Digital Communication Study
Added on - 12 Oct 2019
DATA COMMUNICATIONS, TCP/IP AND NETWORKSECURITY PROTOCOLS
ABSTRACTThe study focuses on digital communication,TCP/IP communication protocol andnetwork security protocols. It also clearlystates about the modulation techniques,protocols used in the TCP or IP and thedifferent types of protocols used in eachlayer of the OSI model. Moreover theimportance of each method is described.INTRODUCTION TO DIGITALCOMMUNICATIONSData communication is one of the sources ofthe information that flows through theinternet .information can be shared fromplace to place within a fraction of asecond.Data communication is one of theresource that people need day by day and allthe routine that is performed in the day areprocessed using Data. Due to the rapidincrease in the technology the people cantrack the data and get information from thedata in real time. This information gatheringis possible through Data communication.We expect the information should beaccurate and accessible 24x7 this kind ofservice is achieved by the physicalcomponents and the speed of thecommunication that happens between thehardware.The information that is to be passed fromone people to other people through a modeof communication can be analog or digitalcommunication. Both communication modesare used in nowadays due to the fact theAnalog communication is old technology isalso used in communication method is someapplications because of the improvement oftechnology all the analog communication isturned into digital informationTYPES OF DIGITALCOMMUNICATIONThere are two types of digitalcommunication. They are analogtransmission and digital transmission.ANALOG TRANSMISSIONAnalog transmission is the process ofconverting the voice information, image,data in the form of continuous signal thatcan be varied using such parameters asphase, amplitude or some properties. Thesignal could be transferred using somemechanisms like analog modulation andfrequency modulation.DIGITAL TRANSMISSIONDigital transmission is the process ofconverting the information using somephysical medium that can be delivered in theform of digital signals. The informationcould not be transmitted in the form of 0’sand 1’s. it must be transmitted in the form ofsignals.The signals can be encoded using thefollowing encoding methods.Signal encodingThis method is used for encoding the digitalsignal and transmitting in the form ofphysical medium. It can be of two types theyare two level encoding methods and threelevel encoding methods.
Two level encoding methodIn this method of encoding, the signals withthe positive value or negative value areconsidered for converting the signal throughthe physical medium.Three level encoding methodIn this method, three values are consideredfor encoding the signals. The values are apositive value, zero and negative values.With these values, the signals are encodedand transmitted through the physicalmedium.NRZ encoding methodNRZ means No return to Zero. It is thesimplest encoding method which is used fortransforming the input signals from 0 tonegative values and 1 to positive values.This method of encoding methods is usedfor delivering the output to know thepresence of a signal.NRZI encoding methodNRZI is an entirely different form NRZencoding method. During the transmissionbit if the value of the bit is 1 the clock statewill change. If the value of the bit is 0 theclock state will not be changed.Manchester encoding method:This encoding method is performed usingthe XOR method and translating the zerosand ones with the XOR operation.Delay encoding method:It is similar to Manchester encoding methodwhere the data bit changed during themiddle of the transmission methods.Bipolar encoding method:In this encoding method, there are threemethods of transmission. If the bit is 0 thenthe value of the bit will also be 0. If the bitvalue is positive or negative value the valuewill be 1.TYPES OF MODULATIONTECHNIQUESModulation is divided into two typesnamely, Analog and digital modulation.Types of analog modulation are AM, PM,FM, PWM and types of Digital modulationare IO, PSK, FSK, and ASK.AMPLITUDE MODULATION (AM)Amplitude modulation is a former most usedmodulation technique that used to transmitvoice via radios. This is used as amodulation technique in electroniccommunication as one of the parts. Inamplitude modulation, the carrier signal ofamplitude oscillates due to the messagesignal and produce difference variables inphase and consistent frequency. There willbe a modulation shortage due to the powerfluctuation, bandwidth increasing capacity,and filtering. Used in PC modems, VHFradios, portable radios.FREQUENCY MODULATION (FM)In frequency modulation, the carrier signalon which the frequency transfers differs asper message signal and amplitudes maydiffer but the phase remains constant.Applications like radar, radio telemetry,protecting monitoring seizures. This ismostly used in broadcasting voice or music,a recording system that uses magnetic tapes,
2-way radio system and system that transfervideos. It will cancel the noise during radiosystems.PHASE MODULATION (PM)In phase modulation, the carrier signal onwhich the phase transfers changes accordingto the message signal. If the phase of thesignal changed it affects the frequency.Phase modulation is used in applications thatuse transmitting waves like GSM, Wi-Fi,and Satellite TV.AMPLITUDE SHIFT KEY (ASK)The carrier amplitude can vary with theproportion to message signal in amplitudeshift key. A modulated carrier signal inamplitude signal is called carrier signal. Theinput data is in on and off signal so theoutput is also like one and off signal and 1indicates the available signal and 0 indicatesthe missing signal. Fibre optical transmitterand receivers, IR remote uses amplitudeshift keys.FREQUENCY SHIFT KEY (FSK)Whenever the changes on data transmittedon frequency signal there will be afrequency shift key. Frequency of thismodulation is wc1 and wc2. Wc1 willtransmit when the data bit is 1. Modems usefrequency shift keys.PHASE SHIFT KEYSModulation that is changed due to phase anduses on and off shift methods is phase shiftkey. Baseband signal is 1 when a carrier istransmitted. Same as amplitude andfrequency it uses on and off method tochange the phase when on off side itindicates as 0 i.e. carrier is not transmitted.During the off set they can send 2bits of dataat a particular time as during this they were4 quadrants that help to increase the speed ofthe phase shift.ADVANTAGES OF DIGITALCOMMUNICATIONIt consumes high powerIt requires more bandwidth fortransmission when compared to theanalog systems.The sampling error of analogtransmission is high