FR2651631A1 - Distribution and selection method for a broadcasting installation and system for implementing it - Google Patents

Abstract

Distribution and selection method for a broadcasting installation comprising a network head (TR) broadcasting information or programmes freely available on a first set of predetermined frequencies, and information or programmes selectively available on a second set of predetermined frequencies, to a group of users each having a user channel (U1, U2, U3, U4) available, some of the said users having paid a subscription fee. The method includes a step of filtering the global information received, in order to extract therefrom only the freely available information, followed by step of distributing the said freely available information on a first group of distribution channels, equal in number to the number of users, a simultaneous step of distributing the global information received on a second group of distribution channels, equal in number to the number of users, and a selection step, for associating, with each user channel, either a channel of the first group of distribution channels, or a channel of the second group of distribution channels, the said selection step being remotely controlled from the network head (TR). Use in broadcasting installations, and especially cabled pay networks.

Description

 The present invention relates to a distribution and selection method for a cable television installation.

 It also relates to a distribution and selection system implementing the method and its application to a cable network for distributing information or video signals.

 Currently, in cable television installations and in particular in cable networks, the selection between subscribed and non-subscribed users is sometimes carried out by the operators of these networks by installing, after the last derivative of the distribution, low-pass type filters, high pass or band pass at the input cables of non-subscribed users in order to obscure part of the frequencies transmitted by the cabal.

 This requires manual intervention at each modification of the situation of the users and implies the installation of as many filters as subscribers. In addition, this distribution and selection process is easily circumvented and is not satisfactory for the operator, who must bear costly management of his cable television installation.

 The object of the invention is to remedy these drawbacks by proposing a distribution and selection method for a cable television installation comprising a head end broadcasting information or free access programs on a first set of predetermined frequencies and information or selective access programs on a second set of predetermined frequencies to a group of users each having a user channel, a portion of said users having subscribed.

 According to the invention, the distribution and selection method comprises a step of filtering the global information received in order to extract only the free access information therefrom, followed by a step of distributing said free access information on a first group of distribution channels, in number equal to the number of users, a simultaneous step of distributing said global information received on a second group of distribution channels in number equal to the number of users, and a selection step to associate with each channel d the user is either a channel from the first group of distribution channels, or a channel from the second group of distribution channels, said selection step being controlled remotely from the network head.

 Thus, with the method according to the invention, the various filterings carried out on each user channel in the previous methods are replaced by a single filtering carried out at the level of the reception of the global information of free or selective access. In addition, it is now possible for the operator of the cable television installation to remotely control the selection and toll system using any known transmission method, eliminating any manual intervention, which has the effect of considerably reducing the response times and management costs while ensuring greater security of the installation with regard to illicit access to paid information.

 According to a particular version of the invention, the method further comprises, at the head end, a step of coding and transmitting coded pilot information, and at the level of the group of users, a step of reception and decoding of said coded pilot information in order to extract from it a selection information processed during the selection step.

 In this way, the remote control of the selection operation by the operator is carried out by using the transmission possibilities of the head end and by using a conventional coding technique used in particular in remote alarm systems. The transmission of coded pilot information, either by coaxial cable or by radio broadcasting, simply solves the problems of the selector remote control.

According to another aspect of the invention, the distribution and selection system, implementing the method according to the invention, is characterized in that it comprises
at the user group level
- means for filtering the information received with a view to extracting only free access information therefrom,
first means for distributing said free access information over a first group of distribution channels in a number equal to the number of users,
second means for distributing the information received over a second group of distribution channels in a number equal to the number of users, and
selection means for associating with each user channel either a channel from the first group of distribution channels or a channel from the second group of distribution channels, said selection means being controlled remotely from the head of the network,
Other features and advantages of the invention will become apparent in the description below.

In the accompanying drawings, given by way of nonlimiting examples
- Figure 1 is a block diagram of a coding and transmission unit implemented at the head end, in one embodiment of the distribution and selection system according to the invention
- Figure 2 is a block diagram of a distribution and selection unit, at the user group level, in the embodiment corresponding to Figure 1.

 The distribution and selection system illustrated in the block diagrams of FIGS. 1 and 2 comprises a transmitting unit 1 located at the level of the network head TR of a cable television and video information installation broadcasting, on the one hand, CP pay channels, and on the other hand, CG free channels. The cable distribution can be carried out either by hertzian transmission (transmitter), or by cable distribution via a cable network DIS through a final amplifier AF with the possibility of remote supplying the receiving units connected to the cable network.

 By way of examples and with reference to current broadcasting standards, the free channels CG correspond to channels 22, 25, 28, 30, 33 of respective frequencies 439, 503, 527, 543, 567 MHz, while to the pay channels, correspond to channels 40, 42, 44, 46, 48 and 06, of respective frequencies 623, 639, 655, 671, 687 and 184 MHz.

 The transmitting unit comprises a control and processing unit MC comprising, for example, a microcomputer PC and a modem M connected by serial link LS to a data input interface CL, such as a keyboard of another microcomputer . This control and processing unit MC provides control of a synthesis and coding unit SY comprising, for example, a module SC of coding switches, an oscillator OSC generating a pilot frequency and a channel selector SCA allowing selecting at least one channel from four channels each corresponding to a predetermined coding of the pilot frequency. The SY synthesis and coding unit, produced according to techniques well known in the telecommunications field, generates an FPC coded pilot frequency broadcast at the level of the head end TR in VHF on a frequency channel 250 MHz. The FPC coded pilot frequency can, of course, be mixed and transmitted by the coaxial cable, in the case of a cable network.

 FIG. 2 illustrates the general structure of a distribution and selection unit 2, placed at the level of a group of users corresponding, for example, to a residential building or any other collective equipment such as a hotel or a hospital. The information arrival cable AI is connected, on the one hand, to a bandwidth filter FPB, by way of example of bandwidth 40-600 MHz, the output of which is applied to a first distributor Ri, and on the other hand, by derivation, directly to a second distributor R2. The first distributor Ri thus distributes a filtered signal containing only free access information (free channels) over a first group of distribution channels while the second distributor R2 distributes a signal carrying all the information received (free channels and paying) on a second group of distribution channels.

Each user, subscribed or not, is associated with a user channel U1, U2, U3, U4 (in the example described, four users) corresponding to a coaxial cable. The selection of the channels coming from the two distributors Ri, R2, which in fact constitute a double distributor R, is carried out by a selector S coupled to the distributors Ri, Rz. This selector S is controlled by a receiver / decoder module RD connected directly to the input coaxial cable of the distributor R2 and thus receiving the coded pilot frequency FPC transmitted from the transmitter headend unit 1. The receiver / decoder module RD, produced according to conventional techniques, comprises a code selection switch D. The selector S can be produced on the basis of relays, bistables or PIN diodes, according to well known techniques. It is of course possible to take advantage of the presence of several channels on the synthesis and coding unit SY, to provide for several extensions
EXT connected by diverter to the AI input coaxial cable and each equipped with an FC channel filter.

 We will now explain the operation of the distribution and selection system according to the invention, at the same time as the method implemented in this system.

 The operator of a cable television installation, in particular of a cable network, equipped with the distribution and selection system according to the invention, can manage from a PC microcomputer, or any other equivalent means, the situation of different users connected to the cable network, with regard to the subscription to pay channels. The situation of each user, of a given group of users: subscriber or non-subscriber, is treated and ultimately leads to the generation of a pilot frequency coded FPC which is the medium for selection information between subscribers and non-subscribers .

 The receiver / decoder module RD, after reception and decoding of the coded pilot frequency FPC, generates a combination of control signals applied to each cell of the selector S which then performs the appropriate turnouts. Only users identified as subscribers receive all the information received, while non-subscribed users receive a hidden signal corresponding to free channels.

 The distribution and selection system can be managed either remotely using the M modem and the LS serial link, or at the level of the user group, in the case for example of a cable distribution in a hotel or any other collective equipment.

 Of course, the invention is not limited to the examples described and shown and numerous modifications can be made to these examples without departing from the scope of the invention.

 It is thus possible to envisage other modes of transmission of the selection control signals using known telecommunication techniques.

 Although the present invention is more particularly intended for controlling the cable distribution of video signals, it can also be applied to the transmission of other types of information, analog or digital when access criteria must be taken into account.

Claims (8)

 1. Distribution and selection method for a cable television installation comprising a headend (TR) broadcasting information or free access programs on a first set of predetermined frequencies and selective access information or programs on a second set of predetermined frequencies to a group of users each having a user channel (U1, U2, U3, U4), a portion of said users having subscribed, characterized in that it includes a step of filtering information global received to extract only free access information, followed by a step of distributing said free access information on a first group of distribution channels equal in number to the number of users, a simultaneous step of distributing information global received on a second group of distribution channels in number equal to the number of users, and a selection step tion to associate with each user channel either a channel of the first group of distribution channels, or a channel of the second group of distribution channels, said selection step being controlled remotely from the network head (TR).  2. Method according to claim 1, characterized in that it further comprises, at the network head (TR), a step of coding and transmitting coded pilot information (FPC), and at the level from the user group, a step of receiving and decoding said coded pilot information (FPC) in order to extract from it a selection information processed during the selection step.  3. Distribution and selection system (1, 2) for a cable television installation comprising a headend (TR) broadcasting free access information or programs on a first set of predetermined frequencies and access information or programs selective on a second set of predetermined frequencies to a group of users each having a user channel (U1, U2, U3, U4), a portion of said users having subscribed, implementing the method according to claims previous, characterized in that it comprises  at the user group level  - means (FPB) for filtering the information received with a view to extracting only free access information therefrom,  first means (R1) for distributing said free access information over a first group of distribution channels in a number equal to the number of users,  second means (Rz) for distributing the information received over a second group of distribution channels in a number equal to the number of users, and  - selection means (S) for associating with each user channel (U1, U2, U3, U4), either a channel of the first group of distribution channels, or a channel of the second group of distribution channels, said means selection (S) being remotely controlled from the network head (TR).  4. System according to claim 3, characterized in that it further comprises, at the network head (TR), means (MC, CL, SY) for generating and transmitting coded pilot information (FPC), and at the user group level, means (RD) for receiving and decoding said coded pilot information (FPC), connected to the selection means (S).  5. System (1, 2) according to claim 4, characterized in that the coded pilot information (FPC) is a signal of predetermined frequency coded by pulse width modulation.  6. System according to one of claims 3 to 5, characterized in that the generation and emission means (MC, CL, SY) comprise  - control and processing means (MC), connected to synthesis and coding means (SY),  - oscillator means (OSC) for generating signals carrying predetermined pilot frequencies,  coding means (SC) of said carrier signals, and  - Channel selection means (SCA) from a predetermined number of available channels to each of which is associated a predetermined pilot frequency.  7. Application of the system (1, 2) according to claim 6 to a cable distribution installation to several groups of users connected to a branch unit by several branch channels, characterized in that the system (1, 2) comprises in addition, at each branch channel, channel filtering means (FC) associated respectively with a predetermined channel frequency.  8. System (1, 2) according to one of claims 3 to 7, characterized in that it further comprises serial link means (LS) for connecting the control and processing means (MC) to the means of synthesis and coding (SY) via interface means (CL)