A positioning system for global navigational satellite system (GNSS) includes a first receiver to measure a first carrier phase of a carrier signal emitted by a satellite and a second receiver to measure a second carrier phase of the carrier signal emitted by the satellite. The, first carrier phase includes a first carrier phase ambiguity as an unknown integer number of wavelengths of the carrier signal travelled between the satellite and the first receiver. Similarly, the second carrier phase includes a second carrier phase ambiguity as an unknown integer number of wavelengths of the carrier signal travelled between the satellite and the second receiver. The GNSS includes a processor to determine an integer ambiguity difference between the first carrier phase ambiguity and the second carrier phase ambiguity from a difference in the measurements of the first carrier phase and the second carrier phase and to detect a multipath of the carrier signal based on a value of the integer ambiguity difference and tracked set of integer ambiguity differences.