Franz Schober ¹⁾, Gerhard Fluch ¹⁾, Ralf Boegel ^2)
1) Research Institute of Wildlife Ecology, Vienna Veterinary University,
Savoyenstrasse 1, A-1160 Vienna, Austria
²⁾ Berchtesgaden National Park, Doktorberg 6, D-83471 Berchtesgaden, Germany

INTRODUCTION For an ecophysiological study on free-ranging Griffon Vultures (Gyps fulvus) a multichannel telemetry system has been developed, which has to fulfil the requirements for long-range transmission and long-term application and should be compatible to commercially available tracking receivers and data logging equipment.

METHODS The radio frequency parts of the design are based on a former design of a repeater system for heart rate and body temperature. The system has to meet the following requirements: i) capability to measure heart rate, body temperature, ambient temperature and air pressure/altitude; ii) applicability under wildlife conditions which require long range (about 5 km), long life, minimum impact on the animals (minimum weight, optimal sociability), and iii) adaptability to other applications (animal species, physical and physiological parameters). In contrast to common wildlife systems the solution could be found in integrating microcontrollers in both the implant and the repeater (PIC16LCxx low power and low voltage family). Heart rate (by QRS detection of an ECG signal) is counted in the implant and transmitted (100 kHz) together with body temperature (using the AD-conversion capability of the microcontroller, accuracy 0.1 °C) as binary numbers to the repeater using pulse modulation with a serial data transmission protocol. In the repeater air pressure and ambient temperature are measured also by AD-conversion. The 4 parameters are transmitted consecutively by pulse-interval modulation (0.5 to 1.5 sec) at 150 MHz. The pulse-duration is changed for identification of the 4 parameters (10, 15, 20 and 25 msec).

RESULTS The implant package is designed for intraabdominal implantation and weighs 45 g. Two ECG electrode leads each 8 cm in length are attached. The repeater device is formed to be carried as a back-pack and has 120 g in weight with an output power of 8 dBm (6 mW). The operating life of the batteries is 2 years. With the implant this could only be achieved by using a very power-saving digital data link to the repeater and by switching off all power-consuming parts of the electronic when they are not in use.

DISCUSSION Prototypes of this system were tested under laboratory conditions up to now. Until the beginning of this symposium tests on animals will be carried out.