1. Development of a Portable Noise Signal Acquisition Device for Use in Local Mining Industrial Applications
Department of Electrical and Computer Engineering
Faculty Mentors: Dr. Jun Qin and Dr. Haibo Wang
Student Researchers: Chaitanya Varma Danduprolu and Jacob Walker
Results
Conclusion
Abstract and Introduction Methods and Materials
Noise induced hearing loss (NIHL) effects over 29 million
American adults. Although some of these adults may have
had these effects from somewhere outside the workplace,
many adults come into contact with harmful levels of noise
every day at the workplace. It is estimated that 30 million
Americans are exposed to this harmful noise on the job. US
miners are included in this number and are in many ways
more exposed to more destructive noise than other job fields.
Noise signals fall into two different categories: steady state
noise (from computers, overhead lights, etc.) and impulsive
noise (dynamite explosions, jack-hammers, etc.).
While all types of noise at a high enough levels can cause
hearing loss, a combination of these two types, called
complex noise, has been shown to cause significantly more
damage to human hearing. Moreover, research has shown
that the high-level noise that miners are exposed to while on
the job, is mostly comprised of complex noise. Therefore,
research into the analysis of this complex noise in the mining
industry can help prevent and manage NIHL and protect the
90,000 miners in the United States.
The purpose of this project has two main objectives. The first
is to research and produce a portable and accurate noise
analysis apparatus utilizing a customized PCB and
preamplified microphones with an analog to digital converter.
Second, the apparatus must be tested both inside the lab as
well as trips to mining installations in the Southern Illinois area
for field testing. With the successful conclusion of this
research, more effective methods can be put in place to
protect miners and prevent NIHL.
In the beginning of the Fall 2014, certain design guidelines
were laid out in order to better ascertain the direction of
which the design of the PCB should be. Initially, it was
decided upon that the circuit would have two portions, an
analog front end that would acquire the signal from the
microphones and a digital back end, that would take the
signal and store it in some fashion. Additionally, so design
constraints were applied, which are listed as such:
• 20Hz – 20KHz Band-Pass Filter
• ~50KHz sampling rate
• A minimum of 8 bit accuracy
• SD Card storage and communication
• 16 bit Microcontroller
• Battery Powered
The next important item is determining a program in which to
design and test the PCB, for our project we decided upon
DIPtrace. We decided on this looking at two main reasons, it
is a standard for what is used and applied in the Electrical
and Computer Engineering Department classes, additionally
it is also freeware and highly adaptable, which was deemed
appropriate and advantageous in the production of the PCB.
After these constraints were addressed, each specific portion
of the PCB was to be designed and tested in DIPtrace. This
involves looking at many different characteristics that
electrical circuits exhibit when given different stimuli.
Ensuring that the circuit performs and behaves to the
specifications of which it was designed for, it could then be
assembled and coding could begin.
A signal chain chart is shown below to illustrate the direction
of which the signal will be processed.
First the audio signal comes in through the microphones,
then the signal is processed through a band pass filter in
order to isolate the frequencies that human hearing range
occurs in, 20hz to 20Khz. Next, the analog to digital convertor
(ADC) converts the analog signal to digital, where it can then
be handled by the microcontroller which will direct it to be
stored in an SD card for processing.
In deciding the components that would become integral in the
implementation of the circuit design, many revisions and
reviews were discussed before deciding on the following
components:
• Microcontroller – DsPIC33E
• Analog to Digital Convertor – ADS7818
• Operational Amplifier – OPA340
These components were selected given that they fulfill our
requirements for our project.
This projected resulted in the production of a dual-channel
PCB board responsible for the acquisition of noise signals
present in mining industrial applications. The next step in the
development of this PCB is to begin programming the
microcontroller for the purpose of acquiring and storing the
data. As the project advances, it is also possible to look into
performing mathematical calculations on the data as it is
acquired by the system, further expanding its functionality.
Project Funded Partially by the SIUC CURCA Program
Methods
Participants
Acknowledgements
This project consisted of a partnership between Drs. Jun Qin
and Haibo Wang, as well as undergrad student Jacob Walker
and graduate student (under Dr. Wang) Chaitanya Varma
Danduprolu. Dr. Qin research interests are in digital
instrumentation, sensors, data acquisition and analysis, as
well as acoustics and noise induced hearing loss. Dr. Wang
research interests are in the area of developing low-power,
intelligent mixed-signal integrated circuits for sensor signal
acquisition and processing.
Analog Front End Testing
The analog circuit is shown below as well as some of the
testing and simulation that was performed in order to verify its
operation.
Below are some of the simulations that we performed on the
analog front end. We were looking for the responsiveness to
the system given different simulated inputs that will be
experienced while testing in the field.
Sine Wave, 3V offset, 1V peak, 5KHz
Sine Wave, 3V offset, 1V Peak, 10Khz
Final PCB Design
Shown below is the finalized 3D implementation of the final
design of the circuit. It has been shipped out to a PCB
manufacturer and programming has begun on making the
microcontroller fully functional.