Modulation techniques are roughly divided into four types. In digital modulation, the modulation technique used is pulse code modulation pcm. Chapter 6modulation techniques shandong university. Therefore, phase modulation is in reality a second form of frequency modulation. Aug 06, 2018 in this video, i have explained ppm pulse position modulation by following outlines. Types of analog pulse modulation systems are options. In particular, all telephone modems faster than 300 bits use quadrature amplitude modulation qam. Demodulation is the opposite process of modulation. So now lets discuss different types of pulse modulation techniques in detail. Digital modulation involves transmission of binary signals 0 and 1. In general when we talk about a digital system, we are usually talking about digital information over an analog medium. Pulse width modulation pwm generation, applications and. Channels, modulation, and demodulation of binary pam where the basic pulse shape pt is a sinc function. We use modulation technique to alter signals in time and frequency to accomplish desired objectives.
Pulse amplitude modulation is the basic form of pulse modulation. Pulse width modulation pwm is a modulation process or technique used in most communication systems for encoding the amplitude of a signal right into a pulse width or duration of another signal, usually a carrier signal, for transmission. The am and fm radios are examples of analog data over analog medium. Aug 28, 2015 when we take the pulse digital modulation, we use a periodic sequence of rectangular pulses as the carrier signal. Digital modulation in communications systems an introduction.
Many signals in modern communication systems are digital also, analog signals are transmitted digitally. Pulse width modulation pwm or pulse duration modulation pdm or pulse time modulation ptm is an analog modulating scheme in which the duration or width or time of the pulse carrier varies proportional to the instantaneous amplitude of the message signal. Even though there are different methods for modulation and demodulation processes, each has its own advantages and disadvantages. The microcontroller is the most efficient tool for generating various pulse width modulation techniques. May 05, 2016 modulation in this section, we will study about what modulation is. Pulse code modulation pcm is a method used to digitally represent sampled analog signals.
As the resultant signal is a coded pulse train, this is called as pulse code modulation. The output of a pcm will resemble a binary sequence. Where as digital modulations are with bit streams or symbols from computing vevices as base band signals. The process of varying any of the three characteristics as the amplitude, frequency or the phase of a carrier signal is called as modulation we know that the information signal to be transmitted can be of any form such as data, music, video etc. Display of dialed telephone numbers on seven segment displays. Modulation allows multiplication by frequency division, a very important technique. In analog pulse modulation some parameter of each pulse is modulated by a particular sample value of the message. In cw modulation schemes some parameter of modulated wave varies.
Pwm is employed in a wide variety of applications, ranging from measurement and communications to power control and conversion. It is a modulation system in which the signal is sampled at regular intervals and each sample is made proportional to the amplitude of the signal at the instant of sampling. Ppm pulse position modulation basics, circuit, working. Oct 03, 2011 this is a ppt for pulse modulation for final year ej diploma. Of them all, the digital modulation technique used is pulse code modulation pcm. Indicates sample amplitude at the nearest predetermined level. Modulation definition need for modulation types of.
Modulation is the process of encoding information from a message source in a manner suitable for transmission. Of them all, the digital modulation technique used is. Pulse width modulation is effective and commonly used as control technique to generate analog signals from a digital device like a micro controller. Analog digital modulation lanalog modulation l the input is continues signal l used in first generation mobile radio systems such as amps in usa.
More importantly we will now turn to the two other kinds of pulse. Pulse amplitude modulation is widely used in modulating signal transmission of digital data, with nonbaseband applications having been largely replaced by pulse code modulation, and, more recently, by pulse position modulation. Cell phone based dtmf controlled garage door opening system. Pulse coded modulation pcm is a form of modulation where there is no carrier, so. Modulation is the process of converting data into electrical signals optimized for transmission.
Modulation, analog modulation, digital modulation, am,fm,pm. Many signals in modern communication systems are digital. The principles of tdm apply to other types of pulse modulation. Pulse modulation in the pulse modulation, the continuous signal is converted into a series of pulses, each proportional to the amplitude of the signal and corresponding in time. There are two types of modulation analog and digital.
Classification and types of analog modulation double sideband suppressed carrierdsb sc introduction. There are many modulation techniques, which are classified according to the type of modulation employed. Some pulse modulation schemes also allow the narrowband analog signal to be transferred as a digital signal i. There are several types of modulation according to the nature of the informative signal analogical or digital and that of carrier. It is analog to digital conversion method where the message information is encoded in the amplitude of the series of signal pulses. Reduced distortion and improvement in signal to noise ratios. Pulse amplitude modulation pam pulse width modulation pwm pulse position. Pulse width modulation pwm is a powerful technique for controlling analog circuits with a processors digital outputs. Analog and digital pulse modulation techniques need. Although pwm is also used in communications, its main purpose is actually to. Analog modulation, digital modulation, pulse modulation, and spread spectrum method. Pulse modulation timedivision multiplex tdm continued advantages of tdm the circuitry required is digital, thus affording high reliability and efficient operation.
A signal is pulse code modulated to convert its analog information into a binary sequence, i. Pulse modulation techniques pam, pwm, ppm, pcm pulse. In digital modulation, the modulating signal or message signal is converted from analog to digital. The phase angle cannot change without also affecting a change in frequency. The following safety and common symbols may be used in this manual and on the equipment. Analog and digital pulse modulation techniques gate study. In digital speech security system dsss, the analog signal is converted into pulse code modulated pcm digital form using an analogto digital converter and encrypted before transmission by a.
Modulation techniques pwm and pulse code modulation. In digital modulation, a message signal is converted from analog to digital message, and. For example, am is used in shortwave and radio wave broadcasting. The main advantages of the digital modulation over analog modulation include available bandwidth, high noise immunity and permissible power. This post will discuss pulse width modulation, various types of modulation techniques, signal generation, its applications, advantages and disadvantages. Chapter 14 modulation introduction as we have seen in previous three chapters, different types of media need different types of electromagnetic signals to carry information from the source to.
Pulse modulation definition, types, block diagrams, pulse. The next installment will examine some of the more complex forms of digital modulation, and explain the use of the time domain and pulsed signals in systems employing pulse modulation e. Modulation techniques can be mainly divided into three categories, namely analogue, pulse and digital. Sometimes it is necessary to digitise an analogue signal. These modulation formats have proven quite effective as a means of transmitting digitized information in noisy environments where analog formats would fail. Pulse amplitude modulation pam theory of and its applications. Digital is more robust than analog to noise and interference. The introduction into television broadcasting practice of component analog and digital forms of signal representation to improve picture quality and the changeover. For a better quality and efficient communication, digital modulation technique is employed. Apr 17, 2017 pulse modulation techniques pam, pwm, ppm and pcm. In this project, we have generated ten different types of pulse width modulation techniques for inverters. In general it involves translating a baseband signal source. Pulse amplitude modulation is a technique in which the amplitude of each pulse is controlled by the instantaneous amplitude of the modulation signal.
It is the standard form of digital audio in computers, compact discs, digital telephony and other digital audio applications. Pdf analog,digital and pulse modulation techniques researchgate. Analog modulation is typically used for am, fm radio, and shortwave broadcasting. Automatic dialing to any telephone using i2c protocol on detecting burglary. Digital pulse interval modulation for optical communication systems. This is a rectangular representation of the polar diagram. In pulse modulation systems, the carrier is a train of pulses rather than a continuous signal. In both the techniques, the baseband information is converted to radio frequency signals, but in analog modulation these rf communication signals are continuous range of values, whereas in digital modulation these. Therefore, the degree of effective amplitude modulation in a system will affect some distortion parameters. This is a one dimensional signal, because the captain uses only one dimension running from left to right to indicate a symbol change. A block diagram showing the basic classification of modulation techniques is given below. Pulse code modulation pcm in digital modulation, the modulation technique used is pulse code modulation pcm.
Each one of these digits, though in binary code, represent the approximate amplitude of the signal sample at that instant. Pulse modulation communications university of toronto. Multiplexingmedium access control 2 digital modulation 3 why modulate. We will continue with our discussion on pulse modulation schemes, that we started last. Pulse modulation of two types analog pulse modulation pulse amplitude modulation pam pulse width modulation pwm pulse position modulation ppm digital pulse modulation. An example of a ir uwb carrier is a gaussian monopulse, shown in fig. Analog modulation delas with the voice, video and regular waves of base band signals. We utilize just one sinusoid as the basis function. In pulse width modulation, there are different types of modulation for analog and digital as shown below. In pulse code modulation, the message signal is represented by a sequence of coded pulses. It is based on creating a sequence of short pulses, modulated by pulse amplitude modulation pam or pulse position modulation ppm. Different types of modulation techniques in communication systems. Modulation is the process of changing the characteristics of the carrier signal in accordance with the instantaneous values of the modulating signal message signal. Categories of modulation analog and digital types of modulation analog and digital 3.