Leading edge detector/reply quantizer
First Claim
1. In a pulse code communications system having a receiver, a video detector producing a composite video signal which may be formed by interfering pulse signals received by said receiver and a leading edge detector/pulse quantizer for processing said composite video signal to separate interfering pulses therein, said leading edge detector including:
- a source of clock signals;
means responsive to the amplitude and rate of change of amplitude of said composite video signal to provide;
(a) a positive slope (PS) signal which persists during the time said rate of change of amplitude increases at a predetermined rate;
(b) a negative slope (NS) signal which persists during the time said rate of change of amplitude decreases at a predetermined rate; and
(c) a quantized video (QV) signal which persists during the time said amplitude exceeds a predetermined level;
a first shift register for propagating said PS signals according to their relative times of appearance;
a second shift register for propagating said NS signals according to their relative times of appearance;
a third shift register for propagating said QV signals according to their relative times of appearance;
each of said first, second and third registers propagating the signals contained therein at a rate determined by said clock signals;
first logic means for examining the contents of said first and third registers to determine the truth of a condition in which;
said third register contains a signal which has persisted for two or more clock signals after the appearance of a first signal in said first register; and
for inserting a signal in said first register at a position two clock signals after said first signal therein if said condition is true;
second logic means for examining the contents of said first and second registers to determine the truth of a condition in which;
a signal is present in said second register at a position of between 11 and 18 clock signals after a first signal appears in said first register and no second signal is present in said first register in said 11-18 clock signal interval; and
for inserting a second signal in said first register at a position corresponding to a time of 7 clock signals before the time of appearance of said signal in said second register; and
means for unloading the contents of said first register in serial-by-bit format after operation of said first and second logic means;
the improvement wherein said first logic means further includes;
means for determining the truth of a second condition in which;
a first and second signal are present in said first register separated by one clock signal interval and said third register contains a signal at the time said first signal of said first register ends; and
means for deleting said second signal from said first register if said second condition is not true.
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Accused Products
Abstract
An improved Leading Edge Detector/Pulse Quantizer (LED) for use in a pulse code communications system. A prior LED included three shift registers for storing in relative time order, according to the time of reception of video pulse signals by an associated receiver, (a) pulse leading edges, (b) pulse trailing edges and (c) Quantized video (quantized video comprises a pulse having a width equal to the time the received video exceeds a threshold amplitude). The prior LED further included a plurality of logic means for examining the contents of the three registers to determine whether pulse leading or trailing edges of the received video signal were possibly missing because of interference between received video pulses and for inserting extra leading edges in the leading edge register if such extra leading edges could be logically inferred to be present.
The improvement of the invention includes expansions of the functions of the logic means for detecting and inferring the presence of leading edges and trailing edges, improved control means to insure that the logic means operate in proper sequence and improved logic means for deleting signals from the leading edge register when their presence is determined to be illogical.
50 Citations
20 Claims
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1. In a pulse code communications system having a receiver, a video detector producing a composite video signal which may be formed by interfering pulse signals received by said receiver and a leading edge detector/pulse quantizer for processing said composite video signal to separate interfering pulses therein, said leading edge detector including:
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a source of clock signals; means responsive to the amplitude and rate of change of amplitude of said composite video signal to provide; (a) a positive slope (PS) signal which persists during the time said rate of change of amplitude increases at a predetermined rate; (b) a negative slope (NS) signal which persists during the time said rate of change of amplitude decreases at a predetermined rate; and (c) a quantized video (QV) signal which persists during the time said amplitude exceeds a predetermined level; a first shift register for propagating said PS signals according to their relative times of appearance; a second shift register for propagating said NS signals according to their relative times of appearance; a third shift register for propagating said QV signals according to their relative times of appearance; each of said first, second and third registers propagating the signals contained therein at a rate determined by said clock signals; first logic means for examining the contents of said first and third registers to determine the truth of a condition in which; said third register contains a signal which has persisted for two or more clock signals after the appearance of a first signal in said first register; and
for inserting a signal in said first register at a position two clock signals after said first signal therein if said condition is true;second logic means for examining the contents of said first and second registers to determine the truth of a condition in which; a signal is present in said second register at a position of between 11 and 18 clock signals after a first signal appears in said first register and no second signal is present in said first register in said 11-18 clock signal interval; and
for inserting a second signal in said first register at a position corresponding to a time of 7 clock signals before the time of appearance of said signal in said second register; andmeans for unloading the contents of said first register in serial-by-bit format after operation of said first and second logic means; the improvement wherein said first logic means further includes; means for determining the truth of a second condition in which; a first and second signal are present in said first register separated by one clock signal interval and said third register contains a signal at the time said first signal of said first register ends; and means for deleting said second signal from said first register if said second condition is not true. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification