Analog Signals

• A signal, of which a sinusoid is only one example, is a set, or sequence of numbers.

• The term ``analog'' refers to the fact that it is ``analogous'' of the signal it represents.

• A ``real-world'' signal is captured using a microphone which has a diaphragm that is pushed back and forth according to the compression and rarefaction of the sounding pressure waveform.

  Figure 1: The electrical signal used to represent the pressure variations of a sound wave is an analog signal.

  

• The microphone transforms this displacement into a time-varying voltage--an analog electrical signal.