PHYSICS

• LASER


  Light Amplification by Stimulated Emission of Radiation, devices that emit coherent and focused beams of light
• Laser signal transmission and reception

  1. Laser Generation

  2. Modulation

  3. Signal Transmission

  4. Optical Detectors

  5. Demodulation

  6. Signal Processing
• Laser Generation


  • Stimulated emission of photons with same frequency and phase, population inversion in active medium, amplification resulting in coherent and collimated beam
• Modulation


  Variation of laser beam parameters (intensity, frequency, phase) to encode information
• Signal Transmission


  Laser beam carrying modulated information transmitted through medium (air, optical fiber, free space)
• Optical Detectors


  Photodetectors (e.g. photodiodes) that convert optical signal to electrical signal
• Demodulation


  Reversing the modulation to extract the original transmitted signal
• Signal Processing


  Amplification, filtering, digitization of electrical signal after demodulation
• Lasers are valuable in telecommunications, data transmission, and remote sensing applications
• RADAR


  Radio Detection and Ranging, technology that uses radio waves to detect, locate, and track objects
• Radar signal transmission and reception

  1. Signal Generation

  2. Transmission

  3. Propagation

  4. Reflection (Scattering)

  5. Reception

  6. Signal Processing

  7. Display and Analysis
• Signal Generation


  Transmitter generates short bursts of radio frequency (RF) electromagnetic energy
• Transmission


  RF signal transmitted into space using an antenna
• Propagation


  Radio waves travel through air until encountering an object
• Reflection (Scattering)


  Radio waves are partially reflected back to the radar system when encountering an object
• Reception


  Receiving antenna captures the reflected radio waves (echo)
• Signal Processing


  Techniques like pulse compression and Doppler processing to extract target information (distance, direction, speed)
• Display and Analysis


  Processed information displayed on radar screen for interpretation, may use automated target detection and tracking
• Radars can operate in various modes (surveillance, tracking, weather monitoring, imaging) for different applications
• AM (Amplitude Modulation)


  The amplitude of the carrier wave is varied in proportion to the instantaneous amplitude of the modulating signal (audio signal)
• FM (Frequency Modulation)


  The frequency of the carrier wave is varied in proportion to the instantaneous frequency of the modulating signal
• As the audio signal changes in AM


  The amplitude of the carrier wave also changes accordingly
• As the audio signal changes in FM


  The frequency of the carrier wave adjusts accordingly
• AM (Amplitude Modulation)


  • AM signals are more susceptible to interference, such as noise and atmospheric disturbances, because changes in amplitude can be affected by external factors
• FM (Frequency Modulation)


  • FM signals are less susceptible to interference
  • The frequency modulation provides better resistance to amplitude variations caused by external factors, resulting in clearer audio quality
• AM (Amplitude Modulation)


  • AM signals generally have a narrower bandwidth compared to FM signals
  • This means that more AM stations can fit within the available frequency spectrum
• FM (Frequency Modulation)


  • FM signals have a wider bandwidth than AM signals, requiring more space in the frequency spectrum
  • This limits the number of FM stations that can operate within a given frequency range
• AM (Amplitude Modulation)


  • AM signals can travel longer distances and are capable of providing coverage over large areas
  • This makes AM suitable for long-range communication, especially in areas with obstacles like mountains or buildings
• FM (Frequency Modulation)


  • FM signals have a shorter range compared to AM signals
  • They are more suitable for local communication and areas with fewer obstacles, as FM signals are affected by terrain and obstacles more than AM signals
• AM (Amplitude Modulation)


  • AM signals are more susceptible to noise and static, which can affect sound quality
  • AM broadcasts may have lower fidelity compared to FM broadcasts
• FM (Frequency Modulation)


  • FM signals generally provide better sound quality because they are less prone to interference
  • FM broadcasts deliver higher fidelity audio, making them suitable for music and high-quality sound reproduction
• Common applications of AM

  • AM radio broadcasting, especially for news and talk shows
  • Aviation communication systems
• Common applications of FM

  • FM radio broadcasting for music and high-fidelity audio
  • Two-way radio communication systems, such as walkie-talkies
• In AM, the frequency of the

  carrier signal is

  Constant
• Who is credited with the

  discovery of electromagnetic

  waves?

  Heinrich Hertz
• FM offers better_

  compared to AM

  Audio quality
• The bandwidth requirement

  for FM is generally_

  compared to AM.

  Higher
• * How does a radio receiver differ from a transmitter in

  radio communication?

  A receiver converts radio waves to audio or visual

  information, while a transmitter generates radio waves.
• Which modulation technique *0/1 is used in analog television broadcasting?

  FM
• Which member of the

  electromagnetic spectrum has

  the most wavelengths?

  Radio waves