A dual mode encoding/decoding technique for use in a digital transmission system

Claim 2

Apparatus for use in a digital transmission system wherein transmitted digital words are limited on average to an allotted number of bits, said apparatus CHARACTERIZED BY first means (101, 105, 106, 127, 130, 131, 134) for encoding an input signal into a preselected combination of first and second digital words such that the average number of bits per word in said combination is not greater than said allotted number of bits, each of said first digital words has more than said allotted number of bits and each of said second digital words is formed using differential coding and has less than said allotted number of bits; second means (101, 105, 106, 148, 144) for encoding said input signal into third digital words each having not more than said allotted number of bits; means (134, 150) for determining the precision provided by said preselected combination relative to a preselected threshold; means (137, 146, 152, 154) responsive to a first result of said precision determination for forming a first output comprising said preselected combination; and means (148, 152, 154) responsive to a second result of said precision determination for forming an alternate output comprising said third digital words.

Claim 3

The apparatus of claim 1 CHARACTERIZED IN THAT the average number of bits per word in said combination is equal to said allotted number of bits.

Claim 4

The apparatus of claim 2 CHARACTERIZED IN THAT each of said third digital words has said allotted number of bits.

Claim 5

The apparatus of claim 3 CHARACTERIZED IN THAT said preselected combination in said first output is arranged into output words each having the allotted number of bits.

Claim 7

The apparatus of claim 1 CHARACTERIZED IN THAT said second digital words are formed using linear interpolated predictions.

Claim 8

The apparatus of claim 6 CHARACTERIZED IN THAT each of said linear interpolated predictions is formed from selected ones of said first digital words.

Claim 9

The apparatus of claim 7 CHARACTERIZED IN THAT each of said second digital words represents said input signal at a given time and said selected ones of said first diqital words represent said input signal at times before and after said given time.

Claim 10

The apparatus of claim 1 CHARACTERIZED IN THAT said first digital words comprises nine bits, said second digital words comprises seven bits, and said third digital words comprises eight bits.

Claim 11

Apparatus for use in a digital transmission system wherein transmitted digital words are limited on average to an allotted number of bits, said apparatus CHARACTERIZED BY first means (301, 304, 306, 317, 328, 330, 331, 332, 336, 338, 339, 342, 344, 345) responsive to a first signal for generating an output signal by decoding a preselected combination of first and second digital words, the average number of bits per word in said combination being not greater than said allotted number of bits, each of said first digital words has more than said allotted number of bits and each of said second digital words has less than said allotted number of bits and was formed using differential coding; and second means (301, 304, 306, 317, 339, 342, 344, 345) responsive to a second signal for generating said output signal by decoding third digital words each having not more than said allotted number of bits.

Claim 12

Apparatus for use in a digital transmission system wherein transmitted digital words are limited on average to an allotted number of bits, said apparatus CHARACTERIZED BY first means (301, 304, 306, 317, 328, 330, 331, 332, 336, 338, 339, 342, 344, 345) responsive to a first signal for generating an output signal by decoding a preselected combination of first and second digital words, the average number of bits per word in said combination being not greater than said allotted number of bits, each of said first digital words has more than said allotted number of bits and each of said second digital words has less than said allotted number of bits and was formed using differential coding; and second means (301, 304, 306, 317, 339, 342, 344, 345) responsive to a second signal for generating said output signal by decoding third digital words each having not more than said allotted number of bits.

Claim 13

The apparatus of claim 10 CHARACTERIZED IN THAT the average number of bits per word in said combination is equal to said allotted number of bits.

Claim 14

The apparatus of claim 11 CHARACTERIZED IN THAT each of said third digital words has said allotted number of bits.

Claim 15

The apparatus of claim 12 CHARACTERIZED IN THAT said preselected combination is arranged into incoming digital words each having said allotted number of bits.

Claim 16

The apparatus of claim 13 CHARACTERIZED IN THAT said first means decodes said second digital words by regenerating linear interpolated predictions.

Claim 17

The apparatus of claim 14 CHARACTERIZED IN THAT each of said linear interpolated predictions is formed from selected ones of said first digital words.

Claim 18

The apparatus of claim 15 CHARACTERIZED IN THAT each of said second digital words is received at a qiven time and said selected ones of said first digital words are received at times before and after said given time.

Claim 19

The apparatus of claim 9 CHARACTERIZED IN THAT said first digital words comprises nine bits, said second diqital words comprises seven bits, and said third digital words comprises eight bits.

Claim 20

A digital transmission system comprising a transmitter and a receiver which respectively encode and decode digital words which are limited on an average to an allotted number of bits, said system CHARACTERIZED BY first transmitter means (101, 105, 106, 127, 130, 131, 134) for encoding an input signal into a preselected combination of first and second digital words such that the average number of bits per word in said combination is not greater than said allotted number of bits, each of said first digital words has more than said allotted number of bits and each of said second digital words is formed using differential coding and has less than said allotted number of bits; second transmitter means (101, 105, 106, 148, 144) for encoding said input signal into third digital words each having not more than said allotted number of bits; third transmitter means (134, 150) for determining the precision provided by said preselected combination relative to a preselected threshold; fourth transmitter means (137, 146, 152, 154) responsive to a first result of said precision determination for forming a first output comprising said preselected combination and a first output identifying signal; fifth transmitter means (148, 152, 154) responsive to a second result of said precision determination for forming an alternate output comprising said third digital words and an alternate output identifying signal; first receiver means (301, 304, 306, 317, 328, 330, 331, 332, 336, 338, 339, 342, 344, 345) responsive to said first output identifying signal for regenerating said input signal by decoding said preselected combination; and second means (301, 304, 306, 317, 339, 342, 344, 345) responsive to said alternate output identifying signal for regenerating said input signal by decoding said third diqital words.

Claim 21

A digital transmission system comprising a transmitter and a receiver which respectively encode and decode digital words which are limited on an average to an allotted number of bits, said system CHARACTERIZED BY first transmitter means (101, 105, 106, 127, 130, 131, 134) for encoding an input signal into a preselected combination of first and second digital words such that the average number of bits per word in said combination is not greater than said allotted number of bits, each of said first digital words has more than said allotted number of bits and each of said second digital words is formed using differential coding and has less than said allotted number of bits; second transmitter means (101, 105, 106, 148, 144) for encoding said input signal into third digital words each having not more than said allotted number of bits; third transmitter means (134, 150) for determining the precision provided by said preselected combination relative to a preselected threshold; fourth transmitter means (137, 146, 152, 154) responsive to a first result of said precision determination for forming a first output comprising said preselected combination and a first output identifying signal; fifth transmitter means (148, 152, 154) responsive to a second result of said precision determination for forming an alternate output comprising said third digital words and an alternate output identifying signal; first receiver means (301, 304, 306, 317, 328, 330, 331, 332, 336, 338, 339, 342, 344, 345) responsive to said first output identifying signal for regenerating said input signal by decoding said preselected combination; and second means (301, 304, 306, 317, 339, 342, 344, 345) responsive to said alternate output identifying signal for regenerating said input signal by decoding said third diqital words.