Data communication system

A data communication system comprising:

• data transmission means connected to a public switching telephone network;
• and
• facsimile communication means connected to said data transmission means through a predetermined transmission line for transmitting a facsimile document to a group 3 party facsimile terminal connected to said public switching telephone network through said predetermined transmission line and said data transmission means,
• said data transmission means including:
• transmission rate determination means, prior to transmission of said facsimile document from said facsimile terminal, for transmitting a training check signal to said party facsimile terminal on said public switching telephone network and when receiving a response to said training check signal from said party facsimile terminal, for determining a transmission rate of said facsimile document;
• notification means for informing said facsimile communication means of said transmission rate determined by said transmission rate determination means;
• and
• error correction control means including first error correction control means for performing error correction control of said party facsimile terminal through data transmission with said party facsimile terminal, second error correction control means for performing error correction control through data transmission with said facsimile communication means, block division means for dividing information to be transmitted into information blocks having a suitable length, and framing means for converting the information blocks divided by said block division means into frames, said framing means includes error detection code generation/application means for generating an error detection code for each of the information blocks divided by said block division means and attaching said error detection code to the associated information block, error correction code generation/application means for generating an error correction code for the information block having said error detection code attached thereto by said error detection code generation/application means and attaching said error correction code to the associated information block, and zero insertion means for inserting a time fill signal in the absence of frame transmission and inserting a suitable number of zero bits in the information having the error correction code attached thereto by said error correction code generation/application means to provide a distinguished boundary between said time fill signal and a frame.

A data communication system comprising:

• data transmission means connected to a public switching telephone network;
• and
• facsimile communication means connected to said data transmission means through a predetermined transmission line for transmitting a facsimile document to a group 3 party facsimile terminal connected to said public switching telephone network through said predetermined transmission line and said data transmission means,
• said data transmission means including:
• transmission rate determination means, prior to transmission of said facsimile document from said facsimile terminal, for transmitting a training check signal to said party facsimile terminal on said public switching telephone network and when receiving a response to said training check signal from said party facsimile terminal, for determining a transmission rate of said facsimile document;
• notification means for informing said facsimile communication means of said transmission rate determined by said transmission rate determination means;
• and
• error correction control means including first error correction control means for performing error correction control of said party facsimile terminal through data transmission with said party facsimile terminal, and second error correction control means for performing error correction control through data transmission with said facsimile communication means, said second error correction control means includes block division means for dividing information to be transmitted into information blocks having a suitable length, framing means for converting the information blocks divided by said block division means into frames and transmitting said frames, and line quality judgement means for judging whether the line quality is good or bad on the basis of a bit error state of a communication line, and wherein said block division means includes means for changing a length of information to be divided according to the good or bad line quality judged by said line quality judgement means.

A data communication system comprising:

• data transmission means connected to a public switching telephone network;
• and
• facsimile communication means connected to said data transmission means through a predetermined transmission line for transmitting a facsimile document to a group 3 party facsimile terminal connected to said public switching telephone network through said predetermined transmission line and said data transmission means,
• said data transmission means including:
• transmission rate determination means, prior to transmission of said facsimile document from said facsimile terminal, for transmitting a training check signal to said party facsimile terminal on said public switching telephone network and when receiving a response to said training check signal from said party facsimile terminal, for determining a transmission rate of said facsimile document;
• notification means for informing said facsimile communication means of said transmission rate determined by said transmission rate determination means;
• and
• error correction control means including first error correction control means for performing error correction control of said party facsimile terminal through data transmission with said party facsimile terminal, and second error correction control means for performing error correction control through data transmission with said facsimile communication means, said second error correction control means includes block division means for dividing information to be transmitted into information blocks having a suitable length, framing means for converting the information blocks divided by said block division means into frames and transmitting said frames, and line quality judgement means for judging whether the line quality is good or bad on the basis of a bit error state of a communication line, wherein said framing means includes error detection code generation/application means for generating an error detection code for information to be transmitted and attaching said error detection code to the information, error correction code generation/application means for generating an error correction code for the information having said error detection code attached thereto by said error detection code generation/application means and attaching said error correction code to the information, and zero insertion means for inserting a time fill signal in the absence of frame transmission and inserting a suitable number of zero bits in the information having the error correction code attached thereto by said error correction code generation/application means to provide a distinguished boundary between said time fill signal and a frame, and wherein said block division means includes means, when said line quality judgement means judges that the line quality is good, for dividing the information into information blocks having a length exceeding an error correctable upper limit code length based on said error correction code.