TEMPERATURE SENSORS

TEMPERATURE SENSORS
Each of AVM's transmitters can be made to function as temperature monitors by the addition of either Temperature Option A or Temperature Option B. Temperature monitors can be used as direction locators at the same time temperature data are being transmitted. However, if temperature transmitters are required for use in laboratory or controlled-environment studies only, their longevities can be greatly extended, by lowering their current drain and power output.

Note that the determination of the longevity of a temperature transmitter is a bit more complicated than a standard battery/transmitter combination because as the temperature of the transmitter increases, so does its current drain. This means that as the temperature increases, the theoretical longevity of the transmitter/battery combination decreases. An approximation of longevity can be obtained by understanding that the current drain of the transmitter goes up 0.10 mA for each 10?C the temperature increases. Thus, if a transmitter is drawing 0.030 mA at 22?C, it will draw 0.130 mA at 32?C.

Temperature readings are determined by analysis of the change in the pulse rate of the transmitter's signal. The user establishes a correlation curve, plotting temperature against either pulse rate or pulse interval, for each individual transmitter.

Temperature transmitter pulse rates may be counted using a stopwatch or AVM's Pulse Interval Timer (PIT) may be used to determine temperatures. See for information about the PIT.

Temperature Option A is primarily used to monitor body core temperature in mammals. It covers a range of approximately 8 Celsius degrees, with resolution to an accuracy of 0.1. This does not mean that the unit cannot monitor temperatures outside the range of the 8 Celsius degrees selected by the researcher. It means that the Temperature A unit will be accurate to 0.1 within the 8 degrees, then its level of accuracy will decrease as temperatures outside the selected range are detected.

Temperature Option B relays temperature readings from 0 to 40 degrees Celsius, with resolution to 0.5 degrees. It is most commonly used to monitor herps and ambient temperatures. It can be built into implant modules designed to monitor body core temperature of herps and hibernating mammals. Temperature B transmitters can be used as habitat identifiers by designing the package such that the thermistor is placed as far away from the body of the animal wearing the transmitter as possible, for instance, on the exterior surface of the collar. Thus, the researcher can determine, by monitoring the temperature of the collar, when the animal moves from the warmth of a nest to the ambient cold of the winter night.

Randall Reiserer, of the University of California at Berkeley's Museum of Vertebrate Zoology, doctoral candidate of Harry Greene, has generously allowed AVM to use one if his great temperature calibration curves. See Goliath the Mojave Rattler's transmitter calibration curve by clicking on the snake!