A method of determining position includes observing a first signal from a first source at a first epoch. The method includes observing a second signal from the first source at a second epoch. The method includes observing a third signal from a second source at the first epoch. The method includes observing a fourth signal from the second source at the second epoch. The method includes generating a first set of comparison data based on the first signal and the second signal. The method includes generating a second set of comparison data based on the third signal and the fourth signal. The method includes determining whether cycle-slip exists based on the first set of comparison data and the second set of comparison data. The method includes determining a current position of a standalone global navigation satellite system (GNSS) receiver in response to a determination that cycle-slip does not exist.