A correlator for a GNSS receiver and a code generator used in the correlator as well as a correlation method are disclosed. In the GNSS, each satellite transmits a data signal and a pilot signal. The correlator is adaptable for executing correlation to the data signal, the pilot signal and various combinations thereof, such as non-coherent and coherent combinations. The code generator generates primary ranging codes of the data and pilot signals as well as various combinations thereof, such as sum or difference of the primary ranging codes of the data and pilot signals. By using the various codes, the correlator is adaptable and flexible for different correlation requirements.