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.