There are 4 choices for Geoid Model for the OEMV series, OEM4-G2 and G2L. These are OSU89B, EGM96, User (user defined), and Table (built in table). These are selected through the UNDULATION command. The factory default for the UNDULATION value (see Volume 2 of the User Manual) is EGM96 (or TABLE) in firmware 2.300 and greater (OEM4) and 3.300 and greater (OEMV). To change the UNDULATION values used in position calculations you must issue the the UNDULATION command. The following example changes the default undulation value to OSU89B: undulation osu89b You can then use the SAVECONFIG commnad to save this setting to the NVM of the receiver.