Difference Between PAM, PWM and PPMIn a communication system, the modulation is an important step. Modulation is the process of transmitting a message signal (Baseband signal with low frequency) from transmitter to receiver without changing its characteristics (like amplitude, frequency, phase) by using a carrier signal (high frequency) which varies in accordance with the instantaneous values of the low frequency wave by keeping its frequency and phase constant.The modulation techniques are classified into two major types: analog and digital or pulse modulation. We have discussed previously the different types of modulation techniques, let us understand the basic difference between PAM, PWM, and PPM. Types of Modulation TechniquesBefore going to discuss the difference between PAM, PWM, and PPM, let us discuss individually each. All these are pulse analog modulation techniques.Pulse Amplitude ModulationBy varying the amplitude of the pulses (the carrier signal) in proportion to the instantaneous values of the analog signal (the message signal).Pulse Amplitude Modulation (PAM) SignalsThe above figure illustrates the time-domain representation of the PAM technique which mentions the analog message and PAM modulated signal as an output.Pulse amplitude modulation is used in the popular Ethernet communication standard. The PAM modulator and demodulator circuits simple compared to other kinds of modulation and demodulation techniques. There are two categories of PAM techniques, one is the pulses have the same polarity and the other in which the pulses can have both positive and negative polarities according to the amplitude of the modulating signal.Pulse Width ModulationThe Pulse width Modulation– By varying the width of the pulses (the carrier signal) in proportion to the instantaneous values of the analog signal (the message signal). The width of the pulse varies, but the amplitude of the pulse remains constant. Amplitude limiters are used to make the amplitude constant. These circuits clip-off the amplitude, to a preferred level and hence the noise is limited.There are three types of PWM. They areThe leading edge of the pulse being constant, the trailing edge varies according to the message signal.The trailing edge of the pulse being constant, the leading edge varies according to the message signal.The center of the pulse being constant, the leading edge and the trailing edge varies according to the message signal.Pulse Position ModulationBy varying the position of the pulses (the carrier signal) in proportion to the instantaneous values of the analog signal (the message signal).Pulse position modulation is done in accordance with the pulse width modulated signal. Each trailing of the pulse width modulated signal becomes the starting point for pulses in the PPM signal.Hence, the position of these pulses is proportional to the width of the PWM pulses. But the main disadvantage of the PPM modulation technique is, The synchronization between transmitter and receiver must be needed.Difference Between PAM, PWM, and PPMIn all the above cases, we detect the message of the pulse modulated signal and reconstruct the original analog signal.Difference Between PAM, PWM, and PPMThe below table gives a detailed difference between PWM, PAM, and PPM.Sr. No.ParameterPAMPWMPPM1Type of CarrierTrain of PulsesTrain of PulsesTrain of Pulses2Variable Characteristic of the Pulsed CarrierAmplitudeWidthPosition3Bandwidth RequirementLowHighHigh4Noise ImmunityLowHighHigh5Information Contained inAmplitude VariationsWidth VariationsPosition Variations6Power efficiency (SNR)LowModerateHigh7Transmitted PowerVaries with an amplitude of pulsesVaries with variation in widthRemains Constant8Need to transmit synchronizing pulsesNot neededNot neededNecessary9Bandwidth depends onBandwidth depends on the width of the pulseBandwidth depends on the rise time of the pulseBandwidth depends on the rise time of the pulse10Transmitter powerInstantaneous transmitter power varies with the amplitude of the pulsesInstantaneous transmitter power varies with the amplitude and width of the pulsesInstantaneous transmitter power remains constant with the width of the pulses11The complexity of generation and detectionComplexEasyComplex12Similarity with other Modulation SystemsSimilar to AMSimilar to FMSimilar to PMThis article is all about the difference between PAM, PWM, and PPM techniques. Furthermore, for any help on Electronic projects or doubts regarding this article, you can contact us by commenting in the comment section given below. Share This Post: Facebook Twitter Google+ LinkedIn Pinterest Post navigation ‹ Previous How to Build A Hybrid Solar Charger And Its ApplicationsNext › Common Base Amplifier Circuit Working And Its Applications Related Content What is a Carey Foster Bridge & Its Working What is WiFi Calling & Its Working What is a Spectrum Analyzer : Working & Its Applications What is the Splicing of Optical Fibers & Their Techniques One Commentthanks, this is VERY GOOD comprehensive explanation;all the best to you; regards survReplyAdd Comment Cancel replyComment:Name * Email * Website