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# CSIS 625 Week 2.

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CSIS 625. 2. Review. Simple and Digital SignalsVocabularyAnalog SignalsDigital SignalsEncoding and ModulationDigital to Digital ConversionAnalog to Digital ConversionDigital To Analog ConversionAnalog to Analog Conversion. CSIS 625. 3. Simple and Digital Signals. Signal - an electromagnetic wave that exchanges data Analog Signal - Continuous arrangement of dataReal NumbersDigital Signals - Discre
Transcripts
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﻿CSIS 625 Week 2 Encoding and Transmission of Data Copyright 2001, 2002 - Dan Oelke Portions Copyright 2000 - Dmitry Gringauz For use by understudies of CSIS 625 for reasons for this class as it were. CSIS 625

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Overview Analog and Digital Signals Vocabulary Analog Signals Digital Signals Encoding and Modulation Digital to Digital Conversion Analog to Digital Conversion Digital To Analog Conversion Analog to Analog Conversion CSIS 625

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Analog and Digital Signals Signal - an electromagnetic wave that exchanges data Analog Signal - Continuous arrangement of information Real Numbers Digital Signals - Discrete arrangement of information Integer Numbers Often twofold (1 or 0 just) Digital Signal Analog Signal CSIS 625

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Periodic versus Aperiodic Signals Periodic Signal A sign that finishes an example in a quantifiable time period Aperiodic Signal A sign that does not display an example All aperiodic signs can be appeared to be a mix of occasional signs APeriodic Signal Periodic Signal CSIS 625

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Signal definitions Amplitude - The "stature" of a sign. Measured in Volts, Amps, Watts, and so on. Period - The measure of time to finish one cycle Frequency - The quantity of periods every second. Measured in Hertz (Hz) Amplitude Period CSIS 625

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Phase The position of a sine wave with respect to time zero. Measured in degrees. 0 Degrees 90 Degrees 1/4 Cycle 180 Degrees 1/2 Cycle 270 Degrees 3/4 Cycle CSIS 625

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Bandwidth - A scope of frequencies Analog - measured in Hz Bandwidth = High-Freq – Low-Freq Spectrum - equivalent word - utilized just as a part of simple estimations. Transfer speed in advanced domain - regularly used to allude to bits-per-second CSIS 625

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Bit Rate Most computerized signs are aperiodic Period and recurrence are not proper to portray advanced signs Bit Interval - time to send one piece Bit rate - number of bits send in a moment. Measured in bits every second bps - Bits Per Second Do NOT utilize Hz when you mean bps or the other way around CSIS 625

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Decomposing an advanced sign A computerized sign can be disintegrated into a boundless number of straightforward sine waves It is not down to earth or important to send these segments Significant Bandwidth - Those frequencies important to reproduce an advanced piece design Significant Bandwidth is identified with bit rate Greater piece rate = Greater critical transfer speed CSIS 625

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Medium Bandwidth and Significant Bandwidth All transmission mediums have constrained data transfer capacity The noteworthy transfer speed of an advanced piece rate must fit inside the restricted data transmission of the medium that conveys it. CSIS 625

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Encoding Information should regularly be encoded before being sent over a medium Four essential sorts of encoding Digital to Digital Analog to Digital to Analog to Analog Encoding plans might be stacked Voice to advanced information to radio waves CSIS 625

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Digital to Digital Encoding Using a computerized sign to speak to computerized information Binary information is meant diverse voltage, current, or light heartbeats that can be transported over the medium. Sorts Unipolar - utilizes 1 signal level Polar - utilizes 2 signal levels Bipolar - utilizes 2 signal levels and 0 CSIS 625

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Digital sign encoding groups 0 1 0 1 0 1 Unipolar NRZL NRZI RZ Manchester Differential Manchester Bipolar-AMI Pseudoternary CSIS 625

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Unipolar Encoding Simplest plan Uses two sign levels 1\'s are encoded with sign present 0\'s are encoded by nonattendance of a sign (Sometimes backwards of the above) Long keep running of 0s or 1s can\'t be taken care of by a few mediums CSIS 625

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Unipolar encoding - synchronization When a sign isn\'t shifting, recipient can\'t decide starting and consummation of every piece Solutions: A different line with a clock signal Asynchronzous Serial lines wrap every byte with begin and stop bit Scrambling of information to guarantee enough moves Use of extra coding plans like 8b10b CSIS 625

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Polar Encoding Uses a positive and a negative flag yet not a zero level Several sorts of Polar encoding NRZ - Non-Return to Zero RZ - Return to Zero Biphase CSIS 625

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Non-Return to Zero - Level NRZL - Non-Return to Zero - Level Simple - precisely like Polar, aside from 1\'s are encoded with positive flag 0\'s are encoded with negative sign (Sometimes converse of the above) Same synchronization issues and arrangements CSIS 625

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Non-Return to Zero - Invert on Ones NRZI - Non-Return to Zero - Invert on Ones An adjustment in voltage level shows a 1 No adjustment in voltage level demonstrates a 0 Synchronization to a lesser degree an issue Every 1 bit causes a sign change A string of 0\'s still causes issues Same synchronization arrangements CSIS 625

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Return to Zero RZ - Return to Zero Not entirely polar - utilizes 0 as a part of expansion to positive and negative Works like NRZL, with the exception of it goes to zero between every piece. Move to/from zero accommodates synchronization Because there are more transisitions (2 for every piece time) it has a higher critical transfer speed than NRZ CSIS 625

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Manchester Coding A biphase instrument Inversion of sign in center of every piece low to high move is 1 high to low move is 0 Mid-piece reversal accommodates both information and synchronization data May have move between bits so right move can be made in center of a bit CSIS 625

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Differential Manchester A biphase system Always has a mid-piece reversal to give timing data Inversion at start of bit time gives information Presence of reversal means 0 No reversal implies 1 CSIS 625

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Bipolar AMI Bipolar Alternate Mark Inversion Mark originates from old telecommunication - implies 1 Encoding 0 = absence of sign (0) 1 = positive or negative qualities rotating for progressive ones CSIS 625

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Pseudoternary Same as Bipolar AMI, yet transforms 1s and 0s Encoding 0 = positive or negative qualities exchanging for progressive zeros 1 = absence of sign (0) CSIS 625

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1 0 1 0 1 0 Binary-AMI V B8ZS V = Bipolar AMI Violation B8ZS Bipolar 8-Zero Substitution An adjustment of Bipolar AMI to take care of the synchronization issue that happens when a long series of 0s happens Substitutes 8 back to back 0s with settled example that contains 2 AMI infringement CSIS 625

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1 0 1 0 1 0 Binary-AMI V HDB3 V = Bipolar AMI Violation HDB3 High Density Bipolar - 3 Zeros Similar to B8ZS Substitutes 4 zeros with an example that contains 1 AMI infringement CSIS 625

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Analog to Digital Encoding Digitizing - simple to computerized change Approximate simple data with an advanced sign Reduces unending number of simple qualities to a limited number of computerized qualities. Codec - Co der-Dec oder Analog to computerized converter CSIS 625

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Pulse Amplitude Modulation (PAM) First means to simple to advanced encoding Sample simple abundancy data at equivalent interims PAM alone not helpful as estimations are still simple qualities CSIS 625

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Pulse Code Modulation (PCM) Modifies PAM yield to make totally advanced sign PCM quantizes Take the examples from PAM and doles out advanced qualities to every estimation. Nyquist hypothesis - To guarantee exact generation of a sign, the specimen rate must be double the most elevated recurrence of the first flag CSIS 625

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PCM & Telephony framework utilizes 8 bits (256 levels) while quantizing A non-straight arrangement of quantizing levels is utilized with the goal that calm sounds are precisely replicated 300-3300Hz is voice range. 8kHz example rate is utilized to cover this reach 8kHz * 8 bits/test = 64,000 bps CSIS 625

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DM - Delta Modulation Analog information is approximated utilizing a staircase capacity that climbs or around one level every examining time. Computerized information is a flood of 1s and 0s that indicate the all over strides. Can be executed utilizing straightforward segments. Not as great quality as PCM Quantizing commotion when slant changes gradually Slope over-burden clamor when incline changes quick CSIS 625

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Digital to Analog Conversion ASK - Amplitude Shift Keying FSK - Frequency Shift Keying PSK - Phase Shift Keying QAM - Quadrature Amplitude Modulation mix of ASK & PSK CSIS 625

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Bit rate versus Baud Rate & Carrier Signal Bit rate is Bits every Second Baud Rate is number of sign units every second Baud rate is not exactly or break even with bit rate Don\'t blend them up! Bearer Signal high recurrence flag that is altered to convey computerized signal CSIS 625

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ASK - Amplitude Shift Keying Amplitude of sign differed for 1 or 0 Frequency and stage stay steady Very powerless to commotion On-Off-Keying - signal and no-sign Example: 1 BIT 0 1 BIT 1 BIT 0 1 BIT 1 CSIS 625

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FSK-Frequency Shift Keying Frequency of the transporter sign is fluctuated to speak to a 1or 0. Stays away from huge numbers of the commotion issues of Amplitude Shift scratching Example: 1 BIT 0 1 BIT 1 BIT 0 1 BIT 1 CSIS 625

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PSK - Phase Shift Keying The period of the bearer sign is differed to speak to a 1 or 0. Dodges clamor issues of ASK Uses less data transmission than FSK Example: 1 BIT 0 1 BIT 1 BIT 0 1 BIT 1 CSIS 625

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QPSK - Quadrature PSK A kind of PSK that utilizations 90° movements rather than 180° movements. Takes into account 2 bits for each baud to be encoded. CSIS 625

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DPSK - Differential PSK The bit design characterizes the stage change, rather than the present stage V.22bis standard at 1200 bps utilizes: 00  90 Degree stage change 01  0 Degree stage change 10  180 Degree stage change 11  270 Degree stage change CSIS 625

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Quadrature Amplitude Modulation The stage and sufficiency of the transporter sign is shifted to give a few bits for each baud Number of various stages is more noteworthy than number of amplitudes Example: 2 amplitudes &

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