Development of GPS data remote retrieval system using wireless LAN

Abstract

A remote retrieval system, using a wireless LAN, was developed to retrieve dual-frequency GPS data. The system consists of a ground observation unit (comprising a dual-frequency GPS logger and a data transmission unit) and a data retrieval unit. In this system, we use the ZigBee communication protocol to transmit control commands (2.4 GHz, 250 Kbps) and a wireless LAN communication to transmit GPS data (2.4 GHz, 54 Mbps). Data of every 30 seconds to transmit to the data retrieval unit are re-sampled from 1-second data at 00 UT each day. We conducted three data-transmission tests with the system: (1) a ground data retrieval test, (2) a data retrieval test from the atmosphere of a few hundred meters high using a small unmanned aircraft, and (3) actual GPS-data retrieval tests from a GPS buoy deployed on sea ice at Nisi-no-ura Cove, Syowa Station, Antarctica. In test (1), we successfully received all the data from the ground observation unit when situated at distances of less than 400 m from the data retrieval unit. In test (2), we obtained approximately 24.5 MB of data from the aircraft at heights of less than 250 m. In test (3), we obtained approximately 23.5 MB of data from the GPS buoy within 10 minutes. The proposed system has the advantage of enabling continuous measurements without aborting the measurement at the data retrievals.