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![• Amplitude modulation (AM) is a modulation technique used in
electronic communication, most commonly for transmitting
information via a radio carrier wave. In amplitude modulation,
the amplitude (signal strength) of the carrier wave is varied in
proportion to the waveform being transmitted.
• Pulse-width modulation (PWM), is a modulation technique
used to encode a message into a pulsing signal. Although this
modulation technique can be used to encode information for
transmission, its main use is to allow the control of the power
supplied to electrical devices, especially to inertial[definition
needed] loads such as motors
• Pulse-Frequency Modulation (PFM) is a modulation method
for representing an analog signal using only two levels (1 and 0).
It is analogous to Pulse-Width Modulation (PWM), in which the
magnitude of an analog signal is encoded in the duty cycle of
a square wave.](https://image.slidesharecdn.com/lasercommunication-170710101126/75/LASER-Communication-19-2048.jpg)
Uploaded byAbdulrahman Kerim
LASER Communication
Laser communication systems are wireless connections that transmit information using laser beams through the atmosphere and operate similarly to fiber optic systems. They are cost-effective, require less infrastructure, and are suitable for various applications including defense, NASA missions, and satellite communications. However, environmental factors like fog and rain can affect performance, making it essential to consider these conditions when implementing laser communications.
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LASER Communication
- 1. LASER ENGINEERING –EE420
- 2. • WHAT ISTHE LASER COMMUNICATION? Laser communications systems are wireless connections through the atmosphere. They work similarly to fiber optic links, except the beam is transmitted through free space.
- 3. • While thetransmitter and receiver must require line-of-sight conditions, they have the benefit of eliminating the need for broadcast rights and buried cables.
- 4. • Laser communicationssystems can be easily deployed since they are inexpensive, small, low power and do not require any radio interference studies.
- 5. • Using LaserBeams to transmit information between two locations • Communication over long distances, e.g between planets • Laser Communication Terminals (LCT) transmit A laser beam and are Capable of receiving Laser beams
- 6. Working principle The Figureshows the block diagram of Laser Communication System
- 7. Transmitter basic circuit Figureshows Basic Transmitter Circuit
- 8. receiver basic circuit Figureshows Basic Receiver Circuit
- 9. Applications • Defense Industryand Sensitive Areas Protection. • Airport Runways. • Mass Communication. • NASA and Space Discovery. • Satellite-to-Satellite Communications.
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- 16. Laser Transmitter • TheTransmitter involves a signal processing circuit, and a laser. • A laser diode is used to create the laser signal. • Laser Diodes include Photodiodes for feedback to insure consistent output.
- 17. Receiver The receiver involves: •Telescope(‘antenna’) • Signal processor • Detector PIN diodes Avalanche Photo Diodes(APD) Single or multiple detectors
- 18. Modulation of OneWay Laser Communication • Amplitude Modulation ( AM ) Easy with gas lasers, hard with diodes • PWM (Pulse Width Modulation) Used by Ramsey in their kit • PFM (Pulsed FM) Potentially the highest bandwidth (>100kHz)
- 19. • Amplitude modulation(AM) is a modulation technique used in electronic communication, most commonly for transmitting information via a radio carrier wave. In amplitude modulation, the amplitude (signal strength) of the carrier wave is varied in proportion to the waveform being transmitted. • Pulse-width modulation (PWM), is a modulation technique used to encode a message into a pulsing signal. Although this modulation technique can be used to encode information for transmission, its main use is to allow the control of the power supplied to electrical devices, especially to inertial[definition needed] loads such as motors • Pulse-Frequency Modulation (PFM) is a modulation method for representing an analog signal using only two levels (1 and 0). It is analogous to Pulse-Width Modulation (PWM), in which the magnitude of an analog signal is encoded in the duty cycle of a square wave.
- 20. Gain Systems InOne-Way Laser Communication • For Transmitter Maximum output power Minimum divergence • For Receiver Maximum lens area Clarity Tight focus on detector
- 21. Filters • Sun shadeover detector • Shade in front of lens • Detector spectral response • Colored filters • Absorb ~50% of available light • Difficult to find exact frequency
- 22. Mounting • Mounts andstands need only be as accurate as beam divergence • Good laser diodes will be 1-2mR (milliRadian) • A 32 pitch screw at the end of a 2' mount will yield 1mR per revolution. Since quarter turns (even eighth turns) are possible, this is more than accurate enough • Higher thread pitches allow shorter mounts which may be more stable (against wind, vibration, wires) • 1mR is 1.5' of divergence every 1000', 3' at 2000 ', etc.
- 23. Pointing • GPS andCompass • Scopes and Binoculars • Strobe lights, large handheld floods, headlights • HTs to yell when laser light is seen at remote location
- 24. Advantages of LaserCommunication Technology • Higher data rates – Compared to RF technology LC provides much higher data rates – Higher data rates are essential as more and more data is moved between diff. locations – Key Driver for investments in Laser Communication Technology • High security regarding interception – A focused laser beam is hard to intercept without notice – Path to Quantum Cryptography 7/10/2017 Technical Seminar-II 24
- 25. Advantages of LaserCommunication Technology • Less frequency restrictions – RF spectrum is crowed and heavily used • Smaller aperture dimensions and thus reduced size and mass – Less weight and power per bit • Autonomous alignment agility resulting in less platform manoeuvres – Less fuel or more flexibility 7/10/2017 Technical Seminar-II 25
- 26. Advantages of LaserCommunication Technology • Laser light has higher intensity, efficiency, as well as better visibility and performance quality. Satellite-to-submarine communication
- 27. Advantages of LaserCommunication Technology • Laser light has a much lower tranmission loss per unit length. An interplanetary TV lin
- 28. Advantages of LaserCommunication Technology • Less costly then cables and much faster then RF.
- 29. Disadvantages There is notreally much disadvantage in laser communication. However, environmental conditions can restrict communication with the laser.
- 30. • For terrestrialapplications, the principal limiting factors are: • Beam dispersion • Atmospheric absorption • Rain • Fog (10..~100 dB/km attenuation) • Snow • Scintillation • Interference from background light sources (including the Sun) • Shadowing • Pointing stability in wind • Pollution / smog Disadvantages
- 31. Conclusion - Laser communicationsoffers a viable alternative to RF communications for inter satellite links and other applications where high-performance links are a necessity. - High data rate, small antenna size, narrow beam divergence, and a narrow field of view are characteristics of laser communications that offer a number of potential advantages for system design.
- 32. - With thedramatic increase in the data handling requirements for satellite communication services, laser inter satellite links offer an attractive alternative to RF with virtually unlimited potential and an unregulated spectrum. - The system and component technology necessary for successful inter satellite link exists today. - FSO is just starting to be applied to solve the Internet “last-mile” interconnectivity problem. Some believe that it may be the unlimited bandwidth solution for the metro urban core of downtown building-to-building communication, as well as the optimal technology for home-to-home and office-to-office connectivity.
- 33. - The systemlevel implications and variations of potential applications including beamwidth and directivity, signal-to-noise- ratio, spectrum constraints, signal power budget, bit-error-rate, information bandwidth, privacy, modulation and detection schemes, transmission channel attenuation and disturbances (atmospheric turbulence, scintillation from index of refraction fluctuations, absorption and scattering from thermal and moisture variation) and beam acquisition tracking and pointing influence on the performance metrics of optical transmission technologies have been investigated. - The high energy laser laboratory at Cleveland State University was also employed to conduct experiments to investigate the feasibility of utilizing the VMJ technology for optical communications, including:
- 34. • Beam profiling(Gaussian beam waist may be detected for fine tracking) • Off axis performance (7% output decrease at 45° off-normal) 151 • Modulation (ability to track 1 kHz square OOK at 350 W, high SNR) • Dynamic range (35.6 dB, linear concurrent WPT and communications) • Polarization (multi-channel demonstrated with ER=10.448 dB) • Applications (challenging atmospheric/oceanographic environments) • Integration (multi-use beamed energy capability)
- 35. REFERENCES • http://www.academia.edu/4781330/LASER_C OMMUNICATION_SYSTEM • http://broadcast.net.ua •https://www.slideshare.net/shashanksachdev a/laser
- 36. References • www.electronicsforu.co • www.lasercommunications.weebly.com. •http://www.space.com/missionlaunches/0601 04_laser_comm.html • http://www.arrl.org/files/file/Technology/tis/i nfo/pdf/9009019.pdf • laser-communication-1222866681398711- 9.ppt
- 37. • ALPER ATEŞ15050552051 • ÜMİT ESKİVAR 15050552032 • ABDULRAHMAN HAJE KARIM 13050241001 • SEZGİN DULKADİR 15050552043 • ŞÜKRÜ CAĞLUOĞLU 15050552113 • H. MURAT DURUKAN 15050552045
Editor's Notes
- #7 This laser communication system transmits the message signal through a laser beam. The intensity of the laser beam changes with the amplitude of the message signal. The variation in the intensity of the laser beam is converted into a variation in the voltage level by using a calculator’s solar panel. The voltage variation on the solar panel is amplified by a low-voltage amplifier.
- #8 The voltage divider (R2, R3 and VR3) keeps the voltage and the current for the laser diode in the safe region. Potmeter VR1 (10-kilo-ohm) is used to change the level of the input audio signal.
- #9 The audio signal transmitted by the laser diode (LD1) is received by the calculator’s solar panel and amplified by IC2. The gain of the amplifier is fixed by capacitor C7. Preset VR4 is used to change the signal level from the solar panel. This signal is fed to input pin 3 of IC2 through coupling capacitor C5 so that the DC value from the solar panel can be eliminated. The amplified output from IC2 is fed to the speaker, which plays the music from the CD player connected at the input (Vin) of IC1.
- #10 The high-speed data communications possible between networks is just the tip of the iceberg as to what is possible with laser communications, many of which derive from the lack of physical connection required. Beams can connect computer chips within computers, cross lands and roads without requiring right-of-way or ownership, and be erected as temporary networks during battles or in disaster conditions. They can provide network redundancy, connect existing optical networks or take us closer to converged voice-data infrastructure -- all with high speed, low error rates and immunity to electromagnetic interference The systems are protocol transparent allowing transmission of digital computer data (LAN interconnect), video, and voice over IP, multiplexed data, or ATM. They are suitable for temporary connectivity needs such as at conventions, sporting events, corporate and university campuses, disaster scenes or military operations
- #11 Laser Defense systems established across the world can detect enemy ships and missiles while at the same time disabling them.
- #12 Laser communication systems on airport runways can send signals back to headquarters letting officers know when and what planes have landed.
- #13 Laser communications have been utilized for mass communications including telephone conversations and even television channels.
- #14 Nasa has created lots of different technologies which include laser communications. One recent NASA accomplishment was a successful exchange of laser pulses with the MESSENGER spacecraft and an earth.
- #15 Nasa has also developed Satellite-to-Satellite communications using laser communications.