M2

• Uses of radio


  • Transmission of sounds (voice and music)
  • Transmission of pictures (television)
• Electric field is fluctuating


  Produces a wave
• Electric field extends out into space


  Produces radio waves as the electric field changes rapidly
• Electrical signals


  1. Converted by a microphone (sounds) or video camera (images)

  2. Amplified

  3. Modulate a carrier wave that has been generated by an oscillator circuit in a transmitter
• Transmitter


  Employed to relay and intercept radio waves
• Amplification


  Added to an antenna that converts electrical signals into space for electromagnetic radiation waves
• Radio wave


  Information-bearing signal carrier
• Receiver


  Employed to relay and intercept radio waves
• It is crucial to verify that the system generates a power level signal consistent with the maximum regulatory threshold
• Modulation


  1. Occasionally interrupting the transmission (as in dot-and-dash telegraphy)

  2. The information can be encoded directly on the wave or impressed by it
• Electric field does not immediately change the distant pieces of it


  The transition is constrained by light velocity
• RADAR


  Device that tracks and fixes the location of targets at a distance using radio waves and operates on the theory of radio echoes
• Operation of RADAR


  Radio echoes bounce back once the wave hits an object and reflects, similar to echolocation used by bats and dolphins
• Stimulated emission (Pump)


  Release of energy from an excited atom by artificial means
• Transmission and interception of radio waves

  Used to generate and receive information-carrying signals
• Modulation of information on radio waves


  Information may be encoded directly on the wave by interrupting its propagation regularly or impressed by a technique called modulation
• RADAR transmitter and receiver roles


  Transmitter produces radio waves, receiver accepts weak target signals, amplifies them, and converts the information from radio frequency (RF) to the baseband
• Modulated signal


  Actual information is contained in the sidebands or the frequencies added to the carrier wave rather than in the carrier wave
• Receiving radio waves


  Induces a very small electromotive force (emf) fed to the radio receiver, then amplified, followed by demodulation to extract the signal, amplified by audio amplifiers, and fed to the speaker for reproduction into sound waves
• Radio waves are produced within electromagnetic waves by fluctuating motion used to transfer information from one radio station to another
• Electromagnetic waves are energy holders produced by the motion of charged particles such as electrons
• Radio waves function as an information-bearing signal carrier
• Lasing Medium


  Substance used to produce the stimulated emission of photons in a laser, can be in gas, liquid, or semi-conducting material
• Operation of LASER

  Device that emits light through optical amplification based on the stimulated emission of electromagnetic radiation, consisting of a lasing medium, a stimulating energy source (pump), and an optical resonator
• The only waveform that the oscillating current generates is typically induced by the shifting electric field and magnetic field
• Wave Frequency


  The number of waves that pass a fixed point in each amount of time. A higher-frequency wave has more energy than a lower-frequency wave with the same amplitude
• Instead of telephone wires, lasers are used in contact with optical fibers
• Radio waves


  A type of electromagnetic radiation with wavelengths in the electromagnetic spectrum longer than infrared light. They range from the length of a football to larger than our planet
• Demodulation


  Extracting the original information-bearing signal from a carrier wave
• Today, lasers have become one of the world’s most significant innovations used in different industries ranging from information technology to telecommunications, medicine, consumer electronics, law enforcement, military equipment, entertainment, and manufacturing
• Receiver


  Uses electronic filters to separate the desired radio frequency signal from all the other signals picked up by the antenna, an electronic amplifier to increase the power of the signal for further processing, and finally recovers the desired information through demodulation
• RADAR


  Radio Detection and Ranging) is a system that uses radio waves to detect and to fix the position of targets at a distance that works on the principle of radio echoes
• Laser action


  1. Stimulated emission (Pump) is the release of energy from an excited atom by artificial means

  2. When more atoms occupy a higher energy state than a lower one under normal temperature equilibrium, it is possible to force atoms to return to an unexcited state by stimulating them with the same energy as mirrors facing each other so that light emitted along the line between the mirrors is reflected back and forth
• Modulation


  The process of changing the parameters of the carrier signal in accordance with the instantaneous values of the modulating signal
• Laser gain media


  • May vary from extended-length glass fibers to the submicron-length semiconductor material
• Electromagnetic waves


  Usually holders of energy formed by the movement of charged particles such as electrons
• Transmission


  The process of sending and propagating an analog or digital signal using wired, optical, or wireless electromagnetic medium
• LASER


  Light Amplification by Stimulated Emission of Radiation) is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation
• Wavelength


  The distance between successive crests of a wave
• Laser communications are ousting radio waves as visible light wavelengths are even more packed and tighter, which can relay more information with a stronger signal per second