Digital decoding of retrospective pulse modulation

Claim 1

A system for decoding data manifested by retrospective pulse modulated marks comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counter pulses for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated be-tween the second mark and a third mark; stepping counter means connected to said register means and to said control generator means, said stepping counter means being repeatedly stepped with a number of stepping counter pulses equal to the previous count, said stepping counter means providing an output signal each time it has been stepped said number of pulses equal to the previous count; long space counter means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said long space counter means for storing each output signal from said long space counter means and for providing at each mark, a first binary data output when the output of said long space counter means agrees with the output of said long space counter means stored in said data output circuit at the preceding mark.

Claim 2

A system for decoding data manifested by retrospective pulse modulated marks comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counter pulses for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated be-tween the second mark and a third mark; stepping counter means connected to said register means and to said control generator means, said stepping counter means being repeatedly stepped with a number of stepping counter pulses equal to the previous count, said stepping counter means providing an output signal each time it has been stepped said number of pulses equal to the previous count; long space counter means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said long space counter means for storing each output signal from said long space counter means and for providing at each mark, a first binary data output when the output of said long space counter means agrees with the output of said long space counter means stored in said data output circuit at the preceding mark.

Claim 3

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counter pulses, said interval counting means being responsive to the sensing of said marks for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated between the second mark and a third mark; stepping counter means connected to said register means and said control generator means, said stepping counter means being repeatedly stepped with a number of said stepping counter pulses equals to the previous count, said stepping counter means providing an output signal each time it has been stepped said number of pulses equal to the previous count; long space counter means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said long space counter means for storing each output signal from said long space counter means and for providing, at each mark, a first binary data output when the output of said long space counter means agrees with the output of said long space counter means stored in said data output circuit at the preceding mark.

Claim 4

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counter pulses, said interval counting means being responsive to the sensing of said marks for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated between the second mark and a third mark; stepping counter means connected to said register means and said control generator means, said stepping counter means being repeatedly stepped with a number of said stepping counter pulses equals to the previous count, said stepping counter means providing an output signal each time it has been stepped said number of pulses equal to the previous count; long space counter means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said long space counter means for storing each output signal from said long space counter means and for providing, at each mark, a first binary data output when the output of said long space counter means agrees with the output of said long space counter means stored in said data output circuit at the preceding mark.

Claim 7

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counting pulses, said interval counting means being responsive to the sensing of said marks for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated between the second mark and a third mark; ones complementing means connected to said register means for providing the ones complement of said previous count; stepping counter means connected to said ones complementing means and said control generator means, said stepping counter means being repeatedly stepped with the ones complement of the previous count, said stepping counter means providing an output signal each time an end carry occurs in said stepping counter means; end carry counting means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said end carry counter means for storing each output signal from said end carry counter means and for providing at each mark, a first binary data output when the output of said end carry counter means agrees with the output of said end carry counter means stored in said data output circuit at the preceding mark.

Claim 8

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space comprising: control generator means for generating stepping counter pulses at a frequency f and interval counter pulses at a frequency f/N; interval counting means connected to said control generator means and advanced by said interval counting pulses, said interval counting means being responsive to the sensing of said marks for accumulating a current count between a first mark and a second mark; register means connected to said interval counting means for storing said current count as a previous count while another current count is being accumulated between the second mark and a third mark; ones complementing means connected to said register means for providing the ones complement of said previous count; stepping counter means connected to said ones complementing means and said control generator means, said stepping counter means being repeatedly stepped with the ones complement of the previous count, said stepping counter means providing an output signal each time an end carry occurs in said stepping counter means; end carry counting means connected to said stepping counter means for providing an output signal when the number of output signals from said stepping counter means has exceeded a predetermined number between two marks; output circuit means connected to said end carry counter means for storing each output signal from said end carry counter means and for providing at each mark, a first binary data output when the output of said end carry counter means agrees with the output of said end carry counter means stored in said data output circuit at the preceding mark.

Claim 9

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space, comprising: mark sensing means providing an output in response to the sensing of a mark; control generator means for generating stepping counter pulses at a frequency f and interval counting pulses at a frequency f/N, said control generator means being further operable in response to the sensing of a mark for providing a single sequence of timing pulses; interval counting means connected to said control generator means operable in response to said sequence of timing pulses for accumulating a current count of said counting pulses representative of the interval between two marks; register means connected to said counting means and said control generator means operable in response to said sequence of timing pluses for storing a previous count of said interval counting means, said previous count being defined as the current count in said interval counting means immediately before said interval counting means is reset; stepping counter means connected to said register means and said control generator means operable in response to said sequence of timing signals for stepping the ones complement of said previous count stored in said register means with said stepping counter pulses, said stepping counter means being reloaded with the ones complement of said previous count stored in said register means each time an end carry occurs; end carry counting means connected to said control generator and said stepping counter means operable in response to said sequence of timing signals for counting the number of end carries performed by said stepping counter means, said end carry counting means providing an output signal when its contents have exceeded a predetermined number, said output signal shifting said register means for dividing the contents of said register means by approximately 2 after said register means has been loaded with the latest previous count; data output circuit means connected to said end carry counter means and said control generator means operable in response to said sequence of timing signals for storing the presence or absence of an output signal from said end carry means and being further operable in response to said sequence timing signals for providing a first binary data output when the present output of said end carry counter means agrees with the presence or absence of an output from said end carry means stored in said data output circuit means at the preceding sequence of timing signals, said data output circuit means further providing a second binary output when the present output of said end carry counter means disagrees with said output of said end carry counter means stored in said data output circuit means at the preceding sequence of timing pulses.

Claim 10

A system for decoding data manifested by the relative spacing between retrospective pulse modulated marks, wherein the space between the first two marks in a series of marks defines a short space, comprising: mark sensing means providing an output in response to the sensing of a mark; control generator means for generating stepping counter pulses at a frequency f and interval counting pulses at a frequency f/N, said control generator means being further operable in response to the sensing of a mark for providing a single sequence of timing pulses; interval counting means connected to said control generator means operable in response to said sequence of timing pulses for accumulating a current count of said counting pulses representative of the interval between two marks; register means connected to said counting means and said control generator means operable in response to said sequence of timing pluses for storing a previous count of said interval counting means, said previous count being defined as the current count in said interval counting means immediately before said interval counting means is reset; stepping counter means connected to said register means and said control generator means operable in response to said sequence of timing signals for stepping the ones complement of said previous count stored in said register means with said stepping counter pulses, said stepping counter means being reloaded with the ones complement of said previous count stored in said register means each time an end carry occurs; end carry counting means connected to said control generator and said stepping counter means operable in response to said sequence of timing signals for counting the number of end carries performed by said stepping counter means, said end carry counting means providing an output signal when its contents have exceeded a predetermined number, said output signal shifting said register means for dividing the contents of said register means by approximately 2 after said register means has been loaded with the latest previous count; data output circuit means connected to said end carry counter means and said control generator means operable in response to said sequence of timing signals for storing the presence or absence of an output signal from said end carry means and being further operable in response to said sequence timing signals for providing a first binary data output when the present output of said end carry counter means agrees with the presence or absence of an output from said end carry means stored in said data output circuit means at the preceding sequence of timing signals, said data output circuit means further providing a second binary output when the present output of said end carry counter means disagrees with said output of said end carry counter means stored in said data output circuit means at the preceding sequence of timing pulses.