Intro

• Significance of Human Communication:

  • Communication is the process of exchanging information
  • Main barriers are language and distance
  • Contemporary society emphasizes the accumulation, packaging, and exchange of information
• Methods of communication:

  • Face to face
  • Signals
  • Written word (letters)
  • Electrical innovations: Telegraph, Telephone, Radio, Television, Internet (computer)
• Electronic Communication:

  • Refers to the sending, reception, and processing of information by electrical means
  • Information source: symbols (letters, numbers, words, sounds, etc) from an alphabet of possible symbols
• Significant Historical Events in Electronics Communications:

  • 1830: Joseph Henry transmitted the first practical electrical signal
  • 1837: Samuel Morse invented the Telegraph
  • 1843: Alexander Bain invented the facsimile
  • 1847: James Clerk Maxwell postulated the Electromagnetic Radiation Theory
  • 1860: Johann Philipp Reis produced a device called Telephone
  • 1864: James Clerk Maxwell established the Theory of Radio or Electromagnetism
• Extremely Low Frequency (ELF):

  • Frequency range from 3Hz to 30kHz
  • Divided into ELF, SLF, and ULF sub-bands
  • Vulnerable to disturbance and easily distorted by atmospheric changes
  • Used in seismic studies and communication with submarines
• Very Low Frequency (VLF):

  • Range from 3 kHz to 30 kHz
  • Used in submarines and time radio stations
• Low Frequency (LF):

  • Range from 30 kHz to 300 kHz
  • Suitable for long-distance communication and reflected by the earth's ionosphere
• Medium Frequency (MF):

  • Range from 300 kHz to 3000 kHz
  • Widely used in AM radio transmission and navigation systems
• High Frequency (HF):

  • Range from 3 MHz to 30 MHz
  • Suitable for long-distance communication and used by the aviation industry
• Very High Frequency (VHF):

  • Range from 30 MHz to 300 MHz
  • Widely used in analog TV broadcasting and FM radio broadcasting
• Ultra High Frequency (UHF):

  • Range from 300 MHz to 3000 MHz
  • Used in GPS navigation systems, satellites, Wi-Fi, Bluetooth, and mobile transmission
• Super High Frequency (SHF):

  • Range from 3 GHz to 30 GHz
  • Used in point-to-point communication, satellite systems, digital TV broadcasting, and mobile networks
• Extremely High Frequency (EHF):

  • Range from 30 GHz to 300 GHz
  • Used in advanced communication systems and radio astronomy
• F is only used in advanced communication systems due to its complex nature and line of sight requirement
• 5G technology is suggested for future transmission networks
• EHF is used in radio astronomy and remote sensing (weather analysis) due to large bandwidth availability
• THF is above 300GHz and is an alternate frequency spectrum for X-rays in terahertz imaging technology
• Basic Elements/Components of Communication System:

  • Transmitter
  • Channel or medium
  • Receiver
  • Noise
• Transmitter:

  • Converts electrical signal into a signal suitable for transmission over a given medium
  • Made up of oscillators, amplifiers, tuned circuits and filters, modulators, frequency mixers, frequency synthesizers, and other circuits
• Communication Channel:

  • Medium by which the electronic signal is sent from one place to another
  • Types of media include electrical conductors, optical media, free space, and system-specific media
• Receivers:

  • Accepts the transmitted message from the channel and converts it back into a form understandable by humans and/or machine
  • Contains amplifiers, oscillators, mixers, tuned circuits and filters, and a demodulator or detector
• Transceivers:

  • Incorporates circuits that both send and receive signals
  • Examples include telephones, fax machines, handheld CB radios, cell phones, and computer modems
• Noise:

  • Undesirable electronic energy that interferes with the transmitted message
  • Degrades or interferes with transmitted information
• Signal attenuation exists in all media of wireless transmission and is proportional to the square of the distance between the transmitter and receiver
• Electronic communications can be classified as:

  1. One-way (simplex) or two-way (full duplex or half duplex) transmissions

  2. Analog or digital signals

  3. Baseband or Modulated Signals
• One-way (Simplex):

  • Referred to as simplex
  • Examples include radio, TV broadcasting, and beepers
• Two-way or Duplex: Full Duplex:

  • Allows people to talk and listen simultaneously
  • Example: telephone
• Two-way or Duplex: Half Duplex:

  • Only one party transmits at a time
  • Examples include police, military radio transmissions, citizen band (CB), and amateur radio
• Analog Signals:

  • Smoothly and continuously varying voltage or current
  • Examples include sine wave "tone," voice, and video (TV) signal
• Digital Signals:

  • Change in steps or discrete increments
  • Most use binary or two-state codes
  • Examples include telegraph (Morse code), continuous wave (CW) code, and serial binary code
• Digital signals often originate in digital form but must be converted to analog form to match the transmission medium
• Baseband Signals:

  • Refers to the information signal, regardless of whether it is analog or digital
• Modulated Signals:

  • Modulation technique must be used to transmit baseband signals by radio
  • Modulation is the process of having a baseband signal modify a high-frequency carrier signal
• Multiplexing allows two or more signals to share the same medium or channel

  • Three basic types of multiplexing are frequency division, time division, and code division
• Modulation makes the information signal more compatible with the medium, while multiplexing allows more than one signal to be transmitted concurrently over a single medium
• Frequency is the number of cycles of a repetitive wave that occur in a given period of time, measured in hertz (Hz)
• Wavelength is the distance traveled by an electromagnetic wave during one cycle, usually expressed in meters
• Wavelength (λ) = speed of light ÷ frequency
• Optical spectrum includes infrared, visible spectrum, and ultraviolet waves
• Infrared radiation is used in astronomy, weapons systems, TV remote controls, wireless LANs, and fiber-optic communication