A RADIO-ACOUSTIC POSITIONING
AND TELEMETRY NETWORK

Ron O'Dor
Dalhousie University
Biology Dept., Halifax, NS, Canada B3H 4J1

INTRODUCTION Radio-linked Acoustic Positioning and Telemetry (RAPT) systems, now in commercial production by Vemco Ltd., Shad Bay, NS, are rapidly finding a wide range of applications around the world. A major advantage of RAPT is that range limitations of the smallest acoustic transmitters on small animals can be offset by saturating an environment with radio buoys that relay acoustic arrival times to a ship or shore base station which triangulates positions and decodes telemetered data. Many critical questions for marine populations require information about the ranges and behaviours of early life history stages obtainable only with the most advanced RAPT systems, using large numbers of buoys to follow tiny transmitters over large areas.

METHODS Initial demonstrations of such systems could best be done by sharing buoys among research groups, but this is hampered by: 1) lack of an international standard for frequencies for this technology, 2) variation in rapidly developing hard- and software, 3) constraints on current software.

RESULTS We propose establishing a user consortium or network to pursue common goals such as international frequency standards and to establish priorities for hard- and software development. This will insure maximum interchangeability, minimize development of redundant or unique application approaches and optimize research output and investment. The Dalhousie telemetry group currently holds several grants for developing this technology, is in contact with 25 user groups in six countries and is strategically located near Vemco to organize such a network. We intend to maintain an emailing list and a Web site for exchange of ideas, requirements and experiences - essentially an online user's manual. It is important to restrict some operational parameters for compatibility but equally important that these restrictions do not eliminate major applications at this early stage of development. The presentation will briefly survey historical applications of RAPT from the first implementation (Nelson & McKibben. 1981. In Proc. 3rd Internat. Conf. Wildlife Biotelemetry) to the prototype for the current system (O'Dor et al. 1989. In Proc. 10th Internat. Symp. Biotelemetry) to a recent 3D study (Sauer et al., In press. Biol. Bull.). It will discuss approaches under consideration, as well as the range of anticipated future improvements and collaborative developments. Critical issues, for example, are the best way to move fluidly between triangulating cells and the tradeoffs between GPS and acoustic self-positioning for buoys.

DISCUSSION These issues need collective consideration because they fix hardware in ways that may rule out certain applications. The ISOB should provide a valuable forum for airing such questions. I will also outline the state of the network at the time of the symposium.