Signal reflection

In

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.[3]

Impedance discontinuities cause

When a returning reflection strikes another discontinuity, some of the signal rebounds in the original signal direction, creating multiple echo effects. These forward echoes strike the receiver at different intervals making it difficult for the receiver to accurately detect data values on the signal. The effects can resemble those of jitter.

Because damage to the cable can cause reflections, an instrument called an electrical time-domain reflectometer (ETDR; for electrical cables) or an optical time-domain reflectometer (OTDR; for optical cables) can be used to locate the damaged part of a cable. These instruments work by sending a short pulsed signal into the cable and measuring how long the reflection takes to return. If only reflection magnitudes are desired, however, and exact fault locations are not required, VSWR bridges perform a similar but lesser function for RF cables.

The combination of the effects of signal attenuation and impedance discontinuities on a

The Bergeron diagram method, valid for both linear and non-linear models, evaluates the reflection's effects in an electric line.

See also

• Crosstalk (electronics)
• Digital subscriber line
• Project Echo
• Fresnel reflection
• Ground-penetrating radar
• Impedance matching
• Signal integrity
• Reflections of signals on conducting lines
• Reflection phase change

References