February 4, 2020 - Vista, California - Axiom Test Equipment, an electronic test equipment rentals and sales company headquartered in North County San Diego, has published a blog post entitled "Finding Faults with TDR Test Instruments." It is about selecting and using time-domain reflectometers (TDRs). This in-depth blog post goes over how TDRs work, which types of test equipment can be used to make TDR measurements, and what performance parameters should be compared when selecting a TDR for your particular test requirements and test environment.
"Time-domain reflectometers (TDRs) are easy-to-use test instruments usually associated with finding faults in cables and antennas. How they work is simple: send a pulse with fast rise time into a cable under test and measure reflected signals that take place where the characteristic impedance (usually 50 Ω) deviates from the nominal value, usually because of a break or disturbance in the line. This approach to finding a fault can also be applied to fiber-optic cables using an optical pulse. Comparisons of the transmitted and reflected signals can provide information about the length of the line, the loss of the line, and the locations of discontinuities and breaks in the line. TDRs have been compared to radar systems, which transmit pulses and measure reflections from illuminated targets.
TDRs find changes in impedance through a transmission line, cable, or antenna by analyzing changes in voltage with time due to reflections. This contrasts with frequency-domain reflectometers (FDRs), which typically send swept-frequency signals into a transmission line and study how the signals are affected due to reflections at impedance junctions. TDRs can make measurements such as distance-to-fault tests with access to only one port, such as a cable connector. FDR-based measurements find faults using scattering parameters (S-parameters) to measure forward and reflected voltages, but they require access to at least two (input and output) ports of a cable under test.
TDR measurements can be made with a pulse or step generator, an oscilloscope, and test software running on a computer, but it is typically more convenient to perform TDR measurements on a single instrument devoted to the task. Such dedicated TDRs are available in rack-mountable benchtop style or as portable, battery-powered units perfect for in-field testing. They are available for measurements on metal cables and optical cables and, with built-in computer power and memory, can be set up automatically for measurements on metal cables with specific impedances and dielectric types or optical cables at different wavelengths. When armed with suitable performance levels, a TDR can handle a wide range of applications, from finding faults in runs of coaxial cable to isolating impedance mismatches in printed circuit boards (PCBs).
What performance parameters should be compared when considering a TDR? The most fundamental consideration is the type of system or component to be tested, since TDRs are available for testing metal cables and transmission lines, as metal TDRs (MTDRs), as well as for optical cables, as optical TDRs (OTDRs). Each type is designed for a specific test environment—MTDRs for a characteristic impedance, such as 50 or 75 Ω, and OTDRs for a wavelength. Adapters are often available for an MTDR, for example, to equip an instrument set up for testing 50-Ω devices to make measurements at 75 Ω, as in cable-television (CATV) systems..."
If you would like help selecting any type of test equipment for your project, contact Axiom Test Equipment's sales department at email@example.com, call 760-806-6600, or browse Axiom Test Equipment's inventory online at www.axiomtest.com.
About Axiom Test Equipment
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Established in 2005, Axiom Test Equipment strives to continually improve itself and offer the best value for its customers. We offer our customers several practical, efficient and cost effective solutions for their business or projects' test equipment needs. Whether you need to rent & buy test equipment, repair test equipment, sell or trade equipment, we are committed to providing superior customer service and high quality electronic test equipment.
At Axiom Test Equipment we provide several services. We rent electronic test and measurement equipment. We also sell test equipment. If you have a piece of malfunctioning or broken test equipment we also have an in-house repair lab. For anyone seeking a way to offload their surplus or obsolete equipment, we offer a trade-in program or we can buy the equipment from you.
We stock a comprehensive inventory of equipment and can use our extensive network to find you those hard to get items. We believe in getting equipment to you quickly and at a competitive price.
Axiom Test Equipment 2610 Commerce Way Vista, CA 92081 Phone: (760) 806-6600 Web: www.axiomtest.com
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