phase—¹ Any of the recurrent stages of variation in the illumination and apparent shape of a moon or a planet. ² The visible aspect of an object. ³ The apparent displacement of an object or signal caused by one side being more strongly illuminated than the other. The resultant error in pointing is similar to the error caused by observing an eccentric signal.

Phase center—A point within a GPS antenna that is the physical center of data reception.

Phase center offsets—Correction (usually only in the horizontal) front the phase center to the point on the antenna vertically above an occupied station.

Phase lock—The alignment of a phase of the receiver’s oscillator signal with that of the reference signal from a satellite. This eliminates phase differences.

Phase of target—Uneven illumination of target, causing error in sighting.

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Source: NSPS “Definitions of Surveying and Related Terms“, used with permission.

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