US 4,357,634 A · Encoding and decoding digital information utilizing time intervals between pulses

Abstract

A method and apparatus for encoding and decoding digital information upon a recording medium using the time interval between adjacent pairs of pulses. A number "n" of unique time intervals between pulse pairs correspond to "n" unique symbols contained within a coding table. Assignment of the durations between pulses adapted to the frequency of occurrence of particular symbols within a data stream materially increases the efficiency of the method. Division of the data stream and numerical transformation of the data stream improve the efficiency of adaptive assignment of the durations between pulses on the basis of frequency of occurrence of particular symbols within a data stream. The method realizes a multiple-fold increase in data storage capacity of rotating magnetic disk memories over common MFM encoding, and the method similarly realizes a multiple-fold increase in data transfer rate for telecommunications applications.

Claims31

Dependent claims

A method for decoding digital information encoded into a first plurality of time intervals respectively between a plurality of successive pairs of digital pulses into a plurality of successive symbols equal in number to said first plurality of time intervals, said encoded data stream having a total time interval equal to the sum of said first plurality of time intervals plus said duration of all of said digital pulses, said plurality of symbols upon decoding making up a data stream, all of said symbols in said data stream being members of a non-empty set of "n" symbols, said second plurality of successive pairs of digital pulses being received by transmission, the method for decoding said encoded digital information comprising the steps of:

(a) providing a coding table coupled to said encoded data stream, said coding table storing a range of time intervals, each respective range of time intervals being related to a symbol in said set of "n" symbols, each range of time intervals further having adaptive assignment with said symbol occurring most frequently in said data stream assigned a range of time intervals in said coding table shorter than said range of time intervals assigned to said symbols occurring less frequently in said data stream, and with successively longer ranges of time intervals assigned to said symbol in said data stream having the next lower frequency of occurrence whereby said correspondence between each range of time intervals stored in said coding table to symbols in said set of "n" symbols minimizes the total time interval of said encoded data stream;
(b) receiving a first digital pulse for indicating the beginning of an encoded data stream;
(c) receiving a digital pulse successive to said preceeding digital pulse;
(d) measuring the time interval between said successive digital pulse and the digital pulse immediately preceeding said successive digital pulse;
(e) comparing said measured time interval with said range of time intervals stored in the coding table whereby each successive symbol is decoded from each successive time interval;
and
(f) successively repeating steps (c), (d) and (e) for all the remaining time intervals in said encoded data stream whereby said encoded data stream is decoded.

4 more elements

A method for encoding digital information for transmission thereof, said digital information including a first plurality of successive symbols making up a data stream with all of said symbols being members of a non-empty set of "n" symbols, comprising the steps of:

(a) providing a coding table coupled to said data stream, said coding table storing time intervals with each respective time interval being related to a symbol in said set of "n" symbols and each time interval having adaptive assignment with said symbol occurring most frequently in said data stream assigned a time interval shorter than said time interval assigned to said symbols occurring less frequently in said data stream, and with successively longer time intervals assigned to said symbol in said data stream having said next lower frequency of occurrence;
(b) generating a first digital pulse for indicating the beginning of an encoded data stream;
(c) determining a time interval for each successive symbol in said plurality of symbols making up said data stream by means of said coding table;
(d) generating a successive digital pulse subsequent to the generation of said immediately preceding digital pulse after a time interval equal to said time interval determined for said symbol by means of said coding table whereby each successive symbol in said data stream is encoded for transmission into a time interval between successive digital pulses;
and
(e) successively repeating steps (c) and (d) for all the remaining symbols in said data stream whereby said entire data stream is encoded into a plurality of time intervals equal in number to said plurality of symbols in said data stream, said time intervals being respectively separated by digital pulses, whereby because of said adaptive assignment said total time interval of said encoded data stream which equals the sum of all said time intervals between successive digital pulses plus said duration of all of said digital pulses is minimized.

3 more elements

A method for decoding digital information encoded into a succession of tones for telecommunications thereof, said digital information including a plurality of successive symbols making up a data stream, all of said symbols in said data stream being members of a non-empty set of "n" symbols, the method for decoding said succession of tones as applied repetitively to decode successive symbols comprising the steps of:

(a) providing a coding table coupled to said encoded data stream, said coding table storing a range of time intervals, each respective range of time intervals being related to a symbol of said set of "n" symbols, each range of time intervals further having adaptive assignment with said symbol occurring most frequently in said data stream assigned a range of time intervals in said coding table shorter than said range of time intervals assigned to said symbols occurring less frequently in said data stream, and with successively longer ranges of time intervals assigned to said symbol in said data stream having said next lower frequency of occurrence whereby said correspondence between each range of time intervals stored in said coding table to symbols in said set of "n" symbols minimizes the total time interval of said encoded data stream;
(b) measuring a time interval between successive zero-crossings of a sinusoid of said tone;
and
(c) comparing said measured time interval to a range of time intervals stored in the coding table whereby each successive symbol is decoded from each successive time interval;
and
(d) successively repeating steps (b) and (c) for all the remaining time intervals in said encoded data stream whereby said encoded data stream is decoded.

3 more elements

A method for encoding digital information for telecommunications thereof, said digital information consisting of a first plurality of successive symbols making up a data stream, all of said symbols in said data stream being members of a non-empty set of "n" symbols, the method for encoding said symbols making up said data stream as applied repetitively to encode successive symbols comprising the steps of:

(a) providing a coding table coupled to said encoded data stream, said coding table storing time intervals, each respective range of time interval being related to a symbol in said set of "n" symbols, each range of time intervals further having adaptive assignment with said symbol occurring most frequently in said data stream assigned to said symbols occurring less frequently in said data stream, and with successively ranges of time intervals assigned to said symbol in said data stream having said next lower frequency of occurrence;
(b) determining a tone for each successive symbol in said plurality of symbols making up said data stream by means of said coding table;
(c) generating a sinusoid of said tone determined by means of said coding table so that a time interval between successive zero-crossings of said sinusoid so generated equals said time interval determined for said symbol by means of said coding table whereby each successive symbol in said data stream is successively encoded into a tone for transmission and whereby, further, said entire data stream is encoded into a plurality of successive tones equal in number to said plurality of symbols in said data stream;
(d) successively repeating steps (b) and (c) for all remaining time intervals whereby said encoded data stream is encoded.

1 more element

A method for decoding digital information encoded into a first plurality of time intervals respectively between a plurality of successive pairs of digital pulses into a plurality of successive symbols equal in number to said first plurality of time intervals, said encoded data stream having a total time interval equal to the sum of said first plurality of time intervals plus said duration of all of said digital pulses, said plurality of symbols upon decoding making up a data stream, all of said symbols in said data stream being members of a non-empty set of "n" symbols, said plurality of successive pairs of digital pulses being received by transmission, the method for decoding said encoded digital information comprising the steps of:

(a) providing a coding table coupled to said encoded data stream, said coding table storing a range of time intervals, each respective range of time intervals being related to a symbol in said set "n" symbols, each range of time intervals stored in said coding table being unique and resolvable from all other ranges of time intervals stored therein whereby said total time interval of said encoded data stream depends both upon the particular occurrence of symbols in said data stream and upon ranges of said time intervals respectively assigned by said coding table to said individual symbols in said set of "n" symbols;
(b) receiving a first digital pulse for indicating the beginning of an encoded data stream;
(c) receiving a digital pulse successive to said preceding digital pulse;
(d) measuring the time interval between said successive digital pulse and the digital pulse immediately preceding said successive digital pulse;
(e) comparing said measured time interval with said range of said time intervals stored in the coding table whereby each successive symbol is decoded from each successive time interval;
and
(f) successively repeating steps (c), (d) and (e) for all the remaining time intervals in said encoded data stream whereby said encoded data stream is encoded.

4 more elements

Dependencies are inferred from the claim text.

Encoding and decoding digital information utilizing time intervals between pulses

Life of this patent

Encoding and decoding digital information utilizing time intervals between pulses

Life of this patent

Abstract

Claims31