Spread-spectrum time-domain reflectometry (SSTDR) is a measurement technique to identify faults, usually in electrical wires, by observing reflected spread spectrum signals. This type of
time-domain reflectometry
Time domain refers to the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the ca ...
can be used in various high-noise and live environments. Additionally, SSTDR systems have the additional benefit of being able to precisely locate the position of the fault. Specifically, SSTDR is accurate to within a few centimeters for wires carrying 400 Hz aircraft signals as well as
MIL-STD-1553
MIL-STD-1553 is a military standard published by the United States Department of Defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed as an avionic data bus for use with ...
data bus signals. AN SSTDR system can be run on a live wire because the spread spectrum signals can be isolated from the system noise and activity.
At the most basic level, the system works by sending spread spectrum signals down a wireline and waiting for those signals to be reflected back to the SSTDR system. The reflected signal is then correlated with a copy of the sent signal. Mathematical algorithms are applied to both the shape and timing of the signals to locate either the short or the end of an open circuit.
Detecting intermittent faults in live wires
Spread-spectrum time domain reflectometry is used in detecting intermittent faults in live wires. From buildings and homes to aircraft and naval ships, this technology can discover irregular shorts on live wire running
400 Hz, 115 V. For accurate location of a wiring system's fault the SSTDR associates the
PN code
A pseudorandom binary sequence (PRBS), pseudorandom binary code or pseudorandom bitstream is a binary sequence that, while generated with a deterministic algorithm, is difficult to predict and exhibits statistical behavior similar to a truly rando ...
with the signal on the line then stores the exact location of the correlation before the arc dissipates. Present SSTDR can collect a complete data set in under 5 ms.
SSTDR technology allows for analysis of a network of wires. One SSTDR sensor can measure up to 4 junctions in a branched wire system.
[Smith,Paul, Furse, Cynthia, Chung Chung, You, Pendayala, Praveeen, Nagoti, Kedarnath and Lo, Chet. "Spread Spectru]
TDR Research , Spread Spectrum Sensors for Wire Fault Location on Live Wire Networks , LiveWireTest.com
Sensors for Critical Fault Location on Live Wires." IEEE Sensors Journal. June, 2005.
See also
*
Spread spectrum
In telecommunication and radio communication, spread-spectrum techniques are methods by which a signal (e.g., an electrical, electromagnetic, or acoustic signal) generated with a particular bandwidth is deliberately spread in the frequency d ...
*
Time-domain reflectometry
Time domain refers to the analysis of mathematical functions, physical signals or time series of economic or environmental data, with respect to time. In the time domain, the signal or function's value is known for all real numbers, for the ca ...
References
External links
* Kingston, Samuel, Evan Benoit, Ayobami S. Edun, Farhad Elyasichamazkoti, Dawn E Sweeney, Joel B. Harley, Paul K. Kuhn, and Cynthia M. Furse.
SSTDR methodology, implementations, and challenges" ''Sensors'' 21, no. 16 (2021): 5268.
* Furse, Cynthia, Smith, Paul, Safavi, Mehdi, and Lo, Chet
Feasibility of Spread Spectrum Sensors for Location of Arcs on Live Wires.IEEE SENSORS JOURNAL, VOL. 5, NO. 6, DECEMBER 2005
* Furse, Cynthia, Smith, Paul, and Lo, Chet
Spread Spectrum Sensors for Critical Fault Location on Live Wire Networks. STRUCTURAL CONTROL AND HEALTH MONITORING, June 2005.
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Electronic engineering