Chapter 4 - The World Was Once Analog

• Introduction
• Sound, Vibrations, And Analog Recording (phonograph record)
  An analog device maintains an exact physical analog of information. For example, bumps on an early phonograph recording correspond to vibrations that we perceive as sound.
• Analog Electronic Devices
  An electronic device is analog if the amount of electrical current it generates is proportional to its input. - cassette tape player
• Many Electronic Devices Are Analog
  At one time, most electronic devices used analog techniques to store, amplify, or emit pictures or sounds - AM/FM radios, stereos, televisions
• The First Analog Communication
  Early telephones used an analog scheme to send voice from one place to another; the amount of electrical current sent between two telephones was proportional to the volume of sound
• Analog Is Simple But Inaccurate
  An analog device always distorts the input and adds noise.
• Sending An Analog Signal Across A Wire [signal loss - attenuation]
• Digital Music
  A technology is digital if it uses numbers to record information instead of a physical analog like bumps on a record or magnetism on a tape
• The Digital Revolution [transistor -> ICs]
• Computers Are Digital [Inside a computer, all information is represented by numbers]
• Digital Recording
• Using Digital To Recreate Analog [A-to-D converter]
• Why Digital Music?
• Summary
  • Information, including audio and video, can be encoded in digital form
  • The chief advantage of using a digital representation arises because the information does not become distorted while being stored, copied, or communicated

• Analog Transmission
• Digital Transmission

Terms

1. analog
2. A-to-D and D-to-A converters
3. digital
4. distortion
5. integrated circuit