Abstract:
A circuit is disclosed for receiving or transmitting signals from or to different receiving or transmitting members. More particularly, the circuit includes, a microprocessor for at least unscrambling and demultiplexing, and a switching matrix for transmitting or receiving different data flows to or from various receiving or transmitting members. The switching matrix having at least a parallel type connection formed by a plurality of conductors and a serial type connection. Certain conductors of a parallel type connection serve at the same time for the serial type connections, and the circuit is provided with logic elements for controlling the switching of the signals corresponding to serial type connections to conductors provided for the signals corresponding to the parallel type connections, as desired.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to an integrated circuit for realizing a television device or peripheral television monitor. 
     It also relates to a TV decoding and receiving device provided with an integrated circuit comprising inter alia unscrambling means, conditional access means, demultiplexing means, and a microprocessor. 
     It finally relates to a connecting interface between a peripheral television monitor device and a television decoding and receiving device. 
     At the present moment most of the connections for the transport of a data flow called “MPEG2 Transport Stream” inside a TV set or monitor are of the parallel type, and it is necessary to provide comparatively complicated switching means involving a large number of conductors so as to be able to send or receive different data flows towards or from different receiving or transmitting members. 
     SUMMARY OF THE INVENTION 
     In the future there will be more and more connections of the serial type. Nevertheless, it remains necessary to have available connections of the parallel type so as to ensure the compatibility with existing circuits. The invention has for its object to offer extensive connection possibilities without using too many conductors, for example: 
     to facilitate the use of several unscrambling and conditional access modules referred to as “DVB Common Interface” in a receiver, 
     generally, to facilitate the use of more external pieces of equipment. 
     To achieve this, an integrated circuit comprises a switching matrix controlled by a microprocessor and designed for transmitting or receiving different data flows of the MPEG type towards or from different receiving or transmitting members, said matrix comprising connections of the parallel type as well as connections of the serial type. 
     Multiple inputs or outputs of the serial type are advantageously constructed on the basis of a parallel connection, while the circuit is provided with means for controlling the application of signals of the serial type to conductors designed for the signals of the parallel type. For example, if a connection of the parallel type requires eleven conductors and a connection of the serial type requires four conductors, it is possible for twelve conductors to constitute either a connection of the parallel type comprising eleven of these twelve conductors or three connections of the serial type comprising four conductors each. 
     A TV receiving and decoding device, or an interface between a peripheral TV monitor and a TV receiving and decoding device advantageously comprises an integrated circuit according to the invention. 
     These and other, more detailed aspects of the invention will be explained further below in a description of an embodiment which forms a non-limitative example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 diagrammatically shows a known TV receiving and decoding device in relation to which various connection possibilities are indicated. 
     FIG. 2 is a diagram of a circuit for unscrambling, conditional access, and demultiplexing in accordance with the principles of the present invention. 
     FIG. 3 is a more detailed diagram of a switching matrix. 
     FIG. 4 is a detailed diagram of an embodiment of a mixed series/parallel conductor. 
     FIG. 5 illustrates a particular application of the invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A known TV receiving and decoding device is shown by way of example in FIG.  1 . It comprises a parabolic antenna  1  here, comprising a frequency conversion block, followed by a tuner  75  and an intermediate frequency amplifier  85 . The signal issuing from the intermediate frequency amplifier is converted into digital values in an A/D converter  95  and is subsequently demodulated by a demodulator  100 . Finally, certain errors are corrected in an error corrector  2  (“Forward Error Correction”). 
     The description given below relates to a non-limitative example: the input of the device might just as well be, for example, connected to a cable distribution system, in which case the modules  75  to  100  would be different. 
     The demodulated signal at the output of the error corrector  2  is called MPEG-2 TS (“MPEG-2 Transport Stream”): this is a signal comprising several programs with sound and data carried by one and the same signal, which may be scrambled in some cases. 
     In the simplest case, this MPEG-2 TS signal is directly supplied through a connection  20  of the parallel type to an unscrambling, conditional access, and demultiplexing integrated circuit  30 . The signal is unscrambled there in an unscrambling circuit  10 , transmitted to a microprocessor  12  via a bus, and then to a demultiplexer  11  also via a bus. The demultiplexer selects a program from the MPEG-2 TS signal. This program is applied in digital form on the one hand to a video decoder  14  and on the other hand to an audio decoder  16 , said decoders supplying analog signals for projecting an image on a screen and generating sound from a loudspeaker, respectively. These decoders are followed by audio  17  and video  15  circuits connected to an external television, the device described here being a box which is designed to be connected to an input of a peripheral TV monitor or a classical TV set. Obviously, all these circuits may alternatively be incorporated in a TV set. 
     Elements shown hatched in the drawing indicate supplementary possibilities which will be described further below. 
     Certain service providers use a scrambling and conditional access method which cannot be treated by the unscrambling circuit  10 , or they do not wish to divulge their scrambling or conditional access method and for this reason provide a dedicated conditional access and unscrambling module, for example in the form of a card of the PCMCIA format, which contains means specially adapted to the method, while the output signal is in accordance with a standard. An interface  70  is used in conjunction with this module; this interface referred to as “DVB Common Interface” is provided with a reader for a PCMCIA card  71 . The signal on the connection  20  is conducted to the input of the interface  70  via a connection  5 , of the parallel type at present, via a switch  9  whose role will be explained further below. The signal unscrambled by the card  71  is sent through the switch  9  to a connection  6  of the parallel type which is connected to an input  23  of the circuit  30 . It is clear that, with the card  71  in the active state, the connection  20  between the lines  5  and  6  must be cut off, for example by means of the switch  22 , and that the unscrambling circuit  10  does not perform any unscrambling actions on the signals which have already been unscrambled. 
     If one wishes to use several PCMCIA cards supplied by different service providers, it is necessary to insert the correct card at the moment one wants to view a transmission, depending on which service provider is involved. To avoid this manipulation, a standard provides for the possibility of inserting several interfaces in series. A second interface  80  provided with a reader for a second PCMCIA card  81  may be installed and operated upon demand by the switch  9 , which is of the remote control type, thus rendering it possible to select either the interface  70  or the interface  80 . 
     Another additional possibility is that a connecting interface  60  is used for an external or peripheral TV monitor device. This connecting interface is connected, for example, by a serial type “1394” connection to a known external device (not shown) which may be inter alia a digital video recorder or a so-called “DVD” recorder/player, or alternatively a computer hard disk. 
     A method of joining the connecting interface  60  to the decoding and receiving device is through the use of an input connection  3  of the parallel type and an output connection  4  of the parallel type which are connected to the connection  20 . It is accordingly a data flow of the MPEG-2 TS type which is received or delivered through the connecting interface  60 . When a signal is provided on the connection  4 , the connection  20  must be cut off, for example by means of a switch  19 . A disadvantage of this solution is that it is not possible to send a partial flow or an unscrambled flow to the exterior. 
     A second method of joining the connecting interface  60 , which is the most widely used nowadays, is through the use of a bidirectional connection  78  of the parallel type which is connected through a switch  18  either directly to an output of the demultiplexer  11  via a connection  8  or to the input of the circuit  10  via a connection  7 . The circuit  10  is provided with two inputs  7  and  23  of the parallel type. This second method offers the advantage that it renders possible the transmission to the exterior of all or part of the MPEG2 TS data flow, unscrambled if so desired, but it can operate only in one direction at a time. A complete solution would be the combination of the two above solutions and, for this purpose, it is necessary to provide a matrix of switching elements which is comparatively complicated. 
     An unscrambling, conditional access, and demultiplexing circuit  30  in which such a matrix  50  is incorporated is shown in FIG.  2 . The matrix  50  has inputs for the connections  6 ,  20 ,  4 , and  78 , as well as outputs for the connections  23 ,  5 ,  78 , and  3 . 
     An example of an embodiment of a switching matrix  50  comprising switches A, B, C, and D is shown in FIG.  3 . 
     In the simplest case, in which a transmission must be received from the parabola  1  and processed by the unscrambler  10 , the connection  20  may be joined to the connection  23  via the switches A and D in cascade arrangement and the connection  223 . 
     If a PCMCIA card is to be used, the connection  20  may be joined to the connection  5  via the switches A and B in cascade arrangement, and the connection  6  may be joined to the connection  23  via the switch D. 
     In the case of the first method described above for connecting the connecting interface  60 , the connection  3  may be joined to the connection  20  via the switch C, and the connection  4  may be joined to the connection  23  via the switch D, while the unscrambler  10  is active. 
     If a dedicated unscrambling and conditional access module is used as in the latter case described above, the input  4  may be joined to the connection  5  via the switch B, while the switch D now joins the connection  23  to the connection  6 . 
     In the second method of connecting the connecting interface  60  via the bidirectional connection  78  of the serial type, the latter is joined both to the input referenced  4 / 78  and to the output  78 ; the connection  4 / 78  can be joined to the connection  23  via the switch D, and the connection  78  is connected directly to the input  8  in the switching matrix. 
     The connections of the parallel type which are normally used comprise eleven conductors; the switches are accordingly switches with eleven “contacts per position”. The expression “contacts per position” is placed between inverted commas because they are neither contacts nor physical positions, but electronic switching elements. The connections, which are shown in the Figure each by a single line, are in reality a bundle of eleven conductors each time in the case of parallel connections, i.e. eight conductors for eight bits plus three additional conductors for a clock, a validation signal, and a synchronization signal. In the case of connections of the serial type, those normally used comprise four conductors: one conductor for a signal bit of the serial type plus three additional conductors for a clock, a validation signal, and a synchronization signal. The number of peripheral conductors of the matrix  50 , especially those which leave the unscrambling, conditional access, and demultiplexing circuit  30 , is very high. Thus the matrix of FIG. 3 comprises eleven conductors here for each of the connections  23  and  8 , i.e. 22 conductors which remain inside the circuit  30 , and eleven conductors for each of the connections  4 / 78 ,  20 ,  5 ,  6 ,  78 ,  3 , i.e. 66 conductors which enter or leave the circuit  30 . 
     To reduce the number of conductors so as to realize the circuit more easily in an integrated form, while the functions explained above are retained, certain connections of the switching matrix may be mixed, i.e. each connection then constitutes either a single connection of the parallel type or a multiple connection of the serial type, i.e. several connections of the serial type. In other words, the matrix may receive or supply signals through certain conductors in parallel form or, using the same conductors, in serial form, the desired configuration for this being obtained through programming. 
     A connection of the parallel type preferably comprises twelve conductors instead of eleven, i.e. a twelfth, apparently useless conductor is provided. In this manner three connections of the serial type can be used instead of two at the price of a single supplementary conductor, i.e. 3×4=12 conductors. All conductors relating to one connection are shown in FIG. 4 by way of example. The connection Po comprises twelve conductors. Eleven of these twelve conductors are used for forming one connection of the parallel type Pi with eleven conductors, as represented by a single line in FIG.  3 . The first four conductors of the twelve conductors of Po form four conductors for a first bundle of the serial type Si 1 . The next four conductors of Po form four conductors for a second bundle of the serial type Si 2 . The final four conductors form four conductors of a third bundle of the serial type Si 3 . Switches such as those of FIG. 3 render it possible to select one or several of the connections Si 1 , Si 2 , Si 3 , Pi. 
     In the application shown in FIG. 5, the matrix  50  has only two connections F and G with twelve conductors each. In this Figure, the number of a connection, for example  20 P or  20 S, indicates the connection having the same number ( 20 ) as in FIG. 1, with a suffix P or S which means “parallel” or “serial”. The connection F renders possible the establishment of a parallel type connection  20 P and the connection G renders possible the establishment of a parallel type connection  78 P. The matrix comprises few conductors, but the connection possibilities are reduced if the connections of the parallel type only are used. However, if a configuration of the serial type is programmable, as explained with reference to FIG. 4, then three connections of the serial type  20 S,  5 S,  6 S can be connected instead of a single connection  20 P, and similarly three connections of the serial type  3 S,  4 S/ 78 S,  78 S can be connected instead of a single connection  78 P. 
     Obviously, the invention is by no means limited to the example given, numerous modifications being readily conceivable: 
     all possible combinations of serial or parallel signals can be used with a number of conductors chosen as a function of the desired connections. It is accordingly possible to optimize the number of conductors as a function of the desired connections. 
     if, for example, the matrix  50  is provided with three connections of twelve conductors each, which would provide for the realization of nine connections of the serial type, the connections  5  and  6  could also be mixed, while a connection of the parallel type for a reader of a state of the art PCMCIA card can be transformed into several connections of the serial type. This possibility may be applied in several cases: 
     if one day “DVB common interfaces” with connections of the serial type should exist. 
     the module  9  with its six connections of the parallel type has 66 conductors. It would be possible to provide several (two in this case) small serial/parallel converter modules to be connected each to a “DVB common interface”  71 ,  81  of the present type via connections of the parallel type, and to connect them to the matrix  50  via connections of the serial type. 
     moreover, a connecting interface  60  as shown in FIG. 1 comprises three connections  3 ,  4 ,  78  of the parallel type, i.e. 33 conductors, without counting the output 1394. This also could be equipped with a matrix of the kind described with reference to FIGS. 4 and 5, which would render it possible with no more than 12 conductors to branch off, for example, either a single connection of the parallel type  78 , or the three connections  3 ,  4 ,  78  if these are of the serial type.