A Short Range Biotelemetry System Used in Experimental Studies on Domestic Animals

The study of domestic and wild animals is more accurate in their natural environment, in order to obtain information free from captivity stress and other influences. For this purpose we have developed an experimental system to perform biosignals acquisition from large domestic animals. The system is composed of two main units and utility software. One of the two units is a small, compact portable module housed in a plastic case and weighting around 200 g. This unit performs the following tasks: 1) data acquisition from 3 sensors (temperature sensor for measuring skin temperature and detecting respiratory rhythm, heart rate sensor-microphone type, and activity sensor with a motion-sensitive mercury switch), 2) data conversion on 12 bits and 3) conversion in serial format - biphase coding and amplitude modulation of a 27 MHz radio carrier. Each subject has a separate frequency in 27 MHz range. The portable unit has an autonomy of at least 24 hours.

The second unit is stationary and composed of a telemetry receiver and PC based data concentrator. This unit has the following functions: amplification and demodulation of HF signals, biphase decoding and conversion to NRZ signals, clock data recovery, and transmission of data in the PC environment.

This monitoring program is designed to perform data collection in two ways. A synthetic (global) menu allows continuous monitoring of all subjects at a programmable time rate, presenting the results on the same screen in separate windows for each subject. Individual menus expand the values indicated in the synthetic menu for each subject and parameter, also indicating the temporal evolution. All data evolution is saved on hard-disk also with a programmable rate. The program also has off-line data processing functions for analyzing various parameters. Special mention can be made for data filtering algorithms, used to eliminate the artifacts from input signals.

The tracking range of the equipment is at least 200 m in open space, which is satisfactory for the purposes of the system. The system is designated to be used in feeding and behavioral studies on domestic animals in the Experimental Farm of University for Agricultural Sciences and Veterinary Medicine of Cluj-Napoca. We intend also to extend the functionality of the system, to reach the possibility of studies on human subjects, in sports medicine and other areas.