AU631608B2

AU631608B2 - System for distributing broadband signals over a branched coaxial cable network

Info

Publication number: AU631608B2
Application number: AU51135/90A
Authority: AU
Inventors: Richard Albert; Josef Doemer
Original assignee: Siemens AG
Current assignee: Kathrein SE; Siemens AG
Priority date: 1989-03-08
Filing date: 1990-03-07
Publication date: 1992-12-03
Anticipated expiration: 2010-03-07
Also published as: NO901061L; NO178130C; EP0386635B1; EP0386635A3; EP0386635A2; DE3907524A1; ATE127980T1; DK0386635T3; NO901061D0; DE59009641D1; AU5113590A; NO178130B

Abstract

A device for distributing broadband signals via a branched coaxial cable network containing several network levels, comprising broadband amplifiers, with amplifier points containing auxiliary devices and with passive arrangements for signal distribution. To increase the transmission capacity, an optical waveguide network is provided in addition to the coaxial cable network, the ends of which are connected via opto-electrical transducers to output amplifiers of the coaxial cable network. The device can be advantageously used for distributing television and/or radio programmes. <IMAGE>

Description

S F Ref: 122030 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class So o o o o 0 S 000 O tf 1 o ao Complete Specification Lodged: Accepted: Published: Pricrity: Related Art: Name and Address of Applicant: itio ea o i 0 0000 Siemens Aktiengesellschaft Wittelsbacherplatz 2 D-8000 Munich 2 FEDERAL REPUBLIC OF GERMANY Kathrein Werke KG 5241 Rosenheim FEDERAL REPUBLIC OF GERMANY Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Address for Service: Complete Specification for the invention entitled: System for Distributing Broadband Signals over a Branched Coaxial Cable Network The following statement is a full description of this invention, including the best method of performing it known to me/us 5845/3 1 Y r I I 1 89 P 8012 DE Abstr.ct System for distributing broadband signals over a branched coaxial cable network System for distributing broadband signals over a branched coaxial cable network containing a plurality of network levels, having broadband amplifiers, having repeater stations containing auxiliary equipment and having passive arrangements for signal distribution. To o increase the transmission capacity, there is provided in 00 addition to the coaxial cable network an optical fibre o network, the ends of which are connected via optoelectrio° o cal transducers to output amplifiers of the coaxial cable o network. The system may be used advantageously for o o0 distributing television and/or radio programmes.

FIG.1 oo 0 o o o o 00 00 0o 0 0oo o Go0 Y I 1 r a I Irrrra 89 P 8012 DE 1A Kathrein Werke KG Siemens Aktiengesellschaft System for distributing broadband signals over a branched coaxial cable network.

The invention relates to a system as stated in the preamble of Patent Claim 1 for distributing broadband signals over a branched coaxial cable network.

A system for distributing broadband signals over o 00 a branched coaxial cable network containing a plurality 00010 of network levels and provided with broadband amplifiers and auxiliary equipment is already known from German Auslegeschrift 2,364,061.

The known system is divided into a plurality of 0 0 Q 0 network levels. The broadband signals conditioned in a headend are distributed via feeder or distribution levels to further network levels, whose lowest network level is constituted by the subscribers. The auxiliary equipment serves for power feeding and fault location. The powerfeeding system comprises devices for inserting the feeding energy and power-separating filters for circum- 0 venting the amplifiers for the feeding current. Serving for fault location is a device for DC fault location, whose evaluation results are transmitted to a central transmitting station. In addition, code frequencies generated in the individual intermediate repeaters are sent to the power-feeding station for evaluation.

Furthermore, it is already known f rom German Offenlegungsschrift 2,346,834 that a system for power feeding is provided in a broadband cable network which is divided into a plurality of levels and is greatly branched at its spurs.

Distribution networks of the aforesaid type are designed for signal transmission within a given frequency range, which permits the transmission of a given number of television and/or radio programmes.

If the transmission capacity of the system no 2 89 P 8012 DE (1

A

010 0 0 0 CI o o 0 0 0 0 0 00 000 0 0000 0 4 0000 (*000 0 0 00 0 00 *0 longer suffices, then the system can be replaced by one having the desired increased transmission capacity.

However, this entails a -relatively large outlay, particularly when auxiliary equipment of the afort~said type is integrated in the existing system to a considerable extent.

It has emerged, however, from considerations within the framework of the invention that it is advantageous, during the desired expansion of the transmission capacity, to use the passive parts of the existing system in each case in the region of the power splitter following the last amplifier up to the interconnection point for the increased transmission capacity, and to install a supplementary optical fibre network in the 15 regions preceding this part of the system.

On the basis of these considerations, it is the object of the invention to expand a system for distributing broadband signals over a branched coaxial cable network, which provides a frequency band which is not, in 20 particular no longer, sufficient for the transmission of the broadband signals to be distributed, in such a way that it is suitable for a distribution of additional broadband signals.

In accordance with the invention, the system for achieving this object is designed in the manner stated in the characterizing part of Patent Claim 1. This results in the passive parts of the coaxial network from the power splitter following the last amplifier up to the interconnection point at the subscriber end being used jointly for both frequency bands in each case.

The advantage is conferred by the measures according to the invention that an existing system for distribuating broadband signals can be consequently expanded in a 'particularly economic manner with respect to its transmission capacity, that the existing system for broadband communication, television programme distribution or the like can continue to be used to a particularly large extent.

89P 8012 DE In the further development according to Claim 2, the ends of the optical f ibre network are situated in each casb in one of the repeater stations. One or more output amplifiers may be connected in this case to the respective end. If necessary, one or more output amplifiers can be connected via coaxial cable to a repeater station at which the optical fibre network ends.

The further development of the invention according to Claim 3 has the advantage that existing passive arrangements for signal distribution can beI retained unchanged during the expansion of an existing 00 0 0 00 coaxial cable network if the resulting increase in 0 transmission capacity suffices.

00 0 The measures according to Claim 4 have the 00000015 advantage that an existing output amplifier can continue 0 to be used, and a supplementary amplifier need only amplify the frequency band to be additionally distributed.

On the other hand, the further development 000 20 according to Claim 5 can prove to be particularly ex- 00 pedient whenever the space available in the respective temia 00etrsainadorteaalbepwr 00 0 00 00feeding capacity is not sufficient for two amplifiers. In this case, the last amplifier in the amplifier chain is designed in such a way that it jointly amplifies both 00 frequencies and feeds the passive part up to the interconnection point, in particular up to the domestic interc onnection point.

Starting from a broadband communication network using coaxial cable technology with a frequency range of from 47 M'Hz to 450 MHz, the frequency range of the broadband signals to be additionally distributed preferably has the limits stated in-Claim 6.

Advantageous' embodiments of the system, in' connection with the distribution of the additional broadband signals, emerge from Claims 7 to 9. All of these variants can be provided jointly, or only partially, in one and the same optical fibre network.

1

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-4 89 P 8012 DE 0o 0 000, 00 0 0 0 go 0 In the further development according to Claim 7, each of the optoelectrical transducers expediently feeds a power splitter. In the case of the system according to Claim 8, each of the amplifiers for the high frequency band expediently feeds, together with the low frequency band, via an electric filter, the passive part up to the interconnection point. Free amplifier outputs for the high frequency band may be connected, if necessary, to adjacent repeater stations.

The measures according to Claim 9 are advantageous when more remote repeater stations are to be fed.

According to Claim 10, an advantageous method of producing the system consists in that, in at least one of the output amplifiers of an existing coaxial cable network, an existing filter is inserted into the signal transmission paths, in the sense of a feeding of the high frequency band.

It is particularly advantageous to employ the system whenever, in connection with an existing coaxial -20 broadband communication network, additional television 0 programmes are to be distributed.

The invention will be explained in greater detail with reference to the exemplary embodiments represented in the figures, in which: Fig. 1 shows a system for distributing broadband signals over a coaxial cable network and an optical fibre network overlaid on the latter, Fig. 2 shows a coaxial cable network before being overlaid by an optical fibre network, Fig. 3 shows a repeater station with two output amplifiers, Fig. 4 shows a repeater Istation with one output amplifier,.

Fig. 5 shows a frequency diagram for a transmission of approximately 50 television programmes, and Fig. 6 shows a frequency diagram for a -transmission of approximately 70 television programmes.

The system illustrated in Figure 1 serves to 0 4 04.00 0000 o o C 00 00 .4 I C 89 P8012 DE distribute television and radio programmes. The distribution is carried out via the branched coaxial cable network 2, which contains a plurality of network levels, and the additionally provided optical fibre network The headend 1 serves for inserting the signals to be distributed into the coaxial cable network 2 and into the optical fibre network 10. If necessary, a separate headend can be provided for inserting the broadband signals to be additionally distributed.

The coaxial cable network 2 contains a number of repeater stations with broadband amplifiers for amplifying the broadband signals to be distributed. These broadband amplifiers are provided with auxiliary equipment such as is usual with systems f or distributing television signals. This auxiliary equipment is, there-I 0 "Upfore, not represented in greater detail in the drawing.

In one part of the repeater stations, the system contains electric output amplifiers 6a. The output of the output amplifier 6a is connected in each case via a passive arrangement for signal distribution to a likewise passive domestic interconnection point 9, in which all signals being distributed, or a selectable portion of the signals, are transferred to a subscriber.

The optical f ibre network contains the optical fibres 10a...l10h connected to the headend 1. The optical CV fibre network 10 ends in each case at one of the repeater stations, that is to say at the location of a broadband amplifier provided there in the coaxial cable network 2.

The ends of the optical f ibre network are in each case connected via an optoelectrical transducer 11a. 11d to one or more of the output amplifiers 6a, 6b of the coaxial cable network 2.

At the location C1 of the system, the output amplifier 6c of the coaxial cable network 2 was retained.

Its bandwidth covers only the low band of the~ two f requency bands provided. The optoelectrical transducer 11a.

is in this case connected via its own amplifier 6c to the output of the output amplifier 6a.

-6- 89 P 8012 DE 0 0, 0 00.

00 0.

0 0 0 000 00 0 0 00 At the repeater station C2, the output amplifier of the coaxial cable network 2 was replaced by the more broadband amplifier 6b, the bandwidth of which covers the two frequency bands provided. The optoelectrical transducer lib is in this case connected to one input of the output amplifier 6b.

Figure 1 shows several expedient embodiments of branching points of the optical fibre network The optical fibre 10a feeds the passive optical splitter 12, which is accommodated in one of the repeater stations, with the high frequency band. Connected to the optical splitter 12 are the terminal repeater station C2 and further terminal repeater stations, not shown. A terminal repeater station is to be understood as meaning 15 a repeater station with output amplifiers.

The optical fibre 10g leads to the optoelectrical transducer lid, which is arranged in one terminal repeater station, and to which the electric amplifier 6ci for the high frequency band is connected. This amplifier 20 6ci has three outputs, two of which are connected to in each case two further amplifiers 6c2 for the high frequency band. Two amplifier outputs 6c2 are used in their own terminal repeater station, the output of the respective amplifier for the high frequency band and the 25 respective output amplifier of the coaxial cable network 2 being connected to a common splitter via a filter. The further outputs of the amplifiers 6c1 and 6c2 are connected, for example, to terminal repeater stations of the coaxial network 2 which are not shown.

The optical fibre 10h is connected to the optoelectrical transducer lc of the terminal repeater station C4. The broadband amplifier 6c is connected to the output of the optoelectrical transducer llc. A first output of the broadband amplifier 6c is connected via the splitter 13 to the electrooptical transducers 14a...14c, the outputs of which are connected to further terminal repeater stations via in each case one of the further optical fibres 15a...15c. Connected to the optical fibre 0 100 0 00 00 0 0 00 00 0 000 -7 89 P 8012 DE is a further optical splitter. The free output of the broadband amplifier 6c and one output amplifier of the terminal repeater station C4 are expediently connected to a common splitter via a filter.

Figure 2 shows a section of a coaxial cable network to be extended. In one branch of the coaxial cable network 2, a plurality of broadband amplifiers, which may belong to a first or second network level A or B, are connected in a cascade. One of these amplifiers 3 is connected to the output amplifier 6 via an additional output. The output of said output amplifier 6 is connected to the apex of the two-way splitter/combiner 16. One of the two outputs of the two-way splitter/combiner is connected to the C splitter 7 of the C level.

The A or B broadband amplifier 3, the C amplifier 6, the 0o00 C two-way splitter/combiner 16 and the C splitter 7 form the repeater station CO/.

The C splitter 7 has a plurality of outputs which are connected to in each case a plurality of domestic o 20 interconnection points via tapping devices. The tapping device connected to one of the outputs of the C splitter 7 consists of a cascade connection of a plurality of taps 00 8.

0 Figure 3 shows the section illustrated in Figire 2 after the coaxial cable network has been extended by ~o the optical fibre network.

The C two-way splitter/combiner 16 located at the output of the C amplifier 6 is no longer connected to one of the two branches, but rather is connected with its apex to the input of the C splitter 7. One of the two branches of the C tap 16 is connected to the C amplifier 6, the other branch of the C tap 16 is connected to the additional amplifier 6c for the high frequency band.

Figure 4 shows the section illustrated in Figure 2 after the coaxial cable network has been extended by the optical fibre network. The C two-way splitter/ceobiner 16 which was originally located at the output of the C amplifier 6 according to Fig. 2, is 8 89 P 8012 DE connected with its apex to the input of the C amplifier 6b. One of the two branches of the C splitter/combiner 16 is connected to the A orB amplifier 3, the other branch of the C splitter 16 is connected to the optoelectrical transducer llb.

Figure 5 shows a first frequency diagram for the system shown in Figures 1, 3 and 4 for distributing broadband signals. In the range of 47 to 450 MHz, 24 or 26 PAL channels and 12 D2-MAC channels are accommodated for transmitting television programmes. Furthermore, a range of radio channels are additionally accommodated in this band. Moreover, services, monitoring channels and u broadband communication backward channels are transmitted 000 00 over the coaxial cable network.

oo 15 Supplementary to the aforesaid transmission bands KX of the coaxial cable network, with the aid of the overlaid optical fibre network 12 PAL channels are transmitted in the frequency range 470 to around 600 MHz of the frequency range LWLI.

20 The frequency diagram according to Figure 6 0 0 corresponds tc' that of Figure 5 with respect to the 0 C 0 frequency band KX. In deviation, approximately 35 PAL 0 00 channels are additionally transmitted over the optical fibre network. The high frequency band ranges here from 470 to 860 MHz.

0 The headend contains electrooptical transducers (not shown) which linearly convert the high frequency band correspondingly. DFB (distributed feedback) lasers with optical isolator are preferably used here. Amplitude modulation with vestigia sideband is used in particular as transmission method. PIN diode receivers are suitable as optoelectrical transducers.

Claims

1. System for distributing broadband signals con- taining- television and/or radio signals of a given frequency range over a branched coaxial cable network (2) containing a plurality of network levels, having at least one headend for inserting signals to be distributed into the coaxial cable network having broadband amplifiers and repeater stations containing at least i-n part auxiliary equipment, and having electrical output amplifiers (6a) in one part of the repeater stations, the outputs of which are connected via a passive arrangement for signal distribution 8) to passive interconnection o o points for transferring at least a portion of the signals to be distributed, characterized in that, in 0 addition to the coaxial cable network the system contains an optical fibre network (10) havi-ng at least one headend for inserting broadband signals to be additionally distributed, the ends of which a-re connected to at least one of the output amplifiers (6a, 6b) in each case via an optoelectrical1 transducer 11ld), and inI that the signals inserted into the optical fibre network cover a frequency band which, after the optical- electrical conversion, lies above the frequency band transmitted over the coaxial cable network

2. System according to Claim 1, characterized in end in one of the repeater stations.

3. System according to Claim 1 or 2, characterized in that the upper limit of the high frequency band is selected in such a way that the high frequency band can be transmitted via the passive arrangement for signal distribution and the passive interconnection points of an existing coaxial cable network.

4. System according to one of Claims 1 to 3, charac- terized in that, at at least one point of the system, the bandwidth of the output amplifier (6a) covers only the low band of the two frequency bands, and the optoelectri- cal transducer (11a) is connected via its own amplifier 89 P8012 DE (6c) to the output of the output amplifier (6a). System according to one of Claims 1 to 3, charac- -terized in that, at at least one point of the system, the bandwidth of the output amplifier (6b) covers both frequency bands, and the optoelectrical transducer (11b) is connected to one input of the output amplifier (6b).

6. System according to one of Claims 1 to 5, charac- terized in that the low frequency band covers the range from 47 MHz to 450 MHz, and the high frequency band begins at 470 MHz, and ends at a frequency which is at least approximately 600 MHz and at most approximately 860

7. System according to one of Claims 1 to 6, charac- terized in that the optical fibre network (10) contains at least one optical fibre (10a) that ends at one of the repeater stations adfeeds one passive optical splitter OG C (12) with the frequency band, and in that the outputs of the optical splitter (12) are in each case connected to an optoelectrical transducer.

8. System according to one of Claims 1 to 7, charac- terized in that the optical fibre network (10) contains at least one optoelectrical transducer (11d) fed via an optical fibre (l0g) with the high frequency band, to which tranducer a plurality of electric amplifiers (6c) for the high frequency band are connected, and that in each case one of these amplifiers (6c) and one of the output amplifiers are connected to a common splitter

9. System according to one of Claims 1 to 8, charac- terized in that a cascade connection of an optoelectrical transducer (11c), an electric amplifier (6c) for the high frequency band and a power splitter (13) is connected to at least one optical fibre (10h) of the optical fibre network and in that the outputs of the power splitter (13) are connected to in each case one electro- optical transducer (14a. 14c), the output of which is connected via at least one further optical fibre 15d) to another repeater station. 11 A system as claimed in any one of the preceding claims, wherein an existing filter of at least one of the output amplifiers serves to feed the high frequency band.

11. A system for distributing broadband signals substantially as described herein with reference to Figs. 1 to 4, or Figs. 5 or 6 of the drawings. DATED this TWENTY-FIFTH day of SEPTEMBER 1992 Siemens Aktiengesellschaft Kathrein Werke KG a ca ao o o o orr a ~o nw a o oanono o oonerro a oo oo ooo o a u o a beao o o u c~ *o ever o e uo o~rr~ a a r a a ua o a r o a Patent Attorneys for the Applicants SPRUSON FERGUSON Ki IAD/9867F