Communication systems are active information systems. Within a communication system, information moves from its source to a destination where it can be acknowledged. If I use words or other signs to name an organization of matter and/or energy, or an interpretation of an area of information as I perceive that it exists, I describe the activities of a communication system. A person may use terms to talk about a system that correlate to different aspects of communication in particular situations, even though the actual matter and energy that connstitutes the system in all these situations is the same. the behavior of information over a particular interval of time, the behavior of the parts, the **, .

I chose the following terms to describe the components of any communication system because they can be used to discuss the simplest instances of information and communication, as well as the most complex. While there are other terms for defining the parts of communication systems, they are not necessarily as versatile.

In his classic text Great Ideas in Information Theory, Language, and Cybernetics, Jagjit Singh says, "No matter whether it is a network of telegraph and telephone lines or of radio and television channels or even a mere living-room conversation, any such network will consist of three main parts:

• transmitter or source
• receiver
• channel which conveys the communique from the transmitter to the receiver.

On page 10 of his book, Singh also provides a more complete list of terms that can account for every bit of the mattter and energy in a communication system, what individual parts of the system do, and how they interact. I'll provide definitions for these terms, based on my own observations and imaginings, my understanding of Singh's own descriptions, and a definition from the Web Dictionary of Cybernetics and Systems.

• transmitter/information or message source -- the organization of information in a communication system from which information is created or sent

• encoder-- the part of a communication system that recognizes an existing organization of matter and/or energy and transforms it into new information by reorganizing another existing set of matter and/or energy to represent that information

• channel-- the matter and/or energy through or by which a message is transmitted to a receiver

• decoder-- the part of a communication system that recognizes the presence of coded information in carried by channel and changes that organization into a form acceptable by the receiver

• receiver-- the part of the communication system that "gets" the information and acknowledges, recognizes, and/or interprets it.

• signal-- the part of the message actually sent over the communication channel that carries the message from the encoder to the decoder

• noise-- defined in the Web Dictionary of Cybernetics and systems as: any undesired information in a communication channel which is not part of the intended message. (http://pespmc1.vub.ac.be/ASC/NOISE.html)

Suppose I spy a mouse sniffing a piece of cheese, and I want to describe the communication between the mouse and the cheese. I can observe what's going on, then isolate the communication in thought and describe how information about the scent of the cheese is being communicated to the mouse.

First, I will map what's going on to the components of the communication system listed earlier:

The transmitter or message source is the cheese. The cheese and the surrounding air interact to form the encoder for the message about the cheese. The channel is the air surrounding the chese and the mouse, and between the cheese and the mouse. The receiver is comprised of the mouse's sensory organs. The decoder, in very general terms, is comprised of the sensory receptors in the mouse's olfactory area and its nervous system. The signal is carried over the channel in the aroma of the cheese. Noise is any other scent in the air that might interfere with the mouse's ability to smell the cheese.

Now I'll worry about the parts of the communication system are behaving. In the next page, I'll talk about some of the processes that are essential to communication.

here are alternative descriptions for the components of a communication system.

do descriptions of information, significance, and meaning change if one bases all instances of how these things should exist in the world on how they should exist in the human mind? shhould the descriptions and definitions be based on direct observations of systems we encounter directly, or theoretical, abstract systems we create? what about _possible_ systems; how do we decide what we think is possible and what we think is not possible?

Medium, message, and audience are words that stand for specific components of a given communication system; each component behaves in a particular way and performs a particular function as information in the system is communicated. A medium is a particular idea, physical object, or area of energy that serves as a source and/or transmitter of information. A message is matter or energy that replicates the pattern of information in a medium and transmits that information to a receiver. An audience is the part of the communication system that receives, processes, and creates new information from the message.

A medium contains encoded information
A message contains encoded information that has been created from information existing in a medium. An audience may act as decoder and receiver.
An audience may act as an encoder, but not while it's acting as an audience.

If I describe a communication system that carries a transmission of music recorded on a compact disc to a listener, then I would say that the medium is the compact disc (and perhaps the machinery used to process the information carried by the disc should also be included in the description). The message is comprised of the sound waves that carry the recorded music to the listener's ear, and the audience is the listener. I also include all the possible forms of matter and energy that could hold a representation of any of the communicated information, and any of the mechanisms involved in transforming it (like the parts of the listener's ear, etc.)

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