Abstract:
When new software is received by air in the form of successive blocks by a video receiver having a specialized digital video processing module ( 19 ), connected by a first bus ( 28 ) to a specialized video memory ( 29 ), and a microprocessor ( 15 ) connected by a second bus ( 27 ) to a rewritable program memory ( 26 ), the microprocessor verifies the blocks of this new software one by one and stores them in the video memory ( 29 ) of the specialized video processing module until the new software is complete. Not until that moment will the new software be transferred to the program memory ( 26 ).

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a method of updating software, in a video receiver that comprises receiver means for receiving video signals and digital data sent by a television transmitter, said receiver means comprising, for example, a specialized digital video processing module connected by a first bus to a specialized video memory, and a microprocessor connected by a second bus to a rewritable program memory in which are written the basic instructions by which it can operate. 
     2. Description of the Related Art 
     The invention also relates to such a video receiver. 
     Updating the software may be decided by a television program provider when an error has been detected in the software of the receivers, or also for adding new functions. This updating consists of replacing old software by new software. Whereas the larger part of the instructions of the new software are identical to those of the old software, it would nevertheless be surprising that each of the instructions of the new software has the same address as the corresponding instruction in the old software. Thus, the software of a receiver, when only partly transformed, becomes totally unusable. A problem is then posed in that the software updating may be interrupted for different reasons during the process. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to solve this problem. 
     For this purpose, when new software is received in successive parts, the parts of the received software are verified, one by one by, the microprocessor and stored in a random access memory until the software level is complete and, not until that moment will the new software be transferred to the rewritable program memory and will the video memory of the specialized video processing module be used for provisionally storing the received parts of the software. 
     A receiver according to the invention comprises updating means for replacing the basic instructions taken as a whole by new software which is sent in successive parts, means for verifying the received software parts one by one and for storing them in a random access memory until the new software is complete, and means for transferring the whole new software when it has been received to the rewritable program memory, while said random access memory is formed by the video memory of the specialized video processing module. 
     Advantageously, the transport of the data from the first bus to the second bus, or vice versa, is realized via the specialized digital video processing module which includes means intended for this purpose. 
     Preferably, the process of acquiring new software is started during a standby period of the receiver and starting the receiver is forbidden during the transfer of new software to the program memory, the microprocessor including means to that effect. 
     Advantageously, a message is displayed by the receiver while new software is being transferred to the program memory, the receiver including means to that effect. 
     These aspects of the invention and also other, more detailed, aspects will provide a better understanding by the following description of an embodiment forming a non-limiting example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The sole FIGURE diagrammatically shows a video receiver incorporating the subject invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The receiver decoder REC shown in FIG. 1 is intended to grant access to coded television programs according to the MPEG-2 standard. It will be clear that the invention also applies to other types of video receivers. 
     The receiver is connected to a parabolic antenna  1 P having a frequency translation module  1 L, and comprises a satellite receiver assembly formed by a tuner  2 , followed by an intermediate frequency amplifier  3 . Then, the intermediate frequency signal is demodulated and certain errors are corrected in a module  4 , after which the signal is descrambled, as appropriate, in a descrambling module  14  connected to a chip card reader  17 . The chip card  17  provides, in known fashion, the information necessary for descrambling television transmissions, such as a distribution key, the reference of a provider, the characteristics of a subscription to a range of programs broadcast by a provider, the type of descrambling. 
     The outgoing signal of the descrambling module  14  undergoes the action of a demultiplexer  16  which separates the various programs. The outgoing signal of this demultiplexer requires to be transformed into an analog signal for displaying an image on a screen and applying the sound to a loudspeaker. This transformation is effected in a video decoder  19  and in a sound decoder  18 . These decoders are connected to a connector  20  for a connection to a conventional television set. By way of a variant, the elements of the FIGURE could also be internal elements of a television set. 
     The video signals processed in the decoder  19  are digital at the input and may be stored in a large-capacity video memory  29  while they are being processed, this video memory being capable of, for example, storing a plurality of images. This memory is connected to the decoder  19  by a dedicated bus  28 . 
     A bus  27 , which is physically different from bus  28 , connects a microprocessor  15  to: 
     a program memory  26  in which are written the basic instructions by which the microprocessor can function, 
     a random access memory  22  for provisionally storing data, 
     an assembly  25  formed by a control keyboard and/or a remote-control receiver associated to a data display screen, 
     and also to the chip card reader  17 . 
     The instructions in the program memory  26 , called flash memory, are not lost when the receiver is turned off, but are capable of being updated. To do this, new software is sent “by air”, that is to say, by the television transmit channel while the sending of various digital data is provided in the transmission standard. In certain systems, there is provided that data can be transmitted via a telephone line; this is certainly not as satisfactory as transmission by air, but the invention can also apply to that. The time necessary for the complete reception of software by air is of the order of one minute, and may be longer if the receiving conditions are unfavorable. To improve the tolerance to any transmission errors and to facilitate the reception by receivers having different capacities, the software is sent in successive parts of blocks alternating with images. In the receiver, this process can only be started in the case where this receiver does not have to decode images, typically when it is in the standby mode, so that the microprocessor is free. Complete software may be up to one megabyte large: the program memory  26  has a capacity of one megabyte. The software is transmitted, for example, in blocks of four kilobytes each. 
     The updating of the software may be interrupted for various reasons, for example: because the user has put the receiver in the receive mode, or because the power has been cut off. In order to avoid the risk of the processor working with partly transformed software, the new software is stored in a memory other than the memory  26  until it is complete and, only at that moment will it be transferred to memory  26  at one time. Here, the memory  29  is used for that purpose. As the bus  28  is physically different from bus  27 , the transport of the data from one bus to another is realized via the decoder  19 . 
     The operation is the following: when the transmitter starts transmitting new software, this fact is indicated by a specific digital data. The number of the version of the software in question is also supplied. The data are acquired by the decoder  19  and transmitted to the microprocessor. When said particular digital data is recognized, the program pointer of the microprocessor is positioned at the old software address of the instructions for handling the receiving process of new software. The microprocessor first verifies whether the software version in question is not the one already in possession of the receiver. Each packet of a software block transmitted to the microprocessor has a signature-type of coding, for example, a Cyclic Redundancy Check (CRC), which permits the microprocessor of analyzing the code and verifying its coherence. If the block turns out to be correct, it is sent to the decoder  19  which writes the block in the memory  29  via the bus  28 . If a block is not correct, the system waits for the next occurrence at which the same block is transmitted. When all the blocks have been received correctly and stored, the microprocessor starts the transfer process to the program memory  26 , which transfer takes place by the bus  28 , the decoder  19  and the bus  27 , under control of the microprocessor  15 . 
     If the user starts the receiver while data are being received, the process is interrupted. It will be resumed later, when the receiver is again in the standby mode. Nevertheless, during the time of the final transfer to the program memory, no interruption is allowed. For this purpose, a function then inhibits the remote control receiver of the assembly  25  to block the start of the receiver and, in order for the user to understood why his receiver refuses to start, a message appears on the screen: for example “CURRENTLY WORKING”.