Time interval measuring system

Claim 1

A time interval measuring system comprising: an N-bit input terminal for receiving a series of digital quantities represented by N bits and sampled at equal time intervals; a first memory connected to the N-bit input terminal for storing the series of digital quantities; at least one N-bit digital comparator means for comparing with each other two digital quantities respectively representing the output from the first memory and a threshold level; means for storing the series of digital quantities in the first memory, means for reading out the series of digital quantities from the first memory for input to the digital comparator means, a second memory formed by an N-bit register having its output connected to the digital comparator means for storing the threshold value, means for storing data in the second memory, at least one waveform discriminator connected to the digital comparator means and operative to remove small time deviations in the compared output near the threshold level and to generate a coincidence signal when the number of slopes crossing with the threshold level reaches a predetermined number; and means for selecting two different addresses of the first memory when said coincidence signal is generated for a distinct set of the threshold value, the polarity and the number of slopes, and for measuring from a difference between said two addresses of the first memory, at a high speed, a time interval between two digital quantities in the first memory.