A time-domain reflectometer ( TDR ) is an electronic instrument used to characterize and locate faults in metallic cables ( for example, twisted wire pairs, coaxial cables ).

If the conductor is of a uniform impedance and is properly terminated, the entire transmitted pulse will be absorbed in the far-end termination and no signal will be reflected toward the TDR.

The resulting reflected pulse that is measured at the output / input to the TDR is displayed or plotted as a function of time and, because the speed of signal propagation is almost constant for a given transmission medium, can be read as a function of cable length.

That is, the TDR had no indication that there is a short at the end of the cable until its emitted pulse can travel down the cable at roughly the speed of light and the echo can return back up the cable at the same speed.

It is only after this round-trip delay that the short can be perceived by the TDR.

Using a TDR, it is possible to pinpoint a fault to within centimetres.

TDR equipment is also an essential tool in the failure analysis of modern high-frequency printed circuit boards whose signal traces are carefully crafted to emulate transmission lines.

The TDR principle is used in industrial settings, in situations as diverse as the testing of integrated circuit packages to measuring liquid levels.

In TDR technology, the impulse velocity is primarily affected by the permittivity of the medium through which the pulse propagates, which can vary greatly by the moisture content and temperature of the medium.

The key to TDR ’ s success is its ability to accurately determine the permittivity ( dielectric constant ) of a material from wave propagation, and the fact that there is a strong relationship between the permittivity of a material and its water content, as demonstrated in the pioneering works of Hoekstra and Delaney ( 1974 ) and Topp et al.

The TDR method is a transmission line technique, and determines an apparent TDR permittivity ( Ka ) from the travel time of an electromagnetic wave that propagates along a transmission line, usually two or more parallel metal rods embedded in a soil or sediment.

In stability monitoring applications using TDR, a coaxial cable is installed in a vertical borehole passing through the region of concern.

The depth of the TDR ( d ) is a known factor and the other is the time that takes the drop of water to reach the that depth ( t ), therefore the speed of water Infiltration ( hydrology ) ( v ) can be determined.

The TDR provides an electrical signature of individual conductive traces in the device package, and is useful for determining the location of opens and shorts.

Starting May 30, 2004, the US Patent and Trademark Office ( USPTO ) Trademark Electronic Business Center's TDR ( Text Document Retrieval ) online record showed a USPTO " Office Action " on application # 78319880, summarily refusing registration on grounds that the proposed mark " merely describes the subject matter and nature of the applicant's goods and / or services ", and also because publishing a journal is not per se a " service " within the meaning of the term in trademark law ( SSC having not provided descriptive evidence or arguments to counter that presumption ).

The propulsion sub-system ( PSS ) is a Throttleable Ducted Rocket ( TDR ) with an integrated nozzleless booster, designed and manufactured by Bayern-Chemie.

The solid propellant nozzleless booster is integrated within the ramcombustor and accelerates the missile to a velocity where the TDR can take over.

Because of this sensitivity to impedance variations, a TDR may be used to verify cable impedance characteristics, splice and connector locations and associated losses, and estimate cable lengths.

* Interstate TDR, a target drone used by the US Navy

This can done by placing the TDRs in different soil layers and measurement of the time of start of precipitation and the time that TDR indicate an increase in the soil moisture content.

TDR have worked in a diverse range of media, including:

In 2005, TDR Records ( formerly known as To Define Records ) released an Over It / Punchline split 7-inch vinyl featuring two exclusive songs.

File: Simple Time Domain Reflectometer Diagram. png | Simple TDR made from lab equipment

File: Time Domain Reflectometer made from common lab equipment. JPG | Simple TDR made from lab equipment

Other lesser known MCs and DJs included Johnny Rock, DJ Candido, DJ Muscle and DJ Shiz ( today known as B. Boy Omega ) who were all Puerto Ricans from The Bronx, while Mr. L of the TDR crew was half Puerto Rican and half Dominican.

A TDR transmits a short rise time pulse along the conductor.

File: TDR trace of cable with open termination. JPG | TDR trace of a transmission line with an open termination

File: TDR trace of cable with a short circuit termination. JPG | TDR trace of a transmission line with a short circuit termination

File: TDR trace of cable with a capacitor termination. jpg | TDR trace of a transmission line with a 1nF capacitor termination

File: TDR trace of cable terminationed with its characteristic impedance. jpg | TDR trace of a transmission line with an almost ideal termination

File: TDR trace of cable with cable terminated on an oscilloscope. JPG | TDR trace of a transmission line terminated on an oscilloscope high impedance input.

So after a round-trip delay, the voltage at the TDR abruptly jumps to twice the originally-applied voltage.

In the first instance, `` mimesis '' is here used to mean the recalling of experience in terms of vivid images rather than in terms of abstract ideas or conventional designations.

A dominant motive is the poet's longing for his homeland and its boyhood associations: `` Not men-folk, but the fields where I would stray, The stones where as a child I used to play ''.

So in these pages the term `` technology '' is used to include any and all means which could amplify, project, or augment man's control over himself and over other men.

But what a super-Herculean task it is to winnow anything of value from the mud-beplastered arguments used so freely, particularly since such common use is made of cliches and stereotypes, in themselves declarations of intellectual bankruptcy.

This text from Dr. Huxley is sometimes used by enthusiasts to indicate that they have the permission of the scientists to press the case for a wonderful unfoldment of psychic powers in human beings.

The men who speculate on these institutions have, for the most part, come to at least one common conclusion: that many of the great enterprises and associations around which our democracy is formed are in themselves autocratic in nature, and possessed of power which can be used to frustrate the citizen who is trying to assert his individuality in the modern world ''.

Properly used, the present book is an excellent instrument of enlightenment.

This prospect did not please Mrs. King any more than did the possibility that her daughter might marry a Bohemian, but she used it to suggest to Thompson that, `` It is not in her nature to love you ''.

On the other hand, the consensus of opinion is that, used with caution and in conjunction with other types of evidence, the native sources still provide a valid rough outline for the English settlement of southern Britain.

The trouble with this machinery is that it is not used and the reason that it is not used is the absence of a conscious sense of community among the free nations.

In addition to his experiments in reading poetry to jazz, Patchen is beginning to use the figure of the modern jazz musician as a myth hero in the same way he used the figure of the private detective a decade ago.

When different colors are used, she is just as likely to color trees purple, hair green, etc..

Berlin is merely being used by Moscow as a stalking horse.

The collection of information is meaningless unless it is understood and used for a definite purpose.

This is used as a reference for comparing the ohmic heating and the electrical energy obtained from the measured current through the element and the measured voltage across the element.