This is an excerpt from
T. Butler, K. Lancaster, M. Middleton, and K. Walp,
"
Water Detector,"
ECE 4512: Design I,
Department of Electrical and Computer Engineering,
Mississippi State University, Fall 2003:
Throughout history people have observed their environment and used
these observations to determine their course of action. Over time the
process of observation has been refined. From the early days of man
when the only way to observe phenomena was with unaided senses, to
today when we are able to visualize electromagnetic waves that
oscillate more than a million times a second with an oscilloscope, we
are always improving the level at which we can acquire knowledge from
our surroundings. Today the need to efficiently observe our
environment is still increasing.
All around us, interesting phenomena are constantly occurring. There
is a great deal of knowledge to be gained through the collection and
interpretation of this data generated by these events, but these
phenomena do not always occur in easily accessible or even survivable
environments. Data collection may also be impractical because of time
or expense. The data that is generated in these inhospitable
locations may be some of the most valuable to us in understanding the
world. Established methods of collecting and recording this valuable
data are inadequate and inefficient. Current technologies are now
using hard-wired sensors. Freeing these sensors from their tethering
wires facilitates their deployment and reconfiguration. By adding
processing capabilities to the sensor nodes, the processing of the
vast amount of raw data can be distributed, thus reducing the amount
of trivial data that must be transmitted to a central data repository.
The problem is that today we are even hungrier for knowledge about our
environment. Enemy troops could be on the move. The moisture level
in the soil of a farm could be too low. Temperature and humidity
levels in a food storage area could vary from those that ensure
maximum shelf life. New and important events could be happening on
the surface of a distant planet. These examples are just a few of the
myriad of events and situations that are constantly occurring but are
not being effectively detected. The existing sensing technology is
inadequate. The existing sensors are severely limited by their
reliance on wires for communication. This limits the situations in
which these types of sensors can be applied. Another shortcoming of
the existing technology is that these sensors are passive,
.dumb,. devices, which simply relay all the overwhelming amounts of
raw information that is collected back to a processing center. They
are not able to react to or interpret the data they are collecting.
All this uncollected data has great significance. Troop movements
provide great insight into ending conflict efficiently with minimal
bloodshed. Moisture levels are important to crop yields. The
temperature at which food is stored can dramatically affect the length
of time it can be stored without fear of spoilage. Events happening
in unexplored regions would provide insight into new discoveries. The
vast amounts of data that are generated are useless unless they are
captured. This valuable data is lost without an efficient way to
collect it. Without this data, fully informed decisions cannot be
made, thus many must be made semi-blindly.
With the use of wireless sensors all this data can be collected and
processed into useful information. With this information in hand,
many processes can be vastly improved in terms of efficiency in both
time and cost. Battles can be won without excessive bloodshed with
minimal troops positioned in locations based on the information
gathered from the sensor network. Cropland can be kept at optimal
growing conditions by using the moisture information to control
irrigation systems. By keeping track of the temperature and humidity
of food storage areas, the environment can be altered by means of
heating and cooling systems and humidity control systems. Sensing
data on far off planets would be prohibitively expensive if humans
were required to be present to collect data. With these sensor
networks new discoveries can be made that will give us a new view of
the universe. These effective actions are only possible when all the
pertinent information is available to the deciding party.
There are several motivations for eliminating wires. Wires are costly
both for the wires themselves and for installation, which may require
invasive installation measures [1]. It also is impractical to install
wired sensors on mobile devises particularly rotating devices. Wires
are impractical for deployment in combat situations; they also may
reveal their presence to an enemy. Curators of historical buildings
and museums may wish to install sensors without compromising the
original architectural integrity.
The military is finding many applications for wireless sensor
networks. One such application is enabling a soldier to .see around
corners [2].. Another is the networking of soldiers. By placing a
sensor on each soldier, a team can form a network in which they can
communicate without the danger of being eavesdropped. Another is
detecting enemy troop movements and hazardous chemicals [3]. Yet
another military application is the monitoring of our borders against
illegal intruders.
A wireless sensor network (WSN) consists of several nodes and a base
station. The nodes transmit data between one another, and each one
can be used for the distributed collection and interpretation of data.
This data is transmitted (either in its raw form or after being
processed) to a central repository. Once stored in the repository,
the data can be aggregated and used for a variety of applications.
These applications may take advantage of the network of sensors to
send commands back out into the field that are in response to
collected data.
Research in the development of wireless sensor network technology is
guided by the need for a small, reliable, power-efficient way to
monitor conditions in a region. Developing improvements to the
technology will pave the way for its inevitable ubiquity. At this
time, however, the technology has not yet been explored to its
fullest. A cheap, small, wireless sensor network system using a power
efficient transceiver and modulation scheme and an optimized channel
coding technique, which minimizes energy per bit transmitted, does not
exist.
Wireless sensors are a major technological innovation. In the near
future, wireless sensors will become an integral part of our everyday
lives, with multiple applications in disparate fields. One such
example is government use of wireless sensor networks for battlefield
surveillance and treaty monitoring. By gluing tiny sensors on each
fingertip, one can create a virtual keyboard. Inventory can manage
itself automatically. Product quality can be monitored and controlled
automatically. Consumer electronics devices can monitor vibration and
offer failure analysis and diagnostic information. Temperature,
humidity, and other environment comfort parameters in a building can
organize themselves to suit the individual.
It can be seen that by human nature we are very curious about our
surroundings. Through time the amount of information necessary to
quench our thirst has increased dramatically. This increase will
continue into the future. By improving our methods of data
collection, we can make better and better decisions and react more
quickly in time critical situations.
In conclusion, wireless sensor networks offer a novel solution to
gathering data and interpreting data over a distributed area. This
fills a great need in today.s world. Today more than ever information
is power. Having accurate intelligence to act upon is invaluable in
nearly every arena. As this technology continues to develop, it will
move into our everyday lives. Soon this technology will become so
pervasive that it will be an unnoticeable yet extremely valuable part
of our lives.