Apparatus for digitizing noisy time duration signals

Claim 1

Apparatus for processing noisy time duration signals which have stable portions represented by a first voltage level and may have transient portions adjacent their leading and trailing edges in which the voltage fluctuates between said first level and a reference level, the apparatus including a. converting means connected to receive said noisy time duration signals and transduce each into digital form, the converting means requiring for each time duration signal a control pulse which is synchronized to the trailing edge of each time duration signal; b. means including a one-shot multivibrator, which also receives said noisy time duration signals and produces an output pulse whenever one of the time duration signals changes from the first level to the reference level, the one-shot multivibrator means comprising two NOT-TYPE logic gates each of which has two inputs, a differentiator connected to receive said time duration signals and to supply its output to one input of the first gate, a second differentiator connected to receive the output of the second gate and to supply pulses to the other input of the first gate, and connections for supplying the output of the first gate to both inputs of the second gate; c. the duration of the output pulse being longer than said transient portions; and d. means which senses said time duration signals and said output pulse and inhibits said control pulse except when the trailing edge of the output pulse occurs at a time when the signal is at the reference level, the sensing means comprising a third differentiator connected to receive the output of said first gate and having an output connection to which said signals are applied through a blocking diode, and a control pulse generator which is connected to be triggered by pulses produced in said output connection.