Class: BE209
Group: R6
Members:Adam Sinensky, Paul Lee, Avi Berkowitz, Andrea DeNunzio,
Jaquie Farag
Temperature Telemetry-Final Report
Date: December, 2002
Introduction:
Temperature telemetry is the transmission of temperature data from
a remote, possibly inaccessible location to another location where the
data can be interpreted. With this technology, “wireless thermometers”
have the possibility to be surgically implanted, swallowed, or carried
on the subject.1
The transmitter of a typical biotelemetry system generates a carrier
and modulates it. This can be accomplished through amplitude-modulated
(AM) and frequency-modulated (FM) carriers where the respective variables
are varied with the transmitted information. Pulse width modulation
(PWM) utilizes a series of short pulses on the transmitter to generate
the carrier, and the lengths of the pulses can determine the signal.
The receiver component is then capable of receiving the transmitted signal
and demodulating it to recover the information.1
A typical transmitter involves infrared radiation light emitting
diodes to encode data to remotely located photodetector-based receivers.3
The transmitter often employs one of two techniques of infrared telemetry,
direct radiation or diffuse IR radiation, where the latter is based on
reflections of the signal from the walls, ceiling, and floor.1
In this project, a thermistor-based, wireless thermometer will be
constructed utilizing a PWM carrier and narrow beam, IR transmission.
The range of the wireless thermometer is dependent on the power and frequency
of the transmitter, relative locations and directions of transmitting and
receiving components, and sensitivity of the receiver. Size, cost,
circuit complexity, power requirements, and operational lifetime are a
few of the variables that could influence the design of a wireless thermometer.
Practical applications of the proposed wireless thermometer require a lightweight,
portable system.
An infrared light carrier will be utilized instead of radio telemetry
because there is much less man-made and natural interference noise; however,
noise is still a great concern in the proposed project.1 In general,
while it suffers from short range and requires proper transmitter/receiver
alignment, IR transmission would be more appropriate in a hospital environment
than radio transmission because of the possible interference from the latter
with medical devices such as pacemakers or infusion-pumps. Another
advantage of the IR light carrier is the lack of large antennae for the
transmitting and receiving components, which are necessary for radio transmission;
this characteristic can aid in the development of a more portable system.