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Integer ambiguity resolution is an indispensable procedure for all high precision GNSS applications.The correctness of the estimated integer ambiguities is the key to achieving highly reliable positioning,but the solution cannot be validated with classical hypothesis testing methods.The integer aperture estimation theory uni_es all existing ambiguity validation tests and provides a new prospective to review existing methods,which enables us to have a better understanding on the ambiguity validation problem.This contribution analyses two simple but e_cient ambiguity validation test methods,ratio test and di_erence test,from three aspects: acceptance region,probability basis and numerical results.The major contribution of this paper can be summarized as: (1) The ratio test acceptance region are overlap of ellipsoids while the di_erence test acceptance region is overlap of half-spaces.(2) The probability basis of these two popular tests is _rstly analyzed.The di_erence test is an approximation to optimal integer aperture,while the ratio test follows an exponential relationship in probability.(3) The limitations of the two tests are _rstly identi_ed.The two tests may under-evaluate the failure risk if the model is not strong enough or the oat ambiguities fall in particular region.(4) Extensive numerical results are used to compare the performance of these two tests.The simulation results show the ratio test outperforms the di_erence test in some models while di_erence test performs better in other models.Particularly in medium baseline kinematic model,the di_erence tests outperforms the ratio test,the superiority is independent on frequency number,observation noise,satellite geometry,while it depends on success rate and failure rate tolerance.Smaller failure rate leads larger performance discrepancy.