binary biphase modulation [GPS]- Phase changes on a constant frequency of either 0 or 180 degrees represented as binary 0 or 1, respectively.

binary pulse code modulation [GPS]- Pulse modulation using a string of binary numbers. This coding is usually represented by ones and zeros with definite meanings assigned to them, such as changes in a phase or in the direction of a wave.

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

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