This document discusses various analog modulation techniques used for transmitting digital data over analog channels. It describes amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK) in detail. It explains the concepts of bit rate, baud rate, modulation index, and provides examples of their calculation. It also introduces higher order modulation schemes like quadrature amplitude modulation (QAM) and provides constellation diagrams to illustrate various modulation techniques.
Digital modulation techniques allow for more efficient transmission of digital data by varying certain properties of the carrier signal, such as amplitude, frequency, or phase, based on the digital bit stream. There are tradeoffs between bandwidth efficiency, power efficiency, and implementation complexity for different modulation schemes. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK), and quadrature amplitude modulation (QAM), with higher-order schemes transmitting more than one bit per symbol. Performance metrics like bit error rate (BER) are used to evaluate and compare modulation techniques.
The document discusses various digital modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) and quadrature phase shift keying (QPSK). It provides details on the basic principles, transmitters, receivers and performance of these modulation schemes. It also covers more advanced topics such as quadrature amplitude modulation (QAM), carrier recovery techniques and differential phase shift keying. The document is presented as lecture slides with explanations and diagrams.
The Presentation includes Basics of Non - Uniform Quantization, Companding and different Pulse Code Modulation Techniques. Comparison of Various PCM techniques is done considering various Parameters in Communication Systems.
This document discusses various digital modulation techniques used in digital communications. It describes amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) including binary PSK (BPSK) and quadrature PSK (QPSK). It provides block diagrams and explanations of modulators and demodulators for ASK, FSK, BPSK and QPSK. It also discusses M-ary encoding techniques that can transmit more than two bits simultaneously to reduce bandwidth.
This document discusses various digital modulation techniques. It begins by explaining binary amplitude-shift keying (ASK), where one amplitude encodes a 0 and another encodes a 1. It then discusses on-off keying (OOK) and multiple amplitude shift keying (MASK). Next, it covers frequency-shift keying (FSK), phase-shift keying (PSK), differential PSK, and quadrature PSK. It also discusses more advanced modulations like quadrature amplitude modulation (QAM), continuous phase modulation (CPM), and Gaussian minimum-shift keying. The document provides examples and discusses the pros, cons, and applications of different modulation schemes. It concludes by discussing a student project involving designing and analyzing a digital
1. Digital modulation techniques are used to modulate digital information so that it can be transmitted via different mediums. Common digital modulation methods include binary amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).
2. FSK conveys information by changing the instantaneous frequency of a carrier wave. It is less susceptible to errors than ASK but has a larger spectrum bandwidth. PSK varies the phase of the transmitted signal. BPSK uses two phases while QPSK uses four phases.
3. The performance of digital modulation techniques can be compared using the energy per bit to noise power spectral density ratio (Eb/N0). Lower Eb/N0 values
This presentation covers:
Some basic definitions & concepts of digital communication
What is Phase Shift Keying(PSK) ?
Binary Phase Shift Keying – BPSK
BPSK transmitter & receiver
Advantages & Disadvantages of BPSK
Pi/4 – QPSK
Pi/4 – QPSK transmitter & receiver
Advantages of Pi/4- QPSK
The document discusses analog communications and the Analog Communications course at Matrusri Engineering College. It includes:
- Course objectives like analyzing analog communication systems, understanding generation and detection of analog modulation techniques, and analyzing noise performance.
- Course outcomes like describing modulation/demodulation schemes and comparing analog modulation schemes.
- A syllabus covering topics like linear modulation schemes, angle modulation schemes, analog pulse modulation schemes, transmitters and receivers, and noise sources and types.
- Details of the course include lesson plans with topics, outcomes, textbooks, and introductions to modules on concepts like amplitude modulation and its time/frequency domain representations.
Digital modulation techniques allow for more efficient transmission of digital data by varying certain properties of the carrier signal, such as amplitude, frequency, or phase, based on the digital bit stream. There are tradeoffs between bandwidth efficiency, power efficiency, and implementation complexity for different modulation schemes. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK), and quadrature amplitude modulation (QAM), with higher-order schemes transmitting more than one bit per symbol. Performance metrics like bit error rate (BER) are used to evaluate and compare modulation techniques.
The document discusses various digital modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) and quadrature phase shift keying (QPSK). It provides details on the basic principles, transmitters, receivers and performance of these modulation schemes. It also covers more advanced topics such as quadrature amplitude modulation (QAM), carrier recovery techniques and differential phase shift keying. The document is presented as lecture slides with explanations and diagrams.
The Presentation includes Basics of Non - Uniform Quantization, Companding and different Pulse Code Modulation Techniques. Comparison of Various PCM techniques is done considering various Parameters in Communication Systems.
This document discusses various digital modulation techniques used in digital communications. It describes amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) including binary PSK (BPSK) and quadrature PSK (QPSK). It provides block diagrams and explanations of modulators and demodulators for ASK, FSK, BPSK and QPSK. It also discusses M-ary encoding techniques that can transmit more than two bits simultaneously to reduce bandwidth.
This document discusses various digital modulation techniques. It begins by explaining binary amplitude-shift keying (ASK), where one amplitude encodes a 0 and another encodes a 1. It then discusses on-off keying (OOK) and multiple amplitude shift keying (MASK). Next, it covers frequency-shift keying (FSK), phase-shift keying (PSK), differential PSK, and quadrature PSK. It also discusses more advanced modulations like quadrature amplitude modulation (QAM), continuous phase modulation (CPM), and Gaussian minimum-shift keying. The document provides examples and discusses the pros, cons, and applications of different modulation schemes. It concludes by discussing a student project involving designing and analyzing a digital
1. Digital modulation techniques are used to modulate digital information so that it can be transmitted via different mediums. Common digital modulation methods include binary amplitude shift keying (ASK), frequency shift keying (FSK), and phase shift keying (PSK).
2. FSK conveys information by changing the instantaneous frequency of a carrier wave. It is less susceptible to errors than ASK but has a larger spectrum bandwidth. PSK varies the phase of the transmitted signal. BPSK uses two phases while QPSK uses four phases.
3. The performance of digital modulation techniques can be compared using the energy per bit to noise power spectral density ratio (Eb/N0). Lower Eb/N0 values
This presentation covers:
Some basic definitions & concepts of digital communication
What is Phase Shift Keying(PSK) ?
Binary Phase Shift Keying – BPSK
BPSK transmitter & receiver
Advantages & Disadvantages of BPSK
Pi/4 – QPSK
Pi/4 – QPSK transmitter & receiver
Advantages of Pi/4- QPSK
The document discusses analog communications and the Analog Communications course at Matrusri Engineering College. It includes:
- Course objectives like analyzing analog communication systems, understanding generation and detection of analog modulation techniques, and analyzing noise performance.
- Course outcomes like describing modulation/demodulation schemes and comparing analog modulation schemes.
- A syllabus covering topics like linear modulation schemes, angle modulation schemes, analog pulse modulation schemes, transmitters and receivers, and noise sources and types.
- Details of the course include lesson plans with topics, outcomes, textbooks, and introductions to modules on concepts like amplitude modulation and its time/frequency domain representations.
Mathematical Explanation of channel capacityHere we can see that the channel capacity is measured with the multiplication of pulses per second and information. This is how we can measure the channel capacity.
Modulation involves adding information to a carrier signal. Digital modulation provides more information capacity, compatibility with digital services, higher security, better quality, and faster availability compared to analog modulation. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK) and their variants. PSK techniques include binary PSK (BPSK), quadrature PSK (QPSK) and differential PSK (DPSK). QPSK transmits twice as much data as BPSK within the same bandwidth. DPSK avoids the need for a coherent reference signal at the receiver. Key considerations in modulation include power efficiency, bandwidth efficiency and bit error rate.
Phase modulation (PM) is a form of modulation where information is represented by variations in the instantaneous phase of a carrier wave. The phase angle of the complex envelope is changed in direct proportion to the message signal. PM can be considered a special case of FM where the carrier frequency modulation is given by the time derivative of the phase modulation. The bandwidth of PM for a single sinusoidal signal is approximately equal to the modulation index multiplied by the carrier frequency.
This document discusses various digital modulation techniques. It begins by defining modulation as adding information to a carrier signal. It then distinguishes between analog and digital modulation. Digital modulation modulates an analog carrier signal with a discrete signal, and can be considered as converting digital-to-analog and vice versa. Some key digital modulation techniques discussed include amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), quadrature amplitude modulation (QAM), and differential phase shift keying (DPSK). Metrics for comparing digital modulation techniques include power efficiency, bandwidth efficiency, and implementation cost-effectiveness.
Pulse amplitude modulation (PAM) is a modulation technique where the amplitude of pulses in a regularly timed sequence is varied according to the amplitude of the modulating signal. There are two types of PAM: single polarity PAM which adds a DC bias to ensure all pulses are positive, and double polarity PAM where pulses can be both positive and negative. PAM is generated by sampling the modulating signal at regular intervals and making each sample proportional to the amplitude of the modulating signal at the time of sampling. The amplitude of the PAM signal then carries the information contained in the modulating signal.
This document discusses various types of pulse modulation techniques. It describes analog pulse modulation techniques including pulse amplitude modulation (PAM), pulse duration modulation (PDM), and pulse position modulation (PPM). It also covers digital pulse modulation techniques such as pulse code modulation (PCM) and delta modulation. For each technique, it provides details on the generator, waveform, and advantages and disadvantages. In conclusion, it summarizes that different pulse modulation techniques were discussed along with how they are transmitted and their waveforms. It also reviews the advantages and disadvantages of these modulation methods.
M-ary encoding allows for digital signals with multiple possible conditions or voltage levels through the use of multiple binary variables. The number of conditions possible is represented by M, while the number of bits needed to produce those conditions is given by the logarithmic relationship N = log2M. M-ary PSK and M-ary QAM are two common types of M-ary encoding. M-ary PSK varies the phase of a carrier signal, while M-ary QAM varies both the amplitude and phase, allowing for greater power efficiency but identical bandwidth efficiency as M-ary PSK. Both modulation schemes use a constellation diagram to represent the multiple symbol states.
This document discusses pulse code modulation (PCM) which converts analog signals to digital data. PCM involves sampling an analog signal, quantizing it to discrete levels, and encoding the samples into binary code. The key aspects covered are the PCM block diagram, process of sampling, quantization and encoding, PCM standards, bit rate and bandwidth requirements, advantages like robustness and disadvantages like requiring large bandwidth. Applications discussed are telephone voice communication, compact discs, and satellite transmission.
It is a digital representation of an analog signal that takes samples of the amplitude of the analog signal at regular intervals. The sampled analog data is changed to, and then represented by, binary data.
This document discusses frequency modulation (FM) and its types: phase modulation and frequency modulation. It describes the key characteristics of FM including its constant amplitude, higher signal-to-noise ratio, and infinite bandwidth. FM is classified as narrowband FM (NBFM) or wideband FM (WBFM) based on the modulation index. The document also covers pre-emphasis and de-emphasis circuits, methods for generating NBFM and WBFM signals including the direct and indirect (Armstrong's) methods.
Gaussian Minimum Shift Keying (GMSK) is a form of continuous-phase frequency shift keying that uses a Gaussian filter to generate a constant envelope signal. It provides better spectral efficiency than MSK through bandwidth reduction while maintaining low intersymbol interference. GMSK is used widely in wireless technologies like GSM and CDPD due to its power efficiency and good bit error rate performance compared to other modulation schemes. While more spectrally efficient than MSK, GMSK also has slightly higher error rates and requires more complex receivers.
This document discusses amplitude modulation and demodulation. It defines amplitude modulation as varying the amplitude of a carrier wave linearly with a message signal while keeping frequency and phase constant. Modulation is used to transmit signals over long distances and allow multiple signals over the same channel. Demodulation recovers the signal intelligence by reversing the modulation process through rectification and filtering. The document describes amplitude modulation and different types of AM demodulation techniques.
Frequency shift keying (FSK) is a digital modulation technique that encodes digital information by shifting the frequency of a carrier wave. There are different types of FSK including binary FSK, which uses two discrete frequencies to represent binary 1 and 0, and double frequency shift keying (DFSK), which uses four frequencies to transmit two independent data streams simultaneously. FSK modulation can be demodulated using either FM detector demodulators, which treat the FSK signal as an FM signal, or filter-type demodulators, which use optimal filters matched to the FSK signal parameters. The filters are used to detect the mark and space frequencies, and a decision circuit then determines which was transmitted.
QAM is a digital modulation technique that encodes data by varying both the amplitude and phase of carrier waves. It can carry higher data rates than schemes using just amplitude or phase. QAM is used widely in applications like digital cable TV, wireless networks, and video broadcasting. Higher order QAM uses more points in its constellation diagram, allowing more bits per symbol but making the signals more susceptible to noise.
The document discusses various propagation mechanisms that affect radio signals, including reflection, diffraction, scattering, and their effects on signal strength over distance. It also covers propagation models like free space path loss, two-ray ground reflection model, and log-distance path loss for estimating average received signal power at a given distance. Fresnel zones and knife-edge diffraction are explained as factors in signal propagation around obstructions. Log-normal shadowing is described as a statistical model to account for variations from the average path loss.
The document discusses various topics related to digital communication systems including:
- Advantages of digital over analog communication systems such as noise immunity and easier implementation of error control coding.
- The process of analog to digital conversion including sampling, quantization, encoding, and pulse code modulation (PCM).
- Digital modulation techniques like differential PCM (DPCM) and delta modulation (DM) that reduce redundancy before encoding.
- Considerations for line coding binary data onto an analog channel such as bandwidth, noise immunity, power efficiency and self-clocking capability.
1) The document discusses the capacity of wireless channels, including Shannon capacity, capacity in additive white Gaussian noise (AWGN) channels, and capacity of flat fading channels with different channel state information scenarios.
2) It describes the optimal power allocation strategy when the transmitter and receiver have channel state information, which is to allocate more power to better channel states using waterfilling.
3) For frequency-selective fading channels, capacity is achieved through waterfilling in frequency to allocate higher power to better subchannels subject to an overall power constraint.
Pulse-amplitude modulation (PAM) encodes message information in the amplitude of signal pulses. A PAM-4 modulator takes two bits at a time and maps them to one of four amplitude levels, such as -3V, -1V, 1V, and 3V. Demodulation detects the amplitude level of each symbol period. PAM is widely used for baseband digital data transmission, though other modulation methods are now more common.
This document discusses various analog and digital modulation techniques used to transmit digital and analog signals. It provides examples of calculating bit rates, baud rates, and bandwidth requirements for different modulation schemes including ASK, FSK, PSK, QAM, AM, and FM. Key modulation techniques covered are the modulation of a digital signal using digital-to-analog conversion and modulation of an analog signal using amplitude, frequency, or phase modulation.
This document discusses various methods of modulating digital and analog data for transmission:
1. It describes digital-to-analog modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM).
2. It explains the relationships between bit rate, baud rate, and bandwidth for different modulation schemes. ASK, FSK, and PSK have baud rate equal to bit rate, while higher-order PSK and QAM can have higher bit rates through multiple bits per symbol.
3. Modems and standards like V.32, V.34, and V.90 are discussed in the context of mod
Mathematical Explanation of channel capacityHere we can see that the channel capacity is measured with the multiplication of pulses per second and information. This is how we can measure the channel capacity.
Modulation involves adding information to a carrier signal. Digital modulation provides more information capacity, compatibility with digital services, higher security, better quality, and faster availability compared to analog modulation. Common digital modulation techniques include amplitude-shift keying (ASK), frequency-shift keying (FSK), phase-shift keying (PSK) and their variants. PSK techniques include binary PSK (BPSK), quadrature PSK (QPSK) and differential PSK (DPSK). QPSK transmits twice as much data as BPSK within the same bandwidth. DPSK avoids the need for a coherent reference signal at the receiver. Key considerations in modulation include power efficiency, bandwidth efficiency and bit error rate.
Phase modulation (PM) is a form of modulation where information is represented by variations in the instantaneous phase of a carrier wave. The phase angle of the complex envelope is changed in direct proportion to the message signal. PM can be considered a special case of FM where the carrier frequency modulation is given by the time derivative of the phase modulation. The bandwidth of PM for a single sinusoidal signal is approximately equal to the modulation index multiplied by the carrier frequency.
This document discusses various digital modulation techniques. It begins by defining modulation as adding information to a carrier signal. It then distinguishes between analog and digital modulation. Digital modulation modulates an analog carrier signal with a discrete signal, and can be considered as converting digital-to-analog and vice versa. Some key digital modulation techniques discussed include amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), quadrature amplitude modulation (QAM), and differential phase shift keying (DPSK). Metrics for comparing digital modulation techniques include power efficiency, bandwidth efficiency, and implementation cost-effectiveness.
Pulse amplitude modulation (PAM) is a modulation technique where the amplitude of pulses in a regularly timed sequence is varied according to the amplitude of the modulating signal. There are two types of PAM: single polarity PAM which adds a DC bias to ensure all pulses are positive, and double polarity PAM where pulses can be both positive and negative. PAM is generated by sampling the modulating signal at regular intervals and making each sample proportional to the amplitude of the modulating signal at the time of sampling. The amplitude of the PAM signal then carries the information contained in the modulating signal.
This document discusses various types of pulse modulation techniques. It describes analog pulse modulation techniques including pulse amplitude modulation (PAM), pulse duration modulation (PDM), and pulse position modulation (PPM). It also covers digital pulse modulation techniques such as pulse code modulation (PCM) and delta modulation. For each technique, it provides details on the generator, waveform, and advantages and disadvantages. In conclusion, it summarizes that different pulse modulation techniques were discussed along with how they are transmitted and their waveforms. It also reviews the advantages and disadvantages of these modulation methods.
M-ary encoding allows for digital signals with multiple possible conditions or voltage levels through the use of multiple binary variables. The number of conditions possible is represented by M, while the number of bits needed to produce those conditions is given by the logarithmic relationship N = log2M. M-ary PSK and M-ary QAM are two common types of M-ary encoding. M-ary PSK varies the phase of a carrier signal, while M-ary QAM varies both the amplitude and phase, allowing for greater power efficiency but identical bandwidth efficiency as M-ary PSK. Both modulation schemes use a constellation diagram to represent the multiple symbol states.
This document discusses pulse code modulation (PCM) which converts analog signals to digital data. PCM involves sampling an analog signal, quantizing it to discrete levels, and encoding the samples into binary code. The key aspects covered are the PCM block diagram, process of sampling, quantization and encoding, PCM standards, bit rate and bandwidth requirements, advantages like robustness and disadvantages like requiring large bandwidth. Applications discussed are telephone voice communication, compact discs, and satellite transmission.
It is a digital representation of an analog signal that takes samples of the amplitude of the analog signal at regular intervals. The sampled analog data is changed to, and then represented by, binary data.
This document discusses frequency modulation (FM) and its types: phase modulation and frequency modulation. It describes the key characteristics of FM including its constant amplitude, higher signal-to-noise ratio, and infinite bandwidth. FM is classified as narrowband FM (NBFM) or wideband FM (WBFM) based on the modulation index. The document also covers pre-emphasis and de-emphasis circuits, methods for generating NBFM and WBFM signals including the direct and indirect (Armstrong's) methods.
Gaussian Minimum Shift Keying (GMSK) is a form of continuous-phase frequency shift keying that uses a Gaussian filter to generate a constant envelope signal. It provides better spectral efficiency than MSK through bandwidth reduction while maintaining low intersymbol interference. GMSK is used widely in wireless technologies like GSM and CDPD due to its power efficiency and good bit error rate performance compared to other modulation schemes. While more spectrally efficient than MSK, GMSK also has slightly higher error rates and requires more complex receivers.
This document discusses amplitude modulation and demodulation. It defines amplitude modulation as varying the amplitude of a carrier wave linearly with a message signal while keeping frequency and phase constant. Modulation is used to transmit signals over long distances and allow multiple signals over the same channel. Demodulation recovers the signal intelligence by reversing the modulation process through rectification and filtering. The document describes amplitude modulation and different types of AM demodulation techniques.
Frequency shift keying (FSK) is a digital modulation technique that encodes digital information by shifting the frequency of a carrier wave. There are different types of FSK including binary FSK, which uses two discrete frequencies to represent binary 1 and 0, and double frequency shift keying (DFSK), which uses four frequencies to transmit two independent data streams simultaneously. FSK modulation can be demodulated using either FM detector demodulators, which treat the FSK signal as an FM signal, or filter-type demodulators, which use optimal filters matched to the FSK signal parameters. The filters are used to detect the mark and space frequencies, and a decision circuit then determines which was transmitted.
QAM is a digital modulation technique that encodes data by varying both the amplitude and phase of carrier waves. It can carry higher data rates than schemes using just amplitude or phase. QAM is used widely in applications like digital cable TV, wireless networks, and video broadcasting. Higher order QAM uses more points in its constellation diagram, allowing more bits per symbol but making the signals more susceptible to noise.
The document discusses various propagation mechanisms that affect radio signals, including reflection, diffraction, scattering, and their effects on signal strength over distance. It also covers propagation models like free space path loss, two-ray ground reflection model, and log-distance path loss for estimating average received signal power at a given distance. Fresnel zones and knife-edge diffraction are explained as factors in signal propagation around obstructions. Log-normal shadowing is described as a statistical model to account for variations from the average path loss.
The document discusses various topics related to digital communication systems including:
- Advantages of digital over analog communication systems such as noise immunity and easier implementation of error control coding.
- The process of analog to digital conversion including sampling, quantization, encoding, and pulse code modulation (PCM).
- Digital modulation techniques like differential PCM (DPCM) and delta modulation (DM) that reduce redundancy before encoding.
- Considerations for line coding binary data onto an analog channel such as bandwidth, noise immunity, power efficiency and self-clocking capability.
1) The document discusses the capacity of wireless channels, including Shannon capacity, capacity in additive white Gaussian noise (AWGN) channels, and capacity of flat fading channels with different channel state information scenarios.
2) It describes the optimal power allocation strategy when the transmitter and receiver have channel state information, which is to allocate more power to better channel states using waterfilling.
3) For frequency-selective fading channels, capacity is achieved through waterfilling in frequency to allocate higher power to better subchannels subject to an overall power constraint.
Pulse-amplitude modulation (PAM) encodes message information in the amplitude of signal pulses. A PAM-4 modulator takes two bits at a time and maps them to one of four amplitude levels, such as -3V, -1V, 1V, and 3V. Demodulation detects the amplitude level of each symbol period. PAM is widely used for baseband digital data transmission, though other modulation methods are now more common.
This document discusses various analog and digital modulation techniques used to transmit digital and analog signals. It provides examples of calculating bit rates, baud rates, and bandwidth requirements for different modulation schemes including ASK, FSK, PSK, QAM, AM, and FM. Key modulation techniques covered are the modulation of a digital signal using digital-to-analog conversion and modulation of an analog signal using amplitude, frequency, or phase modulation.
This document discusses various methods of modulating digital and analog data for transmission:
1. It describes digital-to-analog modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM).
2. It explains the relationships between bit rate, baud rate, and bandwidth for different modulation schemes. ASK, FSK, and PSK have baud rate equal to bit rate, while higher-order PSK and QAM can have higher bit rates through multiple bits per symbol.
3. Modems and standards like V.32, V.34, and V.90 are discussed in the context of mod
This document summarizes key concepts about communication. It discusses the functions of communication including control, motivation, emotional expression, and information sharing. It outlines the communication process and directions including downward, upward, and lateral. It describes interpersonal communication methods like oral, written, and nonverbal. It also examines organizational communication structures, channels, and barriers. Current issues in communication mentioned include gender differences, political correctness, cross-cultural challenges, and semantics. The overall purpose is to provide an overview of communication concepts.
A boundary is where conditions change, and how a wave interacts with a boundary depends on the boundary conditions. Waves can interact with boundaries in four different ways.
The document discusses File Input/Output in Java. It describes FileInputStream and FileOutputStream classes which allow reading and writing of bytes from/to files. FileInputStream can be used to read bytes from a file, while FileOutputStream can be used to write bytes to a file. It also discusses FileReader and FileWriter character stream classes which allow reading and writing of characters from/to files. Examples are provided to demonstrate reading bytes/characters from a file, writing bytes/characters to a file, and copying contents from one file to another using the FileInputStream and FileOutputStream classes.
The document discusses Java networking concepts including sockets, TCP, UDP, client-server programming, and key networking classes like InetAddress, ServerSocket, Socket, DatagramSocket, and DatagramPacket. It provides code examples for basic TCP and UDP client-server applications in Java using sockets to demonstrate sending and receiving data over a network.
The document discusses two main ways for a thread to know when another thread has finished:
1. Calling isAlive() on the thread, which returns true if the thread is still running and false if not.
2. Using join(), which waits for the specified thread to terminate before continuing. Additional forms of join() allow specifying a maximum wait time.
The example code starts three threads and uses join() in the main thread to wait for the child threads to finish before exiting, ensuring the main thread finishes last. Without join(), the main thread could exit before the child threads.
This document discusses synchronization in multithreaded applications in Java. It covers key concepts like monitors, synchronized methods and statements, and inter-thread communication using wait(), notify(), and notifyAll() methods. Synchronized methods ensure only one thread can access a shared resource at a time by acquiring the object's monitor. synchronized statements allow synchronizing access to non-synchronized methods. Inter-thread communication allows threads to wait for notifications from other threads rather than busy waiting.
Phasors are complex numbers that represent the amplitude and phase of sinusoidal signals and are useful for analyzing linear time-invariant systems. Phasors allow representations of electromagnetic fields, circuit elements, and communication systems as sinusoidal signals. By using phasors, time-domain differential operators can be converted to algebraic operations in the frequency domain, simplifying analyses of linear problems where frequency components do not mix.
Phase shift keying is a digital modulation technique where the phase of the carrier signal is changed to represent digital data. For binary PSK, a 0 bit is represented by shifting the carrier phase by 180 degrees and a 1 bit is represented by leaving the phase unchanged. Quadrature phase shift keying uses four phases to encode pairs of bits. Quadrature amplitude modulation contains digital information in both the amplitude and phase of the carrier signal.
The seminar discussed CAD tools and their use in electronic design automation. CAD tools help partition systems, plan chip layouts, and optimize designs to meet goals like minimizing area and interconnect length. System partitioning was demonstrated using the example of the Sun SPARCstation 1, which was broken into custom ASICs, memory modules, and other components. Power dissipation sources like switching current and short-circuit current were also examined. CAD tools provide advantages like evaluating complex conditions and helping to find optimal solutions.
1) La modulación por amplitud en cuadratura (QAM) combina amplitud y fase para transmitir información. 2) QAM utiliza dos portadoras ortogonales moduladas por amplitudes discretas para formar constelaciones de símbolos bidimensionales. 3) Cuanto mayor es el orden M de la modulación QAM, mayor es la eficiencia espectral pero también mayor la complejidad del sistema.
This document provides a 3-paragraph summary of the key concepts of fiber optics:
Fiber optics uses glass or plastic fibers to guide light along its length through the process of total internal reflection. Light is transmitted from a transmitter that converts an electrical signal to light, through the fiber, and received at the other end by a receiver that converts the light back to an electrical signal. Refraction causes light to bend as it passes between materials with different refractive indices, and total internal reflection keeps light confined within the fiber when it encounters a change in index of refraction at the fiber's outer surface.
Miss Rina Ahire presented a seminar on spread spectrum that covered jamming margin, time hopping spread spectrum, the block diagram, synchronization including acquisition and tracking. The key topics were how jamming margin is the ratio of average powers of interference and data signal, how time hopping spread spectrum works, the components in the block diagram, and how synchronization has an initial acquisition phase followed by a tracking phase where acquisition finds coarse synchronization and tracking provides fine synchronization.
This document provides an introduction to information theory, including definitions of key concepts like entropy, marginal entropy, joint entropy, and conditional entropy. It uses examples like coin flips to illustrate these concepts. Entropy quantifies the average amount of information or uncertainty in a random variable, while joint entropy looks at multiple variables together. Conditional entropy considers the information remaining in one variable after another is observed. The document outlines these topics to introduce fundamental information theory concepts.
Introduction of info theory basis for image/video coding, especially, entropy, rate-distortion theory,
entropy coding, huffman coding, arithmetic coding
This document discusses exception handling in Java. It defines exceptions as objects that describe errors during code execution. The try, catch, and finally keywords are used to handle exceptions. Exceptions can be generated by the Java runtime system or manually coded. The try block contains code that could cause exceptions. Catch blocks handle specific exception types. Finally blocks contain cleanup code. All exceptions extend the Throwable class. The Exception class is for program exceptions, while Error is for environmental errors. Uncaught exceptions use the default exception handler.
T com presentation (error correcting code)Akshit Jain
This document discusses error correcting codes, which are used to detect and correct errors that occur during data transmission. It covers different types of block codes like Hamming codes and Reed-Muller codes. Hamming codes can detect and correct single bit errors by adding redundant bits. Reed-Muller codes use a generator matrix to encode data and can detect and correct single bit errors through majority decoding. The document provides examples of encoding and decoding data using Hamming codes and Reed-Muller codes to demonstrate how they can detect and correct errors.
This ppt contains information about concepts of wireless communication, signal propagation effects, spread spectrum, cellular systems, multiple access systems.
This document discusses various digital encoding and modulation techniques used for transmitting digital and analog data over transmission channels. It describes:
- Digital signaling, where digital data is encoded into a digital signal using techniques like NRZ-L, NRZI, etc. to minimize bandwidth and errors.
- Analog signaling, where analog or digital data modulates an analog carrier signal using techniques like ASK, FSK, PSK to transmit over analog lines.
- Specific digital modulation techniques like BPSK, QPSK, MFSK that encode digital data onto signal properties like phase, frequency or amplitude to maximize bandwidth efficiency and minimize errors.
- How analog modulation techniques like AM, FM, PM encode analog data onto an
This document summarizes key concepts from Chapter 5 of William Stallings' book "Data and Computer Communications", 7th Edition. It discusses various techniques for encoding digital data into digital and analog signals, including:
1. Digital data into digital signals using techniques like NRZ-L, NRZI, bipolar AMI, Manchester, and differential Manchester encoding.
2. Digital data into analog signals using modulation techniques like ASK, FSK, PSK and their variations like QPSK, OQPSK for transmission over phone lines or wireless channels.
3. Analog data into digital signals using pulse code modulation (PCM) and delta modulation for digitizing analog signals like voice for digital transmission.
Modulation is the process of varying one or more characteristics of a high-frequency carrier signal based on an information signal that contains the message to be transmitted. Some key points:
1. Modulation is necessary to transmit digital data over analog mediums like phone lines or wireless signals. It converts the digital data into an analog format suitable for transmission.
2. Common analog modulation techniques vary the amplitude, frequency, or phase of the carrier signal, while digital modulation techniques include amplitude-shift keying, frequency-shift keying, and phase-shift keying.
3. More advanced techniques like quadrature amplitude modulation vary both the amplitude and phase of the carrier simultaneously to transmit more data using a given bandwidth
1. The document discusses various techniques for encoding digital and analog data for transmission as digital or analog signals. It describes common encoding schemes like NRZ-L, Manchester, and techniques for modulating analog signals like ASK, FSK, and PSK.
2. Key digital encoding techniques covered are NRZ-L, NRZI, bipolar AMI, Manchester, and differential Manchester. Modulation of analog signals to digital signals using PCM and delta modulation are also discussed.
3. Performance tradeoffs of different encoding schemes like bandwidth requirements, error detection capabilities, and signal-to-noise ratio impacts are compared.
Digital modulation (19ES28) Ghulam Mueed MueedAbbas
This document discusses digital modulation techniques. It describes how digital modulation encodes digital signals into analog carrier signals by varying the amplitude, frequency, or phase. It explains the main digital modulation types: ASK, FSK, and PSK. ASK varies amplitude, FSK varies frequency, and PSK varies phase. BPSK and QPSK are described as phase shift keying techniques. QPSK encodes 2 bits per symbol by shifting the phase by 45 degree increments. The document provides examples and diagrams to illustrate digital modulation encoding.
This presentation discusses various techniques for encoding digital and analog data for transmission as signals. It covers topics such as:
- Digital data encoding techniques including NRZ, Manchester, and scrambling techniques like B8ZS and HDB3. These encode binary data into digital signals.
- Analog modulation techniques for encoding analog data (like voice) into digital or analog signals prior to transmission. This includes PCM for digitizing voice and techniques like ASK, FSK, and PSK for modulating the digital data onto an analog carrier signal.
- Applications of these techniques including early telephone networks using PCM at 56kbps, CD audio using PCM at 1.411Mbps, and DVD/S
This document discusses various digital modulation techniques including ASK, PSK, FSK, and QAM. It provides details on how each technique works by modifying different properties of a carrier signal such as amplitude, frequency, or phase to represent digital data. It also discusses the relationship between baud rate, bit rate, and bandwidth for different modulation schemes and provides examples of calculating bandwidth requirements.
Signal encoding techniques can be used to transmit digital data as either digital signals or analog signals. For digital data as a digital signal, common encoding schemes include NRZ, multilevel binary, and biphase, which encode bits as voltage levels or transitions. Analog data can be converted to a digital signal using techniques like PCM and DM. To transmit digital data as an analog signal, modulation schemes such as ASK, FSK, PSK are used to map bits to properties of a carrier wave. Analog data can also be transmitted directly as an analog signal using amplitude, frequency, or phase modulation.
This document discusses digital communication systems and various digital modulation techniques. It begins with an overview of digital communication systems and their advantages. It then covers different digital modulation schemes including PAM, FSK, PSK, and QAM. It discusses how these schemes work, their bandwidth and power requirements, and how to demodulate the signals. It also covers more advanced topics like differential PSK and M-ary modulation schemes, examining how their bandwidth and power scale with increasing symbol sizes. The document provides detailed explanations of key digital modulation concepts and tradeoffs.
Digital modulation techniques change aspects of a carrier signal to transmit information. This document discusses various digital modulation methods including:
- Amplitude modulation (AM) which varies the amplitude (A) of the carrier.
- Frequency modulation (FM) which varies the frequency (ω) of the carrier.
- Phase modulation (PM) which varies the phase (φ) of the carrier.
It then discusses specific modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK) and their variants like quadrature phase shift keying (QPSK). The document provides illustrations of the modulated signals and discusses their bandwidth efficiency and performance in noise.
This document provides an overview of digital-to-analog modulation techniques used in data communications including: Amplitude Shift Keying (ASK), Frequency Shift Keying (FSK), Phase Shift Keying (PSK), and Quadrature Amplitude Modulation (QAM). It defines these techniques, discusses their advantages and limitations, and provides examples of calculating bit rates and bandwidth requirements. Key points covered include how digital data is modulated onto an analog carrier signal, the relationship between bit rate and baud rate, and how more advanced modulations like QAM combine aspects of ASK and PSK.
This document discusses various techniques for encoding signals for wireless transmission, including:
- Digital data must be converted to analog signals using techniques like amplitude-shift keying, frequency-shift keying, and phase-shift keying. Analog signals can also be modulated to higher frequencies for transmission.
- Analog signals can be converted to digital for transmission using pulse code modulation (PCM) or delta modulation (DM). PCM assigns a binary code to analog samples while DM approximates the analog signal as a staircase function.
- Key factors in signal encoding are the signal-to-noise ratio, data rate, bandwidth, clocking, interference immunity, and cost/complexity of the scheme. Higher data rates
This slide describe the techniques of digital modulation and Bandwidth Efficiency:
The first null bandwidth of M-ary PSK signals decrease as M increases while Rb is held constant.
Therefore, as the value of M increases, the bandwidth efficiency also increases.
The following documents defines the different encoding schemes/Techniques.
These encoding schemes have different way to solve a problem.
The techniques are used in network and wireless devices only. Although there are many different techniques that used in other devices and network as well but i used/ mention these techniques for only network and wireless devices. These techniques are also used in mobile network. There are also many lectures for this but i uploaded only lecture 5 because i found it important to everyone.
This document discusses various digital modulation techniques including amplitude shift keying (ASK), frequency shift keying (FSK), phase shift keying (PSK), and quadrature amplitude modulation (QAM). It provides details on how each technique works by modifying properties of an analog carrier signal like amplitude, frequency, or phase to represent digital data. It also discusses the relationship between baud rate, bit rate, and minimum bandwidth required for different modulation schemes.
The attached narrated power point presentation attempts to explain the various digital communication techniques as applied to optical communications. The material will be useful for KTU final year B tech students who prepare for the subject EC 405, Optical Communications.
This presentation contain each and every single information on the topic.
If you like it do follow and like my presentation.
It would be worth my efforts.
This document summarizes various techniques for encoding digital and analog signals. It discusses encoding digital data into digital signals using techniques like NRZ-L, Manchester encoding, and differential Manchester encoding. It also covers converting analog data to digital signals using pulse code modulation and delta modulation. Additionally, it describes modulating digital and analog data onto analog carriers using techniques like amplitude shift keying, frequency shift keying, and phase shift keying.
This document discusses various techniques for encoding digital signals for transmission, including:
1) Non-return-to-zero (NRZ) encoding schemes which use different voltage levels to represent 1s and 0s without returning to a baseline between bits.
2) Manchester and differential Manchester encoding which add transitions in the middle or start of each bit to provide clocking functionality.
3) Phase-shift keying (PSK) and quadrature PSK (QPSK) which represent data by shifting the phase of the carrier signal.
4) Amplitude-shift keying (ASK), frequency-shift keying (FSK), and quadrature amplitude modulation (QAM) which are used to transmit
This document provides an outline and overview of key topics in digital transmission covered in Chapter 4, including:
- Digital-to-digital conversion techniques like line coding, block coding, and scrambling.
- Analog-to-digital conversion using pulse code modulation (PCM) and delta modulation to convert analog signals to digital data.
- Transmission modes for sending digital data, including parallel transmission of multiple bits at once, and serial transmission of single bits in asynchronous, synchronous, or isochronous formats.
Numerical Analysis_Computer Representation of Numbers.docxadmercano101
This document discusses how computers represent numbers using two main methods: integer and floating-point representation. Floating-point representation is analogous to scientific notation, using a sign, mantissa, base, and exponent. The IEEE 754 standard defines common floating-point formats like 32-bit that break numbers into these components stored in bits. Special values like zero, infinity, and NaN are also defined to handle problematic cases.
This document discusses key concepts about circles, including:
- The standard equation of a circle is (x - h)2 + (y - k)2 = r2, where (h, k) are the coordinates of the center and r is the radius.
- Given the equation or properties of a circle, one can determine its center and radius or write the equation in standard form.
- Points can lie inside, outside, or on a circle, which can be determined by comparing distances or substituting into the equation.
- A circle and line can intersect in 0, 1, or 2 points, which can be found using algebraic techniques.
- The equation of a circle can be found given 3
The document discusses the concept of limits. It explains that as the number of sides of a polygon increases, the area of the polygon approximates the area of the circle it is inscribed in, and the limit of the polygon's area is equal to the area of the circle. It also examines the limit of a function as x approaches 2 from both sides, and defines some fundamental rules of limits, such as the constant rule, sum rule, and multiplication rule. Finally, it outlines several techniques that can be used to calculate limits, including direct substitution, factoring, rationalization, and limits involving infinity and trigonometric, exponential and two-sided limits.
Lecture Presentation on Trigonometry, types of angle, angle measurement, pythagorean theorem, trigonometric function, trigonometric relationship, circle function, co function, reference angle, odd even function,graphing of trigonometric function, special angles and terminology and history of trigonometry
1. Pulse code modulation (PCM) is a method of digitizing analog signals by sampling the signal, quantizing the samples to a set of discrete levels, and encoding the results as digital data.
2. In PCM, an analog signal is sampled, quantized to a certain number of levels, and then encoded as binary digits. At the receiver, the digital signal is decoded, converting it back into an analog waveform.
3. Key aspects of PCM include sampling the analog signal, quantizing the samples to discrete levels, binary encoding the quantized samples, transmitting the encoded data, decoding the data back into quantized samples, and reconstructing the analog signal from the samples. PCM
This document discusses bandwidth utilization and multiplexing techniques. It begins by explaining that bandwidth is a precious commodity in communication and that bandwidth utilization aims to make wise use of available bandwidth. It then discusses various multiplexing techniques including frequency-division multiplexing (FDM), time-division multiplexing (TDM), and wavelength-division multiplexing (WDM). For each technique, it provides examples and applications. It also covers digital carrier systems like T1, T2, T3 and discusses the North American digital multiplexing hierarchy.
CHINA’S GEO-ECONOMIC OUTREACH IN CENTRAL ASIAN COUNTRIES AND FUTURE PROSPECTjpsjournal1
The rivalry between prominent international actors for dominance over Central Asia's hydrocarbon
reserves and the ancient silk trade route, along with China's diplomatic endeavours in the area, has been
referred to as the "New Great Game." This research centres on the power struggle, considering
geopolitical, geostrategic, and geoeconomic variables. Topics including trade, political hegemony, oil
politics, and conventional and nontraditional security are all explored and explained by the researcher.
Using Mackinder's Heartland, Spykman Rimland, and Hegemonic Stability theories, examines China's role
in Central Asia. This study adheres to the empirical epistemological method and has taken care of
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china’s geo economic outreach in central Asian countries and its future prospect. China is thriving in trade,
pipeline politics, and winning states, according to this study, thanks to important instruments like the
Shanghai Cooperation Organisation and the Belt and Road Economic Initiative. According to this study,
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governments. This success may be attributed to the effective utilisation of key tools such as the Shanghai
Cooperation Organisation and the Belt and Road Economic Initiative.
Low power architecture of logic gates using adiabatic techniquesnooriasukmaningtyas
The growing significance of portable systems to limit power consumption in ultra-large-scale-integration chips of very high density, has recently led to rapid and inventive progresses in low-power design. The most effective technique is adiabatic logic circuit design in energy-efficient hardware. This paper presents two adiabatic approaches for the design of low power circuits, modified positive feedback adiabatic logic (modified PFAL) and the other is direct current diode based positive feedback adiabatic logic (DC-DB PFAL). Logic gates are the preliminary components in any digital circuit design. By improving the performance of basic gates, one can improvise the whole system performance. In this paper proposed circuit design of the low power architecture of OR/NOR, AND/NAND, and XOR/XNOR gates are presented using the said approaches and their results are analyzed for powerdissipation, delay, power-delay-product and rise time and compared with the other adiabatic techniques along with the conventional complementary metal oxide semiconductor (CMOS) designs reported in the literature. It has been found that the designs with DC-DB PFAL technique outperform with the percentage improvement of 65% for NOR gate and 7% for NAND gate and 34% for XNOR gate over the modified PFAL techniques at 10 MHz respectively.
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2. 12/13/15 22:49 2
Types of Signal Transmission
Digital transmission
•Baseband data
transmission
•Data is directly transmitted
without carrier
•Suitable for short distance
transmission
Analog Transmission
• Passband data
transmission
• Data modulates high
frequency sinusoidal
carrier
• Suitable for long
distance transmission
4. 12/13/15 22:49 4
Data element vs. Signal element
• a data element (bit) is the smallest
quantity, that can represent a piece of
information
• a signal element (vehicle / carrier)
carries data elements (passengers)
- can contain one or more bits
5. 12/13/15 22:49 5
bit rate : the number of data elements
transmitted per second
baud rate : the number of signal
elements transmitted per second
Bit and Baud
7. 12/13/15 22:49 7
Data (bit) rate vs. signal (baud) rate
• r is the number of data elements carried
by each signal element
• N = bit rate and S = baud rate
• S = N x (1 ÷ r) in bauds
• r = log2 L
where L is the type of signal element
in analog transmission, S ≤ r
8. 12/13/15 22:49 8
An analog signal carries 4 bits per signal
element. If 1000 signal elements are
transmitted per second, find the bit rate.
r = 4
S = 1000
N = S x r = 4000 bps
Example 1Example 1
SolutionSolution
9. 12/13/15 22:49 9
An analog signal has a bit rate of 8000 bps and
a baud rate of 1000 baud.
How many data elements are carried by each
signal element ?
N = 8000
S = 1000
r = (N ÷ S) = 8
Example 1Example 1
SolutionSolution
10. 12/13/15 22:49 10
Analog Transmission
• three mechanisms of modulating digital
data into an analog signal by altering any
of the three characteristics of analog
signal:
amplitude → ASK : amplitude shift keying
frequency → FSK : frequency shift keying
phase → PSK : phase shift keying
12. 12/13/15 22:49 12
Amplitude Shift Keying
•amplitude of the carrier signal is varied
to create signal elements frequency and
phase remain constant
•implemented using two levels
– Binary ASK (BASK)
– also referred to as on-off-keying (OOK)
14. 12/13/15 22:49 14
Amplitude Shift Keying
• modulation produces
aperiodic composite
signal, with continuous
set of frequencies
• bandwidth is proportional
to the signal ( baud ) rate
15. 12/13/15 22:49
• In data communications, it is normally to use full-duplex links
with communication in both directions.
• bandwidth is divided into two with two carrier frequencies, as
• The figure shows the positions of two carrier frequencies
and the bandwidths.
• The available bandwidth for each direction is now 50 kHz,
which leaves us with a data rate of 25 kbps in each direction.
Amplitude Shift Keying
16
16. 12/13/15 22:49 18
4, 8,16 … amplitudes can be used for the
signal
data can be modulated using 2, 3, 4 …
bits at a time
in such cases, r = 2, r = 3, r = 4, ….
Multi-level ASK (MASK)
18. Example 3Example 3
Find the minimum bandwidth for an ASK signal
transmitting at 2000 bps. The transmission mode is
half-duplex.
SolutionSolution
• In ASK: baud rate = bit rate Therefore baud
rate = 2000bps.
• minimum bandwidth =baud rate. Therefore,
minimum bandwidth = 2000 Hz.
12/13/15 22:49 20
19. Given a bandwidth of 5000 Hz for an ASK signal,
what are the baud rate and bit rate?
• baud rate = bandwidth, Therefore, baud rate =
5000 bps.
• baud rate = bit rate, Therefore, bit rate = 5000
bps.
Example 4Example 4
SolutionSolution
12/13/15 22:49 21
20. 12/13/15 22:49 22
• generate carrier using an oscillator
• multiply the digital signal by the carrier
signal
Binary ASK : implementation
21. Merits and Demerits
• Values represented by different amplitudes of
carrier
• Usually, one amplitude is zero
– i.e. presence and absence of carrier is used
• Susceptible to sudden gain changes
• Inefficient
• Typically used up to 1200bps on voice grade
lines
• Used over optical fiber
23
22. 12/13/15 22:49 24
• frequency of the carrier signal is varied
to represent data
• frequency of the modulated signal is
constant for the duration of one signal
element and changes for the next
signal element if the data element
changes amplitude
• Amplitude and Phase remain constant
for all signal elements
Frequency Shift Keying
23. 12/13/15 22:49 25
• implemented using two carrier frequencies:
• F1,(space frequency) data elements 0
• f2, (mark frequency) data elements 1
• both f1 and f2 are 2Δf apart
Binary FSK
24. 12/13/15 22:49 26
0 → regular frequency ; 1 → increased frequency
Binary FSK
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• use of a voltage controlled oscillator (VCO)
• VCO changes its frequency according to
input voltage
Binary FSK : implementation
27. 12/13/15 22:49 30
Minimum Shift Keying FSK
• Continuous-phase frequency shift keying
• Mark and Space frequency are synchronized
with the input bit rate.
• Mark and Space frequency are selected such
that they are separated from the center
frequency by an exact odd multiple of one-
half of the bit rate
29. 32
• it requires synchronizing circuits and is
therefore more expensive to implement.
Merits and Demerits
30. 5.33
We have an available bandwidth of 100 kHz
which spans from 200 to 300 kHz. What should
be the carrier frequency and the bit rate if we
modulated our data by using FSK with d = 1?
Fc = 250 kHz.(midband) We choose 2 f to be 50 kHz;Δ
Example 6Example 6
SolutionSolution
33
31. 5.34
We need to send data 3 bits at a time at a bit rate of 3
Mbps. The carrier frequency is 10 MHz. Calculate the
number of levels (different frequencies), the baud rate,
and the bandwidth.
Example 7Example 7
SolutionSolution
34
33. Merits and Demerits
• Values represented by different frequencies (near
carrier)
• Less susceptible to error than ASK
• Typically used up to 1200bps on voice grade
lines
• High frequency radio
• Even higher frequency on LANs using co-ax
• Used in cordless and paging system
36
34. 12/13/15 22:49 37
• Phase of the carrier signal is varied to
represent two or more different signal
elements
• amplitude and frequency remain
constant
Phase Shift Keying
35. 12/13/15 22:49 38
• helps defining the amplitude and phase
of a signal element
• signal element type is represented as a
dot
• the bit or combination of bits it carries
is written next to the dot
• diagram has two axes
X-axis → related to the in-phase carrier
Y-axis → related to the quadrature carrier
Constellation diagram
44. 12/13/15 22:49 47
• use of two bits at a time in each signal
element → decrease of baud rate →
reduction of required bandwidth
• uses two separate BPSK modulations :
one in-phase and the other out-of-phase
(quadrature)
Quadrature PSK
45. 12/13/15 22:49 48
serial to
parallel
converter
serial to parallel converter sends one bit to one
modulator and the next bit to the other modulator
Quadrature PSK: implementation
50. 12/13/15 22:49 53
ASK BPSK QPSK
uses only an
in-phase carrier
A = 1
P = 0
A = 1
P = 180
A = √2
P = +45
Comparison!!
51. 12/13/15 22:49 54
Differential PSK
– Phase shifted relative to previous
transmission rather than some
reference signal
– eliminates the need for the
synchronous carrier in the
demodulation process and this
has the effect of simplifying the
receiver.
52. – receiver only needs to detect
– phase changes.
Differential PSK
55
53. 12/13/15 22:49 56
• small differences in phase are difficult
to detect (PSK)
• QAM works on the basis of altering two
characteristics of the carrier :
amplitude and phase
• two carriers, one in-phase and another
quadrature with two different levels are
used
Quadrature Amplitude Modulation
54. 12/13/15 22:49 57
Quadrature Amplitude Modulation
• Uses more phase shifts than amplitude
shifts to reduce noise susceptibility
55. 12/13/15 22:49 58
(a) 4-QAM with four signal element types
similar to ASK or OOK
(b) 4-QAM similar to QPSK
(c) 4-QAM with a signal with two positive levels
(d) 16-QAM with 8 signal levels : 4 +ve & 4 -ve
Constellation diagrams
59. ModulationModulation UnitsUnits Bits/BaudBits/Baud Baud rateBaud rate Bit Rate
ASK, FSK, 2-PSKASK, FSK, 2-PSK Bit 1 N N
4-PSK, 4-QAM4-PSK, 4-QAM Dibit 2 N 2N
8-PSK, 8-QAM8-PSK, 8-QAM Tribit 3 N 3N
16-QAM16-QAM Quadbit 4 N 4N
32-QAM32-QAM Pentabit 5 N 5N
64-QAM64-QAM Hexabit 6 N 6N
128-QAM128-QAM Septabit 7 N 7N
256-QAM256-QAM Octabit 8 N 8N
62
Bit and baud rate comparison
60. Example 8Example 8
A constellation diagram consists of eight equally spaced
points on a circle. If the bit rate is 4800 bps, what is the
baud rate?
SolutionSolution
The constellation indicates 8-PSK with the points 45
degrees apart. Since 23
= 8, 3 bits are transmitted with
each signal unit. Therefore, the baud rate is
4800 / 3 = 1600 baud
63
61. Compute the bit rate for a 1000-baud 16-QAM signal.
SolutionSolution
A 16-QAM signal has 4 bits per signal unit since
log216 = 4.
Thus,
(1000)(4) = 4000 bps
Example 9Example 9
64
62. Compute the baud rate for a 72,000-bps 64-QAM signal.
SolutionSolution
A 64-QAM signal has 6 bits per signal unit since
log2 64 = 6.
Thus,
72000 / 6 = 12,000 baud
Example 10Example 10
65
65. Digital to Digital Conversion
68
Techniques:
•Line coding
•Block coding
•Scrambling
• Also known as Line
Encoding
• Baud rate
determine the
bandwidth
66. Digital Transmission Methods
69
• Nonreturn to Zero
• Unipolar
• Bipolar
• Return to zero
• Unipolar
• Bipolar
• Bipolar-AMI
• Manchester
67. Nonreturn to Zero
70
• the signal remains at the binary level assigned to it for the
entire bit time.
• the voltage does not return to zero during the binary 1
interval
• normally generated inside computers, at low speeds, when
asynchronous transmission is being used.
68. Nonreturn to Zero - Bipolar
71
• A bipolar NRZ signal has two polarities, positive and
negative.
• The voltage levels are +12 and -12 V.
• The popular RS-232 serial computer interface uses bipolar
NRZ, where a binary 1 is a negative voltage between -3 and
-25 V and a binary 0 is a voltage between +3 and +25 V.
69. Return to Zero - Unipolar
72
• The binary 1 level occurs for 50 percent of the bit interval,
and the remaining bit interval is zero.
• Only one polarity level is used.
• Pulses occur only when a binary 1 is transmitted; no pulse is
transmitted for a binary 0.
70. Return to Zero - Bipolar
73
• A 50 percent bit interval 13-V pulse is transmitted during a
binary 1, and a 23-V pulse is transmitted for a binary 0.
• Because there is one clearly discernible pulse per bit, it is
extremely easy to derive the clock from the transmitted data.
• For that reason, bipolar RZ is preferred over unipolar RZ.
71. Return to Zero – Bipolar AMI
74
• During the bit interval, binary 0s are transmitted as no pulse.
• Binary 1s, also called marks, are transmitted as alternating
positive and negative pulses.
• One binary 1 is sent as a positive pulse, the next binary 1 as
a negative pulse, the next as a positive pulse, and so on.
72. Manchester
75
• Also referred to as biphase encoding, can be unipolar or
bipolar.
• A binary 1 is transmitted first as a positive pulse, for one half
of the bit interval, and then as a negative pulse, for the
remaining part of the bit interval.
• A binary 0 is transmitted as a negative pulse for the first
half of the bit interval and a positive pulse for the second
half of the bit interval
73. Manchester
76
• The fact that there is a transition at the center of each 0 or 1
bit makes clock recovery very easy.
• However, because of the transition in the center of each bit,
the frequency of a Manchester-encoded signal is two times
an NRZ signal, doubling the bandwidth requirement.
• It is widely used in LANs.
74. Reference
• Data Communication
– by Forouzan
• Advance Electronic Communication
– by Robert Tomasi
• Principles of Electronic Communication Systems
– Louis E. Frenzel Jr.
77