Data transmission process with auto-synchronized correcting code, auto-synchronized coder and decoder, corresponding to transmitter and receiver

Abstract

A data transmission process with auto-synchronised correcting code, auto-synchronised coder and decoder, corresponding transmitter and receiver. According to the invention, synchronisation management signals (HS, SS, ID) are formed and, under the control of these signals, a header is inserted before a data group and after it a correcting code. At receive end, these synchronisation management signals are reconstituted, the presence of a header is detected and any erroneous symbols are corrected. The invention also provides for an auto-synchronised coder and a decoder and for a transmitter and a receiver using them.

What is claimed is: 
     
       1. A data transmission process with auto-synchronized correcting code, comprising:
 defining a timing of bits of the data, to be transmitted, by a clock signal and forming synchronization management signals comprising:
 a symbol clock signal m number of times less fast than the clock signal, where m is an integer, and m bits constituting an information symbol, 
 a symbol synchronization signal capable of designating the first symbol of a packet, and 
 a data acquisition interruption signal intervening every K number of symbols, where K is a pre-set integer; 
 inserting a header before a first group of K symbols and inserting a second group of R symbols after said first group, the second group of R symbols comprising a correcting code corresponding to the K symbols of the first group, R being a pre-set integer dependent on a correcting code type used, the first and second groups of(R+K) symbols forming a packet, and the header being a header specific to this packet, under control of the data acquisition interrupting signal; and 
 modulating and transmitting each packet with its header; 
 demodulating the signal received and extracting the clock signal; 
 implementing a header search process in the demodulated signal and, when the header is detected, inhibiting the header search process and generating a symbol synchronization symbol; 
 processing the received packet so as to correct any erroneous symbols of the first group by the correcting code of the second group and reactivating the header search process after each packet processing, under the control of the symbol clock and symbol synchronization signals; and 
 retrieving, from the corrected symbols, the transmitted data. 
   
     
     
       2. The process according to  claim 1 , wherein:
 at transmission, said modulating is effected by spread spectrum by means of pseudo-random sequences; and   correlating with the pseudo-random sequences at transmission.   
     
     
       3. The process according to  claim 1 , wherein the correcting code is a Reed-Solomon type code. 
     
     
       4. An auto-synchronized coder, comprising:
 means for forming synchronization management signals, wherein the synchronization management signals comprise:
 a symbol clock signal m times less fast as a clock signal timing the data bits, where m is an integer, and m bits constitute an information symbol, 
 a symbol synchronization signal locating the start of each symbol, 
 a data acquisition interruption signal intervening every K number of symbols, where K is a pre-set integer; and 
   means for inserting, under control of the acquisition interruption signal, a packet header before a first group of K symbols, and a second group of R symbols after said first group, the second group of R symbols constituting a correcting code assigned to the K symbols of the first group, R being a pre-set integer based at least in part upon the correcting code type used, the first and second group of (R+K) symbols forming a packet, and the header being a header specific to this packet.   
     
     
       5. A transmitter, comprising:
 a transmission module configured to modulate the data and to spread the spectrum of the data by a pseudo-random sequence; and   an auto-synchronized coda, before said transmission module, comprising:
 means for forming synchronization management signals, the synchronization management signals comprising:
 a symbol clock signal m times less fast than a clock signal timing the data bits, where m is an integer, m bits constituting an information symbol, 
 a symbol synchronization signal locating the start of each symbol, and 
 a data acquisition interruption signal intervening every K number of symbols, where K is a pre-set integer; 
 
 means for inserting, under control of the acquisition interruption signal, a packet header before a first group of K symbols and a second group of R symbols after said first group, the second group of R symbols constituting a correcting code assigned to the K symbols of the first group, R being a pre-sent integer dependent on the correcting code type used, the first and second group of(R+K) symbols forming a packet, and the header being a header specific to this packet. 
   
     
     
       6. A method of receiving a data stream of information symbols including a correcting code, comprising:
 receiving the data stream, the data stream comprising data packets, the data packets comprising a packet header, information symbols and correcting-code symbols a packet header being in the data stream before a group of K information symbols in the data stream, the packet header being associated with and being specific to the group of K information symbols, the correcting-code symbols comprising a group of R correction code symbols in the data stream after the group of K information symbols, and R comprising an integer value that is based at least in part on the correcting code;   generating a symbol clock signal and a symbol synchronization signal based at least in part on a timing of bits in an information symbol, the symbol clock signal including a frequency that is m times less than the timing of bits of an information symbol and the symbol synchronization signal capable of designating a first symbol of a group of K information symbols;   detecting a packet header in the received data stream including the correcting code;   extracting from the detected data stream the group of K information symbols associated with the detected packet header based at least in part on a timing provided by the symbol clock signal and the symbol synchronization signal; and   using the corresponding group of R correction code symbols to correct one or more symbols in the group of K symbols.   
     
     
       7. The method according to claim 6, wherein the received data stream has been modulated based at least in part on a spread-spectrum modulation technique, and
 wherein receiving the data stream including the correcting code further comprises demodulating the modulated received data stream.   
     
     
       8. The method according to claim 6, wherein the correcting code comprises a Reed-Solomon-based correcting code. 
     
     
       9. A decoder, comprising:
 means for generating a symbol clock signal and a symbol synchronization signal from a data stream, the data stream comprising data packets, the data packets comprising a packet header, information symbols and correcting-code symbols, wherein a packet header is in the data stream before a group of K information symbols in the data stream and is associated with and being specific to the group of K information symbols, and a group of R correction code symbols is in the data stream after the group of K information symbols, the group of R correction code symbols comprising a correcting code for the group of K information symbols and R comprising an integer value that is based at least in part on the correcting code, the symbol clock signal including a frequency that is m times less than a timing of bits of an information symbol and the symbol synchronization signal capable of designating a first symbol of a data packet; and   means for implementing a packet header search process for a packet header in the data stream for inhibiting the packet header search process if a packet header is detected and for processing a data packet corresponding to a detected packet header based at least in part on the symbol clock signal and the symbol synchronization signal by correcting one or more information symbols included in the data packet using correcting-code symbols included in the data packet and for reactivating the packet header search process after processing a data packet.   
     
     
       10. A decoder according to claim 9, wherein the correcting code symbols comprise a Reed-Solomon-based correcting code. 
     
     
       11. A decoder according to claim 9, wherein the received data stream comprises a data stream modulated at least in part based on a spread-spectrum modulation technique and
 wherein the decoder further comprises means for demodulating the modulated received data stream.   
     
     
       12. A decoder, comprising:
 a clock generator adapted to generate a symbol clock signal and a symbol synchronization signal from a data stream the data stream to comprise data packets, the data packets to comprise a packet header, information symbols and correcting-code symbols, wherein a packet header is in the data stream before a group of K information symbols in the data stream and is associated with and is specific to the group of K information symbols, and a group of R correction code symbols is in the data stream after the group of K information symbols the group of R correction code symbols comprising a correcting code for the group of K information symbols, and R comprising an integer value that is based at least in part on the correcting code, the symbol clock signal including a frequency that is m times less than a timing of bits of an information symbol and the symbol synchronization signal capable of designating a first symbol of a data packet; and   a packet-header searcher adapted to search for a packet header in the data stream, adapted to inhibit the packet header search process if a packet header is detected, adapted to process a data packet corresponding to a detected packet header based at least in part on the symbol clock signal and the symbol synchronization signal by correcting one or more information symbols included in the data packet using corrccting-code symbols included in the data packet, and adapted to reactivate the packet header search process after processing a data packet.   
     
     
       13. A decoder according to claim 12, wherein the correcting code symbols comprise a Reed-Solomon-based correcting code. 
     
     
       14. A decoder according to claim 12, wherein the received data stream comprises a data stream modulated at least in part based on a spread-spectrum modulation technique and wherein the decoder further comprises a demodulator adapted to demodulate the modulated received data stream. 
     
     
       15. A receiver, comprising:
 a receive module adapted to receive a data stream, the data stream comprising data packets, the data packets comprising a packet header, information symbols and correcting-code symbols, wherein a packet header is in the data stream before a group of K information symbols in the data stream and is associated with and is specific to the group of K information symbols, and a group of R correction code symbols is in the data stream after the group of K information symbols, the group of R correction code symbols comprising a correcting code for the group of K information symbols, and R comprising an integer value that is based at least in part on the correcting code, the symbol clock signal including a frequency that is m times less than a timing of bits of an information symbol and the symbol synchronization signal capable of designating a first symbol of a data packet; and   a decoder, comprising:
 a clock generator adapted to generate a symbol clock signal and a symbol synchronization signal from the data stream, the symbol clock signal including a frequency that is m times less than a timing of bits of an information symbol and the symbol synchronization signal capable of designating a first symbol of a data packet, 
 a header searcher adapted to implement a packet header search process for a packet header in the data stream, the header searcher adapted to inhibit the packet header search process if a packet header is detected; and 
 a data packet processor adapted to process a data packet corresponding to a detected packet header based at least in part on the symbol clock signal and the symbol synchronization signal by correcting one or more information symbols included in the data packet using correcting-code symbols included in the data packet, and adapted to reactivate the packet header search process after processing a data packet. 
   
     
     
       16. A receiver according to claim 15, wherein the correcting code symbols comprise a Reed-Solomon-based correcting code. 
     
     
       17. A receiver according to claim 15, wherein the received data stream comprises a data stream modulated at least in part based on a spread-spectrum modulation technique,
 and wherein the decoder further comprises a demodulator adapted to demodulate the modulated received data stream.