stations T12 to Tl9 are
located at circumferences of cells C12 to Cl9, resl)ec~ ely. With arrows arl2 to arl9,
~e.iLi~ely, main Ll~-~s---;ll;-~g directions of the tr~ncmittPr stations are inf~ t~d~ the
tr~ncmittPr stations T12, T13, T16, and T17 generally tr~ncmitting along the first
geo~.dl)hical axis axl of the system 1, and the n,.~ lll;LI~ stations TT14, T15, T18, and Tl9
gen~Pr~lly 1- .n~...;ll;ng along the second geogldl~hical axis ax2. T1An-~---;II;ng ~nte~n~c of the
n~...;LIte~ stations T12 to Tl9 are positioned at suitable locations along the circumference of
the cells C12 to Cl9, i.e. generally on top of high buildings so that a clear line of sight is
...n~ for the majority of subscribers serviced by the tr~ncmitter stations T12 to Tl9.
WO 95/31070 21 6 G 5 ~ 7 PCT/IB95/00313
The pn~g~ ls or services offered by the tr~n~mitttor stations T12 to Tl9 may vary per
l.,.nc~ r station. Such a configuration can be applied in a flat terrain ft. The positioning of
the ~ lll;llrl stations T12 to Tl9, as described, contributes to h~lGlrGrGmce free reception by
t`he receiving stations covered he.Gwilll.
S Fig. 5 shows positioning of ra~liatr)rs TAla, TAlb, .. , TAli in a
tc~ station casing cs according to the present invention, which is placed outdoors.
The complexity of radiators TAla, TAlb, ..., TAli form the tran~mitting ant~nna TAl. A
part of the tr~nsmitter station's electronics, scl-~...; ~;r~lly shown by a box bx, is put into the
casing cs. One casing cs may comprise nine l.,.r,.~"~;ll;"g ch~nnPl~, with one radiator per
10 ch~nn~ Eight tr~nSmitting cllannPl~ are used ~imnlt~neously~ whereas a ninth channel is a
spare ch~nne] which can be used if a chann~l fails. In the given example, the nine ra-liator~
TAla, TAlb, ..., TAli are intc..ll;ll.~ ly hori7Ontally and vertically polarized from top to
bottom of the casing cs so as to achieve polari7~tinn diversity within a cell. This intermittent
polari7~tion is achieved by rot~ti~ s ally displacing the radiators with respect to each other by
15 90 with respect to a fixed construction~l feature of the ant~onn~ TAl. In Fig. 5, 90 rotation
of the radiators with respect to each other is sc~ ;r~lly intiir~tPd with 90 rotated horn
radiators, which have an a~llu~ angle of 64, so as to cover a cell. With respect to
pGl~. ;, .~;nn the radiators are adjustably mounted within the casing cs (IlleçhAnirAl adj
details are not shown in detail, but can be any suitable adju~tm~nt means from the
20 ..,~hAnir~l art). The r~ tnr~ can thus be vertically or hol;~n~ .lly polqri7P~l. Also,
",~ ir~lly, the same l,.r~ , can be applied, ...ounl~:l in the same way, hol;~ol,tal or
vertical pol~i;cation being achieved by a dirrel~nt wave guide eYciting mode, known per se.
In a manner known per se, the radiators can also be circularly pol~ri7~cl, either to the left or
to the right. Typically four casings cs are mounted in one tr~n~mittlor station Tl, thus
25 s.~ ling 32 active chann~l~, and 4 spare chann~l~ The ant~nna TAl thus typically is
forrned by a co",pleAily of 36 radiators. In Fig. 5, the radiators TAla, TAlb, ..., TAli are
all shown to point into the same direction d, for all tran~mi~r casings in the cell. For
achieving some kind of prog~ l diversity within a cell, radiators of groups of channtol~ may
be di-e.:led to dirre e,lt sectors of the cell. The radiators then have a smaller a~ ~ulc angle
30 than 64.
Fig. 6 shows an el~triçal ~ gram of the tr~n~mitter stations Tl to Tl9
according to the present invention, showing clec~nics distributed over outdoor units as
decrrihed in Fig. S and indoor units coupled to outdoor units by cabling, the trAncmitter
stations Tl to Tl9 1~;1n~...;ll;ng in the 40.5-42.5 GHz microwave band. Trancmicci~n channel
WO 95/31070 2 1 6 6 ~ ~ 7 PCT/IB95/00313
9
chl to chn cornprise IF (IntermeAi~te Frequency) exciters IFl to IFn, n being an integer. The
IF-exciters IF1 to IFn provide 1.5-1.83 GHz intermeAi~te signals, to be up-converted to said
microwave band. Preferably, the 1.5-1.83 GHz signals are obtained by up conversion in two
steps, a first mod~ tion step to 479.75 MHz using modlll~tion means known per se for
5 mo~ul~tion of video, audio or data signals, 479.75 MHz being an official intermP~i~te
Lequency in s~tellit~P receivers, and a second up conversion step to a 1.5-1.83 GHz wave
band in which the tr~ncmiccion c-h~nnPl is adjustable. F~c~luency adjuctment signals fal to fan
are applied by a system m~n~gPr unit SMU to the IF-exciters I~;1 to IFn so as to CG ~lete~y
inde~..~ ly adjust the çh~nnPlc chl to chn within said microwave band. The system
10 manager unit SMU can be a ~onal co,l",l~ler of known type being provided with I/O
(input/output) cards for digital and/or analog signals and being coupled to a keyboard/display
unit VDU. Valious signals to be tr~ncmitt-P~l are fed to the IF-exciters IFl to IFn, such as
video signals vsl to vsn, and audio signals asl to asn, or, alternative data signals. The IF-
exciters IF1 to IFn are coupled to 13 GHz up converters UC1 to UCn, lcs~ ively, i.e. X-
15 band converters. The up converters UCl to UCn comprise mixers 601 to 60n, band passfilters 611 to 61n, and ~mplifiPrc 621 to 62n. The mixers 601 to 60n are coupled to a 12
GHz synthPci7~/nine-way power splitter unit SYNT. The adj-lctmPnt signals fal to fan can
be supplied by the system m~n~gPr unit SMU, can be provided by thumb-wheel s~vilches (not
shown), or can be t~ ;c signals. The up converters UCI to UCn are coupled to
20 frequency tripler units FTUl to FTUn, which can be varactor diodes suitable for opeldting in
said 40.5-42.5 GHz wave band. Outputs of the frequency tripler units are coupled to
ecli~re radiators TA11 to TAln, the complexity of radiators TAll to TAln forming the
n~.nna TAl. The system manager unit SMU is programmed to monitor various
signals of the cl-~nnPlc chl to chn, such as signals val to van of the varactors FIIJl to
25 FTUn, ~ ~nL~ of the ~mplifiers 621 to 62n, or the like. In this way the system ~ n~er
unit SMU can dc;l~ ine a defect ~h~nne.l and switch over to a spare ch~nnPl The system
system manager SMU is further plog.~...-n~d to switch over a given program or signal to be
t~ncmittPli from one ch~nnPI to another ch~nnpl~ to switch on/off a ~ g ch~nn~l~ to
CO~ nlmit`~t~P with local service suppliers or with public pfog,dm suppliers (not shown) for
30 getting a variety of ~lOgldll~S and/or services.
Fig. 7 shows a part of the IF-exciter IFl according to the present
invention, to which said 479.75 MHz signal is fed. The choice of this first inLl...P~ P
frequency has the advantage that for suc~cive filtering cheap SAW (Surface Acoustic
Wave) filters can be applied. Said part comI)rices an amplifier 71, a SAW-filter 72, an
WO 9~/31070 2 1 6 ~ 5 5 7 PCT/IB95/00313
amplifiPr 73, a mixer 74, an amplifier 75, and a band pass fi ter 76 at an output of which
said 1.5-1.83 GHz band signal is provided. An input of the mixer 74 is coupled to an
fi~ue-l~ adjustable channel synthPci7Pr CSYN.
Fig. 8 shows an electric~ gram of a signal combining part in a
5 I.,.nc...il~er station acc~l.ling to the present invention, which is a part of the IF-exciter IFl.
In ~irliti~n to the video signal vsl, audio signals asll, asl2, and asl3 are provided to the
co,--l)ining part. Alt~Prn~tively, q~ tllre data signals I and Q can be provided to the
comhining part, the data signals having a bit-ste between 0-40 M-hitls. The video signal vsl
is ~.ucessed in a way known per se, in a first analog l,-vce~ g block 80 amplication and
10 filtPring being done, and in a second analog processing block clal--pil g and pre-emphasis and
being done inter alia. Various audio signals can be FM modlllatPA onto an auxiliary carrier,
such as the audio signals asll and asl2, which are FM-mod~ tPd by means of FM-
modulat~ rs 82 and 83. Also a digital audio signal can be provided for, such as the digital
audio signal asl3 modlll~tP~l by means of a so-called NICAM-modulator 84 (Near
15 T~ .-t~nçQus Comp~nd~P~d Audio Modlll~tis)n). At least one of the audio signals asll, asl2,
and asl3, and the video signal vsl are combined in a combining unit 85 of which an output
signal is fed to an adding unit 86. Also an output signal from a PLL (Phase Locked Loop)
low pass filter 87 is ~u~l)lied to the adding unit 86. An output signal of the adding unit 86 is
coupled to a VCO (Voltage Controlled Oscillator) 88 so as to obtain a modlll~tP~ audi/video
20 signal at 479.75 MHz. To this end, also a phase ~etP~tc-r 89 is provided, of which inputs are
col-rl-~ to an output of the VCO 88 and a crystal osçill~tQr 90. Alternatively, for the sake of
- data tran~mi~ion, the I and Q data signals are provided to a QPSK-mo~ tor (Qua-ir~tllre
- Phase Shift Keying) 91, an input of which is coupled to a 70 MHz oscill~t-~r 92. An output
of the QPSK-modlll~tor 91 is coupled to an input of a mixer 93 of which a further input is
25 coupled to a 409.75 MHz osçillat-~r 94 so as to obtain a 479.75 MHz ii~ PA;~IP data signal
which is fed to an ~mplifiPr 95. Alternatively, an 479.75 MHz audio/video signal or a
479.75 data signal, being output signals of the VCO 88 or the amplifier 95 are fed to an high
frequency switch 96.
Fig. 9 shows an el~t iC~l diagram of receiver stations Rl to R8 in the
30 point-to-multipoint cellular television tr~n-~mi~ion system 1 according to the present
invention. The receiver station Rl comprises the directional ~ntenn~ RAl having an a~llu,e
angle of a fwe degrees. A received signal is filtered by means of an image rejection filter
100, and thereafter fed to a mixer 101 to which also a local osçill~t~r signal is fed from a
local osc~ tor 102 gç~ ;,-g a 9.5 GHz signal, when receiving a low band signal in the
WO 9S/31070 2 1 ~ 6 5 5 7 PCT/IB95/00313
11
40.5~1.5 GH~ wave band and gG~ dLing a 9.833 GHz signal when receiving a high band
signal in the 41.5-42.5 GHz wave band. An output signal of the osçill~tor 102 is first
-Amplified by rneans of an Amplifi~r 103, and then tripled by means of a frequency tripler 104
using a varactor diode, before being fed to the mixer 101. An output signal of the mixer 101
S is fed to a standard Low Noise Converter 105, such as applied for SAt~llite TV. Such a Low
Noise Converter can be a Philips type SC 813/15 which is available on the market. By using
a standard low noise converter, costs are reduced and the noise figure of the overall receiver
is improved. The LNC 105 compri~s an amplifier 106, a mixer 107, and an ~Amplifier 108
of which an output provides a 950-2000 MHz signal which is fed to a standard domestic
10 indoor unit as used for ~Atellite reception (not shown). To the mixer 107 a signal from a
local oscillAtor 109 if fed via an AmplifiPr 110. For a more detailed descripdon of the
receiver R1 referred is to a Patent ApplicAtion of the same Applicant, No.. (PHN ... ).
The receiver station R1 can have adjustable attenuating means for Alle~ AI;llg the received
signal, so as to adapt the receiver station R1 to a variable ~ Ai~ce to the trAn~mitt~r stadon
15 Tl in a cell. Such an adju~l...f- ~ can be done with in~tAlAtion of the receiver station R1. The
adjustable Atl~ AIor means can be an A~ (not shown), coupled to the dire
receiving Antelm~ RA1.
Fig. 10 SC11~IIAI;CA11Y shows an in-house receiver station R1 acco-ding to
the present invention. In COnIIA~I to the outdoor/indoor receiver stadon R1 as described in
20 Fig. 9, the receiver station Rl can be an entirely indoor station to be placed behind a
window of a building, or the like. Then, the receiver station Rl may be comprised in a
casing csr on top of which a parabolic mirror mir is mounted, as an ~nt~nnA, which can
simply be an alu...;nh.... mirror. A received signal rsg is ~rn~;~ed by the parabolic mirror
mir via an al~e,lul~ ap to a converter con as described in Fig. 9. Via a sAtellite receiver like
25 unit sat, which is coupled to the converter con, standard TV signals are fed to a TV receiver
(not shown).
