Ambiguity decorrelation is a useful technique for rapid integer ambiguity f
ixing. It plays an important role in the least-squares ambiguity decorrelat
ion adjustment (Lambda) method. An approach to multi-dimension ambiguity de
correlation is proposed by the introduction of a new concept: united ambigu
ity decorrelation. It is found that united ambiguity decorrelation can prov
ide a rapid and effective route to ambiguity decorrelation. An approach to
united ambiguity decorrelation, the HL process, is described in detail. The
HL process performs very well in high-dimension ambiguity decorrelation te
sts.