US4829526A — Data transmission

Claim 1

Independent Claim 119 words

A method of coding and transmitting a series of binary digits, characterised in that it comprises: forming the binary digits into sections of length N bits, where N has a predetermined maximum value N Max; forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmitting the interleaved bits.

Claim 2

Independent Claim 119 words

A method of coding and transmitting a series of binary digits, characterised in that it comprises: forming the binary digits into sections of length N bits, where N has a predetermined maximum value N Max; forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmitting the interleaved bits.

Claim 3

Dependent Claim 49 words

A method of coding and transmitting binary digits according to claim 1 in which the digits are counted and the time intervals between the digits are sensed, the digits being formed into a section whenever either the count N reaches N max or a predetermined time interval is sensed.

Claim 4

Dependent Claim 34 words

A method of coding and transmitting binary digits according to claim 1 or claim 2 further comprising adding to each frame an indication of the value of N for the section within the frame.

Claim 5

Dependent Claim 25 words

A method of coding and transmitting binary digits according to claim 3 further comprising adding to each frame an indication of the frame sequence number.

Claim 6

Dependent Claim 91 words

A method of coding and transmitting binary digits according to claim 1 in which the binary digits represent alphanumeric characters characterised by further comprising an initial encoding step of assigning a different 4-bit code to each of the 8 most frequently occurring alphanumeric characters and assigning a different at least 5-bit code to each of the remaining characters, the first bit of each 4-bit code being identical and being different from the first bit of each at least 5-bit code whereby the number of binary digits to be transmitted is reduced.

Claim 7

Dependent Claim 160 words

A method as in claim 1 wherein said interleaving step includes: (a) providing a bit sequence of a certain length consisting of the first bit of each of said codewords, (b) providing a bit sequence of said certain length consisting of the next bit of each of said codewords, (c) repeating said providing step (b) until the last bit of each of said codewords has been provided in a bit sequence of said certain length, (d) providing a bit sequence of said certain length consisting of the first of said check bits associated with each of said codewords, (e) providing a bit sequence of said certain length consisting of the next of said check bits associated with each of said codewords, and (f) repeating said providing step (e) until the last of each of said check bits has been provided in a bit sequence of said certain length, wherein said certain length is variable and depends upon said length N.

Claim 8

Dependent Claim 25 words

A method as in claim 6 wherein said subdividing step comprises subdividing each variable length frame into more than two codewords of said fixed length.

Claim 9

Independent Claim 184 words

A method of coding, transmitting, receiving and decoding binary digits characterised in that it comprises: forming the binary digits into sections of length N bits, where N has a predetermined maximum value N max: forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; transmitting the interleaved bits; receiving the transmitted interleaved bits; deinterleaving the received bits; applying the fixed number of check bits to correct a known number of errors within the associated codeword; forming the error-corrected codewords into a variable length frame; applying the cyclic redundancy check digits to detect an error in the data bits section within the frame; and forming the corrected data bit sections into a series of binary digits.

Claim 10

Independent Claim 184 words

A method of coding, transmitting, receiving and decoding binary digits characterised in that it comprises: forming the binary digits into sections of length N bits, where N has a predetermined maximum value N max: forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; transmitting the interleaved bits; receiving the transmitted interleaved bits; deinterleaving the received bits; applying the fixed number of check bits to correct a known number of errors within the associated codeword; forming the error-corrected codewords into a variable length frame; applying the cyclic redundancy check digits to detect an error in the data bits section within the frame; and forming the corrected data bit sections into a series of binary digits.

Claim 11

Dependent Claim 106 words

A method of coding, transmitting, receiving and decoding binary digits according to claim 8 in which the binary digits represent alphanumeric characters in which: before transmission there is applied an initial encoding step of assigning a different 4-bit code to each of the 8 most frequently occurring alphanumeric characters and assigning a different at least 5-bit code to each of the remaining characters, the first bit of each 4-bit code being identical and being different from the first bit of each at least 5-bit code whereby the number of binary digits to be transmitted is reduced; and after receipt there is applied an equivalent decoding step.

Claim 12

Dependent Claim 61 words

A method of coding, transmitting, receiving and decoding binary digits according to claim 9 further comprising continuously evaluating the frequency of occurrence of the alphanumeric characters, and intermittently altering the assignment of the 4-bit and at least 5- bit codes, said alteration being arranged so that the same assignment of codes is applied to encode and to decode the binary digits.

Claim 13

Dependent Claim 121 words

Apparatus for transmitting a series of binary digits, characterised in that it comprises: frame buffer means (20) for forming the binary digits into sections of length N bits, Where N has a predetermined maximum value N max; CRC coder means (14) for supplying sets of binary digits which comprise a cyclic redundancy check which is added to the sections of length N bits contained within frame buffer (20); encoding and interleaving means (22) for subdividing each variable length frame into codewords of fixed length, for adding to each codeword a fixed number of check bits, and for interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmission means (24,26) for transmitting the interleaved bits.

Claim 14

Dependent Claim 121 words

Apparatus for transmitting a series of binary digits, characterised in that it comprises: frame buffer means (20) for forming the binary digits into sections of length N bits, Where N has a predetermined maximum value N max; CRC coder means (14) for supplying sets of binary digits which comprise a cyclic redundancy check which is added to the sections of length N bits contained within frame buffer (20); encoding and interleaving means (22) for subdividing each variable length frame into codewords of fixed length, for adding to each codeword a fixed number of check bits, and for interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmission means (24,26) for transmitting the interleaved bits.

Claim 15

Dependent Claim 87 words

Apparatus according to claim 14 further comprising initial encoding means (14,16) for applying to binary digits which represent alphanumeric characters an initial encoding step of assigning a different 4-bit code to each of the 8 most frequently occurring alphanumeric characters and assigning a different at least 5-bit code to each of the remaining characters, the first bit of each 4-bit code being identical and being different from the first bit of each at least 5-bit code whereby the number of binary digits to be transmitted is reduced.

Claim 16

Dependent Claim 142 words

Apparatus for receiving and decoding a series of binary digits comprising: receiving means (36,46) for receiving interleaved codewords of fixed length within a variable length frame; deinterleaving and error correction means (48) for deinterleaving the received codewords based on an interleave depth dependent on a frame length N and applying a fixed number of check bits to correct a known number of errors within a codeword; frame buffer means (50) for forming the error-corrected codewords into a frame of said length N; CRC decoder means (56) for applying a cyclic redundancy check to the received frame and for detecting the presence of uncorrected errors; variable length decoder means (52) for decoding said received frame into data bit sections; buffer means (58) for temporary storage of the data bit sections; and run length decoding means (60) for further decoding said data bit sections.

Claim 17

Dependent Claim 142 words

Apparatus for receiving and decoding a series of binary digits comprising: receiving means (36,46) for receiving interleaved codewords of fixed length within a variable length frame; deinterleaving and error correction means (48) for deinterleaving the received codewords based on an interleave depth dependent on a frame length N and applying a fixed number of check bits to correct a known number of errors within a codeword; frame buffer means (50) for forming the error-corrected codewords into a frame of said length N; CRC decoder means (56) for applying a cyclic redundancy check to the received frame and for detecting the presence of uncorrected errors; variable length decoder means (52) for decoding said received frame into data bit sections; buffer means (58) for temporary storage of the data bit sections; and run length decoding means (60) for further decoding said data bit sections.

Claim 18

Independent Claim 204 words

A method of coding and transmitting a series of binary digits representing alphanumeric characters comprising: assigning a different 4-bit code to each of the eight most frequently occurring alphanumeric characters; assigning a different at least 5-bit code to each of the remaining characters not included in the eight most frequently used characters, the first bit of each of said 4-bit codes being different from the first bit of any of said 5-bit codes; initially encoding said series of binary digits in accordance with said assignments to provide a second series of binary digits which is of reduced length; forming said second series of binary digits into sections of length N bits where N has a predetermined maximum value N max; forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmitting the interleaved bits.

Claim 19

Independent Claim 204 words

A method of coding and transmitting a series of binary digits representing alphanumeric characters comprising: assigning a different 4-bit code to each of the eight most frequently occurring alphanumeric characters; assigning a different at least 5-bit code to each of the remaining characters not included in the eight most frequently used characters, the first bit of each of said 4-bit codes being different from the first bit of any of said 5-bit codes; initially encoding said series of binary digits in accordance with said assignments to provide a second series of binary digits which is of reduced length; forming said second series of binary digits into sections of length N bits where N has a predetermined maximum value N max; forming the sections into variable length frames by adding to each section of N bits a set of binary digits which comprise a cyclic redundancy check for detecting errors within that section; subdividing each variable length frame into codewords of fixed length; to each codeword adding a fixed number of check bits which allow correction of a known number of errors within that codeword; interleaving the codewords and their associated check bits, the interleaving depth being dependent on N; and transmitting the interleaved bits.

Claim 20

Dependent Claim 37 words

A method of coding and transmitting binary digits according to claim 14 further comprising continuously evaluating the frequency of occurrence of the alphanumeric characters, and intermittently altering the assignment of the 4-bit and at least 5-bit codes.

Claim 21

Dependent Claim 41 words

A method of coding and transmitting binary digits according to claim 15 in which the intermittent alteration of the assignment of the 4-bit and at least 5-bit codes occurs after the transmission of all interleaved codewords within a variable length frame.

Claim 22

Dependent Claim 33 words

A method of coding and transmitting binary digits according to claim 16 in which the binary digits to be transmitted are eight-bit ASCII code, and the at least 5-bit code is 9-bit code.

Claim 23

Dependent Claim 33 words

A method of coding and transmitting binary digits according to claim 16 in which the binary digits to be transmitted are seven-bit ASCII code and the at least 5-bit code is 8-bit codes.

Claim 24

Dependent Claim 72 words

A method of coding and transmitting binary digits according to claim 14 in which the initial encoding step is preceded by the application to the alphanumeric characters to be transmitted of a prior run length encoding step, by which a run of a repeated character is replaced by a shorter sequence comprising one occurrence of said character, a control character indicating a run, and an indication of the length of the run.

Claim 25

Dependent Claim 52 words

A method of coding and transmitting binary digits according to claim 14 wherein said forming step comprises counting the digits and sensing the time intervals between the digits, said forming step forming the digits into a section whenever either the count N reaches N max or a predetermined time interval is sensed.

Claim 26

Dependent Claim 31 words

A method of coding and transmitting binary digits according to claim 20 further comprising adding to each frame an indication of the value of N for the section within the frame.

Claim 27

Dependent Claim 25 words

A method of coding and transmitting binary digits according to claim 21 further comprising adding to each frame an indication of the frame sequence number.

Claim 28

Dependent Claim 122 words

Apparatus for receiving and decoding a series of binary digits comprising: receiving means (36,46) for receiving interleaved codewords; deinterleaving and error correction means (48) for deinterleaving the received codewords and applying a fixed number of check bits to correct a known number of errors within a codeword; frame buffer means (50) for forming the error-corrected codewords into a frame of length N; CRC decoder means (56) for applying a cyclic redundancy check to the received frame and for detecting the presence of uncorrected errors; variable length decoder means (52) for decoding said received frame into data bit sections; buffer means (58) for temporary storage of the data bit sections; and run length decoding means (60) for further decoding said data bit sections.

Claim 29

Dependent Claim 122 words

Apparatus for receiving and decoding a series of binary digits comprising: receiving means (36,46) for receiving interleaved codewords; deinterleaving and error correction means (48) for deinterleaving the received codewords and applying a fixed number of check bits to correct a known number of errors within a codeword; frame buffer means (50) for forming the error-corrected codewords into a frame of length N; CRC decoder means (56) for applying a cyclic redundancy check to the received frame and for detecting the presence of uncorrected errors; variable length decoder means (52) for decoding said received frame into data bit sections; buffer means (58) for temporary storage of the data bit sections; and run length decoding means (60) for further decoding said data bit sections.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-05-08	1992-11-07	1993-05-09	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-05-08	1996-11-07	1997-05-09	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-05-08	2000-11-07	2001-05-09	$7700.00	Window Closed / Lapsed

Data transmission

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