Ambiguity resolution Basic problem is determine the integer number of cycles in the carrier phase double differences Two generic classes of approach Searching methods: T wo basic types Search over integer ambiguities checking RMS fit of phase residuals Search over position, minimizing a fit function that does not jer part of an ity(e.g. Cosine of phase Estimation and then resolution using statistical testing Statistical Resolution The most common method now is estimation with statistical assessment of fitting to integer Generic classes of cases: NNNNN.01+0.01 Pretty clearly can be resolved NNNNN. 35+0.40 Highest probability answer is nnnnn but NNNNN+1 also has >10% of being correct. Since 10-100 ambiguities need to be resolved 1-10 of them would be incorrect in the above case NNNNN.01+0.55 clearly close to an integer but+1 value also very likely NNNNN. 35+0.01 should be resolvable to integer but value is ar from integer05/07/03 12.540 Lec 22 7 Ambiguity resolution differences. – Searching methods: Two basic types • Search over integer ambiguities checking RMS fit of phase residuals • Search over position, minimizing a fit function that does not depend on integer part of ambiguity (e.g.. Cosine of phase residuals) – Estimation and then resolution using statistical testing. • Basic problem is determine the integer number of cycles in the carrier phase double • Two generic classes of approach: 05/07/03 12.540 Lec 22 8 • The most common method now is estimation with statistical assessment of fitting to integer. • Generic classes of cases: NNNNN+1 also has >10% of being correct. Since 10-100 ambiguities need to be resolved 1-10 of them would be incorrect in the above case. very likely far from integer, Statistical Resolution – NNNNN.01±0.01 Pretty clearly can be resolved – NNNNN.35±0.40 Highest probability answer is NNNNN but – NNNNN.01±0.55 clearly close to an integer but +1 value also – NNNNN.35±0.01 should be resolvable to integer but value is 4