Editing Time-domain reflectometer (section)

== Example traces ==
These traces were produced by a time-domain reflectometer made from common lab equipment connected to approximately {{convert|100|feet|m}} of coaxial cable having a [[characteristic impedance]] of 50&nbsp;ohms. The propagation velocity of this cable is approximately 66% of the speed of light in vacuum.

<gallery perrow="4" mode="packed" heights="150">
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
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. The blue trace is the pulse as seen at the far end. It is offset so that the baseline of each channel is visible
File:TDR Step Same Baseline.JPG|TDR trace of a transmission line terminated on an oscilloscope high impedance input driven by a step input from a matched source. The blue trace is the signal as seen at the far end.
</gallery>

These traces were produced by a commercial TDR using a step waveform with a 25&nbsp;ps risetime, a sampling head with a 35&nbsp;ps risetime, and an {{convert|18|inch|m|adj=on}} SMA cable.<ref>Hamilton Avnet part number P-3636-603-5215</ref> The far end of the SMA cable was left open or connected to different adapters. It takes about 3&nbsp;ns for the pulse to travel down the cable, reflect, and reach the sampling head.  A second reflection (at about 6&nbsp;ns) can be seen in some traces; it is due to the reflection seeing a small mismatch at the sampling head and causing another "incident" wave to travel down the cable.
<gallery perrow="4" mode="packed" heights="200">
File:TDR SMA open.svg|TDR of step into disconnected SMA male connector (non-precision open)<br />horizontal: 1&nbsp;ns/div<br />vertical: 0.5&nbsp;&rho;/div
File:TDR SMA APC7 open.svg|TDR of step into disconnected APC-7mm connector
File:TDR SMA APC7 prec open.svg|TDR of step into APC-7mm precision open
File:TDR SMA APC7 prec load.svg|TDR of step into APC-7mm precision load
File:TDR SMA APC7 prec short.svg|TDR of step into APC-7mm precision short
File:TDR SMA APC7 prec open 20ps.svg|TDR of step into APC-7mm precision open<br />horizontal: 20&nbsp;ps/div
File:TDR SMA BNC BNC term.svg|TDR of step into mated BNC connector pair; the peak reflection is 0.04<br />horizontal: 200&nbsp;ps/div<br />vertical: 20&nbsp;m&rho;/div
</gallery>