Information Technologies and Instrumentation Flashcards
Test for 12.13.19.
Electric Telegraph (Morse Code)
The electric telegraph is an old form of communication most known for its use in transmitting Morse Code in the early 1800s. In a telegraph, an electric current is sent as signals through a wire to a receiving end. The signals at the receiving end have to be decoded.
Alexander Graham Bell (telephone)
In 1876, Alexander Graham Bell eliminated the need for decoding by the receiver by inventing the telephone. The telephone operates by converting sound energy from the transmitter into electric energy as it travels through a wire and back to sound energy at the receiving end.
Wavelength v. Frequency
The Electromagnetic Spectrum is arranged by wavelength and frequency. So, Gamma Rays have the highest frequency, shortest wavelengths, and highest energy. Radio Waves have the longest wavelength.
Mechanical Wave v. Non-Mechanical Wave
Electromagnetic waves do not need a medium to travel, unlike ocean waves which travel through water. Electromagnetic waves are therefore called non-mechanical and can travel through empty space. Waves that require a medium are called mechanical waves. Electromagnetic waves are also good for communication because they travel from one place to another very quickly.
Speed of Light
The Speed of Light is 300,000,000 meters per second.
Radio Waves
The most common EM waves that are used for wireless communication are radio waves. Radio waves are generated by vibrating electrons. Conversations, data and even music are transmitted and received wirelessly using radio waves over long distances. But radio waves are also used for wireless communication over short distances.
Lasers
Lasers produce a narrow beam of coherent light waves.
Coherent Light
The narrow beam of coherent light waves produced by lasers can be efficiently transferred from one place to another using fiber optics.
Fiber Optics
An optical fiber is a flexible, transparent fiber made of glass or plastic. It is only slightly thicker than a human hair. The laser beam source transmits the light through one end of the optical fiber. The light undergoes a series of internal reflections until it reaches the receiver. The light received from the lasers can be coded with information such as images or text. Fiber optics are so small that they are usually bundled into fiber optic cables. Because fiber optics can be bundled, a much higher volume of information can be transmitted compared to an electrical wire. Additionally, the internal reflections of the light in the fiber optic results in very little loss of light. Therefore, the data transmitted remains high quality even over long distances. One of the biggest uses today of fiber optics is the Internet, which is information that fiber optic cables send digitally.
Internal Reflection
Internal Reflection occur when the laser beam source transmits the light through one end of the optical fiber. The light undergoes a series of internal reflections until it reaches the receiver.