High speed serial data link

Abstract

A high bit-rate serial communications link encodes data by inserting non-data 0's and 1's. These extra bits are removed by a decoder at the receiving end of the link. Transmission of data can be made along optical fibers.

What is claimed is: 
     
       1. A method for transmitting data comprising a plurality of data words, each said data word composed of a plurality of 1's and 0's, comprising the steps of: (a) providing said plurality of data words in a parallel representation thereof;   (b) prepending a unique signal to each data word for indicating the start of a transmitted data word;   (c) converting each prepended data word to a serial representation thereof;   (d) converting each serial representation of a prepended data word to a serial representation thereof having no more than a first preselected number of consecutive 1's and no more than a second preselected number of consecutive 0's by inserting extra 0's and 1's into said data word to convert strings of 1's and 0's therein longer than the first and second preselected numbers, respectively, into at least two shorter strings;   (e) transmitting the serial representation of (d) to a receiver;   (f) receiving the transmitted serial representation;   (g) removing the unique signal, prepended in step (b), from the received serial representation;   (h) deleting the extra 0's and 1's inserted into the serial representation in step (d); and   (i) converting the serial representation of (h) into a data word.   
     
     
       2. A system for transmitting data using an asynchronous serial data link, comprising: (a) an encoder for convening data words represented in parallel format into serial bit streams representing each data word, each data word having a unique start-of-word sequence, said encoder including means for insuring that no more than preselected numbers of consecutive 0's and 1's are present in each said data word including means for inserting extra 1's and 0's into sequences in a data word containing more than such preselected numbers;   (b) a decoder for detecting and removing unique start-of-word sequences and any extra 0's or 1's inserted by said encoder to convert said serial bit streams into data words; and   (c) transmission means coupled to said encoder and said decoder for communicating serial bit streams from said encoder to said decoder.   
     
     
       3. The system of claim 2, wherein said transmission means comprises an optical system including: an optical transmitter coupled to said encoder;   an optical receiver coupled to said decoder; and   a fiber optic link coupled to said optical transmitter and to said optical receiver,   said optical system having a defined bandwidth, said preselected number being determined by said defined bandwidth.   
     
     
       4. The system of claim 3, further comprising means, coupled to said optical receiver, for recovering a clock signal from data transmitted by said fiber optic link. 
     
     
       5. A method for transmitting data comprising a plurality of data words, each said data word composed of a plurality of 1's and 0's, comprising the steps (a) providing said plurality of data words in a parallel representation thereof;   (b) prepending a unique signal to each data word for indicating the start of a transmitted data word;   (c) providing an optical data link including a transmitter and a receiver, said data link having a defined bandwidth;   (d) convening each prepended word to a serial representation thereof;   (e) converting each serial representation of a prepended data word to a serial representation thereof having no more than a first preselected number of consecutive 1's and no more than a second preselected number of consecutive 0's by inserting extra 0's and 1's into said data word to convert strings of 1's and 0's longer than said first and second preselected numbers, respectively, into at least two shorter strings, said preselected number providing a data transition time less than the maximum permissible time between data transitions for the optical data link;   (f) transmitting said serial representation of (c) to a receiver;   (g) receiving the transmitted serial representation;   (h) removing the unique signal, prepended in step (b), from the received serial representation;   (i) deleting the extra 0's and 1's inserted into the serial representation in step (e); and   (j) converting the serial representation of (i) into a data word.   
     
     
       6. The .[.system.]. .Iadd.method .Iaddend.as set forth in claim 5 wherein step (h) further includes converting said data word into a parallel representation thereof. .Iadd.7. A method for transmitting data comprising a plurality of data words, each data word composed of a plurality of 1's and 0's, comprising the steps of: (a) prepending a unique signal to each data word for indicating the start of a transmitted data word, thereby forming a prepended data word;   (b) converting each prepended data word into an encoded data word having no more than a first preselected number of consecutive 1's and no more than a second preselected number of consecutive 0's by inserting 1's and 0's into said prepended data word to convert strings of 1's and 0's therein longer than the first and second preselected numbers, respectively into at least two shorter strings; and   (c) serially transmitting said encoded data word one bit at a time. .Iaddend. .Iadd.8. The method of transmitting data of claim 7 wherein:   said step (c) includes transmitting said encoded data word via a medium having a maximum time between data transitions of T max  ; and   said step (b) includes preselecting said first preselected number of 1's and second preselected number of 0's whereby the maximum number of permitted consecutive 1's and the maximum number of permitted consecutive 0's in said encoded data word are transmitted in a time of less than   
     
     
        T max . .Iaddend. .Iadd.9.  The method of transmitting data of claim 7, wherein each of said data words are provided in a parallel representation, said method further comprising: converting each data word from the parallel representation to a serial representation. .Iaddend. .Iadd.10. The method of transmitting data of claim 7, wherein:   said step (c) includes serially transmitting said encoded data words via an fiber optic cable. .Iaddend. .Iadd.11. The method of receiving data words, each data word including a number of 1's and 0's, said method comprising the steps of:   (a) receiving serially transmitted data;   (b) searching received serially transmitted data for a unique signal;   (c) removing said unique signal from the received serially transmitted data;   (d) converting data received between receipts of said unique signal into received data words;   (e) counting the number of consecutive 1's in the received data words and removing a next bit following the receipt of a first preselected number of consecutive 1's;   (f) counting the number of consecutive 0's in the received data words and removing a next bit following receipt of a second preselected number of consecutive 0's. .Iaddend. .Iadd.12. The method of receiving data of claim 11 further comprising the steps of:   converting the data words having the next bit following receipt of said first preselected number of consecutive 1's removed and the next bit following receipt of said second preselected number of consecutive 0's   
     
     
        removed into a parallel representation. .Iaddend. .Iadd.13.  The method of receiving data of claim 11 further comprising the steps of: recovering a clock signal from the received serially transmitted data. .Iaddend. .Iadd.14. The method of receiving data of claim 11, wherein:   said step (a) includes receiving serially transmitted date via a fiber optic cable. .Iaddend.