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'''Phase coherent ultrasonic tracking''' is a type of [[ultrasonic tracking]] that measures the phase of the signal and compares it with a reference signal to determine the translation of a moving point. It was one of the first types of 3D tracking used for a head-mounted display, and was used in [[Ivan Sutherland's 3D display]].

Phase coherent methods work like this: The difference between two successive measurements of phases allows to compute the distance change since the last measurement.<ref name="u518">{{cite web | last=Mazuryk | first=Tomasz | last2=Gervautz | first2=Michael | title=History, Applications, Technology and Future | website=ResearchGate | date=1999-12-30 | url=https://www.researchgate.net/publication/2617390_Virtual_Reality_-_History_Applications_Technology_and_Future | access-date=2024-09-27}}</ref> Basically, the translational movement of an ultrasonic emitter results in the receiver sensing a different phase. The receiver compares the sensed signal with a reference signal to determine the phase.<ref name="u518"/> It is a relative system.

Phase coherent methods rely on slow movement. In its raw form it is not resilient to doppler effect.

It is at risk of multi-path interference, meaning sound can bounce off of walls and interfere.<ref name="j609">{{cite web | title=COMP 4010 Lecture5 VR Audio and Tracking | website=SlideShare | date=2016-08-23 | url=https://www.slideshare.net/slideshow/comp-4010-lecture5-vr-audio-and-tracking/65257828 | access-date=2024-10-06}}</ref>

==References==
<references />

[[Category:Position and orientation tracking]]

Phase coherent ultrasonic tracking - Revision history

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