WO1993005550A1

WO1993005550A1 - Method for inserting an additional module in a cable network provided with at least one tap box and module to be used therein

Info

Publication number: WO1993005550A1
Application number: PCT/BE1992/000039
Authority: WO
Inventors: Frank Loosen; Eugène ADRIAENSENS
Original assignee: Zuivere Interkommunale Voor Teledistributie Van Het Gewest Antwerpen 'integan' Cooperatieve Vennootschap
Current assignee: Zuivere Interkommunale Voor Teledistributie Van Het Gewest Antwerpen 'integan' Cooperatieve Vennootschap
Priority date: 1991-09-04
Filing date: 1992-09-04
Publication date: 1993-03-18
Anticipated expiration: 1994-03-04
Also published as: BE1005305A3

Abstract

The invention relates to a method for inserting an additional module (5) with at least an intensity equalizing function in a cable network provided with at least one tap box (4) which is provided with at least a first (7) and a second (8) connector for a cable (3), in which method the cable (3) connected to one of said first and second connectors (7, 8) is disconnected therefrom and connected to a third connector (11) of the module (5), and a fourth connector (12) of the module (5) is connected to a free connector (8) of the tap of the box (4) by attaching this module (5) at said free connector (8) to the tap box (4). The invention further also relates to a module to be used in this method.

Description

"Method for inserting an additional module in a cable netvorlc provided with at least one tap box and module to be used therein" This invention relates to a method for inserting an additional module with at least an intensity equalizing function ("line equalizer") in a cable network provided with at least one tap box, in particular in a cable television and/or cable radio network, which tap box is attached for example against an outer wall of a building, in a shaft or in a distribution box and provided with at least a first and a second connector connected both to a cable of said cable network. In practice, it is regularly observed that the spectrum of radio or TV signals gets too much "tilt" when the signals have travelled a certain distance through the network which can cause disturbances in the radio or TV signal. The expression "tilt" indicates here the difference in intensity level between the signals modulated on a carrier wave of a higher frequency and the signals modulated on a carrier wave of a lower frequency. In order to prevent the production of too much "tilt", an additional module with an intensity equalizing function is taken up in the cable network.

According to a known method, such additional modules are inserted in the cable itself. A drawback of this known method is that the cable has to be cut through and that the cable structure is changed therefore. Inserting such a module in a cable results in the formation of two additional reflection points, namely at the two connections of the cable to the module. Such reflection points have a negative influence on the quality of the signals transmitted through the cable.

A further drawback of this known method, in particular when the cable is fixed for example against an outer wall of a building, is that the additional module has also to be fixed against this wall which involves additional difficulties; on the one hand, it is for example necessary to inform the owner of the house in advance about the intended works, which works can, on the other hand, also cause damages.

An object of the present invention is to provide a method which offers a solution for the hereabove mentioned problems and which allows therefore to insert an additional module in a simple way, in a cable network without having to cut the cable through. To this end, the cable connected to one of said first and second connectors of the tap box is disconnected therefrom and connected to a third connector of the module, and a fourth connector of the module is connected to a free connector of the tap box, in particular onto the connector of the tap box which became free, by attaching this module at said free connector to the tap box. In this method according to the invention, use is therefore made of a module which is provided to be fixed onto the tap box in such a manner that this module can be inserted easily in the cable network without any necessity to drill for example holes for attaching this module. Attaching the module on the tap box causes hardly any further reflection in the cable network. A further important advantage of the method according to the invention is that inserting an additional module does not affect the cable structure. The present invention relates also to a module to be used in a method according to the invention, which module comprises electronic components with at least an intensity equalizing function ("line equalizer") , characterized in that said components are contained in a housing provided with first attachment means for attaching the module onto said tap box.

An important advantage of this module is that it can be fixed easily onto a tap box of a cable network without having to drill holes for example.

In a preferred embodiment of the module according to the invention, said first attachment means belong to said fourth connector and are provided to be attached onto said free connector of said tap box. When fixing the module onto the tap box, it is simultaneously connected in this way to this tap box.

Other particularities of the method and the module according to the invention will become apparent from the following description of some embodiments according to the invention. This description is only given by way of example and does not limit the scope of the present invention. The reference numerals used in this description relate to the annexed drawings wherein : Figure 1 shows schematically a row of buildings against which a cable and tap boxes of a cable network are attached;

Figures 2 and 3 show a spectrum of signals travelling through the cable, respectively at the beginning and at the end of the row of buildings of Figure 1, and modulated on carrier waves of different frequencies;

Figure 4 shows in the same way as Figure 3 the intensity of a number of signals travelling through the cable at the end of the row of buildings of Figure 1, and modulated on carrier waves of different frequencies, an additional module with an intensity equalizing function ("line equalizer") being, however, inserted in the cable network against this row of buildings; Figure 5 shows a diagram of the electronic components of the additional module;

Figure 6 shows schematically a tap box and an additional module fixed thereon according to the invention; and Figure 7 shows, on a larger scale, a side elevational view of an example of the module according to the invention.

In the different figures, the same reference numerals relate to the same or analogous elements. Figure 1 shows a row of buildings 1 provided with a cable network, for example a cable television and/or cable radio network. The cable network comprises a cable 3 fixed against the outer walls 2 of these buildings and tap boxes 4. The cable network has a tree structure according to which the cable (stem) splits up at the tap box into a number of branches. In such an existing antenna network, the spectrum of signals transmitted through the cable 3 at the beginning of the row of buildings 1 sometimes shows after having travelled a certain distance too much "tilt", for example due to the connection of additional subscribers or due to an extension of the cable 3, which may cause disturbances in the radio or TV signal. This "tilt" is caused by the fact that signals modulated on a carrier wave of a high frequency are weakened stronger in intensity when travelling through the cable 3 than signals modulated on a carrier wave of a lower frequency. Too much "tilt" means therefore that the difference in intensity between signals modulated on a carrier wave of a high frequency with respect to signals modulated on a carrier wave of a lower frequency becomes too big. The same phenomenon arises also in other cable networks such as for example in LAN's.

Figure 2 shows the intensities I (vertical axis) of a series of antenna signals each modulated on a carrier wave of a different frequency f (horizontal axis) . These carrier waves are indicated by means of vertical lines (f.., f₂, ... f_n) . The signals shown in this figure form a spectrum with little "tilt" such as for example near the main station or at the outlet of an amplifier box taken up in the network. Figure 3 shows the intensities I of the same signals as those in Figure 2 but which have travelled a certain distance through the cable, such as for example at the end of the row of buildings 1. From this figure, it appears that the spectrum of these signals shows too much "tilt" in such a manner that the signals modulated on a carrier wave of a high frequency became too weak. In order to remedy this, at least one additional module with an intensity equalizing function ("line equalizer") has to be inserted in the cable 3 in order to obtain at the end of the row of buildings 1 signals which, as represented in Figure 4, are indeed weakened, but the spectrum of which shows little "tilt". These weakened signals can be amplified back by an amplifier. Figure 5 shows an electronic diagram of such an additional module 5. The electronic components of this module 5 comprise a "line equalizer" 20 which compensates for the excessive "tilt" and which is known per se. Further they comprise moreover an alternating current by-pass provided with a coil 21 which transmits the supply current for example for the following amplifiers.

As represented in Figure 5, a duplex filter 22, 23 can further be provided in the module 5 on both sides of the "line equalizer" 20 for maintaining the possibility of a two way network, notwithstanding the presence of the line equalizer 20.

The present invention relates now to a method which allows to insert easily and quickly an additional module 5 as represented in Figure 5 in the cable network without having cut the cable through and without having to drill further holes in the outer wall. To this end, the module 5 is no longer fixed against the wall but it is fixed, according to the invention, onto the tap box 4. The tap box 4 is screwed for example by means of screws applied in holes 6 against an outer wall of a building (see Figure 6) . The tap box 4 shown in Figure 6 is provided with a first 7 and a second connector 8 for the cable 3 and with further connectors 9 for branching cables 10 leading to the subscribers. In order to insert an additional module 5 in the cable network near this tap box 4, the cable 3 is disconnected for example from the second connector 8 and the disconnected extremity of the cable 3 is connected to a third connector 11 of the module 5. This module 5 is further provided with a fourth connector 12 which is connected to a free connector 8 of the tap box 4. This free connector 8 does not always have to be the just disconnected connector but can be formed possibly by a further connector 9.

In the method according to the invention, use is made of a module 5 provided for being attached onto the tap box 4 so that inserting such a module 5 can be done easily and quickly without having to drill additional holes. The module 5 according to the invention is provided with first attachment means for fixing this module 5 onto the tap box 4.

Figure 7 shows a module 5 according to the invention. This module 5 comprises an elongated housing 13 of a substantially hexagonal prismatic shape, the third 11 and the fourth connector 12 of this module 5 being each provided on an extremity of this housing 13. The hexagonal shape of the housing offers the advantage that it is suited in this way for the use of a spanner which is used during the assembling for screwing the module onto the tap box. The connector 11 is provided with a contact sleeve which has not been shown in the figures and which fits with pressure onto the contact pin of the free cable extremity. The fourth connector 12 comprises a contact pin 14 which fits with pressure in a not represented contact sleeve of the free connector 8 of the tap box 4. This fourth connector 12 is adapted to be fixed onto the free connector 8 of the tap box 4 in such a manner that by attaching the module 5, it is connected at the same time electrically to the tap box 4. Depending on the free connector 8 of the tap box 4, a number of variant embodiments of the module 5 and in particular of the connectors of this module 5 can be considered.

A first, preferably used embodiment is represented in Figure 7. The connector 12 forms in this embodiment a rigid unit with the housing 13 and is provided with an outer thread 15 adapted to a not represented inner thread provided in said free connector 8 of said tap box 4. The third connector 11 of the module 5 is in this case preferably provided with a nut 16 which can be rotated freely with respect to the housing 13 and which is adapted to be screwed onto a not represented thread provided on the disconnected cable 3. This rotatable nut 16 allows to screw the disconnected cable 3 in a simple way to the module 5, even when this module 5 has been screwed already first also in a simple way onto the tap box 4. Between the nut 16 and the housing 13 there is provided a seal ring 17. Such a seal ring 18 is also provided on the fourth connector 12 of the module 5. In a possible variant of the hereabove described embodiment, which is not represented in the figures, is the fourth connector 12 of the module 5 provided with an inner thread adapted to an in this case outer thread provided on said free connector 8 of said tap box 4. In this variant embodiment, the third connector 11 of the module 5 is preferably also provided with an outer thread over which the disconnected cable 3, in particular a nut which is preferably applied on the extremity of this cable 3, can be screwed.

In the hereabove described variant embodiments, the screw axis of the thread 15 provided onto the module 5 coincides preferably with the longitudinal axis of the housing 13, which simplifies considerably the step of screwing the module 5 onto the tap box.

In a further possible variant embodiment, a nut which can be rotated freely with respect to the housing 13 and which is provided with an inner thread is provided on the fourth connector 12 of the module 5, which nut is adapted to be screwed onto a thread provided on said free connector 8 of the tap box.

Claims

1. A method for inserting an additional module (5) with at least an intensity equalizing function ("line equalizer") in a cable network provided with at least one tap box (4) , in particular in a cable television and/or cable radio network, which tap box (4) is provided with at least a first (7) and a second connector (8) connected both to a cable (3) of said cable network, characterized in that the cable (3) connected to one of said first and second connectors (7, 8) is disconnected therefrom and connected to a third connector (11) of the module (5) , and a fourth connector (12) of the module (5) is connected to a free connector (8) of the tap box (4) by attaching this module (5) at said free connector (8) to the tap box (4) .

2. A module to be used in a method according to claim 1, which module (5) comprises electronic components with at least an intensity equalizing function ("line equalizer") , characterized in that said components are contained in a housing (13) provided with first attachment means for attaching the module (15) onto said tap box (4) .

3. A module according to claim 2, characterized in that said first attachment means belong to said fourth connector (12) and are provided to be attached onto said free connector (8) of said tap box (4).

4. A module according to claim 3, characterized in that said first attachment means comprise an internally threaded nut which can be rotated freely with respect to the housing (13) and which is adapted to be screwed onto a thread provided onto said free connector (8) of said tap box (4) .

5. A module according to claim 3, characterized in that said first attachment means form together with said housing (13) a rigid unit and are provided with an outer thread (15) adapted to an inner thread provided in said free connector (8) of said tap box (4) .

6. A module according to claim 5, characterized in that said third connector (11) comprises a nut (16) which can be rotated freely with respect to the housing and which is adapted to be screwed onto a thread provided on the disconnected cable (3).

7. A module according to claim 3, characterized in that said first attachment means form together with said housing (13) a rigid unit and are provided with an inner thread adapted to an outer thread provided on said free connector (8) of said tap box (4) .

8. A module according to claim 7, characterized in that said third connector is provided with an outer thread adapted to an inner thread provided on the disconnected cable (3) .

9. A module according to any one of the claims 5 to 8, characterized in that said housing (13) comprises a substantially hexagonal prismatic portion while said thread (15) of the first attachment means is provided in such a manner that its screw axis coincides substantially with the axis of said prismatic portion.

10. A module according to any one of the claims 3 to 9, characterized in that said fourth connector (14) and/or said free connector (18) comprises a contact pin (14) which fits with pressure in a contact sleeve provided in said free (8) respectively in said fourth connector (12) .