Download LAMBDA and Ps-LAMBDA source code

The key of precise GNSS applications is to resolve the double-differenced (DD) carrier phase ambiguities. One of the methods to do this is the LAMBDA method which was introduced by Teunissen (1993) and developed at the Delft University of Technology in the 1990s. LAMBDA stands for Least-squares AMBiguity Decorrelation Adjustment.

With the LAMBDA method, the integer least squares (ILS) ambiguity estimates are computed in two steps. First the ambiguities are decorrelated, by means of the Z-transformation. The decorrelation is essential to allow for an efficient search for the integer candidate which solves the integer minimization problem. This search is the second step in the LAMBDA method.

Two open source Matlab toolboxes have been developed by Delft University of Technology and Curtin University. The LAMBDA toolbox can be used within your GNSS processing for ambiguity resolution. Users may choose whether to use integer least squares, integer bootstrapping or integer rounding. Options are included for partial ambiguity resolution and ambiguity testing with the ratio test. In addition, the Ps-LAMBDA toolbox is provided, which allows evaluation of the ambiguity resolution success rate for the different ambiguity estimators and with the option to choose between different approximations, lower or upper bounds.

Fill the form below and press Submit to obtain the compressed file with the latest version of LAMBDA and Ps-LAMBDA or LAMBDA (Python) . It may be necessary to use 7zip to decompress the file. For questions or problems concerning the toolboxes please contact Sandra Verhagen or Dimitrios Psychas.