8.2.3 Introduction to Ambiguity Resolution

SEARCHING INTEGER AMBIGUITY SETS

All techniques rely on some "search" technique that tests a range of neighbouring values around the initial ambiguity values (see Figure below). For example, in the case of six tracked satellites there are five (double-differenced) ambiguities to be resolved. If the search window is three integers wide (one on either side of the round-off value), then there are 3⁵ ambiguity set to be tested (here = 243 )

Real-valued ambiguity estimates and candidate integer values to be tested.

The following is a partial listing of the 243 candidate ambiguity sets in the above example, where n^kl is the double-differenced ambiguity for a baseline ij (subscript deleted) involving satellites k and l, n(-)^kl is one integer value less, and n(+)^kl is one integer greater than the round-off value. Each line lists five possible integer ambiguity values that could reasonably be expected to be the correct values that convert the ambiguous phase observations to unambiguous carrier-range measurement:

< TD>n¹² < TD>n(+)³⁴

n(-)12	n(-)23	n(-)34	n(-)45	n(-)56
n(-)12	n(-)23	n(-)34	n(-)45	n(-)56
n(- )12	n(-)23	n(-)34	n< sup>45	n(-)56
n(-)12	n(-)23	n34	n(-)45	n(-)56
n(-)12	n23	n(-)34	n(-)45	n(-)56
n12	n(-)23	n(-)34	n(-)45	n(-)56
n(-)12	n(-)23	n(-)34	n45	n56
n(-)12	n(-)23	n34	n(-)45< /TD>	n56
n(-)12	n23	n(-)34	n(-)45	n56
n12	n(-)23	n(-)34	n(-)45	n56
n(-)12	n23	n34	n45	n(-)56
n(-)12	n23	n(-)34	n45	n (-)56
n12	n(-)23	n(-)34	n45	n(-)56
.	.	.	.	.
.	.	.< /TD>	.	.
.	.	.	.	.
.	.	.	.	.
n(+)23	n(+)34	n(+)45	n(+)56
n(+)12	n23	n(+)34	n(+)45	n(+)56
n(+)12	n(+)23	n34	n(+)45	n(+)56
n(+)12	n(+)23	n45	n(+)56
n(+)12	n(+)23	n(+)34	n(+)45	n56
n(+)12	n(+)23	n(+)34	n(+)45	n(+)56

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© Chris Rizos, SNAP-UNSW, 1999