Abstract: Based on the conventional theories of cycle-slip detection,a method is developed to detect cycle slips in real time for quality control.The method utilizes two linear combinations,the Geometry-free and Melbourne-Wübbena combinations.The characteristics of the two combinations are analyzed and the filer techniques are used to deal with the time series of combination observations.Real-time simulation tests are implemented using both vehicle kinematic data and on-board kinematic data.The results show that single-cycle slips can be reliably detected in real time.