Noise-domain Reflectometry

	Noise-domain Reflectometry Noise-domain reflectometry is a type of reflectometry where the reflectometer exploits existing data signals on wiring and does not have to generate any signals itself. Noise-domain reflectometry, like time-domain reflectometry, time-domain and Spread-spectrum time-domain reflectometry, spread-spectrum time domain reflectometers, is most often used in identifying the location of wire faults in electrical lines. Time-domain reflectometers work by generating a signal and then sending that signal down the wireline and examining the Reflection (electrical), reflected signal. Noise-domain reflectometers (NDRs) provide the benefit of locating wire faults without introducing an external signal because the NDR examines the existing signals on the line to identify wire faults. This technique is particularly useful in the testing of live wires where data integrity on the wires is critical. For example, NDRs can be used for monitoring aircraft wiring while in flight. See also * Spread-spect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon]
	Time-domain Reflectometry In mathematics and signal processing, the time domain is a representation of how a signal, function, or data set varies with time. It is used for the analysis of mathematical functions, physical signals or time series of economic or environmental data. In the time domain, the independent variable is time, and the dependent variable is the value of the signal. This contrasts with the frequency domain, where the signal is represented by its constituent frequencies. For continuous-time signals, the value of the signal is defined for all real numbers representing time. For discrete-time signals, the value is known at discrete, often equally-spaced, time intervals. It is commonly visualized using a graph where the x-axis represents time and the y-axis represents the signal's value. An oscilloscope is a common tool used to visualize real-world signals in the time domain. Though most precisely referring to time in physics, the term ''time domain'' may occasionally informally refer to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon]
	Spread-spectrum Time-domain Reflectometry 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 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 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon]
picture info	Reflection (electrical) In telecommunications, signal reflection happens when a signal is transmitted along a transmission medium (such as a copper cable or an optical fiber) and part of it is reflected back toward the source instead of reaching the end. This reflection is caused by imperfections or physical variations in the cable (such as abrupt changes in its geometry) that lead to impedance mismatches. These mismatches disrupt the signal and cause some of it to bounce back. In radio frequency (RF) systems, this is typically measured using the voltage standing wave ratio (VSWR), with device called a VSWR bridge. The amount of reflected energy depends on the degree of impedance mismatch and is mathematically describe by the reflection coefficient. Because the principles are the same, this concept is perhaps easiest to understand when considering an optical fiber. Imperfections in the glass create mirrors that reflect the light back along the fiber. Impedance discontinuities cause attenuation, atten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon]
	Time-domain Reflectometry In mathematics and signal processing, the time domain is a representation of how a signal, function, or data set varies with time. It is used for the analysis of mathematical functions, physical signals or time series of economic or environmental data. In the time domain, the independent variable is time, and the dependent variable is the value of the signal. This contrasts with the frequency domain, where the signal is represented by its constituent frequencies. For continuous-time signals, the value of the signal is defined for all real numbers representing time. For discrete-time signals, the value is known at discrete, often equally-spaced, time intervals. It is commonly visualized using a graph where the x-axis represents time and the y-axis represents the signal's value. An oscilloscope is a common tool used to visualize real-world signals in the time domain. Though most precisely referring to time in physics, the term ''time domain'' may occasionally informally refer to p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon]