Tracking of Wild Life: A Convergence of Technologies
Stanley M. Tomkiewicz, Jr.
Director, Environmental Programs,
Telonics, Inc., 932 East Impala Avenue, Mesa, Arizona 85204. USA
Beginning in the 1950's, radio telemetry began to emerge as a dominant and critically important tool used in the developing sciences of wildlife management and ecology. Used first to determine positional information, radio telemetry capabilities expanded to include the relaying of important physiological and behavioral data to research biologists from free ranging animals. For many years the basic technology (now often referred to as conventional VHF telemetry) was refined and expanded and now represents a reliable tool used to study many species.
In the late 1970's, the use of the Argos Data Collection and Location System to track wide ranging migratory species opened a new door to the understanding of long range movements of animals. Migration timing, routes, and stopovers were determined with greater frequency and resolution than previously possible with aircraft monitoring. These studies had direct impact on basic biological research, wildlife management in general, the protection of endangered species, and resource development issues. The use of low power microprocessors to control sophisticated satellite transmitters allowed the development of a new level of sensor technologies (i.e., subsurface pressure and activity sensors), and made available to the research community. In addition, this new processing capability allowed the development of on-board processing and data reduction techniques that reduced the requirements for data transfer.
In the 1990's, the incorporation of reduced powered GPS units into subsystems capable of being placed on free ranging animals further opened the door to different lines of research requiring the repeatable high accuracy positioning. The 1990's have seen the proliferation of GPS systems that can store positional data on board the unit for later downloads after recovery of the unit. Data links were also developed to allow GPS and additional supplementary data to be recovered directly across a radio link or indirectly via a satellite system such as Argos.
The telemetry technologies developed over the past 40 years represent unique and specific tools available to the researcher studying a wildlife question. Careful study selection of the appropriate tool will aid in obtaining answers to the specific scientific questions under study. In entering the next millennium these individual tools are also becoming integrated into subsystems that blend the benefits of several individual tools. This coordinated integration of technology affords an unprecedented benefit to researchers with complex questions.
The topic I present today deals with the integration of technologies that has been occurring in the telemetry field. Several examples have been presented during this symposium that demonstrate the integration and convergence of numerous biotelemetry technologies as it applies to tracking fish. This paper will deal more extensively with technologies that are used to track birds and mammals. It represents an overview of technologies beginning with the development of conventional VHF systems in the 1950's and progressing to the development of GPS systems of the 1990's.
Beginning in the 1950's, radio telemetry began to emerge as a dominant and critically important tool used in the developing sciences of wildlife and fishery's management and ecology. Used first to determine positional information, radio telemetry capabilities expanded to include the relaying of important physiological and behavior data to research biologists studying free ranging animals. For many years the basic technology (now often referred to as conventional VHF telemetry) was refined and expanded. In the early days it was not uncommon to see the "classical telemetry report" wherein a researcher purchased ten transmitters: two did not work upon arrival, one more failed before the units left his laboratory for the field, and two more units failed in the first week while deployed on animals. Another unit failed after a month, one unit's signal was lost after only three months in operation, and three other units lasted about six months. Often in the conclusion of the paper there was a statement to the effect that "radio telemetry was a viable tool for the study of unrestrained animals". It appears the conclusion was more wishful thinking than a scientific assertion.
Somewhere between those early developmental reports in the 1950's and 1960's and the present, telemetry has developed into a sophisticated and reliable scientific tool for research. This technology has been used to study hundreds of species ranging in size from passerine birds and mice to elephants and whales. The technology has allowed researchers to repeatedly find individual animals and monitor the animal's location, determine if the animal is alive or dead, establish an activity level, monitor body temperatures, and collect numerous behavioral observations. Conventional VHF technologies were refined through the 1960's, 70's and 80's; however the basic systems that were deployed remained virtually the same function throughout this time. The use of discrete and integrated circuit hardware allowed the development of a few new sensors (i.e., delayed time mortality/activity sensors) but options were limited and the development of hardware solutions was time consuming and expensive. The real changes in system functionality arrived with the development of small microprocessor controlled units that allowed functions like seasonal duty cycling to extend the operational life of systems, the ability of the unit to send ID codes and to process data from an array of sensors. These advances occurred in the 1990's and revolutionized the technology into a much more versatile and powerful tool for research.
Besides advances in transmitter functionality, sophisticated receiver-scanner technology and the development of data acquisition, technology has progressed allowing data to be acquired and stored in the field at unattended stations. In some cases, data is linked between remote sites and the laboratory through other advancing communications' technologies, i.e., cell phone, satellite telemetry or other alternatives.
For many years VHF telemetry for terrestrial and avian species and ultrasonic telemetry for fish were the only tools available to the research community. In the early 1970's the use of the Argos system to track wide ranging and migratory species opened a new door to understanding the long range movements of animals. Migration timing, routes, and stopovers were determined with greater frequency and with resolution not previously possible. The studies had direct impact on basic biological research, wildlife management in general, the protection of endangered species and resource development issues. The availability of low power microprocessors to control sophisticated satellite transmitters had a secondary outcome in allowing the development of new sensor technologies (including pressure sensors) that could be used to determine such things as surfacing times, depth of dive, and even dive profiles of marine mammals. Since the microprocessor was already onboard, specialized sensors were more easily developed and incorporated into transmitting subsystems.
In addition to this new "smart" control capability, microcontrollers allowed the development of on-board processing and data reduction techniques that reduced the volume of data transferred. In fact, the incorporation of low power, low current microprocessors in this technology is what actually led to the development and crossover of these microprocessor-controlled systems into conventional VHF telemetry a few years later.
In the 1990's the incorporation of low powered GPS units into subsystems capable of being placed on free ranging animals further opened the door to the development of numerous novel and divergent lines of research requiring repeatable high accuracy positioning. The 1990's have seen the proliferation of GPS systems which can store positional data onboard the unit for later download after recovery of the unit. Data links were also developed in order to allow GPS and additional supplementary data to be recovered directly across a radio link or indirectly via satellite systems such as Argos.
The following series of slides depict the general configuration of the three basic GPS systems: The first is the Store-on-Board system. In this case the data are GPS positions specifically obtained and stored in nonvolatile memory for later download. In this system the unit must be physically recovered to obtain the data. This system does not have a radio frequency (RF) link. These store on board systems are usually physically smaller and weigh less than systems which require a data transmitter to implement an RF link. A second related system that has been developed is often called the GPS-SST system. In this system, GPS positions are obtained and stored in memory. This system can then transfer information across a Spread Spectrum (SST) data link on command. A third system is the GPS/Argos system. In this system GPS positions are obtained and stored in memory and the data system transfers the data through the Argos-NOAA satellite system. In this case information can be obtained without the researcher being in the field, and be linked back through a satellite system from very remote locations.
Much as been learned about collecting and processing GPS data from remote sites and from animal born packages over the past five years. As with most engineering efforts actual field trials and deployments provide more information than any other source. For example, our techniques for dealing with power management have been substantially refined. The new second generation GPS units consume less power and have a longer operational life as compared with early units. Further, new generation units also incorporate smaller, lower power GPS receiver technologies capable of more rapid time to first fix (TTFF). This advancement further extends the operational field life of contemporary units.
Today's GPS tracking units incorporate either a user interface serial port or RF link as a means to provide the researcher the ability to reprogram user changeable parameters. This capability allows the alteration of duty cycles and GPS fixed time schedules as well as other perimeters.
In addition, the memory available onboard the newer GPS units has been greatly expanded to allow this storage of additional positions "fixes". In many units there is sufficient memory to handle up to 20,000 differentially correctable positions in memory for later download and post processing.
New GPS receiving antennas are smaller, consume less power and can be packaged in smaller housings than earlier GPS antennas designed for the first generation systems.
In conclusion, the most significant trend in the biotelemetry field is the increasing reliance upon microprocessor technology in all of our contemporary telemetry subsystems. The reduced power consumption and low voltage operation of these new microprocessors has lead to the development of "smart" and versatile VHF transmitting subsystems. In addition, it has led to even "smarter" receiver technology. Animal born technologies are being used in conjunction with one another to create highly customized equipment capable of aiding the research community in answering new and important research questions. For example, the combination of ultrasonic and radio transmitter technologies used in an integrated configuration in tracking fish. In addition, there are systems that contain Argos satellite telemetry and VHF systems, GPS systems with VHF backup beacons, GPS systems with Argos satellite telemetry capability, GPS systems with Argos satellite telemetry capability with VHF being used as a backup beacon function.
These technologies are being integrated in novel ways that allows numerous combinations of modules to assure a system that can meet the requirements of research. In general it is the convergence of all these technologies which continues to make the biotelemetry field an exciting area for research and development. As new technologies feed into this field, equipment gets smaller, more intelligent and more versatile. This trend should extend well into the next millennium.
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