What is a signal?
Q: What is a signal?
A: A signal is any time-varying quantity.
Q: How would you define a signal specifically in information theory?
A: In information theory, a signal is a codified message, i.e., the sequence of states in a communications channel that encodes a message.
Q: What happens in a communications system?
A: In a communications system, a transmitter encodes a message into a signal, which is carried to a receiver by the communications channel.
Q: Can you give an example of how a message might be transmitted in a communications system?
A: For example, the words "Mary had a little lamb" might be the message spoken into a telephone. The telephone transmitter converts the sounds into an electrical voltage signal. The signal is transmitted to the receiving telephone by wires; and at the receiver it is reconverted into sounds.
Q: Is the concept of a signal easy to define precisely?
A: No, the concept of a signal is broad and hard to define precisely.
Q: What is a common practice in defining the term signal in subfields?
A: Definitions specific to subfields are common.
Q: In which fields is the concept of signal used?
A: The concept of signal is used in the fields of communications, signal processing, and in electrical engineering more generally.
