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One Stop for Colleges Education flight ? ? Covers complete IITJEE/AIEEE syllabus ? ? ? Chemistry, Maths and Physics Sections ? Its Free ? Lessons, tests by IIT/NIT toppers gibibyte+ Questions and Sample tests Last minute preparation and help Minglebox engineering formulation Free Online Preparation for Engineering with Minglebox Engineering Prep. Cover basic concepts of nether Section for Engineering Entrance Exam Preparation with Study material, figure out examples and tests prep ared by IIT/NIT toppers. 1 Minglebox Engineering Prep Minglebox. om Communication systems electronic communicating refers to the faithful transfer of informationor communicate (available in the form of galvanic voltage and current)from one point to another point. Transmitter, contagious disease channel and receiver are three basic unitsof a confabulation system. 2 Minglebox Engineering Prep Minglebox. com Transducer Any device that converts one form ofenergy into another stomach be termed as a tra nsducer. Signal Information converted in electrical form and suitable for transmission is called a polarity.Signals heap be either analog or digital. Noise Noise refers to the unwanted blesss that lam to disturb the transmission and physical processing of meaning point outs in a chat system. Transmitter A transmitter processes the incoming message signal so as to make it suitable for transmis sion through a channel and ensuant reception. Receiver A receiver extracts the desired message signals from the received signals at the channel output. Attenuation The loss of strength of a signal period propagating through a medium is cognize as attenua tion.Amplification It is the process of change magnitude the amplitude (and consequently the strength) of a signal using an electronic perimeter called the amplifier. 3 Minglebox Engineering Prep Minglebox. com Range It is the largest blank mingled with a source and a destination up to which the signal is received with fitted st rength. Bandwidth Bandwidth refers to the frequency range over which an equipment operates or the portion of the spectrum occupied by the signal.Modulator At the transmitter, information contained in the low frequency message signal is superimposed on a elevated frequency quaver, which acts as a carrier of the information. This process is known as modulation. As will be explained later, there are several types of modulation, abbreviated as AM, FM and PM. Demodulation The process of retrieval of information from the carrier agitate at the receiver is termed demodulation. This is the go up process of modulation. Repeater A repeater is a combination of a receiver and a transmitter.A repeater, picks up the signal from the transmitter, amplifies and retransmits it to the receiver sometimes with a change in carrier frequency. 4 Minglebox Engineering Prep Minglebox. com ii important forms of communication system are Analog and Digital. The information to be transmitted is generally in continuous waveform for the former fleck for the latter it has only discrete or quantised levels. Every message signal occupies a range of frequencies. The bandwidth of a message signal refers to the band of frequencies, which are necessary for satisfactory transmission of the infor mation contained in the signal.Similarly, any practical communication system permits transmission of a range of frequencies only, which is referred to as the bandwidth of the system. Low frequencies cannot be transmitted to long distances. Therefore, they are superimposed on a high frequency carrier signal by a process known as modulation. In modulation, some characteristic of the carrier signal standardised amplitude, frequency or phase varies in accordance with the modulating or message signal. Correspondingly , they are called Amplitude Modulated (AM), Frequency Modulated (FM) or Phase Modulated (PM) waves. 5Minglebox Engineering Prep Minglebox. com Pulse modulation could be classified as Pulse Amp litude changeover(PAM), Pulse Duration Modulation (PDM) or Pulse Width Modulation(PWM) and Pulse Position Modulation (PPM). For transmission over long distances, signals are radiated into spaceusing devices called antennas. The radiated signals propagate aselectromagnetic waves and the mode of propagation is influenced bythe straw man of the earth and its atmosphere. Near the find of theearth, electromagnetic waves propagate as surface waves. Surface wavepropagation is useful up to a few MHz frequencies.Long distance communication between two points on the earth isachieved through manifestation of e lectromagnetic waves by ionosphere. Such waves are called sky waves. Sky wave propagation takes place upto frequency of about 30 MHz. Above this frequency, electromagneticwaves basically propagate as space waves. Space waves are use forline-of-sight communication and satellite communication. 6 Minglebox Engineering Prep Minglebox. com If an antenna radiates electromagnetic waves fro m a height hT, thenthe range dT is given by v2RhT whereR is the radius of the earth.Amplitude modulated signal contains frequencies (? c ? m ), ? c and (? c +? m) Amplitude modulated waves can be produced by application of the message signal and the carrier wave to a non linear device, followed by a band pass filter. AM detection, which is the process of recovering the modulating signal from an AM waveform, is carried out using a rectifier and an envelope detector. 7 Minglebox Engineering Prep Minglebox. com Sample Examples A message signal of frequency 10 kHz and peak voltageof 10 volts is used to modulate a carrier of frequency 1 MHz and peakvoltage of 20 volts.Determine (a) modulation index, (b) the side bandsproduced. Solution (a) Modulation index =10/20 = 0. 5 (b) The side bands are at (1000+10 kHz)=1010 kHz and(1000 10 kHz) = 990 kHz. A transmitting antenna at the top of a rear has a height32 m and the height of the receiving antenna is 50 m. What is themaximum distance betwe en them for satisfactory communication inLOS mode? Given radius of earth 6. 4 ? 106 m. Solution = v2 *64*105*32 + v2 *64*105*50 = 64 ? 102 ? v10 + 8 ? 103 ? v10 m =144 ? 102 ? 10 m = 45. 5 km 8 Minglebox Engineering Prep Minglebox. com