Time domain reflectometry apparatus and method
OwnerDavid Needleinventor
Life of this patent
Estimating the term…
Abstract
A reference length of electrically conductive material having a predetermined electrical length and impedance permanently inserted in a time domain reflectometer measuring path prior to the connection point to the cable-under-test. Measurement to the start of the reference length is used to establish a reference position within the measurement path for subsequent time domain reflectometry measurements.
Claims13
A method of establishing a reference position in the measurement path of a time domain reflectometer comprising the steps of:
- inserting a reference length of electrically conductive material in said measurement path where said reference length has a predetermined electrical length and impedance;
- using the measurement of said reference length to establish a reference position within said measurement path,
- calibrating the operation of the time domain reflectometer utilizing said reference position,
- providing an additional offset from the reference position to prevent said reference length from influencing subsequent measurements made by said time domain reflectometer.
A method of calibrating a time domain reflectometer comprising the steps of:
- performing a time domain reflectometer measurement starting at an internal time reference;
- measuring the time from said internal time reference to a reference position to establish a reference time;
- add an offset to the reference time, said offset being larger than the sum of a reference length incorporated in the time domain reflectometer and a predetermined convenience wire length to be employed with the time domain reflectometer to establish a stop enable time;
- and
- adjust the time domain reflectometer to delay the enabling of the capture of any signals during the established stop enable time while keeping the initial signal of the time domain reflectometer at the internal reference time, effectively starting measurement by the time domain reflectometer at the end of said stop enable time.
Time domain reflectometry apparatus for testing a cable, said apparatus including:
- electrical signal generator means;
- cable connector means for connecting a cable to said apparatus;
- means defining a time domain reflectometer measurement path for directing electrical signals generated by said electrical signal generator means to said cable connector means and for receiving reflected electrical signals from a cable attached to said cable connector means;
- and
- a reference length of electrically conductive material permanently positioned in said time domain reflectometer measuring path between said electrical signal generating means and said cable connector means for calibrating the operation of the time domain reflectometry apparatus.
A method of testing a cable with a time domain reflectometer comprising the steps of:
- generating an electrical signal;
- conveying said electrical signal along a time domain reflectometer measurement path to a cable under test;
- while conveying said electrical signal along said time domain reflectometer measurement path, passing said electrical signal through a reference length of electrically conductive material positioned in said time domain reflectometer measurement path to establish a reference position for time domain reflectometer measurement;
- reflecting said electrical signal from said cable back through said time domain reflectometer measurement path and through said reference length of electrically conductive material;
- and
- comparing the generated electrical signal with the electrical signal reflected from said cable after passage thereof through the reference length of electrically conductive material.
Dependencies are inferred from the claim text.