Abstract:
Certain providers, notably of television programs, subsidize the receivers and want to avoid that these apparatuses can also be used for the services offered by other providers. On the other hand, manufacturers of these apparatuses prefer selling multipurpose apparatuses and users do not want to have several similar apparatuses, which, moreover, is cumbersome. To obtain a compromise between these contradictory requirements, it is proposed to permit reception by the apparatus of services offered by a provider other than the provider who has subsidized the apparatus, when the subscription taken out by said provider has reached a certain period or length of service.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a method of operating an apparatus intended to permit access to services provided on subscription by a first provider, which method enables access to services offered by a second provider. 
     The invention also relates to an apparatus provided with means intended to permit access to services provided on subscription by a first provider, which apparatus enables access to services offered by a second provider. 
     2. Description of the Related Art 
     To develop the market for receivers/decoders enabling access to pay-TV programs, the providers of these programs want the price of these apparatuses to be as low as possible for the user. To obtain an artificially low price, certain providers either offer a subsidy on the purchase of these apparatuses, or buy them themselves so as to offer them for hire. In either case, they want their investments to produce profits by preventing an apparatus subsidized by a first provider from receiving programs supplied by a second provider, and to this end, certain receiver/decoders are provided with means for verifying whether the provider of a program which a subscriber wants to receive is the provider who has let or owns the apparatus. On the other hand, manufacturers of apparatuses prefer selling multipurpose apparatuses and users do not want to be obliged to be furnished with several apparatuses of the same type, which is expensive and cumbersome: an apparatus based on the use of several smart cards for television programs offered by several providers is known from the document EP 0 562 295 in which several card readers are connected and controlled by a single processor. 
     The same kind of problem is likely to occur in mobile telephony (“GSM”). 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a solution eliminating the contradiction between the providers and users&#39; wishes. 
     To this end, access to services offered by a second provider is refused by the apparatus, except when the subscription taken out by the first provider has a certain period or length of service. 
     In this way, a compromise is obtained between the contradictory requirements stated above. 
     In a preferred embodiment of the method, the apparatus, making use of scrambled communication, verifies two conditions, namely, on the one hand, if the scrambling method is the same for the two providers and, on the other hand, if the period of the subscription taken out by the first provider exceeds a given period of time, and authorizes access to services offered by the second provider if these two conditions are satisfied. 
     Advantageously, the date of first use of the subscription is automatically registered by the apparatus when it is put into use for the first time. 
     An apparatus according to the invention is provided with control means for authorizing or prohibiting access to services offered by a second provider, means for computing the difference between the date of first use of the subscription taken out by the first provider and the current date, and the control means are arranged to authorize access to services offered by the second provider if said difference between the dates exceeds a given value. 
     This apparatus is advantageously provided with means for automatically registering the date of first use of the subscription when the apparatus is put into use for the first time, and means for delivering a warning message when the subscription period is not sufficient to authorize access to certain services. 
     These and other aspects of the invention are apparent from and will be elucidated with reference to the embodiments described hereinafter. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
     FIG. 1 shows diagrammatically a television receiver/decoder, 
     FIG. 2 is a diagram illustrating how the date of first use is registered, 
     FIG. 3 is a diagram illustrating the operation of the control and computing means. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The following description is based on the embodiment of a television receiver/decoder, but the elements relating to access authorization may be alternatively used as such for access control of any other type of apparatus. 
     The receiver/decoder shown in FIG. 1 is intended to allow access on subscription to at least one block of television programs coded in accordance with the MPEG2 standard. It will be evident that the invention may be alternatively applied to apparatuses adapted to another standard. 
     The apparatus comprises a satellite reception unit constituted by a parabolic antenna  1  and a tuner  2 , and followed by an IF amplifier  3 . The IF signal is subsequently demodulated and certain errors are corrected in a module  4 . At this level, the signal is descrambled in a descrambling module  14  connected via a bus  27  to a unit  23  for reading a microprocessor card  17 , referred to as chip card, and to a microprocessor  15 . The microprocessor  15  comprises a read-only memory in which the basic instructions are stored. It is associated with a random-access memory  22  for instantaneous data, a memory  26  of the EEPROM type for storing semipermanent program elements, i.e. elements which can be preserved when the apparatus is switched off but which can also be updated, and with a card reader  23 , a keyboard and/or a remote control receiver  25  connected to a data display screen. The descrambled signal is submitted to the influence of a demultiplexer  16  connected to the microprocessor  15  which separates the different programs from each other. The signal supplied by this demultiplexer has a digital form and must be transformed into an analog signal for displaying an image on a screen and for applying the sound to a loudspeaker. This transformation is effected in a video decoder  19  and an audio decoder  18 . These decoders are connected to a connector  20 , for example, for connection to a conventional television set. 
     The card unit  23  for reading the chip card  17  is to be used for reading the information required to descramble the television broadcasts in known manner. The card contains information such as a distribution key, a provider&#39;s reference, characteristic features of a subscription to a block of programs transmitted by a provider, and the scrambling type. 
     The microprocessor  15  is provided with a software element for automatically registering the date of first use of the subscription when the card is inserted into the apparatus for the first time. 
     A diagram illustrating the part relating to this software is shown in FIG.  2 . Whenever the apparatus is put into use, a program is automatically executed. This program configures the microprocessor and positions certain variables in an initialization step  29 . At  30 , the date of the day D 2 , which is received by the apparatus in a coded form from any transmitter, is registered in the memory  22 . At  32 , it is verified whether the apparatus is put into use for the first time. Several known methods may be used for this purpose. For example, during manufacture of the apparatus, a flag is positioned in the EEPROM memory to indicate that the apparatus has never been used: it is sufficient to test this flag. Another method is to verify whether a memory field D 1 , which normally comprises the starting date of the subscription taken out by the provider who has subsidized the apparatus, is empty, which is the case before the first time of use. If the first time of use is concerned (Y), the process proceeds to  33  where the date D 2  of the day is read into the memory  22 , and subsequently to  34  where this date of the day D 2  is written in the field D 1  of memory  26 . If the first time of use is not concerned (N), the process proceeds to  35  for effecting other operations which do not relate to the invention. 
     The microprocessor  15  also comprises control software for authorizing reception of a program according to which the provider of the program which the subscriber wants to receive is or is not the one who has subsidized the apparatus. This software comprises means for evaluating the subscription period by computing the difference between the date of first use of the subscription and the current date, obtained by reception of a program. It authorizes the reception of the requested program if the subscription period exceeds a given period of time, even in the case where the provider is not the one who has subsidized the apparatus. The necessary subscription period may be, for example, six months or any other longer or shorter period based on the provider&#39;s policy and on the value of the initially granted subsidy. It should be noted that the types of scrambling methods used by the two providers must be compatible. 
     A diagram illustrating the part relating to this software is shown in FIG.  3 . The software input is denoted by the reference numeral  5  (the part cut off above the input  5  will be explained hereinafter). At  6 , the reference B 1  of the provider who has subsidized the apparatus is read, for example in the read-only memory. At  7 , the reference B 2  of the provider of the program which the user wants to watch is read from card  17  by the card reader  23 , because one card corresponds to each program provider, or, in the case where several cards are placed in advance in a multicard reader (not shown), the reference would be read from the memory  22 , with the information then being given by a user command via the keyboard or the remote control receiver  25 , the code of which command is stored in the memory  22 . At  8 , a comparison is made between the two references B 1  and B 2 . If they correspond (Y), there is no problem and the process proceeds to  12  for authorizing the operation of the known receiver/decoder. If the two providers B 1  and B 2  are different (N), the process proceeds to  9  where the starting date D 1  of the subscription taken out by the provider who has subsidized the apparatus is read from the memory  26 . At  10 , the date D 2  of the day is read from the memory  22 . At  11 , the difference between the dates D 1  and D 2  is computed and compared with a predetermined value. If this difference is sufficient (Y), the process proceeds to  24  where the scrambling type S 1  used by the first provider is determined, subsequently to  36  where the scrambling type S 2  used by the second provider is determined; at  31 , it is verified whether these two scrambling types are the same and, if this is the case, the process proceeds to  12 . If, at  11 , the subscription is judged to be very recent (N), the process delivers, in a step  13 , a warning message indicating that the subscription period is not sufficient to authorize reception of the program, and subsequently returns to the start. It will be clear that the steps  6 ,  7 ,  8 , on the one hand, and the steps  9 ,  10 ,  11 , on the other hand, may be interchanged without modifying the result obtained. In other words, it does not make any difference to verify the identity of the two providers first and then the subscription period, or conversely; nevertheless, in many cases, the user will only use a card of the first provider and it is preferable to start from step  8  so as to avoid useless tests. It is alternatively possible to carry out an auto-programming procedure, namely, if the test step at  8  shows that the subscription has expired, given the fact that this information is definitive, the program may be modified in an irreversible manner by cutting off the access to the input  5  (part cut off above the input  5 ), so as to arrive directly at  24  via the line indicated as a broken line. Those skilled in the art may easily render this software more complicated by introducing means for verifying a password so as to prevent unauthorized persons from falsifying the software with the intention of extending the date D 1  or eliminating the test procedure.