Arctic Ocean trials of Trackpoint ultrashort baseline acoustic positioning systems

As part of the development of Theseus, an under-ice autonomous underwater vehicle, trials were conducted to evaluate the performance of Trackpoint II and LXT ultrashort baseline (USB) acoustic positioning systems. These systems have been proposed to provide long range vehicle homing and surface station tracking of the Theseus AUV. These trials were carried out in the Arctic Ocean in 1992 and 1993. The trials were performed by operating the Trackpoint master stations from temporary ice stations with warm tents and living quarters. Helicopters or snow machines were used to carry the remote field party and transponders to distant sites for range and bearing measurements. GPS positioning systems and a Geodometer laser survey instrument were used for position reference. Measured range and bearing error data for the USB positioning systems are presented. Ray trace analysis was used to give understanding into acoustic propagation anomalies. The experience gained through these field trials was used in selection of USB positioning systems for the Theseus vehicle.