WO1998059442A1 - Systeme de distribution de frequences radio - Google Patents

Systeme de distribution de frequences radio Download PDF

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Publication number
WO1998059442A1
WO1998059442A1 PCT/IT1998/000152 IT9800152W WO9859442A1 WO 1998059442 A1 WO1998059442 A1 WO 1998059442A1 IT 9800152 W IT9800152 W IT 9800152W WO 9859442 A1 WO9859442 A1 WO 9859442A1
Authority
WO
WIPO (PCT)
Prior art keywords
communications
control unit
radio frequency
amplifying
amplifier
Prior art date
Application number
PCT/IT1998/000152
Other languages
English (en)
Inventor
Luciano Campi
Original Assignee
Infostrada S.P.A.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Infostrada S.P.A. filed Critical Infostrada S.P.A.
Priority to AU77881/98A priority Critical patent/AU7788198A/en
Publication of WO1998059442A1 publication Critical patent/WO1998059442A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/10—Small scale networks; Flat hierarchical networks
    • H04W84/14—WLL [Wireless Local Loop]; RLL [Radio Local Loop]
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W16/00—Network planning, e.g. coverage or traffic planning tools; Network deployment, e.g. resource partitioning or cells structures
    • H04W16/24—Cell structures
    • H04W16/26—Cell enhancers or enhancement, e.g. for tunnels, building shadow

Definitions

  • This invention relates to a radio frequency communication distribution system comprising a central control unit and cordless devices suitable for exchanging radio frequency communications with the central control unit in accordance with a predefined communication protocol.
  • the invention relates in particular to a system for making WWL (Wireless Local Loop) or ⁇ last-mile' type connections.
  • WWL Wireless Local Loop
  • each device for instance a portable telephone, conducts a dialogue with a central control unit, or DECT cell, at radio frequency by means of antennas .
  • DECT cell central control unit
  • each DECT cell has its antennas located at the top of buildings or similar structures in order to "cover" a sufficiently wide surface area, about 1.5 Km, and accordingly communicate with the largest possible number of portable telephones present in the surrounding area.
  • the WWL type connections are therefore effective only if the portable telephone is used outside the buildings; if the telephone is brought into a building, whether an office, the home, or other, the connection becomes precarious or is dropped, because the radio signals of the DECT cell and of the telephone are attenuated by the walls of the building to a greater extent than is permissible for assurance of the link. Disclosure of the Invention
  • the technical problem that this invention intends to solve is that of making WWL connections between a central control unit or DECT cell and portable devices brought inside buildings effective. It is also an object of this invention to provide a solution to the technical problem described above that permits the use of infrastructures already present in the buildings, such as for example telephone and television leads, without requiring the setting up of new and surely more expensive infrastructure in the buildings.
  • the radio frequency communication distribution system characterized by converting means between the central control unit and the cordless devices for converting the radio frequency communications to intermediate frequency communications and for converting again the intermediate frequency communications to radio frequency communications.
  • the radio frequency communication distribution system also comprises an innovative amplifier module capable of avoiding the so-called feedback effect.
  • the two monodirectional channels that constitute a bidirectional connection are separated in time; accordingly, the time frame comprises a sequence of two time periods, the first of which, Tx, of roughly 5 msec, associated with one direction of transmission and the other, Rx, of the same duration, associated with the opposite direction and with a stand-by time of roughly 51 ⁇ sec for the inversion from transmitter to receiver and vice versa.
  • Tx Time Division Duplex
  • Rx Receiver
  • the solution described herein envisages use of an amplifier which, for the whole time Tx, is used in the Transmitter (T) to Receiver (R) direction and, for the time Rx, in the R to T direction.
  • the inversion is controlled by a Pilot Circuit equipped with a simplified receiving station capable of: permanently receiving, synchronising with the signal received in order to recognise the times at which to invert from receiver to transmitter and vice versa, and outputting the piloting signal in the form of a clock period synchronised with the alternation of the semi- periods relative to transmissions in one direction and then in the other.
  • Fig. 1 is an example of the architecture of the system according to the invention.
  • Fig. 2 is a block diagram of the outdoor device of the system of Fig. 1; and Fig. 3 is a block diagram of the indoor device of the system of Fig. 1. Best mode for Carrying Out the Invention
  • the system 10 for the distribution of radio frequency communications comprises a central control unit 11 suitable for exchanging radio frequency communications with portable devices 14, for example telephones, present in a predetermined field of action of the central control unit 11.
  • the central control unit 11 comprises one or more antennas 12, generally situated on the top of a building, and consists for example of the radio base station described in the patent application N. TO97A000090 filed on 5 th February 1997 by the Applicant.
  • the system 10 also comprises, as essential elements of the present invention, an outdoor device 21, suitable both for exchanging radio frequency communications with the central control unit 11 and for translating these communications to an intermediate frequency, and indoor devices 31, suitable both for translating the communications from the intermediate frequency to radio frequency and for exchanging the radio frequency communications with the portable devices 14 brought into a building.
  • an outdoor device 21 suitable both for exchanging radio frequency communications with the central control unit 11 and for translating these communications to an intermediate frequency
  • indoor devices 31 suitable both for translating the communications from the intermediate frequency to radio frequency and for exchanging the radio frequency communications with the portable devices 14 brought into a building.
  • the outdoor device 21 comprises one or more antennas 22, for the exchange of communications with the central control unit 11, a first and a second antenna jack 25 and 27 (fig. 1 and fig. 2) and is situated in the vicinity of a television control unit 45 and relative TV antenna 43 of a known type centralised television installation 40, transmitting Intermediate Frequency (IF) television signals to apartment television sets 46.
  • IF Intermediate Frequency
  • the outdoor device 21 is connected, through the first antenna jack 25 and a first antenna cable 26, to the television control unit 45 or to the TV antenna 43, and through the second antenna jack 27 and a second antenna cable 28 to antenna down-leads 48 of the centralised TV installation 40 and is suitable for exchanging communications between the central control unit 11 and the centralised TV installation 40, as will be described later in detail.
  • the first and the second antenna cable 26 and 28, of known type, are for example common coax cables carrying television signals.
  • the outdoor device 21 also comprises a first bidirectional pass-band (PB) filter 23 connected to the antenna 22, a bidirectional radio frequency amplification module (RF amplifier) 50, a bidirectional band translation module
  • the first PB filter 23 is suitable for filtering noise out of the RF signals coming to the antenna 22 from the central control unit 11.
  • the RF amplifier 50 a further characteristic element of the present invention, has two input/output (I/O) ports and is suitable for amplifying the RF signals received or to be sent with the antenna 22, avoiding the above mentioned feedback effect.
  • the RF amplifier 50 comprises a directional coupler 59, having a total of four ports, two I/O ports, one connected to the PB filter 23 and the other to a first electronic switch 55, and two output-only ports respectively connected to an automatic gain control (AGC) circuit 54 and to a switching logic 57.
  • AGC automatic gain control
  • the RF amplifier 50 also comprises a second electronic switch 56, a first monodirectional band amplifier (Tx amplifier) 52, for amplifying the signals to be transmitted, connected to the first electronic switch 55, a potentiometer 53, connected to the Tx amplifier 52 and to the second electronic switch 56, and a second band amplifier (Rx amplifier) 51, for amplifying the signals received, connected between the first and the second electronic switch, 55 and 56 respectively.
  • Tx amplifier monodirectional band amplifier
  • Rx amplifier second band amplifier
  • the known type directional coupler 59 is suitable for allowing signals to pass in the two directions between the PB filter 23 and the electronic switch 55 and for extracting part of the signals that pass and transmitting them to the AGC circuit 54 and to the switching logic 57.
  • the electronic switches 55 and 56 are selectively and alternatively connectable to the Rx amplifier 51 and to the Tx amplifier 52 in such a way that only one at a time of the two amplifiers 51 and 52 amplifies respectively the signals received from the antenna 22 or the signals to be transmitted through the antenna 22.
  • the potentiometer 53 is suitable for adjusting the amplification level of the Tx amplifier 52 so that the output level of the antenna 22 is within the design limits and is controlled by the AGC circuit 54.
  • the known type switching logic 57 comprises a bistable switch which, in relation to the signals extracted by the directional coupler 59, is suitable for commanding, by means of a control circuit A, both the switches 55 and 56 to switch in times less than or equal to the stand-by time between two consecutive semi-periods, Rx and Tx respectively, and the Rx amplifier 51 or the Tx amplifier 52 to amplify respectively the signals received or those to be transmitted.
  • the known type band translator 60 comprises a frequency mixer circuit 61, a local oscillator (LO) 62, connected to the mixer 61 and suitable for generating a predefined frequency, for example a frequency of 1728 Mhz, and two pass-band filters (PB) , respectively a bidirectional PB filter for RF (RF filter) 65 and a bidirectional PB filter for IF (IF filter) 66.
  • LO local oscillator
  • PB pass-band filters
  • the mixer 61 has an I/O port connected to the RF filter 65 and a second I/O port connected to the IF filter 66 and is suitable for combining the band input by the two ports with the frequency of the LO 62 to produce a new band translated from RF to IF in one direction and from IF to RF in the other direction.
  • the RF filter 65 is connected to the switch 56 of the RF amplifier 50 and is suitable for letting pass to the RF amplifier 50 only the RF band desired, for example a band of 20 Mhz around the 2 Ghz mark, typical of DECT connections .
  • the IF filter 66 is suitable for letting pass to the IF amplifier 70 only the IF band desired, for example a band of about 20 Mhz in the range between 260 and 280 Mhz. Characteristics and structure of the IF amplifier 70 are similar to those of the RF amplifier 50, that is to say it is suitable for amplifying signals, in this case, the IF signals avoiding the feedback effect.
  • the IF amplifier 70 comprises a first and a second electronic switch, 75 and 76 respectively, a first monodirectional band amplifier (Rx amplifier) 71 for amplifying the band of signals received and a second monodirectional band amplifier (Tx amplifier) 72 for amplifying the band of signals to be transmitted.
  • the first electronic switch 75 has an I/O port connected to the IF filter 66 and is selectively and alternatively connectable to the Rx amplifier 71 or to the Tx amplifier 72.
  • the second electronic switch 76 has an I/O port connected to the PB filter 24 and is selectively and alternatively connectable to the Rx amplifier 71 or to the Tx amplifier 72 in sync with the first electronic switch 75. Commutation of the electronic switches 75 and 76 and activation of the Rx and Tx amplifiers 71 and 72 is commanded by the switching logic 57 through the control circuit A, in the same way as described for the RF amplifier 50 so that the bands of signals received and to be transmitted are amplified alternatively.
  • the known type bidirectional coupler 29 is connected to the PB filter 24 and is suitable both for picking up the signals coming from the indoor devices 31 through the antenna down-lead 48 of the centralised installation 40, as will be described later in detail, and for transferring to the antenna down-lead 48 the IF signals coming from the IF amplifier 70.
  • the known type PB filter 24 is suitable for filtering the band of signals passing through the centralised installation 40 so that only the IF band corresponding to the signals to be transmitted with the antenna 22 and coming from the indoor devices 31 is transferred to the IF amplifier 70, as will be described later in detail.
  • the indoor device 31 (Fig. 1 and Fig. 3) is suitable for exchanging communications between the portable devices 14 present inside the building and the centralised TV installation 40 and comprises an antenna 32 for the exchange of the communications with the portable devices 14 present inside the building, a first antenna jack 35 suitable for connection to the TV set 46, by means of a known type television cable 36, and a second antenna jack 37 suitable for connection to an apartment television socket 41 by means of a known type antenna cable 38.
  • the indoor device 31 also comprises a bidirectional coupler 39 placed between the first and the second antenna jacks, 35 and 37 respectively, a bidirectional IF pass-band filter
  • PB filter 34 connected to the bidirectional coupler 39, a bidirectional IF amplifier module (IF amplifier) 80 and a bidirectional band translator module 90.
  • the known type bidirectional coupler 39 is suitable both for picking up the IF signals coming from the antenna downlead 48 through the antenna jack 37 and for transferring to the antenna down-lead 48 the signals coming through the PB filter 34.
  • the PB filter 34 is suitable for letting pass to the IF amplifier 80 only the IF band desired, for example the band of about 20 Mhz in the range between 260 and 280 Mhz.
  • the IF amplifier 80 which is of similar structure and characteristics to those already described for the IF amplifier 70 of the outdoor device 21, is suitable for amplifying the signals received and to be transmitted avoiding the feedback effect and comprises a directional coupler 89, having a total of three ports, two of which I/O ports, one connected to the antenna 32 and the other to a first bidirectional radio frequency pass-band filter (RF filter) 95 of the band translator 90, and the other an output-only port connected to a switching logic 87.
  • RF filter radio frequency pass-band filter
  • the IF amplifier 80 also comprises a first electronic switch 85, a first monodirectional band amplifier (Rx amplifier) 81, for amplifying the signals received, connected to the first electronic switch 85 and to a second electronic switch 86, a second band amplifier (Tx amplifier) 82, for amplifying the signals to be transmitted, connected between the first and the second electronic switch, 85 and 86 respectively.
  • the known type directional coupler 89 is suitable for allowing the signals between the PB filter 95 and the antenna 32 to pass in the two directions and for extracting part of the signals passing and transmitting them to the switching logic 87.
  • the electronic switches 85 and 86 are selectively and alternatively connectable to the Rx amplifier 81 and to the Tx amplifier 82 so that only one of the two amplifiers 81 and 82 is on at a time, for a determined period of time, and amplifies the signals received through the centralised TV installation or the signals to be transmitted by way of the same installation 40.
  • the known type switching logic 87 consists of a bistable switch which, in relation to the signals extracted by the directional coupler 89, is suitable for commanding through a control circuit B both the switches 85 and 86 to switch in times less than the stand-by time between two consecutive semi-periods, respectively Rx and Tx, and the Rx amplifier 81 or the Tx amplifier 82 to amplify respectively the signals received and those to be transmitted.
  • the known type band translator 90 comprises a frequency mixer circuit 91, a local oscillator (LO) 92, connected to the mixer 91 and suitable for generating a predefined frequency, for example the frequency of 1728 Mhz, and two pass-band filters, respectively a bidirectional PB filter for RF (RF filter) 95 and a bidirectional PB filter for IF (IF filter) 96.
  • LO local oscillator
  • the mixer 91 has an I/O port connected to the RF filter 95 and a second I/O port connected to the IF filter 96 and is suitable for combining the band input from the two ports with the frequency of the LO 92 to produce a new band translated from RF to IF in one direction and from IF to RF in the other direction.
  • the RF filter 95 is connected to the directional coupler 89 and is suitable for letting pass to the antenna 32 the band of signals received, for example the band of 20 Mhz around the 2 Ghz mark, typical of DECT connections.
  • the IF filter 96 is suitable for letting pass to the IF amplifier 80 and the centralised TV installation 40 only the IF band desired, for example the band of about 20 Mhz in the range between 260 and 280 Mhz.
  • the RF amplifier 50 by means of the directional coupler 59, extracts part of the signal received to transfer it to the switching logic 57 for it to be synchronised with the central control unit 11 and command the electronic switches 55 and 56 to close the amplification circuit in reception and the Rx amplifier 51 to amplify the data received.
  • the data thus amplified is transferred to the band translator 60 which, in the mixer 61, combines the band of data received, which is of about 2 Ghz, with the band of the local oscillator 62 to produce, after filtering effected by the IF filter 66, the frequency of about 260 Mhz to be transferred to the IF amplifier 70.
  • the IF amplifier 70 in a similar way to the RF amplifier 50, amplifies the data received, bringing the signal level to a value compatible with TV signal levels and transfers the amplified data to the bidirectional coupler 29 which associates the data thus manipulated with the antenna signals coming from the centralised TV antenna 40. In this way, both the telephone data coming from the central control unit 11 and the TV signals are transferred through the antenna down-lead 48 to the apartment TV sockets 41.
  • the indoor device 31 which is connected to the apartment TV socket 41, picks up the signals passing by means of the bidirectional coupler 39 and filters these signals with the PB filter 34 in order to transfer only the band corresponding to the telephone data received to the IF amplifier 80.
  • the IF amplifier 80 and the band translator 90 arranged in cascade fashion, respectively bring the data received to the desired level and translate the band to its original frequency of about 2 Ghz so that the antenna 32 may exchange the data with the portable device 14 present in the apartment .
  • the operation of the system 10 in the direction from portable device 14 to central control unit 11 is as follows.
  • the portable device 14 transmits packets of data to the antenna 32 of the indoor device 31 which transfers it to the band translator 90 for it to be translated into the desired IF band by the mixer 91, which combines the band of data to be transmitted with the band of the local oscillator 92 to produce, after filtering in the IF filter 96, the IF band desired.
  • This band is amplified by the amplifier 80 and transferred to the bidirectional coupler 39 to be put into the antenna down-leads 48 of the centralised installation 40 and thus reach the outdoor device 21 which in turn, through the antenna jack 27, the antenna cable 28 and the bidirectional coupler 29, picks up the transiting IF data.
  • the PB filter 24 filters the data to be transmitted from the IF band and transfers it cascade fashion to the IF amplifier 70, the band translator 60, the RF amplifier 50 and the antenna 22.
  • the RF amplifier 50 controls the level of amplification of the Tx amplifier 52 by way of the potentiometer 53 on the basis of the level of the signal picked up by the directional coupler 59.
  • WWL type communications may be transferred from the outside of buildings to the inside of buildings using, as in the example, the antenna cables of a centralised installation and an IF band that does not interfere with a band already occupied by a television channel .
  • the outdoor device 21 may include only the RF amplifier 50 and not necessarily also the IF amplifier 70, in the case where the prescribed amplification level in reception and transmission can be reached by means of the RF amplifier 50 alone.
  • the outdoor device 21 may be coupled, instead of with the indoor device, with another outdoor device 21 to form a WWL type transmission repeater station.
  • the two outdoor devices are located in close proximity, outside the building and connected directly through a physical link, of copper or fibre for example.
  • the outdoor device 21 may be connected directly to the central control unit 11, without the need for antennas to make the link.
  • the amplifiers 50, 60 and 80 respectively which, as described, are suitable for avoiding the feedback effect, may also be produced by using a single monodirectional amplifier appropriately connected to the switches, as may easily be imagined by those acquainted with the sector art. This solution, however, may only be implemented when the level of gain is the same in transmission and reception. Changes may be made to the dimensions, shapes, materials, components, circuit elements, connections and contacts, as also to details of the circuitry and of the construction illustrated and of the method of operation, without departing from the spirit of the invention.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radio Relay Systems (AREA)

Abstract

L'invention porte sur un système (10) de distribution de fréquences radio entre une unité centrale de commande (11) et des terminaux portables sans fils (14) ne pouvant pas être directement atteints par l'unité de commande (11). Le système (10) comporte un dispositif de conversion (21, 31) placé entre l'unité de commande (11) et les terminaux portables sans fils (14) convertissant les liaisons sur fréquences radio en liaisons à fréquence intermédiaire, les transférant sur un câble (28, 38), puis les reconvertissant en liaisons à fréquence radio pouvant atteindre les dispositifs portables (14). Le dispositif (21, 31) sert en particulier à la fois à distribuer les signaux par un réseau local sans fil (WWL) dans les immeubles et à étendre la zone de couverture de l'unité centrale de commande (11) pour des liaisons de ce type. Le dispositif (21, 31) comporte également un nouvel amplificateur de bande objet de l'invention capable de supprimer les effets dits de retour.
PCT/IT1998/000152 1997-06-23 1998-06-09 Systeme de distribution de frequences radio WO1998059442A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU77881/98A AU7788198A (en) 1997-06-23 1998-06-09 Radio frequency communication distribution system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT97TO000550A IT1293384B1 (it) 1997-06-23 1997-06-23 Sistema per la distribuzione di comunicazioni a frequenza radio.
ITTO97A000550 1997-06-23

Publications (1)

Publication Number Publication Date
WO1998059442A1 true WO1998059442A1 (fr) 1998-12-30

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/IT1998/000152 WO1998059442A1 (fr) 1997-06-23 1998-06-09 Systeme de distribution de frequences radio

Country Status (3)

Country Link
AU (1) AU7788198A (fr)
IT (1) IT1293384B1 (fr)
WO (1) WO1998059442A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR19990072537A (ko) * 1998-02-13 1999-09-27 루센트 테크놀러지스 인크 무선원격통신시스템및방법
EP2063549A1 (fr) * 2007-11-23 2009-05-27 Bouygues Telecom Répéteur pour la retransmission à l'intérieur d'une habitation d'un signal radiodiffusé de type DVB-H
EP2119270A2 (fr) * 2006-12-22 2009-11-18 LGC Wireless, Inc. Systèmes et procédés destinés à fournir une zone de couverture à distance pour des communications sans fil

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987002538A1 (fr) * 1985-10-15 1987-04-23 Minori Kawano Circuit d'intensification pour radiotelephones cellulaires
EP0690637A2 (fr) * 1994-07-01 1996-01-03 US WEST Technologies, Inc. Procédé et système pour réaliser une terminaison d'abonné numérique, "sans-fil"
WO1996023370A1 (fr) * 1995-01-26 1996-08-01 Nokia Telecommunications Oy Systeme radio cellulaire, repeteur et station de base
JPH09139705A (ja) * 1995-11-13 1997-05-27 N T T Ido Tsushinmo Kk 無線中継装置

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1987002538A1 (fr) * 1985-10-15 1987-04-23 Minori Kawano Circuit d'intensification pour radiotelephones cellulaires
EP0690637A2 (fr) * 1994-07-01 1996-01-03 US WEST Technologies, Inc. Procédé et système pour réaliser une terminaison d'abonné numérique, "sans-fil"
WO1996023370A1 (fr) * 1995-01-26 1996-08-01 Nokia Telecommunications Oy Systeme radio cellulaire, repeteur et station de base
JPH09139705A (ja) * 1995-11-13 1997-05-27 N T T Ido Tsushinmo Kk 無線中継装置

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 097, no. 009 30 September 1997 (1997-09-30) *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR19990072537A (ko) * 1998-02-13 1999-09-27 루센트 테크놀러지스 인크 무선원격통신시스템및방법
EP2119270A2 (fr) * 2006-12-22 2009-11-18 LGC Wireless, Inc. Systèmes et procédés destinés à fournir une zone de couverture à distance pour des communications sans fil
EP2119270A4 (fr) * 2006-12-22 2012-12-12 Lgc Wireless Inc Systèmes et procédés destinés à fournir une zone de couverture à distance pour des communications sans fil
EP3209087A1 (fr) * 2006-12-22 2017-08-23 CommScope Technologies LLC Système et procédé permettant de fournir une zone de couverture à distance pour des communications sans fil
EP2063549A1 (fr) * 2007-11-23 2009-05-27 Bouygues Telecom Répéteur pour la retransmission à l'intérieur d'une habitation d'un signal radiodiffusé de type DVB-H
FR2924291A1 (fr) * 2007-11-23 2009-05-29 Bouygues Telecom Sa Repeteur pour la retransmission a l'interieur d'une habitation d'un signal radiodiffuse de type dvb-h

Also Published As

Publication number Publication date
AU7788198A (en) 1999-01-04
ITTO970550A1 (it) 1998-12-23
ITTO970550A0 (fr) 1997-06-23
IT1293384B1 (it) 1999-03-01

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