Sponsored By: Dr. Charles Croskey, Professor, Penn State University
TEAM MEMBERS:
Designed Fall Semester, 2002, at Penn State University
taken from http://www.accessnoaa.noaa.gov/aug0701/oncamera.html
used with permission
Summary of the Project Goal
Current techniques of measuring the temperature of the lower to the middle atmosphere do not provide high enough resolution measurements for many applications. The ACTMP Balloon Design Team has designed and built an acoustic temperature sensor that will provide a spatial resolution of one measurement per centimeter of altitude, which is 500 times the resolution of typically used thermistors.
Our acoustic temperature sensor will utilize ultrasonic transducers as the transmitter and receivers, and will operate on a 41 kHz signal pulsed at approximately 500 Hz. The phase conversion and waveform generation will be controlled by an HC11 and exterior electronics. This instrument will fly on a weather balloon from Norway in the summer of 2002, and will take accurate data up to 30 km.
How will it work?
The speed of sound is proportional to the square root of the temperature of the medium, if the medium is an ideal gas. Our sensor utilizes ultrasonic transducers to transmit and receive pulses at 41kHz. The block diagram is shown below:
As can be seen in the block diagram, there are two receivers in our sensor. The phase between the two receivers is measured, and this phase is used to calculate the temperature.
The Future of the Acoustic Temperature Sensor
This sensor will fly on a weather balloon launched from Norway in the summer of 2002. The results from our sensor will be compared with the temperatures from the thermistor. If the results are good, the acoustic temperature sensor may be used on future balloon flights to provide high resolution temperature measurements of the lower and middle atmosphere.
Created April 18, 2002, by Mimi Abel.