MXPA99008544A - Signal generation and broadcasting - Google Patents

Abstract

The invention includes a mostly conventional digital television system (2000) to transmit compressed digital signals. A multiplexer (2004) receives a plurality of further input signals, assembles one or more transport streams and transmits compressed digital signals to a transmitter (2008) of the broadcast centre via linkage (2010). The transmitter (2008) transmits electromagnetic signals via uplink (2012) towards a satellite transponder (2014), where they are electronically processed and broadcast via notional downlink (2016) to earth receiver (2018). The signals received by receiver (2018) are transmitted to an integrated receiver/decoder (2020) connected to the end user's television set (2022). The receiver/decoder (2020) decodes the compressed MPEG-2 signal into a television signal for the television set (2022). A conditional access system (3000) is connected to the multiplexer (2004) and the receiver/decoder (2020), and is located partly in the broadcast centre and partly in the decoder. It enables the end user to access digital television broadcasts from one or more broadcast suppliers. A smartcard, capable of decrypting messages relating to one or several television programmes sold by the broadcast supplier, can be inserted into the receiver/decoder (2020). Using the decoder (2020) and smartcard, the end user may purchase commercial offers in either a subscription mode or a pay-per-view mode. A number of features of particular interest are disclosed, involving the randomization of EMMs, mixing parameter lengthand identifier on EMMs and the like to save space, dynamic allocation of bandwidth for specific EMMs, and the STM being separate from the SMS.

Description

GENERATION AND TRANSMISSION OF SIGNALS The present invention relates to a transmission system, with a transmission and reception system, with an apparatus for generating signals (including messages), with analogous methods, and with signals for use with the systems, apparatuses and methods mentioned above. In particular, but not exclusively, the invention relates to a mass market transmission system, which has one or all of the following preferred characteristics: - • This is a system of information transmission, preferably a transmission system of radio and / or television • This is a satellite system (although this may be applicable to cable or terrestrial transmission) • This is a digital system, which preferably uses the MPEG compression system, most preferably the MPEG-2 for data / signal transmission • This provides the possibility of interactivity. Again, in particular, but not exclusively, the invention relates to a Subscriber Authorization System (SAS) that is part of a conditional access system for a transmission system. By a Subscriber Authorization System is meant any device, device or system to authorize users to access the conditional access system, regardless of the end use. The Subscriber Authorization System may be for use with a radio and / or television transmission system, but may also be for authorizing users, for example, in computer networks, in parking lots, and so on. The Subscriber Authorization System preferably has the function of generating adequate accreditation messages. One function of known Subscriber Authorization Systems is to manage access rights to television programs, available as commercial offers and sold in accordance with different marketing modes (subscription mode, pre-contract mode, impulse mode). The Subscriber Authorization System, in accordance with those rights and with the information received from a Subscriber Management System (SMS) generates, using a message generator, the so-called "Management Messages" (EMMs) that are transmitted through a sender of messages, through a multiplexer, to a receiver / decoder of the subscriber to authorize it. In a known system, the sender of the message has no ability to detect or control what it issues to the multiplexer. Accordingly, it has been understood, in accordance with the present invention, that it is possible for the message issuer to transmit back to back two Accreditation Management Messages that will receive and decode the receiver / decoder. In these circumstances, it is possible that if the Accreditation Management Messages are insufficiently separated, the receiver / decoder will be unable to properly detect and decode the second of the Accreditation Management Messages. This can create severe authorization problems. The present invention, in a first aspect, seeks to solve this and other problems. In accordance with a first aspect of the present invention, there is provided an apparatus for repetitively generating a set of messages, comprising: elements for generating a plurality of messages; elements for repetitively randomizing the sequence of the messages, to form a plurality of sets of those messages, in such a way that the messages of each set are in random sequence; and elements to output the plurality of message sets. By repetitively randomizing the sequence of messages, the possibility of two messages that are being transmitted only back to back after a number of repetitions can be made insignificantly small.

Preferably, the message generating elements include elements for storing the generated messages, and, if so, the scrambling elements are preferably configured to form each of the message sets by means of retrieving the messages in random sequence from the storage element. This can be a particularly efficient way to put the invention into practice, since the messages do not have to be generated again each time the message sequence is randomized. For ease of access, the storage element is preferably configured to store the messages in an array at least two-dimensional. Other dimensions can be added, for example, to represent different operators from which messages can be generated. Preferably, the apparatus also comprises elements coupled to the output elements to vary the speed at which the plurality of message sets is output. In this way you can take account of any bit rate transfer command from the multiplexer. For the same reason, the apparatus also preferably comprises elements coupled to the storage element, to evaluate the size of the messages stored in the storage element, and the elements coupled to the output elements, to vary the speed at which it is stored. it removes the plurality of message sets, depending on the size of the messages. Preferably, the generation elements and the scrambling elements are coupled by a First-in-First-Out device. Since these two components can be separated a great distance, the provision of the FIFO device can allow them to operate independently independently in case of failure of one of them. For the same reason, the output elements preferably include an element for storing at least one of the sets of messages, such that, again, the latter can operate effectively in the stand-alone mode. A plurality of output elements may be provided, in which case the apparatus also preferably comprises a multiplexer for receiving the plurality of message sets that exit through the plurality of output elements. The present invention extends to an access control system for a transmission and reception system, the access control system including, at the transmission end, an apparatus as mentioned above, and, at the receiving end, an device to receive those messages. The message may be an accreditation message for transmission to the receiving device. In turn, the accreditation message can be an EMM or ECM. In the preferred embodiment, the output element comprises an EMM Injector to inject EMMs into the data stream to be transmitted. The present invention also extends to a transmission and reception system that includes an access control system as mentioned above.; The system can be for the digital transmission of television programs. The present invention extends to a method for repetitively generating a set of messages, comprising: generating a plurality of messages; repetitively randomizing the sequence of the messages, to form a plurality of sets of those messages, in such a way that the messages of each set are in random sequence; and output the plurality of message sets. Preferably, the method includes the step of storing the messages generated in the generation step, and in the preference scrambling step each of the message sets is formed by retrieving the messages in random sequence.

The invention also provides a method for controlling the access of a user to a transmission and reception system, which includes, at the transmission end, a method for repetitively generating a set of messages as cited above, and, at the end of reception, the step of receiving those messages. Preferably, the message is an accreditation message for reception through the reception step. Now another aspect of the present invention will be discussed. Conventionally in the transmission of a digital bit stream, the information is transmitted as a packet of digital data and an identifier for the packet; the identifier has at least two bytes in length. In accordance with the present invention, preferably the output element referred to above is configured to output the plurality of message sets as a digital signal that includes a packet (most preferably many packets) of digital data and an identifier for the packet, the identifier being less than two bytes (and preferably one byte or less) in length. This can result in a reduced bandwidth requirement. The feature is provided independently. Accordingly, in accordance with a second aspect of the present invention, there is provided an apparatus for generating a digital signal comprising a digital data packet and an identifier for the packet, comprising: elements for generating the data packet; and elements to generate the identifier; wherein: the identifier generating element is configured to generate an identifier that is less than two bytes in length. The identifier may comprise an identity parameter and a length parameter, in which case preferably these parameters are each 4 bits long for ease of implementation. Preferably, the digital value of the length parameter is not directly proportional to the actual length of the 'packet. This may allow a greater range of actual packet length, than the range of the digital value of the length parameter. The apparatus may also comprise elements for storing a search table by mapping the digital value of the length parameter and the actual length of the packet. This aspect of the present invention also extends to a transmission and reception system that includes, at the transmission end, the apparatus as recited above and, at the receiving end, a device for receiving that signal.

In addition, in the method as cited above, the plurality of messages may come out as a digital signal comprising a packet of digital data and an identifier for the packet, the identifier being less than two bytes in length. In this independent method form, the second aspect of the present invention provides a method for generating a digital signal comprising a digital data packet and an identifier for the packet, comprising: generating the data packet; and generate the identifier; where: the identifier is less than two bytes in length. Preferably, the identifier comprises an identity parameter and a length parameter. Preferably also, the digital value of the length parameter is not directly proportional to the actual length of the packet. The second aspect of the present invention also provides a digital signal, comprising: a packet of digital data; and an identifier for the package; where: the identifier is less than two bytes in length.

Preferably, the identifier comprises an identity parameter and a length parameter, the identity and length parameters are each 4 bits long, and the digital value of the length parameter is not directly proportional to the actual length of the packet. A third aspect of the present invention will now be discussed. Conventional transmission systems are typically subjected to severe bandwidth constraints. Thus, preferably, if the aforementioned transmission and reception system also comprises elements for transmitting data, this also comprises elements for producing a control command representative of a data characteristic, and the output element includes elements for repetitively transmitting the plurality of data. sets of messages, at a variable repetition rate, and to vary the repetition rate in response to the control command. This feature is provided, in the third aspect of the present invention, independently. In accordance with this third aspect, a transmission system is provided comprising: elements for transmitting data; elements to produce a control command representative of a data characteristic; and elements for repetitively transmitting a message, at a variable repetition rate; the message transmission elements being configured to vary the repetition rate, in response to the control command. By varying the repetition rate in response to the control command, the bandwidth can be allocated dynamically for specific messages. In the preferred embodiment, the data are signals representative of program events (preferably digital television or radio program events), and the element for producing the control command is configured to produce the command to be representative of the transmission time of a particular program event, and in addition to preference the message is an Accreditation Management Message. This aspect of the invention is particularly relevant for Pay Per View (PPV) events, where demand by viewers for authorization to view a Payment event occurs.

Per particular event will generally vary according to the proximity of the event. The control command can be produced by the transmitter of the program, possibly through a so-called "Server for Program Transmitter" (SPB). Preferably, the message transmission element is configured to vary the repetition rate near the time of transmission of the event. Also preferably, the message transmission element is configured to increase the repetition rate before the transmission time of the event, as well as to increase the repetition rate during the transmission time of the event. For example, for a particular Pay Per View program event, the increased speed may start perhaps 30, 20, 15, 10 or 5 minutes before the event's transmission time, and may continue until half the time has elapsed. of, or three quarters of, or until the entire event. The lowest speed can be a transmission every 30 or 15 minutes, while the increased speed can be a transmission every 2 or one minute or every 30 seconds. The real speed naturally does not have to be exactly the figures mentioned; Intermediate figures are also possible, and the lowest speed can be slower once every 30 minutes, and the increased speed can be faster once every 30 seconds. The third aspect of the invention extends to a transmission and reception system that includes, at the transmission end, a system as cited above, and, at the receiving end, a device for receiving the data and transmission messages. This aspect also provides a method for transmitting, comprising: transmitting data; produce a control command representative of a data characteristic; and repetitively transmitting a message, at a variable repetition rate that varies in response to the control command. Preferably, the data are signals representative of program events, and the control message is representative of the time of transmission of a particular program event. In addition to preference, the repetition rate varies near the time of transmission of the event, more preferably, the repetition rate is increased earlier also, preferably, as during the transmission time of the event. In conventional conditional access systems problems may arise due to the failure of the link between the Subscriber Administration System and the Subscriber Authorization System, since these may be separated some physical distance. In accordance with a fourth aspect of the present invention, there is provided a conditional access system for providing conditional access to subscribers, comprising: a subscriber management system (SMS); and a subscriber authorization system (SAS) coupled to the subscriber management system, the authorization system comprising elements to generate subscriber renewal commands and elements to authorize the renewal of subscribers depending on those commands. By placing the elements to generate the subscriber renewal commands in the subscriber authorization system, instead of in the subscriber management system as up to date, the exchange of commands between the authorization system of the subscriber can be minimized. subscriber and the subscriber management system. Consequently, in addition, the interoperability requirement of the subscriber authorization system and the subscriber management system can be reduced. The fourth aspect of the invention also provides a conditional access system for providing conditional access to subscribers, comprising: a subscriber management system for managing subscribers, which includes a database with. information about the subscribers and elements to generate (preferably from the database) a stop command that a particular subscription is to be stopped, - and a subscriber authorization system, to authorize subscribers, coupled to the subscriber management system, and configured to receive the stop command; the subscriber authorization system comprising elements to generate a subscriber renewal command for each subscriber, depending on the stop command for that subscriber, and elements to authorize the renewal of the subscribers in dependence on the subscriber renewal commands. Preferably, the subscriber management system includes elements for generating (again preferably from the database) a start command that a particular subscription is to be started, and the generating element of the subscriber renewal command of the subscriber system. Subscriber authorization is configured to generate each subscriber renewal command in additional dependency to the start command. Consequently, the SAS can handle not only the renewal of existing subscribers, but also the renewal and initial authorization of new subscribers. The subscriber authorization system may also include a database with information about the subscriber, in which case it also preferably includes elements to update the information in that database, depending on the information in the system database of subscriber management. This can protect against link failures between the SMS and the SAS.

For the same reason, a first-in-first-out device is provided between the subscriber renewal command generator element and the renewal authorization element, to average the command flow, and ensure that no command is lost in the case of failure. The renewal authorization element may include exit elements to issue the authorization accreditation messages to the subscribers, to authorize the renewal. In the preferred mode, these messages are EMMs. The subscriber authorization system may be able to provide special rights (such as, for example, free rights for a limited period) for new subscribers. This can give versatility to the system. The invention extends to a conditional access system, which is for a transmission and reception system, the system comprising, at the transmission end, a system as cited above, and the system further comprising, at the receiving end, a device to receive those messages. The invention also extends to a transmission and reception system that includes a conditional access system as cited above. The system is typically for the transmission of digital television or radio programs. The preferred features of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: - Figure 1 shows the overall architecture of a digital television system in accordance with the preferred embodiment of the present invention. Figure 2 shows the architecture of a conditional access system of the digital television system. Figure 3 shows the structure of a Message from Accreditation Administration that is used in the conditional access system. Figure 4 is a schematic hardware diagram of a Subscriber Authorization System (SAS) in accordance with a preferred embodiment of the present invention. Figure 5 is a schematic diagram of the SAS architecture. Figure 6 is a schematic diagram of a Subscriber Technical Administration server, which is part of the SAS. Figure 7 is a flow diagram of the procedure for automatic renewal of subscriptions as implemented by the SAS. Figure 8 is a schematic diagram of a group subscription bitmap that is used in the automatic renewal procedure. Figure 9 shows the structure of an EMM that is used in the automatic renewal procedure. Figure 10 shows in detail the structure of the EMM. Figure 11 is a schematic diagram of a centralized order server when used to receive commands directly through the communication servers. Figure 12 illustrates diagrammatically a part of Figure 2, showing one embodiment of the present invention. Figure 13 is a schematic diagram of the centralized order server when used to receive commands from the subscriber authorization system to request a call back. Figure 14 is a schematic diagram of the communication servers. Figure 15 shows the manner in which the speed of the EMM emission cycle is varied, in accordance with the timing of a Pay Per View event. Figure 16 is a schematic diagram of a Message Emitter that is used to issue EMMs. Figure 17 is a schematic diagram showing how to store EMMs inside the Message Emitter. Figure 18 is a schematic diagram of a smart card. Figure 19 is a schematic diagram of a configuration of zones in the memory of the smart card. Figure 20 is a schematic diagram of a pay-per-event event description. In Figure 1 there is shown an overview of a digital television transmission and reception system 1000 according to the present invention. The invention includes A 2000 mostly conventional digital television system, which uses the known MPEG-2 compression system to transmit compressed digital signals. In more detail, the 2002 MPEG-2 compressor in a transmission center receives a digital signal stream (typically a video signal current). The compressor 2002 is connected to a multiplexer and encoder 2004 by the link 2006. The multiplexer 2004 receives a plurality of more input signals, assembles one or more transport streams and transmits the compressed digital signals to a transmitter 2008 of the transmission center through the link 2010, which of course can take a wide variety of forms, including telecom links. The transmitter 2008 transmits electromagnetic signals by means of the 2012 uplink, to a 2014 satellite transmitter-receiver, where these are processed electronically and transmitted via the 2016 speculative downlink to the land receiver 2018, conventionally in the form of a own dish or rented by the end user. The signals received by the receiver 2018 are transmitted to an integrated receiver or decoder 2020 owned or rented by the end user, and connected to the television set 2022 of the end user. The receiver / decoder 2020 decodes the MPEG-2 signal to a television signal for the television set 2022. A conditional access system 3000 is connected to the multiplexer 2004 and the receiver / decoder 2020, and is located partially in the transmission center, and partially in the decoder. This allows the end user to access the digital television transmissions from one or more transmission providers. A smart card can be inserted, capable of deciphering messages related to commercial offers (that is, one or many television programs sold by the transmission provider), within the receiver / decoder 2020. Using the decoder 2020 and the smart card, the end user can buy events either in a subscription mode or a payment-by-ect mode. An interactive system 4000, also connected to the multiplexer 2004 and the receiver / decoder 2020, and again partially located in the transmission center and partially in the decoder, allows the end user to interact with different applications by means of a modulated return channel 4002. -desmodulated. The conditional access system 3000 will now be described in more detail. With reference to Figure 2, in the overview the conditional access system 3000 includes a Subscriber Authorization System (SAS) 3002. The SAS 3002 is connected to one or more Subscriber Management Systems (SMS) 3004, an SMS for each transmission provider, through a respective TCP-IP 3006 link (although other types of links can alternatively be used). Alternatively, an SMS can be shared between two transmission providers, or a provider can use two SMSs, and so on. The first coding units in the form of key-setting units 3008, using "mother" intelligent 3010 cards, are connected to the SAS via link 3012. The second coding units again in the form of 3014 key-setting units , using "mother" smart cards 3016, are connected to the multiplexer 2004 via link 3018. The receiver / decoder 2020 receives a "daughter" smart card 3020. This is connected directly to the SAS 3002 via the Communications Servers 3022 via the modulated-demodulated return channel 4002. The SAS sends, among other things, subscription rights to the daughter smart card on the request. Smart cards contain the secrets of one or more commercial operators. The smart card "mother" codes different types of messages, and smart cards "daughters" decode the messages, if they have the rights to do so. The first and second encryption units 3008 and 3014 comprise a grid, an electronic VME card with software stored in an EEPROM, up to 20 electronic cards and a smart card 3010 and 3016, respectively, for each electronic card, one (card 3016). ) to code the ECMs and one (card 3010) to code the EMMs. The operation of the conditional access system 3000 of the digital television system will now be described in more detail, with reference to the different components of the television system 2000 and the conditional access system 3000.

Multiplexer and Encoder With reference to Figures 1 and 2, in the transmission center, the digital video signal is first compressed (or the bit rate is reduced), using the 2002 MPEG-2 compressor. This compressed signal is then transmitted to the multiplexer and encoder 2004 via link 2006 in order to be multiplexed with other data, such as other compressed data. The encoder generates a control word which is used in the coding process and which is included in the MPEG-2 stream in the multiplexer 2004. The control word is generated internally and allows the integrated end-user decoder / decoder 2020 to decode the program. The access criteria that indicate how the program is marketed are also added to the MPEG-2 stream. The program can be marketed in any of a number of "subscription" modes and / or one of a number of "Pay Per View" (PPV) modes or events. In the subscription mode, the end user subscribes to one or more commercial offers, or "bouquets", thus obtaining the rights to see all the channels within those bouquets. In the preferred mode, up to 90 commercial offers of a bunch of channels can be selected. In Pay Per View mode, the end user is given the ability to buy events as he wishes. This can be achieved either by pre-contracting the event in advance ("prior hiring mode"), or by buying the event as soon as it is transmitted ("impulse mode"). In the preferred mode, all users are subscribers, whether they see in subscription or PPV mode or not, but of course PPV viewers do not necessarily need to be subscribers. Both the control word and the access criteria are used to build an Accreditation Control Message (ECM); this is a message that is sent in relation to a coded program; the message contains a control word (which allows the decoding of the program) and the access criteria of the transmission program. The access criteria and the control word are transmitted to the second key-in unit 3014 via link 3018. In this unit, an ECM is generated, keyed and transmitted to the multiplexer and encoder 2004. Each transmission of services by a transmission provider in a data stream comprises a number of different components; for example, a television program includes a video component, an audio component, a subtitle component, and so on. Each of these components of a service is individually coded and encrypted for subsequent transmission to the 2014 transceiver. With respect to each coded component of the service, a separate ECM is required.

Program Transmission The multiplexer 2004 receives electrical signals comprising EMMs coded from the SAS 3002, ECMs coded from the second co-unit 3014, and compressed programs from the 2002 compressor. The 2004 multiplexer encodes the programs and transmits coded programs, coded EMMs and coded ECMs, such as electrical signals to a transmitter 2008 of the transmission center, by means of the 2010 link. The transmitter 2008 transmits the electromagnetic signals to the transmitter-receiver 2014 by means of the upward link 2012.

Receiving Programs The 2014 satellite transmitter-receiver receives and processes the electromagnetic signals transmitted by the transmitter 2008, and transmits the signals to the ground receiver 2018, conventionally in the form of a plate owned or rented by the end user, by means of the link 2016 descending. The signals received by the receiver 2018 are transmitted to the integrated receiver or decoder 2020 owned or rented by the end user, and are connected to the television set 2022 of the end user. The receiver / decoder 2020 demultiplexes the signals to obtain the programs coded with the EMMs coded and the ECMs coded.

If the program is not encoded, that is, no ECM has been transmitted with the MPEG-2 current, the receiver / decoder 2020 decompresses the data and transforms the signal to a video signal for transmission to the television set 2022. If the program is encoded, the receiver / decoder 2020 extracts the corresponding ECM from the MPEG-2 stream, and passes the ECM to the "daughter" smart card 3020 of the end user. This is inserted into a slot inside a housing in the receiver / decoder 2020. The smart daughter card 3020 controls whether the end user has the right to decrypt the ECM and access the program. If not, a negative state is passed to the receiver / decoder 2020 to indicate that the program can not be decoded. If the end user has the rights, the ECM is decrypted and the control word is extracted. Then the decoder 2020 can decode the program using this control word. The MPEG-2 stream is decompressed and translated into a video signal for progressive transmission to television set 2022.

Subscriber Management System (SMS) A Subscriber Management System (SMS) 3004 includes a 3024 database that manages, among others, all the files of the end user, commercial offers (such as rates and promotions), subscriptions, details of PPV, and data regarding the consumption and authorization of the end user. The SMS may be physically away from the SAS. Each SMS 3004 transmits messages to SAS 3002 through the respective link 3006, which implies modifications to, or creations of, Accreditation Management Messages (EMMs) to be transmitted to the end users. SMS 3004 also transmits messages to SAS 3002, which does not imply any modification or creation of EMMs, but only implies a change in an end-user status (related to the authorization granted to the end user when ordering products, or with the quantity with which the final user will be charged). As described below, SAS 3002 sends messages (typically requesting information such as callback information, or billing information) to SMS 3004, so that it will be evident that the communication between the two is in both directions.

Accreditation Management Messages (EMMs) The EMM is a message dedicated to an individual end user (subscriber), or a group of end users, only (in contrast to an ECM, which is dedicated to only a coded program, or a set of coded programs if they are part of the same commercial offer Each group can contain a given number of end users This organization as a group is aimed at the optimization of the bandwidth, that is, access to a group can allow to reach a greater number of end users Different specific types of EMM are used in putting the present invention into practice Individual EMMs are dedicated to individual subscribers, and are typically used in the provision of Pay Per View services, these contain the identifier of group and the position of the subscriber in that group.The so-called "Group" subscription EMMs are dedicated to groups of, say, 256 individual users. dual, and are typically used in the administration of some subscription services. This EMM has a group identifier and a group bitmap of subscribers. Audience EMMs are dedicated to whole audiences, and can be used by a particular operator to provide certain free services, for example. An "audience" is the totality of subscribers that have smart cards that carry the same Operator Identifier (OPI). Finally, a "unique" EMM addresses the unique identifier of the smart card. The structure of a typical EMM will now be described with reference to Figure 3. Basically, the EMM, which is implemented as a series of digital data bits, comprises a header 3060, the appropriate EMM 3062, and a signature 3064. The header 3060 in turn comprises a type identifier 3066, to identify whether the type is individual, group, audience, or some other type, an identifier 3068 in length that gives the length of the EMM, an optional address 3070 for the EMM, an identifier Operator 3072 and a key identifier 3074. The appropriate EMM 3062 of course varies greatly, in accordance with its type. Finally, signature 3064, which is typically 8 bytes long, provides a number of checks against corruption of the remaining data in the EMM.

Subscriber Authorization System (SAS) Messages generated by SMS 3004.se 'are passed through link 3006 to the Subscriber Authorization System (SAS) 3002, which in turn generates messages recognizing the reception of messages generated by SMS 3004, and passes these acknowledgments to SMS 3004. As shown in Figure 4, at the hardware level the SAS understands the way a main frame 3050 computer (in the preferred embodiment a DEC machine) connected to one or more keyboards 3052 for data entry and commands, one or more Visual Display Units (VDUs) 3054 for the visual display of the output information, and 3056 data storage elements. Some redundancy in the hardware can be provided. At the software level, the SAS operates, in the preferred embodiment, in a standard open VMS operation system, a software collection whose architecture will now be described in general view, with reference to Figure 5; it will be understood that the software can be implemented alternatively in the hardware. In general, the SAS comprises an area 3100 of Subscription chain to give rights for the subscription mode, and to renew the rights automatically every month, a 3200 area of Pay Per View chain to give rights for PPV events, and a 3300 EMM Injector to pass the EMMs created by the Subscription and PPV chain areas to the multiplexer and encoder 2004, and consequently to feed the MPEG stream with EMMs. If other rights, such as Payment Per File (PPF) rights are to be granted in the case of downloading computer software to a user's Personal Computer, other similar areas are also provided. One function of the SAS 3002 is to manage access rights to television programs, available as commercial offers in subscription mode, or sold as PPV events, in accordance with different marketing modes (pre-contract mode, impulse mode) . SAS 3002, in accordance with those rights and with the information received from SMS 3004, generates EMMs for the subscriber. The 3100 area of the Subscription Chain comprises one Command Interface (Cl) 3102, a server 3104 of Technical Subscriber Management (STM), a Message Generator (MG) 3106, and Coding Unit 3008. The PPV Chain area 3200 comprises an Authorization Server (AS) 3202, a relationship database 3204 for storing relevant details of the end users, a support list database 3205, Servers 3206 Database for the database, a Centralized Order Server (OCS, for its acronym in English) 3207, a Server for Transmitter Program (SPB, for its acronym in English) 3208, a Message Generator ( MG, for its acronym in English) 3210 whose function is basically the same as that of the area of Subscription Chain and consequently is no longer described in any detail, and Unit 3008 Coding. The 3300 EMM injector comprises a plurality of Message Emitters (MEs) 3302, 3304, 3306 and 3308, and Software Multiplexers (SMUXs) 3310 and 3312. In the preferred embodiment, there are two MEs, 3302 and 3304 for Message Generator 3106, with the other two MEs 3306 and 3308 for Message Generator 3210. The MEs 3302 and 3306 are connected to the SMUX 3310, while the MEs 3304 and 3308 are connected to the SMUX 3312. Now each of the three main components of the SAS (the Subscription Chain area, the service area) will be considered in more detail. PPV chain and the EMM Injector).

Subscription Chain Area Considering first the area 3100 of the Chain of Subscription, the Command Interface 3102 is mainly for dispatching messages from the SMS 3004 to the 3104 STM server, as well as to the OCS 3206, and from the OCS to the SMS. The Command Interface takes as input from the SMS any direct commands or batch files containing commands. It performs parsing in the messages that come from the STM server, and is capable of issuing exact messages when an error occurs in a message (parameter out of range, missing parameter, and so on). It tracks the commands that enter in text form in a tracking file 3110, and also in binary form in a repeat file 3112, in order to be able to repeat a series of commands. Traces can be disabled and the size of the files can be limited. A detailed discussion of the STM server 3104 is now provided with particular reference to Figure 6. The STM server is effectively the main machine of the Subscription Chain area, and is intended to administer free rights, the creation of new ones. Subscribers and the renewal of existing subscribers. As shown in the figure, the commands are passed to the Message Generator 3106, however in a different format from that in which the commands are passed to the STM server. For each command, the STM server is configured to send an acknowledgment message to the Cl, only when the relevant command has been successfully processed and sent to the MG. The STM server includes a subscriber database 3120, in which all the relevant parameters of the subscribers are stored (smart card number, commercial offers, status, group and position in the group, and so on). The database performs semantic verifications of the commands sent by Cl 3102 against the contents of the database, and updates the database when the commands are valid. The STM server also manages a 3122 First-In-First-Out (FIFO) buffer between the STM server and the MG, as well as a FIFO 3124 backup disk. The purpose of the FIFOs is to average the command flow from Cl, if the MG is not able to respond for a while for any reason. They can also ensure that in the event of a failure of the STM server or the MG, no command will be lost, since the STM server is configured to flush (that is, send to the MG) its FIFOs when they are restarted. The FIFOs are implemented as files. The STM server includes a server in its core 3126 automatic renewal that automatically generates renewals, and, if required by operators, free rights. In this context, one can think of the generation of renewals as including the generation of rights for the first time, although it will be understood that the generation of new rights starts in the SMS. As will be evident, the two can be treated by almost the same commands and EMMs. Having the STM separate from the SAS, and the automatic renewal server inside the SAS, instead of (in known systems) in the SMS 3004, is a particularly important feature, since this can significantly reduce the number of commands that need to be passed. from SMS to SAS (keeping in mind that SMS and SAS can be in different locations and operated by different operators). In fact, the two main commands that are required of the SMS are merely commands that a new subscription must be started, and that an existing subscription must be stopped (for example, in the case of non-payment). By minimizing the exchange of commands between the SMS and the SAS, the possibility of failure of the transfer of commands on link 3006 between the two is reduced; In addition, generally the design of the SMS does not need to take into account the characteristics of the conditional access system 3000. The automatic renewal proceeds in the manner indicated in the flow diagram of Figure 7. In order to reduce the bandwidth, and given that a very high percentage of all renewals are standard, the renewal proceeds in groups of subscribers; in the preferred modalities there are 256 individual subscribers per group. The flow chart begins with step 3130 starting, and proceeds to step 3132, where a monthly activation of the renewal function is performed (although of course it will be noted that other frequencies are also possible). With a monthly frequency, the rights are given to the end user for the current month and all of the next month, at which point they expire if they are not renewed. In step 3134 the subscriber's database 3120 is accessed with respect to each group and each individual within that group, to determine if the rights for the particular individual will be renewed. As shown in Figure 8, in step 3136, a group subscription bitmap is established, in accordance with the content of the subscriber database. The bitmap comprises a group identifier (in this case Group 1 - "Gl") 3138, and 256 individual subscriber zones 3140. The individual bits in the bitmap are set to l or zero, according to whether the particular subscriber is going to renew their rights or not. The figure shows a typical set of binary data. In step 3142, the appropriate commands, including the group subscription bitmap, are passed to Message Generator 3106. In step 3143 the Message Generator sets a disuse date, to indicate to the smart card the date beyond which the particular subscription EMM is not valid; Typically this date is set as the end of the next month. In step 3144 the Message Generator generates from the appropriate group subscription EMMs commands, and asks the Coding Unit 3008 to code the EMMs, the encoded EMMs being passed then to the EMM Injector 3300, which, in step 3146, injects the EMMs into the MPEG-2 data stream. Step 3148 indicates that the procedure described above is repeated for each and every group. The process is finally brought to an end in step 3150 of unemployment. The flow chart described above with reference to Figure 7 is in fact related specifically to the renewal of subscriptions. The STM also administers the free audience rights and the new subscribers in a similar way.

In the case of free audience rights, available for specific television programs or groups of those programs, these are made available through the STM that issues a command to the Message Generator to generate appropriate hearing EMMs (for an entire audience), consequently with a disuse date a number of days (or weeks) given. The MG calculates the precise disuse date based on the STM command. In the case of new subscribers, these are treated in two stages. First, the purchase of the smart card in the receiver / decoder 2020 (if desired by the operator) gives the subscriber free rights for a given period (typically a few days). This is. get through the generation of a bitmap for the subscriber, which includes the relevant date of disuse. Then the subscriber passes his finished paperwork to the operator that manages the subscriber (in the SMS). Once the paperwork has been processed, the SMS provides the SAS with a start command for that particular subscriber. Upon receipt by the SAS of the start command, the STM instructs the MG to assign a unique address to the new subscriber (with a particular group number and position within the group), and to generate a special subscription EMM, called " commercial offer "(as opposed to the more usual" group "subscription EMM used for renewals), to provide the particular subscriber with rights until the end of the following month. From this point the subscriber renewal can happen automatically as described above. Through this two-stage process it is possible to grant rights to new subscribers, until the SMS issues a stop command. It should be noted that the commercial offer subscription EMM is used for new subscribers and for the reactivation of existing subscribers. The group subscription EMM is used for renewal and suspension purposes. With reference to Figure 9, an appropriate typical subscription EMM (i.e., ignoring the header and signature) generated by the above procedure, comprises the following main portions, typically a subscription bitmap 3152 (or group of subscribers) 256-bit, 128-bit keys 3154 management encoding for EMM encoding, 64 bits of each utilization encoding key 3156 to enable the smart 3020 card to decrypt a control word, to provide access to transmission programs , and 16 bits of date 3158 of disuse to indicate the date beyond which the smart card will ignore the EMM. In fact, in the preferred embodiment, three utilization keys are provided, one set for the present month, one set for the next month, and one for resumption purposes in the case of system failure.

In more detail, the appropriate group subscription EMM has all of the above components, except the administration encoding keys 3154. The appropriate commercial offer subscription EMM (which is for an individual subscriber) includes, instead of the complete subscriber group bit map 3152, the group ID followed by the position in the group, and then the coding keys 3154 of administration, and three keys 3156 of aprovechamiento, followed by the date 3158 of desuso relevant. The Message Generator 3106 serves to transform the commands issued by the STM server 3104 into the EMMs, to pass them to the Message Transmitter 3302. With reference to Figure 5, first, the MG produces the appropriate EMMs and passes them to the Coding Unit 3008 for coding with respect to the administration and utilization keys. The CU terminates signature 3064 in the EMM (see Figure 3) and passes the EMM back to the MG, where the 3060 header is added. The EMMs that are passed to the Message Emitter are thus complete EMMs. The Message Generator also determines the start and stop time of the transmission, and the emission speed of the EMMs, and passes these as appropriate addresses along with the EMMs to the Message Emitter. The MG only generates a given EMM once; This is the ME that performs its cyclic transmission. Again with reference to Figure 5, the Message Generator includes its own EMM database 3160 that stores during the lifetime of the relevant EMM. This is deleted once its duration has expired. The database is used to ensure consistency between the MG and the ME, so that, for example, when an end user is suspended, the ME will not continue to send renewals. In this respect, the MG calculates the relevant operations and sends them to the ME. Upon generation of an EMM, the MG assigns a unique identifier to the EMM. When the MG passes the EMM to the ME, it also passes the EMM ID. This allows the identification of a particular EMM in both the MG and the ME. Also with respect to the area of Subscription Chain, the Message Generator includes two FIFOs 3162 and 3164, one for each of the Issuers 3302 and 330.4 of relevant Messages in the EMM Injector 3300, to store the encoded EMMs. Since the Subscription Chain area and the EMM Injector can be separated by a significant distance, the use of FIFOs can allow full continuity in EMM transmission even if links 3166 and 3168 between the two fail. Similar FIFOs are provided in the Pay Per View chain area. A particular characteristic of the Message Generator in particular, and the conditional access system in general, has to do with the way in which it reduces the length of the appropriate EMM 3062, by mixing the length of the parameter and the identifier to save space. This is now described with reference to Figure 10, which illustrates an exemplary EMM (in fact a PPM EMM, which is the simplest EMM). The reduction in length occurs in the Pid (Package identifier or "Parameter") 3170. This comprises two portions, the actual ID 3172, and the length parameter for the 3174 packet (necessary in order to be able to identify the start of the next package). All Pid is expressed in just one byte of information, with 4 bits reserved for the ID, and four for the length. Because 4 bits are not enough to define the length in true binary form, a different correspondence between the bits and the actual length is used, this correspondence being represented in a look-up table, stored in the storage area 3178 in the Generator of Messages (see Figure 5). The correspondence is typically as follows: - 0000 = 0 0001 = 1 0010 = 2 0011 = 3 0100 = 4 0101 = 5 0110 = 6 0111 = 7 1000 = 8 1001 = 9 1010 = 10 1011 = 11 1100 = 12 1101 = 16 1110 = 24 1111 _ 32 It will be seen that the length parameter is not directly proportional to the actual length of the packet; the relationship is in part more quadratic rather than linear. This allows a greater range of package length.

Payment Chain Area Per Event With respect to the 3200 area of the Pay Per View Chain, with reference to Figure 5, in more detail, the Authorization Server 3202 has as its client the Centralized Order Server 3207, which requests information about each subscriber that connects to the Communications Servers 3022 to buy a PPV product. If the subscriber is known from AS 3202, a set of transactions takes place. If the subscriber is authorized for the order, the AS creates an invoice and sends it to the OCS. Otherwise, it tells the OCS that the order is not authorized. It is only at the end of this set of transactions that the AS updates the 3204 database of end users by means of the database servers (DBAS) 3206, if at least one transaction was authorized; this optimizes the number of database accesses. The compliance criteria with which the AS authorizes the purchase are stored in the database, accessed through the DBAS processes. In one modality, the database is the same as the database accessed through the STM. Depending on the profile of the consumer, authorization may be denied (PPV_Forbidden, Casino_Forbidden ...). This kind of criteria is updated through STM 3104, in favor of SMS 3004. Other parameters are verified, such as the limits allowed to buy (either by credit card, automatic payment, or number of authorized password purchases by day) . In the case of payment with a credit card, the card number is verified against a local backup list, stored in database 3205 of the local backup list. When all verifications are successful, the AS: -1. It generates an invoice and sends it to the OCS, which ends this invoice and stores it in a file, this file being subsequently sent to the SMS for processing (actual customer billing); and 2. Update the database, mainly to establish new purchase limits. It should be noted that the AS has a reduced amount of information regarding the subscriber, compared to the one that the SMS has. For example, the AS does not contain the name or address of the subscriber. On the other hand, the AS does contain the subscriber's smart card number, the consumer category of the subscriber (so that different offers can be made to different subscribers), and different flags that establish whether, for example, the subscriber can buy on credit, or if your smart card is stolen or has been stolen. The use of a reduced amount of information can help reduce the amount of time it takes to authorize a particular subscriber request. The main purpose of the DBASs 3206 is to increase the functioning of the database seen from the AS, by means of putting the accesses in parallel (so that really does not make much sense to define a configuration with only one DBAS). An AS parameter determines how many DBASs should be connected. A given DBAS can be connected to only one AS. The OCS 2307 deals mainly with PPV commands. This operates in many ways. First, it operates to process the process commands issued by the SMS, such as regeneration (for example, if the SMS already stored the invoice, the OCS does not generate an invoice), update the portfolio on the smart 3020 card, and cancel / session update. The different steps in the procedure are: -1. Identify the relevant subscriber (using AS 3202); 2. If it is valid, generate the appropriate commands to the Message Generator, in order to send an appropriate EMM. The commands can be: Product Commands, Update of the portfolio, Deletion of the session. Note that these operations do not involve the creation of billing information, since billing is already known by SMS. These operations are assimilated to buy "free products". Secondly, the OCS deals with the commands that are received from the subscribers, through the Communications Servers 3022. These can be received either by means of a modem connected to the receiver / decoder 2020, or by voice activation by means of the telephone 4001, or by key activation by means of a MINITEL, PRESTEL or similar system where it is available . Third, the OCS deals with the callback requests that the SMS issues. The last two modes of operation will now be discussed in more detail. In the second type of mode described above it was established that the OCS deals with the commands that are received directly from the end user (subscriber), through the Communication Servers 3022. These include product orders (such as for a particular PPV event), a subscription modification requested by the subscriber, and a reset of a parent code (a parent code being a code by which parents can restrict the right of access to certain programs or program classes). The way in which these commands are dealt with will now be described in more detail, with reference to Figure 11. 1. Identify, through the AS, the caller who is making a call through CS 3022, who orders a particular product; 2. Verify the validity of the caller's request, again using the AS (where the order is placed using the receiver / decoder 2020, this is achieved by verifying the details of the smart 3020 card); 3. Find out the price of the purchase; 4. Verify that the price does not exceed the credit limit of the caller, etcetera; 5. Receive a partial invoice from the AS; 6. Fill in additional fields on the invoice to form a complete invoice; 7. Add the finished invoice to a billing information storage file 3212 for further processing; and 8. Send the corresponding command (s) to the PPV Message Generator 3210 to generate the relevant EMM (s). The EMM (s) is sent either on the line. 4002 of the modem, if the consumer placed the order of the product using the receiver / decoder 2020 (further details on this are described later), or otherwise it is transmitted. The only exception to this is when there is some failure of the modem connection (in the case where the consumer places the order using the receiver / decoder); in this event the EMM is transmitted through the air. A subscription modification that a subscriber requires includes: 1. Identifying the caller (using the AS); 2. Send the information to the Command Interconnection (Cl, for its acronym in English); Cl in turn sends this information to the SMS; and 3. Through the CI, the OCS then receives a response from the SMS (in terms of the cost of the modification, if the modification is possible). If the modification was requested using the receiver / decoder, the OCS generates a confirmation to the SMS. Otherwise, for example, in the case of the telephone or the Minitel, the subscriber is asked for confirmation and this response is sent to the SMS through the OCS and the Cl. The restoration of a maternal code includes: 1. Identify the caller (using the AS); and 2. send a command to the MG to generate an appropriate EMM that carries an appropriate reset password. In the event that the maternal code is restored, the command to reset the code is not allowed to originate from the receiver / decoder, for security reasons. Only the SMS, the telephone and the MINITEL or similar, can originate that command. Therefore, in this particular case, only the EMM (s) are transmitted to the air, never over the telephone line. From the previous examples of the different modes of operation of the OCS, it will be understood that the user can have direct access to the SAS, and in particular to the OCS and the AS, because the Communication Servers are connected directly to the SAS, and in particular to the OCS. This important feature is interested in reducing the time for the user to communicate his command to the SAS. This feature is further illustrated with reference to Figure 12, from which it can be seen that the Superior Box of the end user, and in particular its receiver / decoder 2020, has the ability to communicate directly with the Communications Servers 3022, associated with SAS 3002. Instead of the connection from the end user to the Communications Servers 3022 of SAS 3002 through SMS 3004, the connection is direct to SAS 3002. In fact, as mentioned directly, Two direct connections are provided. The first direct connection is through a voice link using a 4001 telephone and the appropriate telephone line (and / or by MINITEL or similar connection where available), where end users have to enter a series of voice commands or code numbers, but saves time compared to communication via SMS 3004. The second Direct connection is from the receiver / decoder 2020 and the data entry is automatically achieved by the end user who inserts his own secondary 3020 smart card, thus freeing the user from the work of having to enter the relevant data, which, in turn, reduces the time it takes and the probability of errors when making that entry. An additional important feature that emerges from the above discussion is related to reducing the time it takes for the resulting EMM to be transmitted to the end user, with the aim of initiating the look by the end user of the product that was selected. In broad terms, and with reference to Figure 12, the feature is again achieved by providing the receiver / decoder 2020 of the end user with the ability to communicate directly with the Communications Servers 3022, associated with SAS 3002. As described above, the integrated receiver / decoder 2020 is connected directly to the Communications Servers 3022 via the modulated-demodulated return channel 4002, so that the SAS 3002 processes the commands from the decoder 2020, the messages generated (including the EMMs) and then sent back directly to the decoder 2020 through the return channel 4002. A protocol is used in the communication between the CS 3022 and the receiver / decoder 2020 ( as will be described later), so that the CS receives the acknowledgment of receipt of the relevant EMM, adding with the same certainty to the procedure. . Thus, for example, in the case of a pre-contracting mode, the SAS 3002 receives the messages from the end user by means of the smart card and the decoder 2020 by means of its modem and by the telephone line 4002, requesting access to a event / specific product, and a suitable EMM returns via the telephone line 4002 and the modem to the decoder 2020, the modem and the decoder preferably located together in a Superior Box (STB). This is achieved, therefore, without having to transmit the EMM in the 2002 MPEG-2 data stream through the multiplexer and the demodulator 2004, the uplink 2012, satellite 2014, and data link 2016, to allow the end user to see the event / product. This can save considerably in terms of time and bandwidth. HE "provides the implicit certainty that as soon as the subscriber has paid for their purchase, the EMM will arrive at the receiver / decoder 2020. In the third type of operation mode of the OCS 3207 that was described above, the OCS deals with requests and calls This is illustrated with reference to Figure 13. The typical callback requests are intended to ensure that the receiver / decoder 2020 calls back to the SAS using the return channel 4002 modulated-demodulated with the information required by the receiver / decoder SAS As instructed in the Command Interconnection 3102, the Message Generator 3106 of the subscription chain generates and sends a call EMM back to the receiver / decoder 2020. The Encryption 3008 encodes this EMM for security reasons.The EMM can contain the time / date in which the receiver / decoder should be lifted and a call made. return by itself, without having requested it explicitly; The EMM can also typically contain the telephone numbers that the terminal should dial, the number of additional attempts after unsuccessful calls, and the delay between the two calls. When the EMM is received, or at the specified time-date, the receiver / decoder connects to the Communication Servers 3022. The OCS 3207 first identifies the caller, using the AS 3202, and verifies certain details, such as the smart card operator and the details of the subscriber. Next, the OCS asks the 3020 smart card to send a different coded information (such as the relevant session numbers, when the session was observed, how many times the user is allowed to see the session again, how it was seen the session, the number of passwords remaining, the number of sessions previously contracted, etc.). The Message Generator 3210 of the PPV chain decrypts this information, again using the Encryption Unit 3008. The OCS adds this information to a storage file 3214 of callback information for further processing and passing it to the SMS 3004. The encryption is encrypted. Information for security reasons. The entire procedure is repeated until there is more to read on the smart card. A particular feature that is preferred of the installation of the call back, is that before reading the smart card (right after the identification of the caller using the AS 3202, as described above), the SAS 3002 makes a verification that the receiver / decoder is really a genuine version instead of a pirated version or an operator simulation. This verification is done as follows. The SAS generates a random number, which receives the receiver / decoder, encoded, and then returns it to the SAS. The SAS deciphers this number. If the decryption is successful and the original random number is retrieved, it is concluded that the receiver / decoder is genuine, and the procedure continues. Otherwise, the procedure is discontinued. Other functions that may occur during the return call are the deletion of the obsolete sessions on the smart card, or the filling of the portfolio (the latter being described later under the section entitled "Smart Card").

Also in regard to the 3200 area of the Pay Per View Chain, a description of the Communications Servers 3022 is now made. At the hardware level, these comprise in the preferred embodiment, a parallel processing machine DEC Four. At the software design level, with reference to Figure 14, in many respects the Communication Servers are conventional. A particular divergence of the conventional designs arises from the fact that the Servers must serve both the receivers / decoders 2020, and the voice communication with the conventional 4001 telephones, as well as possibly the MINITEL or similar systems. It will be noted in passing, that Figure 14 shows two Centralized Order Servers 3207 (such as "OCS1" and "0CS2"). Naturally, any desired number can be provided. The Communication Servers include two main servers ("CS1" and "CS2"), as well as a number of front servers ("Front 1" and "Front 2"); although two front servers are shown in the Figure, typically 10 or 12 will be provided per main server. In fact, although two main CS1 and CS2 servers and two front servers, Frontal 1 and Frontal 2, have been shown, any number can be used. Usually some redundancy is desirable. CS1 and CS2 are coupled to OCS1 and OCS2 via high-level 3230 TCP / IP links, while CS1 and CS2 are coupled to Frontal 1 and Frontal 2 via additional 3232 TCP / IP links. As illustrated, CS1 and CS2 understand the servers for "SENDR" (transmission), "RECVR" (reception), "VTX" (MINITEL, PRESTEL, or similar), "VOX" (voice communication), and " TRM "(communication with the receiver / decoder). These are coupled to the "BUS" for the communication of signals to the Frontal servers. The CS1 and the CS2 communicate directly with the receiver / decoder 2020 through their modulated-demodulated return channels, using the common public network protocol X25. The relatively low level protocol between the Communications Servers 3022 and the receivers / decoders 3020 is based, in a preferred embodiment, on the standard international CCITT protocol V42, which provides reliability by having error detection and data retransmission facilities , and uses a checksum routine to verify the integrity of the retransmission. An escape mechanism is also provided in order to avoid the transmission of rejected characters. On the other hand, the voice telephone communication is made through the Frontal Communications Servers, each capable of lifting, say, 30 simultaneous voice connections from the 3234 connection to the local telephone network through the standard telephone ISDN lines high speed "T2" (The). The three particular functions of the software portion of the Communications Servers (which could of course be fully implemented alternatively in the hardware) will first convert the relatively low level protocol information that was received from the receiver / decoder, into the relatively high level protocol information that goes out to the OCS, will secondly attenuate or control the number of simultaneous connections that are being made, and thirdly it will provide different simultaneous channels without any mixing. In this last respect, the Communications Servers play the role of a multiplexer form, with the interactions in a particular channel being defined by a given Session ID, which is in fact used throughout the entire chain of communication. communication. Finally, with respect to the area 3200 of the Pay-Per-Order Chain, and with reference again to Figure 5, the Server for the Transmission of the Program (SPB) 3208 to one or more 3250 Program Transmitters (which would typically be located remotely from the SAS), to receive the program information. The SPB filters for the additional use of the information that corresponds with the PPV events (sessions).

A particularly important feature is that the SPB passes the event information of the filtered program to the MG, which in turn sends a directive (control command) to the ME to change the speed of the cyclic issuance of the EMMs in given circumstances; this is done through the ME that finds all the EMMs with the relevant session identifier and that changes the speed of the cycle that is assigned to those EMMs. You can think of this feature as a dynamic allocation of bandwidth for specific EMMs. The cyclic EMM emission is discussed in more detail in the section below that relates to the EMM Injector. Now we describe the circumstances in which the cycle speed is changed, with reference to Figure 15, which shows how the 3252 cycle speed is raised one moment (say 10 minutes) before a particular PPV program event, until the end of the event from a slow cycle speed of, say, once every 30 minutes, to a fast cycle speed of, say, once every 30 seconds to 1 minute, in order to meet the extra demand anticipated by the user for PPV events at those times. In this way, bandwidth can be assigned dynamically, in accordance with the user's anticipated demand. This can help reduce the total bandwidth requirement.

You can also vary the cycle speed of other EMMs. For example, the cycle speed of subscription EMMs may be varied by the Multiplexer and Scrambler 2004 that sends the appropriate bit rate policy.

EMM Injector With respect to the EMM 3300 Injector, details of the Message Emitters 3302 to 3308, which are part of the EMM Injector and act as output means for the Message Generator, are now described with reference to the Figure 16. Its function is to take the EMMs and pass them in a cyclical way (in the manner of a carousel), through the respective links 3314 and 3316 to the Software Multiplexers 3310 and 3312 and from there to the hardware multiplexers and demodulators 2004. In change, the software multiplexers and the demodulators 2004 generate a global bit rate directive to control the total cycle speed of the EMMs; to do this, the MEs take into account different parameters, such as the cycle time, the size of the EMM, and so on. In the Figure, EMM_X and EMM_Y are the group EMMs for the X and Y operators, while EMM_Z are other EMMS, either for the operator X or the operator Y. An additional description is provided for an instance of the Message Emitters; it will be appreciated that the remaining MEs operate in a similar manner. The ME operates under the control of MG directives, most notably the start and time of suspension of the transmission and the speed of the issue, as well as the session number if the EMM is a PPV EMM. In relation to the speed of the emission, in the preferred modality the relevant directive can take one of five values from Very fast to Very slow. The numerical values are not specified in the directive, but rather the ME maps the directive to a current numerical value, which is supplied by the relevant part of the SAS. In the preferred mode, the 5 emission speeds are as follows: 1. Very fast - every 30 seconds 2. Fast - every minute 3 3 .. M Meeddiiaa - every 15 minutes 4. Slow - every 30 minutes 5. Very slow - every 30 minutes The ME has databases 3320 and 3322 first and second. The first database is for those EMMs that have not yet achieved their dissemination date; these are stored in a series of chronological files in the database. The second database is for EMMs for immediate transmission. In the case of a system crash, the ME is configured so that it has the ability to reread the relevant stored file and perform the correct transmission. All the files stored in the databases are updated by request of the MG, when the MG wants to maintain the consistency between the incoming directives and the EMMs that were already sent to the ME. The EMMs that are actually broadcast in the Random Access Memory 3324 are also stored. A combination of the FIFOs 3162 and 3164 in the Message Generator and the 3320 and 3322 databases in the Message Emitter means that both can operate in stand-alone mode if the 3166 link is temporarily broken between them; the ME can still spread the EMMs. The Software Multiplexers (SMUX) 3310 and 3312 provide an interconnection between the MEs and the hardware multiplexers 2004. In the preferred modality, each one receives EMMs from two of the MEs, although in general there is no restriction on the number of MEs that They can be connected with an SMUX. The SMUXs concentrate the EMMs and then pass them in accordance with the EMM type to the appropriate hardware multiplexer. This is necessary because the hardware multiplexers take the different types of EMMs and place them in different places in the MPEG-2 stream. The SMUX also sends the global bit rate directives from the hardware multiplexers to the MEs. A particularly important feature of the ME is that it emits the EMMs in random order. The reason for this is as follows. The Message Emitter does not have the ability to detect or control what it outputs to the multiplexer. Therefore, it is possible that you can transmit two EMMs that will be received and decoded by the receiver / decoder 2020, back to back. In such circumstances, additionally, it is possible that if the EMMs are insufficiently separated, the receiver / decoder and the smart card will not be able to detect or decode the second of the EMMs appropriately. Cyclically issuing EMMs in random order can solve this problem. The manner in which randomization is achieved is now described, with reference to Figure 17; in the preferred modality, the logic of the necessary software in the ADA computer language is implemented. A particularly important part of the scrambling is the correct storage of EMMs in databases 3320 and 3322 (which are used for backup purposes) and in RAM 3324. For a particular cycle speed and operator, they are stored EMMs in a two-dimensional configuration, through the 3330 range (ranging from, say A to Z) and the 3332 rank number (ranging from 0 to N). A third dimension is added by the cycle speed 3334, so that there are as many two-dimensional configurations as there are cycle speeds. In the preferred embodiment, there are 256 rows and typically 200 or 300 EMMs in each row; There are 5 cycle speeds. A final dimension is added to the configuration through the presence of different operators; There are as many three-dimensional configurations as there are operators. The storage of the data in this manner may allow recovery in case the MG wishes to delete a particular EMM. The storage of the EMMs is carried out in accordance with the "random check" algorithm (which is otherwise known as the "one-way random check function"). This operates in a module approach, so that the successive rows are filled before a higher number is used in the row, and the number of EMMs in each row remains approximately constant. The example is considered as being of 256 rows. When the MG sends to the ME an EMM with the identifier (ID) 1, the rank "1" is assigned to this EMM, and it takes the first number 3332 in the range 3330. The rank "2" is assigned to the EMM with the ID 2, and so on, up to the 256 rank. Again the rank "1" is assigned to the EMM with the ID 257 (based on the module function), and it takes the second number in the first row, and so on. The recovery of a specific EMM, for example when the MG requests the deletion of a specific EMM, is carried out by means of the inverse of the above. The randomization algorithm is applied to the ID of the EMM to obtain the row, after which the number in the row is found. The current scrambling occurs when the EMMs are removed, on a cyclic basis, from the RAM 3324 using the scrambling means 3340, which is implemented in the hardware and / or software of the Message Emitter. The recovery is random, and is based again on the random check algorithm. First, a random number (in the previous example initially in the range of 1 to 256) is chosen to produce the particular range of interest. Second, a random number is chosen to produce the particular number in the row. The furthest random number is selected in accordance with the total number of EMMs in a given row. Once a given EMM has been selected and broadcast, it moves to a second identical storage area in RAM 3324, again using the random check function. Therefore, the first area decreases in size as EMMs are diffused, to the extent that, once a full range has been used, this is suppressed. Once the first storage area is completely empty, it is replaced by the second storage area, before a new transmission period of the EMM, and vice versa. In the previous mode, after two or three cycles of the EMMs, statistically insignificant are the probabilities of transmitting back to back any of the two EMMs intended for the same end user. At regular intervals, while the EMMs are being stored, the computer 3050 calculates the number of bytes in storage and from this, calculates the bit rate of the transmission, given the global bit rate directive from the multiplexer and the software multiplexer. Reference was previously made to backup databases 3320 and 3322. These are in fact, in the preferred mode, sequential file repositories, which hold a backup version of what is in RAM 3324. In the case of the Message Emitter failure and the subsequent reboot, or more generally, when the ME is rebooting for any reason, a link is made between the RAM and the databases, on which the EMMs are loaded into the RAM. In this way, the risk of losing the EMMs in case of failure can be removed. Storage of the PPV EMMs similar to that described above occurs in relation to the subscription EMMs, with the range typically corresponding to a given operator and the number in the range corresponding to the session number. Figure 18 schematically shows a secondary, or "subscriber", smart card 3020, and comprises an 8-bit microprocessor 110, such as a Motorola 6805 microprocessor, having an input / output busbar coupled to a configuration contact standard 120, which are connected when in use, to a corresponding configuration of contacts in the card reader of the receiver / decoder 2020, the card reader being of conventional design. Microprocessor 110 with busbar connections to ROM 130, RAM 140 and EEPROM 150 is also preferably provided with masks. The smart card complies with the standard protocols of ISO 7816-1, 7816-2 and 7816-3, which determine certain physical parameters of the smart card, the positions of the contacts on the chip and certain communications between the external system (and particularly the receiver / decoder 2020) and the smart card respectively, and which, therefore, will not be further described here. One function of the microprocessor 110 is to handle the memory in the smart card, as will now be described. The EEPROM 150 contains certain dynamically created operator zones 154, 155, 156 and dynamically created data zones, which will now be described with reference to Figure 19. With reference to Figure 19, the EEPROM 150 comprises a 8-byte zone 151 of permanent "card identifier" (or manufacturer), which contains a permanent subscriber's smart card identifier, established by the manufacturer of the 3020 smart card. When the smart card is reset, the microprocessor 110 emits a signal to the receiver / decoder 2020, the signal comprising an identifier of the conditional access system using the smart card and the data that is generated from the data stored in the smart card, including the identifier card. This signal is stored by the receiver / decoder 2020, which subsequently uses the signal that was stored to verify whether the smart card is compatible with the conditional access system using the receiver / decoder 2020. The EEPROM 150 also contains an area 152 of the permanent "random number generator", which contains a program for generating pseudo-random numbers. These random numbers are used to diversify the transaction output signals that are generated by the smart card 3020 and sent back to the transmitter. Below the zone 152 of the random number generator, a permanent "management" zone 153 of 144 bytes is provided. The permanent management zone 153 is a specific operator zone that uses the program in ROM 130 in the dynamic creation (and removal) of zones 154, 155, 156 ... as described below. The permanent management zone 153 contains the data that relates to the rights of the smart card to create or remove the zones.

The program to create and remove the zones in a dynamic way is responsive to the EMMs of creation (or removal) of specific zone, which are transmitted through SAS 3002 and which are received by the receiver / decoder 2020 and are passed to the subscriber smart card 3020. In order to create the EMMs, the operator requires specific keys that are dedicated to the administration area. This prevents an operator from deleting areas that are related to another operator. Below the administration area 153, there is a series of zones 154, 155, 156 of "operator identifier" for operators 1, 2 ... N, respectively. Normally, at least one operator identifier area will be preloaded in the EEPROM of the subscriber's smart card 3020, so that the end user can decrypt the transmission of programs through that operator. However, additional areas of the operator identifier may be created subsequently dynamically, using the management zone 153 in response to a transaction output signal generated by the end user (subscriber) by his smart card 3020, as will be described subsequently. . Each zone of the operator 154, 155, 156 contains the identifier of the group to which the smart card 3020 belongs, and the position of the smart card within the group. This data allows the smart card (along with the other smart cards in its group) to be responsive to a subscription EMM of the transmission "group" that has the address of that group (but not the position of the smart card in the group). group), as well as an "individual" EMM (or subscription of commercial offers) that is directed only to that smart card within the group. There may be smart cards of 256 members from each of these groups and therefore, this feature significantly reduces the bandwidth that is required to broadcast the EMMs. In order to further reduce the bandwidth required to broadcast the "group" subscription EMMs, the group data is continuously updated in each operator zone 154, 155, 156 and all similar zones in the network. EEPROM of the smart card 3020 and of the other secondary smart cards, to facilitate that a particular smart card changes its position in each group to fill any void that is formed, for example, by the deletion of a member of the group. The gaps are filled by SAS 3002, as in the STM 3104 server there is a list of these gaps. In this way, fragmentation is reduced and the membership of each group is maintained at or near the maximum of 256 members.

Each operator area 154, 155, 156 is associated with one or more "operator data objects" which are stored in the EEPROM 150. As shown in Figure 19, a series of objects 157-165 of "operator data" "dynamically created is located below the areas of the operator's identifier. Each of these objects is labeled with: a) an "identifier" 1, 2, 3 ... N corresponding to its operator 1, 2, 3, ... N associated, as shown in its section on the right side in Figure 19; b) an "identifier" that indicates the type of object; and c) a "data" area that is reserved for the data, as shown in the right-hand section of each relevant operator object in Figure 19. It should be understood that each operator is associated with a similar set of objects of 'data, so that the following description of the data types in the data objects of operator 1 is also applicable to data objects of all other operators. It will also be noted that the data objects are located in the contiguous physical regions of the EEPROM, and that their order does not matter. The deletion of a data object creates a "gap" 166 in the smart card, that is, the number of bytes that the data objects had previously occupied is not immediately occupied. The number of bytes, or "gap" that was "freed up" in this way, is labeled with: a) an "identifier" 0; and b) an "identifier" indicating that the bytes are free to receive an object. The next data object that is created fills the gap, as identified by the identifier 0. In this way, the limited memory capacity (4 kilobytes) of the EEPROM 150 is used. Returning now to the set of associated data objects with each operator, the examples of the data objects are now described. The data object 157 contains an EMM key that is used to decrypt the key EMMs that were received by the receiver / decoder 2020. This EMM key is permanently stored in the data object 157. This data object can be created 157 before distribution of the smart card 3020, and / or can be created dynamically when a new operator zone is created (as described above). The data object 159 contains the ECM keys, which are sent by the associated operator (in this case operator 1), to facilitate the end user deciphering the particular "bouquet" of programs to which it has subscribed. New ECM keys are typically sent each month, along with an EMM group subscription (renewal), which renews the total right of the end user to see the transmission from (in this case) operator 1. The use of the keys Separate EMM and ECM allow viewing rights to be purchased in different ways (in this mode by subscription and individually (Pay Per View)) and also increases security. The mode of Pay Per View (PPV) will be described in a subsequent way. Because ECM keys are sent periodically, it is essential to prevent a user from using old ECM keys, for example by turning off the receiver / decoder or resetting a clock to avoid expiration of an old ECM key , so that a timer can be bypassed in the receiver / decoder 2020. Accordingly, the operator area 154 comprises an area (which typically has a size of 2 bytes), which contains a date of disuse of the keys ECM. The smart card 3020 is configured to compare this date with the current date, which is contained in the ECMs that were received and to avoid deciphering if the current date is after the date of disuse. The disuse date is transmitted through the EMMs, as described above. The data object 161 contains a 64-bit subscription bit map, which is an exact representation of the transmission operator programs to which the subscriber has subscribed. Each bit represents a program and is set to "1" if it is subscribed and "0" if it is not.

The data object 163 contains a number of passwords that can be used by the consumer in the mode of PPV, to buy the rights of vision to an imminent transmission, for example in response to a free advance or other propaganda. The data object 163 also contains a limit value, which can be adjusted in, for example, a negative value to allow credit to the consumer. Password passwords can be purchased, for example on credit and through the return channel 4002 modulated-demodulated, or through the use of a voice server in combination with a credit card, for example. You can load a particular event as a passcode or a number of passwords. The data object 165 contains a description of a PPV event, as shown with reference to table 167 of Figure 20. The event description 167 of PPV contains a "session identifier" 168, which identifies the viewing session (corresponding to the program and the time and date of dissemination), a "session mode" 169 that indicates how the right of vision is being purchased (for example, in the previous hiring mode), a "session index" 170 and a "session view" 171. With respect to receiving a program in the PPV mode, the receiver / decoder 2020 determines whether the program is one that was sold in the PPV mode. If so, the decoder 2020 verifies, using the items stored in the description 167 of the PPV event, whether the session identifier for the program is stored therein. If the identifier of the session is stored in it, the control word is extracted from the ECM. If the identifier of the session is not stored therein, the receiver / decoder 2020 visually displays a message, by means of a specific application, to the end user indicating that he has the right to see the session at a cost of, for say, 25 passwords, as read from the ECM or to connect to the 3022 communication servers to buy the event. Using the passwords, if the end user answers "yes" (via the remote controller 2026 (see Figure 2)), the decoder 2020 sends the ECM to the smart card, the smart card decreases the wallet of the card. credit 3020 for 25 passwords, write the session identifier 168, the session mode 169, the session index 170 and the session view 171 in the description 167 of the PPV event and extract and decrypt the control word from the ECM. In the "pre-contracting" mode, an EMM will be passed to the smart card 3020 so that the smart card will write the session identifier 168, the session mode 169, the session index 170, and the session view 171 in the description 167 of the PPV event, using the EMM. The session index 170 can be adjusted to differentiate one transmission from another. This feature allows authorization for a subset of broadcasts, for example, 3 times of 5 broadcasts. As soon as an ECM is passed with a session index different from the current session index 170 stored in the 167 description of the PPV event to the smart card, the number of the session view 171. is decreased by one. session reaches zero, the smart card will refuse to decrypt an ECM with a session index different from the current session index. The initial value of the session view depends only on the manner in which the transmission provider wishes to define the event to which it relates; the session view for a respective event can take any value. The microprocessor 110 in the smart card implements a count and a comparison program to detect when the limit for the number of views of a particular program has been reached. All session identifiers can be extracted 168, session mode 169, session index 170 and session view 171 in description 167 of the PPV event from the smart card using the "call back" procedure, as previously described. Each receiver / decoder 2020 contains an identifier, which can either uniquely identify the receiver / decoder, or identify its manufacturer or can classify it in any other way in order to allow it to work only with a particular individual smart card, a class particular of smart cards made by the same or a corresponding manufacturer or any other 'class of smart cards, which are intended to be used with that kind of receiver / decoder exclusively. In this way, the receivers / decoders 2020 that have been supplied by a consumer transmission provider are protected against the use of unauthorized secondary 3020 smart cards. Additionally or alternatively to this first "link establishment" between the smart card and the receiver, the EEPROM of the smart card 3020 could contain a field or bitmap that describes the categories of the receivers / decoders 2020 with which it can function. These could be specified either during the manufacture of the 3020 smart card or through a specific EMM. The bit map that is stored in the smart card 3020 typically comprises a list of up to 80 receivers / decoders, each identified with a corresponding receiver / decoder identifier, with which the smart card can be used. Associated with each receiver / decoder is a level "1" or "0" which indicates whether the smart card can be used with the receiver / decoder or not, respectively. A program in the memory 2024 of the receiver / decoder searches for the identifier of the receiver / decoder in the bitmap stored in the smart card. If the identifier is found, and the value associated with the identifier is "1", then the smart card is "enabled"; if not, then the smart card will not work with that receiver / decoder. In addition, if, typically due to an agreement between the operators, it is desired to authorize the use of other smart cards in a particular receiver / decoder, specific EMMs will be sent to those smart cards to change their bitmap through the 2014 transceiver. Each transmission provider can differentiate its subscribers in accordance with certain previously determined criteria. For example, a number of subscribers can be classified as "VIPs". In accordance with the above, each transmission provider can divide its subscribers into a plurality of subsets, each subset comprising any number of subscribers.

The subset to which a particular subscriber belongs in SMS 3004. In turn, SAS 3002 transmits an EMM to the subscriber, which writes the information (typically 1 byte length) in relation to the subset to which the subscriber belongs. within the data area of the relevant operator, say 154, of the EEPROM of the smart card. In turn, as the events are broadcast by the broadcast provider, an EMC, typically 256 bits, is transmitted to the event and indicates which of the subsets of subscribers the event can see. If, in accordance with the information stored in the operator's area, the subscriber does not have the right to see the event, as determined by the ECM, the view of the event is denied. This facility can be used, for example, to turn off all the smart cards of a given operator in a particular geographical region during the transmission of a particular program, in particular a program that relates to a sporting event that is taking place in that region. geographical. In this way, football clubs and other sports bodies can sell broadcast rights outside their locality, while preventing local supporters from watching the meeting on television. In this way, local supporters are encouraged to buy tickets and go to the meeting. It is considered that each of the characteristics • associated with zones 151 to 172 is a separate invention independent of the dynamic creation of the zones. It will be understood that the present invention has been described above purely by way of example, and any modifications of the detail may be made within the scope of the invention. Each feature described in the description may be provided, and (where appropriate) the claims and drawings independently or in any appropriate combination. In the preferred embodiments mentioned above, certain features of the present invention have been implemented, using computer software.

However, it will of course be clear to the experienced person that any of these features can be implemented, using the hardware. Additionally, it will be readily understood that the functions performed by the hardware, computer software, and the like, are performed on or using electrical or similar signals. The cross reference is made to our pending requests, all of them having the same filing date, and titled Signal Generation and Transmission (Lawyer Reference Number PC / ASB / 19707), Card Intelligent to use with a Key Transmit Signal Receiver, and Receiver System (Lawyer Reference Number PC / ASB / 19708), Transmission and Reception and Conditional Access System for it (Attorney Reference Number PC / ASB / 19710 ), Downloading a Computer File from a Transmitter through a Receiver / Decoder to a Computer (Lawyer Reference Number PC / ASB / 19711), Transmission and Reception of Television Programs and Other Data (Lawyer Reference Number PC / ASB / 19712), Downloading Data (Lawyer Reference Number PC / ASB / 19713), Computer Memory Organization (Lawyer Reference Number PC / ASB / 19714), Development of Television Control System o'Radio (Lawyer Reference Number PC / ASB / 19715), Extracting Data Sections from a Transmitted Data Stream (Lawyer Reference Number PC / ASB / 19716), Access Control System (Lawyer Reference Number PC / ASB / 19717), Data Processing System (Lawyer Reference Number PC / ASB / 19718), and Transmission and Reception System, and Receiver / Decoder and Remote Controller for it (Lawyer Reference Number PC / ASB / 19720). The descriptions of these documents are incorporated herein by reference. The list of applications includes the present application.

Claims (57)

1. CLAIMS 1. The apparatus for repetitively generating a set of messages, comprising: means for generating a plurality of messages; means for repetitively randomizing the sequence of the messages to form a plurality of sets of these messages, so that the messages of each set are in random sequence; and means for outputting the plurality of message sets. The apparatus according to claim 1, wherein the means for generating messages include means for storing the messages that were generated. The apparatus according to claim 2, wherein the scrambling means is configured to form each set of messages by means of retrieving the messages in random sequence from the storage means. The apparatus according to claim 2 or 3, wherein the storage means is configured to store the messages in at least one two-dimensional configuration. The apparatus according to any of the preceding claims, characterized in that it further comprises means coupled to the output means for varying the speed at which the plurality of sets of messages are output. The apparatus according to any of claims 2 to 4, characterized in that it further comprises means coupled to the storage means for evaluating the size of the messages stored in the storage means, and means coupled to the output means to vary the speed at which the plurality of message sets is output, with dependence on that size of the messages. The apparatus according to any of the preceding claims, wherein the generating means and the scrambling means are coupled by means of a First In and First Out device. The apparatus according to any of the preceding claims, wherein the output means includes means for storing at least one of the message sets. The apparatus according to any of the preceding claims, wherein a plurality of sets of messages are provided, and further comprising a multiplexer for receiving the plurality of sets of messages to which the plurality of output means outputs. . 10. An access control system for a transmission and reception system, the access control system including, at the end of the transmission, the apparatus according to any of the preceding claims, and, at the receiving end, a device to receive those messages. An access control system according to claim 10, wherein the message is an accreditation message for transmitting to the receiving device. 12. A transmission and reception system that includes an access control system, in accordance with claim 11. 13. A method for repetitively generating a set of messages, comprising: generating a plurality of messages; repetitively randomizing the sequence of the messages, to form a plurality of sets of these messages, so that the messages of each set are in random sequence; and output the plurality of message sets. 14. A method in accordance with the claim 13, characterized in that it includes the step of storing the messages that are generated in the generation step, and wherein, in the randomization step, each set of messages is formed by means of retrieving the messages in random sequence. 15. A method for controlling the access of a user to a transmission and reception system, including, at the transmission end, a method for repetitively generating a set of messages, in accordance with claim 13 or 14, and, in the end d reception, the step of receiving these messages. 16. A method according to claim 15, wherein the message is an accreditation message to be received by the receiving step. 17. The apparatus as substantially described herein with reference to, and as illustrated in the accompanying drawings, and especially Figure 16 and 17 thereof. The apparatus according to any of claims 1 to 9, wherein the output means is configured to output the plurality of message sets as a digital signal that includes a digital data packet and an identifier for the packet , the identifier being less than two bytes in length. 19. The apparatus for generating a digital signal, comprising a digital data packet and an identifier for the packet, comprising: means for generating the data packet; and means for generating the identifier; wherein: the identifier generation means are configured to generate an identifier, which is less than two bytes in length. 20. The apparatus according to claim 18 or 19, wherein the identifier comprises an identity parameter and a length parameter. 21. The apparatus according to claim 20, wherein the identity and length parameters are each 4 bits in length. 22. The apparatus according to claim 20 or 21, wherein the digital value of the length parameter is not directly proportional to the actual length of the packet. 23. The apparatus according to any of claims 20 to 22, characterized in that it further comprises means for storing a look-up table that gives the correspondence between the digital value of the length parameter and the actual length of the packet. 24. A transmission and reception system including, at the transmission end, the apparatus according to claims 18 to 23, and, at the receiving end, a device for receiving that signal. 25. A method according to any of claims 13 to 16, wherein the plurality of messages is output as a digital signal comprising a packet of digital data and an identifier for the packet, the identifier being less than two bytes of length. 26. A method for generating a digital signal comprising a digital data packet and an identifier for the packet, comprising: generating the data packet; and generate the identifier; where: the identifier is less than two bytes in length. 27. A method according to claim 25 or 26, wherein the identifier comprises an identity parameter and a length parameter. 28. A method according to claim 27, wherein the digital value of the length parameter is not directly proportional to the actual length of the packet. 29. A digital signal, comprising: a packet of digital data; and an identifier for the package; where: the identifier is less than two bytes in length. 30. A signal according to claim 29, wherein the identifier comprises an identity parameter and a length parameter. 31. A signal according to claim 29, wherein the identity and length parameters are each 4 bits in length. 32. A signal according to claim 29, wherein the digital value of the length parameter is not directly proportional to the actual length of the packet. 33. The apparatus as substantially described herein with reference to, and as illustrated in the accompanying drawings, and especially Figure 10 thereof. 34. A transmission and reception system according to claim 12, characterized in that it further comprises means for transmitting data, and means for producing a control command representative of a data characteristic, and wherein the output means includes means for repetitively transmitting the plurality of message sets, at a variable repetition rate, and to vary the repetition rate in response to the control command. 35. A transmission system, comprising: means for transmitting the data; means for producing a control command representative of a data characteristic; and means for repetitively transmitting a message, at a variable repetition rate, the message transmission means being configured to vary the repetition rate, in response to the control command. 36. A system in accordance with the claim 34 or 35, wherein the data are representative signals of program events, and the means for producing the control command is configured to produce the command that will be representative of the transmission time of a particular program event. 37. A system according to claim 36, wherein the message transmission means are configured to vary the repetition rate, close to the transmission time of the event. 38. A system according to claim 36 or 37, wherein the message transmission means are configured to increase the repetition rate, before the transmission time of the event. 39. A system according to claim 36, 37 or 38, wherein the message transmission means are configured to increase the repetition rate, during the transmission time of the event. 40. A transmission and reception system including, at the transmission end, a system according to any of claims 35 to 39, and, at the receiving end, a device for receiving transmission data and messages. 41. A method to transmit, comprising: transmitting the data; produce a control command representative of a data characteristic; and transmitting a message repetitively, at a variable repetition rate, which is varied in response to the control command. 42. A method in accordance with the claim 41, wherein the data are signals representative of program events, and the control message is representative of the time of transmission of a particular program event. 43. A method in accordance with the claim 42, where the repetition rate is varied, close to the transmission time of the event. 44. A method in accordance with the claim 42 or 43, where the repetition rate increases, before the transmission time of the event. 45. A method according to claim 42, 43 or 44, wherein the repetition rate is increased, during the transmission time of the event. 46. A transmission system as substantially described herein with reference to, and as illustrated in the accompanying drawings, and especially Figures 5 and 15 thereof. 47. A conditional access system to provide conditional access to subscribers, comprising: a subscriber management system; and a subscriber authorization system that is coupled to the subscriber's management system, the authorization system comprising means for generating subscriber renewal commands and means to authorize the renewal of the subscriber with dependency on these commands. 48. A conditional access system to provide conditional access to subscribers, comprising: a subscriber management system for managing subscribers, including a database with subscriber information and means for generating a suspension command that a particular subscription should be suspended; and a subscriber authorization system to authorize subscribers, which is coupled to the subscriber management system, and which is configured to receive the suspend command; the subscriber authorization system comprising means for generating a subscriber renewal command for each subscriber with dependency on the suspension command for that subscriber, and means for authorizing the renewal of the subscribers with dependency on the subscriber renewal commands. 49. A conditional access system according to claim 48, wherein the subscriber management system includes means for generating a start command that a particular subscription should be initiated, and means for generating the renewal command are configured of the subscriber of the subscriber authorization system, to generate the renewal command of each subscriber with additional dependency on the start command. 50. A conditional access system according to claim 47, 48 or 49, wherein the subscriber authorization system includes a database with subscriber information. 51. A conditional access system according to claim 48 or 49, wherein the subscriber's authorization system includes a database with the subscriber's information and means to update the information in the database with dependency on the information in the database of the subscriber's management system. 52. A conditional access system according to any of claims 47 to 51, wherein a First Inside First Device is provided between the means for generating the subscriber renewal command and the authorization means of the renewal. 53. A conditional access system according to any of claims 47 to 52, wherein the renewal authorization means include output means for outputting authorization accreditation messages to the subscribers. 54. A conditional access system according to any of claims 47 to 53, wherein the subscriber authorization system may provide special rights for new subscribers. 55. A conditional access system that is for a transmission and reception system, the system comprising, at the transmission end, a system according to any of claims 47 to 54, further comprising, at the receiving end , a device to receive these messages. 56. A transmission and reception system, the system including a conditional access system according to any of claims 47 to 55. 57. A conditional access system as substantially described herein with reference to, and as illustrated in the accompanying drawings, and especially Figures 5, 6 or 7 thereof. SUMMARY The invention includes a digital television system (2000) mostly conventional for transmitting compressed digital signals. A multiplexer (2004) receives a plurality of additional input signals, assembles one or more transport streams and transmits compressed digital signals to a transmitter (2008) of the transmission center via link (2010). The transmitter (2008) transmits electromagnetic signals via the uplink (2012) to a transmitter-receiver (2014) by satellite, where they are processed and broadcast electronically by means of the imaginary downlink (2016) to the receiver (2018) of Earth. The signals received by the receiver (2018) are transmitted to an integrated receiver / decoder (2020) which is connected to the television set (2022) of the end user. The receiver / decoder (2020) decodes the compressed MPEG-2 signal into a television signal for the television set (2022). A conditional access system (3000) is connected to the multiplexer (2004) and the receiver / decoder (2020), and is located partially in the transmission center and partially in the decoder. This allows the user to access digital television transmissions from one or more transmission providers. A smart card can be inserted, which can decode messages in relation to one or more television programs sold by the transmission provider, inside the receiver / decoder (2020). Using the decoder (2020) and the smart card, the end user can buy commercial offers in either a subscription mode or a pay-per-event mode. A number of characteristics of particular interest are described, which include the scrambling of the EMMs, the mixing of the length of the parameter and the identifier in the EMMs and the like to save space, the dynamic distribution of the bandwidth for the specific EMMs, and that the STM is separated from the SMS.