In electronics, crosstalk (XT) is any phenomenon by which a signal transmitted on one circuit or channel of a transmission system creates an undesired effect in another circuit or channel. Crosstalk is usually caused by undesired capacitive, inductive, or conductive coupling from one circuit, part of a circuit, or channel, to another.
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In structured cabling, crosstalk can refer to electromagnetic interference from one unshielded twisted pair to another twisted pair, normally running in parallel.
In telecommunication or telephony, crosstalk is often distinguishable as pieces of speech or signaling tones leaking from other people's connections.[2] If the connection is analog, twisted pair cabling can often be used to reduce the effects of crosstalk. Alternatively, the signals can be converted to digital form, which is much less susceptible to crosstalk.
In wireless communication, crosstalk is often denoted co-channel interference, and is related to adjacent-channel interference.
In integrated circuit design, crosstalk normally refers to a signal affecting another nearby signal. Usually the coupling is capacitive, and to the nearest neighbor, but other forms of coupling and effects on signal further away are sometimes important, especially in analog designs. See signal integrity for tools used to measure and prevent this problem, and substrate coupling for a discussion of crosstalk conveyed through the integrated circuit substrate. There are a wide variety of possible fixes, with increased spacing, wire re-ordering, and shielding being the most common.
In a music recording setting, the term "crosstalk" can refer to the leakage or "bleeding" of sound from one instrument into a microphone placed in front of another musical instrument or singer. A common example is the leakage of the high-pitched, heavily-amplified sound of the lead guitar into the microphones for other instruments. Note that this is nearly always an acoustic effect, not electrical.
In stereo audio reproduction crosstalk can refer to signal leaking across from one program channel to another. This is an electrical effect and can be quantified with a crosstalk measurement.
In full-field optical coherence tomography, "crosstalk" refers to the phenomenon that due to highly scattering objects, multiple scattered photons reach the image plane and generate coherent signal after traveling a pathlength that matchs that of the sample depth within a coherence length.
In Stereoscopic 3D Displays, "crosstalk" refers to the incomplete isolation of the left and right image channels so that one leaks or bleeds into the other - like a double exposure. In this area, crosstalk and ghosting are often used interchangeably, however crosstalk is a physical entity and can be objectively measured, whereas ghosting is a subjective term and refers to the perception of crosstalk.