Fault detection system and method
First Claim
1. A time domain reflectometer comprising a transmitter for generating a test signal, a multiplexer connected to the transmitter and to a test port, the test port having a plurality of outputs, each being connectable to one of a plurality of transmission media to be tested, wherein the multiplexer is controllable to route signals from the transmitter to a selected output of the test port, and means is provided to determine, select or confirm the return ground path for the selected output port, and wherein the reflectometer further comprises means for analysing reflected signals received back from the transmission media to be tested and the return ground path thereby enabling impedance changes along the length of the transmission media to be determined and the respective distance to the impedance changes, for transmission media of known and unknown impedance.
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Accused Products
Abstract
A non-intrusive, fully automated, variable Cable and impedance-based, multiplexed cable testing system is described that uses Time Domain Reflectometry techniques. The system can process more than one cable type, with varying characteristics, at any one time during which it confirms and processes both the characteristics of the cable type under test and any discontinuities encountered during its operational life due to the impedance variations defined and processed. Furthermore, the system provides an extensive range of Real-Time Diagnostic and Prognostic data together with accurate location and interpretation of any said data and or discontinuity including, but not limited to, the additional mapping of impedance variations along the length of the cable.
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Citations
26 Claims
- 1. A time domain reflectometer comprising a transmitter for generating a test signal, a multiplexer connected to the transmitter and to a test port, the test port having a plurality of outputs, each being connectable to one of a plurality of transmission media to be tested, wherein the multiplexer is controllable to route signals from the transmitter to a selected output of the test port, and means is provided to determine, select or confirm the return ground path for the selected output port, and wherein the reflectometer further comprises means for analysing reflected signals received back from the transmission media to be tested and the return ground path thereby enabling impedance changes along the length of the transmission media to be determined and the respective distance to the impedance changes, for transmission media of known and unknown impedance.
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19. A time domain reflectometry method comprising the steps of:
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a) transmitting a signal down a transmission medium;
b) monitoring for transmitted signals reflected in the transmission medium;
c) measuring time expired since transmission;
wherein upon detection of a transmitted signal reflected in the transmission medium, d) recording time expired since transmission;
e) sampling and processing reflected pulse or pulses;
f) determining pulse characteristics for all reflected pulses;
g) comparing all reflected pulses with threshold values;
h) transmitting a further signal down the transmission medium;
i) monitoring at a higher resolution for transmitted signals reflected in the transmission medium, the resolution being dependent on the comparison in g). - View Dependent Claims (20, 21, 22, 23)
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24. A time domain reflectometry method comprising the steps of:
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prior to testing, performing a reference trace across a correctly terminated cable to be tested; and
,subtracting the reference trace from subsequent scans, to thereby eliminate any DC offsets and/or predictable noise.
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25. A method of determining velocity factor for a cable type comprising the steps of:
obtaining for a number of different sample lengths of cable a number of differing levels of return reflections; and
, averaging the obtained results as a function of time.- View Dependent Claims (26)
Specification