A method for synchronization of an external device's clock 324 with a GPS device 104 is provided. The method can comprise processing one or more data sentences received at the external device 106 from the GPS device to determine a data sentence containing the best available time information that is most accurate among the data sentences. Also, an amount of correction can be determined to compensate for one or more variable time delays introduced by one or more processes. The one or more processes can selected from a group consisting of a process performed by the GPS device t.sub.1b, a data sentence transmission from the GPS device to the external device t.sub.2b, and a data processing step performed by the external device t.sub.3b. A synchronization time using the amount of correction and the best available time information can be provided. The method can further comprise correcting a timing error introduced into time stamp values by the external device clock. This step can include removing an accumulate error by restarting the method after a pre-defined amount of time (e.g., one hour).