초록 ▼

A differential GPS system for precise time and/or location tagging of an event. Reference and rover units cooperate to compensate for delayed availability at the rover unit of error-correction data transmitted via a two-way, high-latency communication link. A reference unit calculates and stores err

A differential GPS system for precise time and/or location tagging of an event. Reference and rover units cooperate to compensate for delayed availability at the rover unit of error-correction data transmitted via a two-way, high-latency communication link. A reference unit calculates and stores error-correction data. A rover unit collects and stores uncorrected GPS fix data, and transmits a message demanding error-correction data. The message preferably includes a time stamp indicating the time for which the error-correction data is to be valid. In reply to a demand message from a rover unit, the reference unit retrieves stored error-correction data and transmits it to the rover unit via the high-latency communication link. The reference unit includes a time stamp indicating the valid time of the error correction data if the valid time is not implicit in the reply. The rover unit uses the stored, uncorrected GPS fix data and the received error-correction data to compute a differentially-corrected GPS fix.

대표청구항 ▼

A method for obtaining optimally error-corrected GPS position and time fixes in near real-time at a remote rover unit, comprising the steps of: a. positioning the rover unit at a selected location and, at the rover unit, receiving GPS signals, storing uncorrected data from which a GPS fix can be com

A method for obtaining optimally error-corrected GPS position and time fixes in near real-time at a remote rover unit, comprising the steps of: a. positioning the rover unit at a selected location and, at the rover unit, receiving GPS signals, storing uncorrected data from which a GPS fix can be computed, and transmitting a demand for error-correction data over a communication link having a two-way communication latency unacceptable for realtime communication of DGPS error-correction data; b. at a known location remote from the rover, receiving GPS signals, computing error-correction data and storing a sequence of error-correction data for a plurality of times, receiving the demand for error correction data, retrieving error-correction data from storage, and transmitting error-correction data over the communication link to the rover unit; c. at the rover unit, receiving the transmitted error-correction data, and computing a differentially-corrected fix using the received error correction data and the stored uncorrected data.