Apparatus for measuring pulse signal delay interval

A method for mesuring the length of a path by measuring the time required for pulses to propagate along said path, comprising the steps of:

• providing a transmitter and a receiver to define the ends of said path;
• producing a start signal;
• transmitting said start signal to said transmitter to cause said transmitter to generate pulses which propagate along said path;
• generating a stop signal responsive to receipt of said pulses at said receiver;
• producing a train of reference pulses at a predetermined frequency;
• counting the pulses received at said receiver between said start and stop signals using a coarse counter;
• providing fine measurement interpolator means;
• and
• causing said fine measurement interpolator means to determine two residual times, one between said stop signal and a predetermined edge of the next following reference pulse, and a second residual time between said start signal and a predetermined edge of the next following reference pulse.

Apparatus for measuring the length of a path by measuring the time required for a pulse to propagate along said path, the combination comprising:

• a transmitter and a receiver defining the ends of said path;
• a logic control circuit;
• means for producing a start signal;
• means to transmit said start signal to said transmitter to cause said transmitter to generate a pulse which propagates between the transmitter and the receiver;
• means responsive to receipt of said pulse at said receiver to generate a stop signal;
• means for producing reference pulses;
• coarse counter means having first, second and third inputs and an output for counting whole ones of said reference pulses;
• time interpolator means having first and second inputs and an output for evaluation of segments of said reference pulses smaller than whole ones of said reference pulses which may occur at the beginning and at the end of a path length measurement;
• an OR-gate having first and second inputs and an output;
• means to connect said first input of said OR-gate to said means to transmit said start signal to said transmitter;
• means to connect said second input of said OR-gate to said stop signal generating means;
• an edge detector having first and second inputs and an output;
• means to connect said output of said OR-gate to both said first input of said time interpolator means and said first input of said edge detector;
• means to supply said reference pulses to said second input of said edge detector, said time interpolator means and said coarse counter means;
• means to connect said output of said edge detector to said second input of said time interpolator means and to said second input of said coarse counter means;
• means to interconnect said means to transmit said start signal with said third input of said coarse counter means;
• and
• means to interconnect said logic control circuit with said output of said coarse counter means and said output of said time interpolator means.