Abstract：As integer ambiguity is affected by atmospheric delay error, it is difficult to correctly fix ambiguity between BDS middle-range baseline. We propose the algorithm of triple-frequency ambiguity resolution between BDS middle-range baseline. We use the combination of MW to determine B2-B3 extra-wide-lane integer ambiguity, and then solve the B1-B3 wide-lane integer ambiguity using the closer characteristic of ionospheric delay error between B2-B3 extra-wide-lane and B1-B3 wide-lane combination observation. We use the ionosphere-free combination observation to estimate narrow-lane integer ambiguity and relative zenith tropospheric delay error, and finally the real-time dynamic positioning is realized. We test this algorithm by the measured BDS middle-range baseline. The results indicate that the method can fix the triple-frequency carrier phase ambiguity between middle-range baseline correctly and effectively, and positioning accuracy to the centimetre level can be achieved.
