This document discusses pulse modulation techniques for analog to digital conversion in communication systems. It covers the basics of sampling theory including the Nyquist sampling theorem. It then describes three main types of pulse modulation: pulse amplitude modulation (PAM) where the amplitude of pulses varies according to the signal, pulse duration modulation (PDM) where pulse width varies, and pulse position modulation (PPM) where the position of pulses varies. For each technique, it discusses how the modulation works, bandwidth requirements, advantages and disadvantages compared to the other techniques.
this lecture provide the different features of pulse code modulation it explains the concept using example and explained step by step shows the flat sampling and other type shows the advantage of pam provides the pcm system block diagram a brief introduction about delta modulation
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 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.
This document discusses various digital modulation techniques. It defines modulation as changing the properties of a high frequency carrier signal based on a low frequency message signal. It then explains several digital modulation methods including Pulse Code Modulation (PCM) used for digital audio, Pulse Width Modulation (PWM) used to control LEDs and motors, and Phase-shift Keying (PSK) used for wireless communication. The document provides examples of common uses for each modulation technique.
Pulse modulation schemes aim to transfer an analog signal over an analog channel as a two-level signal by modulating a pulse wave. Some schemes also allow digital transfer of the analog signal with a fixed bit rate. Pulse modulation includes analog-over-analog methods like PAM, PWM, and PPM as well as analog-over-digital methods like PCM, DPCM, ADPCM, DM, and delta-sigma modulation. Sampling is the reduction of a continuous signal to a discrete signal by taking values at points in time. The Nyquist-Shannon sampling theorem states that a bandlimited signal can be perfectly reconstructed from samples if the sampling rate is at least twice the highest frequency in the signal.
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.
This document discusses digital pulse modulation techniques. It provides an overview of pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). It describes the basic principles of each technique, including how the signal is modulated by varying different pulse parameters. It also discusses sampling, quantization, encoding, and other components involved in digital pulse modulation systems.
this lecture provide the different features of pulse code modulation it explains the concept using example and explained step by step shows the flat sampling and other type shows the advantage of pam provides the pcm system block diagram a brief introduction about delta modulation
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 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.
This document discusses various digital modulation techniques. It defines modulation as changing the properties of a high frequency carrier signal based on a low frequency message signal. It then explains several digital modulation methods including Pulse Code Modulation (PCM) used for digital audio, Pulse Width Modulation (PWM) used to control LEDs and motors, and Phase-shift Keying (PSK) used for wireless communication. The document provides examples of common uses for each modulation technique.
Pulse modulation schemes aim to transfer an analog signal over an analog channel as a two-level signal by modulating a pulse wave. Some schemes also allow digital transfer of the analog signal with a fixed bit rate. Pulse modulation includes analog-over-analog methods like PAM, PWM, and PPM as well as analog-over-digital methods like PCM, DPCM, ADPCM, DM, and delta-sigma modulation. Sampling is the reduction of a continuous signal to a discrete signal by taking values at points in time. The Nyquist-Shannon sampling theorem states that a bandlimited signal can be perfectly reconstructed from samples if the sampling rate is at least twice the highest frequency in the signal.
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.
This document discusses digital pulse modulation techniques. It provides an overview of pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). It describes the basic principles of each technique, including how the signal is modulated by varying different pulse parameters. It also discusses sampling, quantization, encoding, and other components involved in digital pulse modulation systems.
Digital communication viva questions.( 50+)
MCQ of digital communication (50+)
communication systems MCQ. (50+)
communication systems viva questions (50+)
covered topic list:
sampling,quantization,digital,discrete,AM,FM,PM,ASK,FSK,PSK,DM,DPCM,QPSK,ADM,differences,modulation,block diagram,applications,PAM,PWM,PPM,line encoding,polar encoding,bipolar encoding,unipolar encoding,RZ,NRZ,AMI,HDB3,B8ZS
Pulse modulation techniques can encode an analog signal for transmission. This document discusses several techniques including:
- Pulse-amplitude modulation (PAM) which varies pulse amplitudes based on sample values of the message signal.
- Pulse code modulation (PCM) which assigns a binary code to each analog sample. PCM is commonly used in digital communications systems.
- Delta modulation which transmits one bit per sample indicating if the current sample is more positive or negative than the previous. It requires higher sampling rates than PCM for equal quality.
1. PCM uses time division multiplexing to transmit multiple telephone calls over a single transmission line by sampling each call and transmitting the samples in brief time slots.
2. During sampling, the amplitude of an analog signal is measured at regular intervals and assigned a digital code. This process is called quantization and results in quantization distortion from approximating the original signal.
3. Non-uniform quantization, called companding, is used to provide more quantization levels for smaller amplitudes that are more common in speech, improving the signal-to-noise ratio across all amplitudes.
1) The document discusses various topics related to digital communication including sampling theory, analog to digital conversion, pulse code modulation, quantization, coding, and time division multiplexing.
2) In analog to digital conversion, an analog signal is sampled, quantized by assigning it to discrete amplitude levels, and coded by mapping each level to a binary sequence.
3) The Nyquist sampling theorem states that a signal must be sampled at a rate at least twice its highest frequency to avoid aliasing when reconstructing the original signal.
This document provides an overview of pulse amplitude modulation (PAM). It defines PAM as a modulation technique where the message information is encoded in the amplitude of a series of signal pulses. There are two types: 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 used to modulate digital data transmission and involves sampling the message signal to vary the amplitude of a carrier pulse train. The modulated signal is then detected by measuring the amplitude level of each carrier pulse.
Pulse modulation techniques encode information by manipulating pulse characteristics such as amplitude, width, and position. Common pulse modulation types include pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). PCM is the most widely used technique, where an analog signal is sampled, quantized into discrete levels, and encoded into a binary digital signal for transmission.
Pulse Code Modulation (PCM) is a method to convert an analog signal into a digital signal. It involves three main steps: 1) sampling the analog signal at regular intervals, 2) quantizing the sampled signal into discrete levels, and 3) encoding the quantized levels into binary digits. The sampling rate must be at least twice the highest frequency of the analog signal according to the Nyquist theorem to avoid aliasing. Quantization divides the signal amplitude range into discrete levels and assigns a unique code to each level. This introduces quantization error but more quantization levels reduce the error. The bit rate of the encoded PCM signal depends on the number of bits per sample and the sampling rate.
Okay, here are the steps to find the velocity of the rocket at t = 10s:
1) Take the derivative of the position function x(t) to get the velocity function v(t):
v(t) = 4 + 14t + 15t^2 - 1.4t^3
2) Plug t = 10s into the velocity function:
v(10) = 4 + 140 + 1500 - 140 = 1404 m/s
So the velocity of the rocket at t = 10s is 1404 m/s.
This document summarizes various pulse modulation techniques including:
- Pulse-amplitude modulation (PAM) where the carrier amplitude changes with the message signal amplitude.
- Pulse-duration modulation (PDM) where the carrier width changes with the message signal amplitude.
- Pulse-position modulation (PPM) where the carrier position changes with the message signal amplitude.
- Digital pulse modulation techniques like pulse code modulation (PCM) and differential PCM (DPCM) are also discussed. Advantages and disadvantages of each technique are provided.
The document discusses pulse code modulation (PCM) for encoding analog waveforms into digital signals. It covers:
1. PCM involves sampling, quantizing, and encoding analog signals. Sampling makes the signal discrete in time. Quantizing makes it discrete in amplitude by rounding to discrete levels. Encoding maps quantized values to binary code words.
2. Quantization introduces distortion but sampling noise can be eliminated if the Nyquist criterion is met. Uniform quantizers are optimal for uniformly distributed inputs.
3. A practical PCM system was designed for telephone systems using 8-bit samples at 8 kHz to encode voice signals between 300-3400 Hz, producing a 64 kbps digital signal. The bandwidth
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 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 chapter discusses various pulse modulation techniques including pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). PAM varies the amplitude of pulses, PWM varies the width of pulses, PPM varies the position of pulses, and PCM converts an analog signal to a digital signal using sampling and quantization then encodes it as a binary code. Digital communication using these pulse modulation techniques offers advantages like more reliable signal reception and the ability to store, clean up, amplify, encode, and reconstruct the original signal.
This document provides an overview of digital communications and source encoding. It discusses why digital communication is preferable to analog, describes the basic block diagram of a digital communication system, and defines key terms like the information source and channel encoder. The document then covers some of the foundational work in digital communications, including Nyquist's sampling theorem and Shannon's channel capacity theorem. It discusses ideal sampling and the Nyquist rate, as well as practical sampling techniques like sample-and-hold. The document also covers quantization, quantization noise, and how the step size and number of quantization levels affect the signal-to-quantization noise ratio. In closing, it briefly mentions pulse code modulation and nonuniform quantization.
Data encoding and modulation techniques are discussed. Modulation involves varying properties of a high-frequency carrier signal according to a message signal. This allows transmission of baseband signals over long distances. Common modulation types are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Encoding converts data into formats for transmission, storage, processing and more. Common encoding schemes for digital data transmission include non-return to zero (NRZ) encoding and Manchester encoding. Pulse modulation can transmit signals as pulses using techniques like pulse code modulation (PCM).
Pulse code modulation (PCM) is a method of digitally representing sampled analog signals. It involves sampling an analog signal, quantizing the samples to discrete levels, and encoding the quantized samples as binary digits.
Analog to digital converters (ADCs) sample an analog signal and quantize the samples to discrete levels represented by binary digits. The sequence of 1s and 0s output from the ADC is called a PCM signal.
Quantization is the process of converting analog samples to digital samples by dividing the range of possible analog values into discrete quantization levels. Each analog sample is approximated by the value of the nearest quantization level. This introduces quantization error, which is the difference between the
The document discusses various digital communication techniques including linear vs nonlinear PCM encoding, idle channel noise reduction methods, coding methods like level-at-a-time, digit-at-a-time and word-at-a-time. It also discusses analog companding using A-law and μ-law, digital companding, vocoders, delta modulation, DPCM, intersymbol interference causes and eye patterns.
Pulse code modulation (PCM) involves sampling an analog signal at regular intervals, quantizing the sample values, and encoding the samples as digital code. The analog voice signal is sampled 8000 times per second, with each sample represented by an 8-bit binary number. This results in a digital data rate of 64,000 bits per second to represent the original voice signal. Quantization assigns the sample values to discrete levels, introducing quantization error between the original and encoded signals.
A general overview of signal encoding
You will learn why to use digital encoding, how signal is transmitted and received and how analog signals are converted to digital
Some digital encoding methods
A presentation prepared by my friend's friend. I have done no editing at all, I'm just uploading the presentation as it is.
Digital modulation involves transmitting digitally modulated analog signals between points in a communication system. It offers advantages over analog systems like ease of processing, multiplexing, and noise immunity. Digital modulation techniques include pulse amplitude modulation, pulse width modulation, and pulse position modulation. Pulse code modulation is a digital pulse modulation technique where analog signals are sampled, quantized into discrete levels, and encoded into binary code for transmission. The minimum sampling rate required by the Nyquist theorem is twice the maximum signal frequency to avoid aliasing during reconstruction.
DIGITALModulation.pptx "Advanced Digital Modulation Techniques"neltalagtag025
"Advanced Digital Modulation Techniques" explores cutting-edge methods shaping modern communication systems. This comprehensive guide delves into intricate algorithms and protocols enhancing data transmission efficiency and reliability. From phase-shift keying (PSK) to quadrature amplitude modulation (QAM), readers uncover the intricate nuances of signal modulation, demodulation, and error correction. The text navigates through the evolution of digital modulation, shedding light on emerging trends like orthogonal frequency-division multiplexing (OFDM) and software-defined radio (SDR). Engineers, researchers, and students alike benefit from practical insights, case studies, and simulations, empowering them to design, optimize, and troubleshoot complex digital communication systems in today's dynamic technological landscape.
Digital communication viva questions.( 50+)
MCQ of digital communication (50+)
communication systems MCQ. (50+)
communication systems viva questions (50+)
covered topic list:
sampling,quantization,digital,discrete,AM,FM,PM,ASK,FSK,PSK,DM,DPCM,QPSK,ADM,differences,modulation,block diagram,applications,PAM,PWM,PPM,line encoding,polar encoding,bipolar encoding,unipolar encoding,RZ,NRZ,AMI,HDB3,B8ZS
Pulse modulation techniques can encode an analog signal for transmission. This document discusses several techniques including:
- Pulse-amplitude modulation (PAM) which varies pulse amplitudes based on sample values of the message signal.
- Pulse code modulation (PCM) which assigns a binary code to each analog sample. PCM is commonly used in digital communications systems.
- Delta modulation which transmits one bit per sample indicating if the current sample is more positive or negative than the previous. It requires higher sampling rates than PCM for equal quality.
1. PCM uses time division multiplexing to transmit multiple telephone calls over a single transmission line by sampling each call and transmitting the samples in brief time slots.
2. During sampling, the amplitude of an analog signal is measured at regular intervals and assigned a digital code. This process is called quantization and results in quantization distortion from approximating the original signal.
3. Non-uniform quantization, called companding, is used to provide more quantization levels for smaller amplitudes that are more common in speech, improving the signal-to-noise ratio across all amplitudes.
1) The document discusses various topics related to digital communication including sampling theory, analog to digital conversion, pulse code modulation, quantization, coding, and time division multiplexing.
2) In analog to digital conversion, an analog signal is sampled, quantized by assigning it to discrete amplitude levels, and coded by mapping each level to a binary sequence.
3) The Nyquist sampling theorem states that a signal must be sampled at a rate at least twice its highest frequency to avoid aliasing when reconstructing the original signal.
This document provides an overview of pulse amplitude modulation (PAM). It defines PAM as a modulation technique where the message information is encoded in the amplitude of a series of signal pulses. There are two types: 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 used to modulate digital data transmission and involves sampling the message signal to vary the amplitude of a carrier pulse train. The modulated signal is then detected by measuring the amplitude level of each carrier pulse.
Pulse modulation techniques encode information by manipulating pulse characteristics such as amplitude, width, and position. Common pulse modulation types include pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). PCM is the most widely used technique, where an analog signal is sampled, quantized into discrete levels, and encoded into a binary digital signal for transmission.
Pulse Code Modulation (PCM) is a method to convert an analog signal into a digital signal. It involves three main steps: 1) sampling the analog signal at regular intervals, 2) quantizing the sampled signal into discrete levels, and 3) encoding the quantized levels into binary digits. The sampling rate must be at least twice the highest frequency of the analog signal according to the Nyquist theorem to avoid aliasing. Quantization divides the signal amplitude range into discrete levels and assigns a unique code to each level. This introduces quantization error but more quantization levels reduce the error. The bit rate of the encoded PCM signal depends on the number of bits per sample and the sampling rate.
Okay, here are the steps to find the velocity of the rocket at t = 10s:
1) Take the derivative of the position function x(t) to get the velocity function v(t):
v(t) = 4 + 14t + 15t^2 - 1.4t^3
2) Plug t = 10s into the velocity function:
v(10) = 4 + 140 + 1500 - 140 = 1404 m/s
So the velocity of the rocket at t = 10s is 1404 m/s.
This document summarizes various pulse modulation techniques including:
- Pulse-amplitude modulation (PAM) where the carrier amplitude changes with the message signal amplitude.
- Pulse-duration modulation (PDM) where the carrier width changes with the message signal amplitude.
- Pulse-position modulation (PPM) where the carrier position changes with the message signal amplitude.
- Digital pulse modulation techniques like pulse code modulation (PCM) and differential PCM (DPCM) are also discussed. Advantages and disadvantages of each technique are provided.
The document discusses pulse code modulation (PCM) for encoding analog waveforms into digital signals. It covers:
1. PCM involves sampling, quantizing, and encoding analog signals. Sampling makes the signal discrete in time. Quantizing makes it discrete in amplitude by rounding to discrete levels. Encoding maps quantized values to binary code words.
2. Quantization introduces distortion but sampling noise can be eliminated if the Nyquist criterion is met. Uniform quantizers are optimal for uniformly distributed inputs.
3. A practical PCM system was designed for telephone systems using 8-bit samples at 8 kHz to encode voice signals between 300-3400 Hz, producing a 64 kbps digital signal. The bandwidth
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 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 chapter discusses various pulse modulation techniques including pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). PAM varies the amplitude of pulses, PWM varies the width of pulses, PPM varies the position of pulses, and PCM converts an analog signal to a digital signal using sampling and quantization then encodes it as a binary code. Digital communication using these pulse modulation techniques offers advantages like more reliable signal reception and the ability to store, clean up, amplify, encode, and reconstruct the original signal.
This document provides an overview of digital communications and source encoding. It discusses why digital communication is preferable to analog, describes the basic block diagram of a digital communication system, and defines key terms like the information source and channel encoder. The document then covers some of the foundational work in digital communications, including Nyquist's sampling theorem and Shannon's channel capacity theorem. It discusses ideal sampling and the Nyquist rate, as well as practical sampling techniques like sample-and-hold. The document also covers quantization, quantization noise, and how the step size and number of quantization levels affect the signal-to-quantization noise ratio. In closing, it briefly mentions pulse code modulation and nonuniform quantization.
Data encoding and modulation techniques are discussed. Modulation involves varying properties of a high-frequency carrier signal according to a message signal. This allows transmission of baseband signals over long distances. Common modulation types are amplitude modulation (AM), frequency modulation (FM), and phase modulation (PM). Encoding converts data into formats for transmission, storage, processing and more. Common encoding schemes for digital data transmission include non-return to zero (NRZ) encoding and Manchester encoding. Pulse modulation can transmit signals as pulses using techniques like pulse code modulation (PCM).
Pulse code modulation (PCM) is a method of digitally representing sampled analog signals. It involves sampling an analog signal, quantizing the samples to discrete levels, and encoding the quantized samples as binary digits.
Analog to digital converters (ADCs) sample an analog signal and quantize the samples to discrete levels represented by binary digits. The sequence of 1s and 0s output from the ADC is called a PCM signal.
Quantization is the process of converting analog samples to digital samples by dividing the range of possible analog values into discrete quantization levels. Each analog sample is approximated by the value of the nearest quantization level. This introduces quantization error, which is the difference between the
The document discusses various digital communication techniques including linear vs nonlinear PCM encoding, idle channel noise reduction methods, coding methods like level-at-a-time, digit-at-a-time and word-at-a-time. It also discusses analog companding using A-law and μ-law, digital companding, vocoders, delta modulation, DPCM, intersymbol interference causes and eye patterns.
Pulse code modulation (PCM) involves sampling an analog signal at regular intervals, quantizing the sample values, and encoding the samples as digital code. The analog voice signal is sampled 8000 times per second, with each sample represented by an 8-bit binary number. This results in a digital data rate of 64,000 bits per second to represent the original voice signal. Quantization assigns the sample values to discrete levels, introducing quantization error between the original and encoded signals.
A general overview of signal encoding
You will learn why to use digital encoding, how signal is transmitted and received and how analog signals are converted to digital
Some digital encoding methods
A presentation prepared by my friend's friend. I have done no editing at all, I'm just uploading the presentation as it is.
Digital modulation involves transmitting digitally modulated analog signals between points in a communication system. It offers advantages over analog systems like ease of processing, multiplexing, and noise immunity. Digital modulation techniques include pulse amplitude modulation, pulse width modulation, and pulse position modulation. Pulse code modulation is a digital pulse modulation technique where analog signals are sampled, quantized into discrete levels, and encoded into binary code for transmission. The minimum sampling rate required by the Nyquist theorem is twice the maximum signal frequency to avoid aliasing during reconstruction.
DIGITALModulation.pptx "Advanced Digital Modulation Techniques"neltalagtag025
"Advanced Digital Modulation Techniques" explores cutting-edge methods shaping modern communication systems. This comprehensive guide delves into intricate algorithms and protocols enhancing data transmission efficiency and reliability. From phase-shift keying (PSK) to quadrature amplitude modulation (QAM), readers uncover the intricate nuances of signal modulation, demodulation, and error correction. The text navigates through the evolution of digital modulation, shedding light on emerging trends like orthogonal frequency-division multiplexing (OFDM) and software-defined radio (SDR). Engineers, researchers, and students alike benefit from practical insights, case studies, and simulations, empowering them to design, optimize, and troubleshoot complex digital communication systems in today's dynamic technological landscape.
The attached narrated power point presentation attempts to explain the methods of computation of total power loss and system rise time in a fiber optic link. The material will be useful for KTU final year B Tech students who prepare for the subject EC 405, Optical Communications.
Digital Instrumentation
The document discusses digital instrumentation and data acquisition systems. It covers topics like analog and digital signals, data sampling, the sampling theorem, anti-aliasing, sample and hold circuits, data acquisition systems, and interfacing with computers. Key points include:
- Analog signals are continuous while digital signals are discrete. Sampling converts a continuous signal to a discrete one.
- The sampling theorem states the sampling rate must be at least twice the highest frequency component to avoid aliasing.
- Sample and hold circuits create and store samples of an input voltage to digitize analog signals for data conversion.
- Data acquisition systems collect data from sensors, condition signals, convert to digital, and transfer to computers or
The document discusses digital transmission and multiplexing techniques. It begins by defining digital transmission as the transmission of digital signals between two or more points in a communications system. It then describes several multiplexing techniques including time-division multiplexing (TDM), frequency-division multiplexing (FDM), and code-division multiplexing (CDM). The document also discusses the evolution of digital multiplexing standards from Plesiochronous Digital Hierarchy (PDH) to Synchronous Digital Hierarchy (SDH), noting that SDH provides a simpler, more economical, and flexible telecom infrastructure compared to PDH.
This document describes a circuit designed to improve optical communication by reducing power consumption and increasing transmission rates. The circuit uses lasers and optical fibers to transmit digital or analog signals with low error rates. It works by converting electrical signals to optical pulses using a laser, transmitting the pulses through optical fibers, and then converting them back to electrical signals. By switching to optical fiber transmission, the circuit avoids issues like noise, signal loss over long distances, and interference from electromagnetic fields. It further optimizes the system using techniques like pulse amplitude modulation and assigning more bits to represent lower probability values to reduce power usage.
The document discusses various types of pulse modulation techniques including pulse amplitude modulation (PAM), pulse width modulation (PWM), pulse position modulation (PPM), and pulse code modulation (PCM). It provides details on the basic principles, components, and advantages of each technique. PCM is described as the digital form of pulse modulation where the analog signal is converted to digital pulses by sampling, quantizing, and encoding the signal. The minimum sampling rate required by the Nyquist theorem and examples of calculating bit rates for PCM are also covered.
The document describes experiments performed on time division multiplexing, pulse code modulation, differential pulse code modulation, delta modulation, frequency shift keying, and differential phase shift keying. The experiments aim to study the principles and characteristics of these digital communication techniques by using equipment like multiplexing/demultiplexing trainer kits, PCM modulator and demodulator kits, and oscilloscopes. The procedures involve applying input signals, observing the output waveforms on oscilloscopes, and analyzing the effects of varying signal parameters.
1) The document discusses various pulse modulation techniques including pulse amplitude modulation (PAM), pulse width modulation (PWM), and pulse position modulation (PPM).
2) It provides details on the generation and detection of PAM and PWM signals, explaining the use of sampling, comparators, sawtooth waves, and filters.
3) The document compares different sampling techniques for PAM including natural sampling, flat top sampling, and discusses the need for analog to digital conversion in communication systems.
The document discusses the sampling theorem, which states that a signal must be sampled at a rate at least twice the highest frequency present in the signal (fs > 2fa(max)) in order to perfectly reconstruct the original signal from the samples. If the sampling rate is lower than this Nyquist rate, aliasing distortion will occur as frequency components fold over each other. Digital transmission is preferable to analog as the signal is more robust to noise and can be easily recovered, corrected, and amplified. There are three main sampling methods: ideal sampling uses an impulse, natural sampling uses a short pulse, and flat top sampling "samples and holds" a single amplitude value.
This document summarizes key concepts in sampling and pulse code modulation (PCM). It discusses:
- The sampling theorem which states that a signal can be reconstructed from samples if sampled at twice the bandwidth or higher.
- How PCM works by sampling an analog signal, quantizing the samples into digital values, coding the values into binary numbers, and transmitting the digital data.
- Key advantages of PCM include using inexpensive digital circuits, enabling all-digital transmission and further digital processing.
- Techniques like companding, differential PCM, and increasing bit depth can improve the quality and efficiency of PCM systems.
This document provides an overview of digital transmission topics covered in a 10-hour syllabus, with a focus on Pulse Code Modulation (PCM). Key concepts include: PCM involves sampling analog signals and encoding samples into binary codes for transmission; the minimum sampling rate must be at least twice the highest analog frequency to avoid aliasing; and PCM is used widely in telephone networks by encoding voice signals using an analog-to-digital conversion process involving sampling, quantization, coding, transmission and decoding.
communication concepts on sampling processNatarajVijapur
This document discusses principles of communication systems including sampling, quantization, pulse amplitude modulation (PAM), time division multiplexing (TDM), and pulse position modulation (PPM). It provides details on how analog signals are converted to digital through sampling and quantization. It explains the generation and detection of PAM, TDM, and PPM signals. Key advantages of digital transmission and various modulation techniques are summarized.
1) Analog to digital conversion involves sampling, quantizing, and encoding an analog signal to represent it as discrete digital values. Pulse code modulation is the most common technique which uses a low pass filter, sampler, and encoder.
2) Digital to analog conversion reconstructs the analog signal from discrete digital values using techniques like amplitude shift keying, frequency shift keying, and phase shift keying that modulate properties of a carrier signal.
3) A wireless sensor network is an ad hoc network of sensors that monitor physical conditions and communicate wirelessly, enabling applications in areas like environmental monitoring and healthcare. Challenges include energy efficiency, security, and coping with node failures.
This document discusses various analog pulse modulation schemes, including pulse amplitude modulation (PAM), pulse width modulation (PWM), and pulse position modulation (PPM). PAM varies the amplitude of pulses in a carrier signal based on the modulating signal. PWM varies the width of pulses, while PPM varies the position of pulses. The document describes the generation and demodulation of these different modulation types. It also discusses sampling theory and the advantages and disadvantages of PAM.
The sampling theorem can be explained as follows:
1. According to the sampling theorem, a continuous-time signal x(t) that has no frequency components higher than B Hz can be perfectly reconstructed from its samples if it is sampled at a frequency fs that is greater than 2B samples/second. This minimum sampling frequency fs is called the Nyquist rate.
2. The sampling theorem states that for a bandlimited signal with maximum frequency B Hz, the signal must be sampled at a frequency fs that is greater than 2B samples/second in order to avoid aliasing and allow perfect reconstruction of the original continuous-time signal from the samples.
3. Aliasing occurs when the signal is sampled at a rate lower than
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2. Chapter Outline
PART 1:
• Basic sampling technique
• Generation and recovery
– Pulse Amplitude Modulation (PAM)
– Pulse Duration Modulation (PDM)
– Pulse Position Modulation (PPM)
• Advantages & Disadvantages
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3. Sampling
To convert a signal from continuous time to
discrete time, a process called sampling is
used. The value of the signal is measured at
certain intervals in time. Each measurement is
referred to as a sample.
When the continuous analog signal is sampled
at a frequency F, the resulting discrete signal has
more frequency components than did the analog
signal. To be precise, the frequency components
of the analog signal are repeated at the sample
rate.
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4. Sampling
• Sampling a signal: Analog → Digital conversion by
reading the value at discrete points
• A process of taking samples of information signal at a rate of
Nyquist’s sampling frequency.
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5. • Nyquist’s Sampling Theorem :
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The original information signal can be reconstructed at the receiver
with minimal distortion if the sampling rate in the pulse modulation
system equal to or greater than twice the maximum information
signal frequency.
fs >= 2fm (max)
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infinite bandwidth cannot be sampled.
the sampling rate must be at least 2 times the highest
frequency, not the bandwidth.
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A complex low-pass signal has a bandwidth of
200 kHz. What is the minimum sampling rate for
this signal?
Solution:
The bandwidth of a low-pass signal is between 0 and f,
where f is the maximum frequency in the signal.
Therefore, we can sample this signal at 2 times the
highest frequency (200 kHz). The sampling rate is
therefore 400,000 samples per second.
Example 1
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A complex bandpass signal has a bandwidth of
200 kHz. What is the minimum sampling rate for
this signal?
Solution :
We cannot find the minimum sampling rate in this case
because we do not know where the bandwidth starts or
ends. We do not know the maximum frequency in the
signal.
Example 2
9. Undersampling & Oversampling
Undersampling is essentially sampling too
slowly, or sampling at a rate below the
Nyquist frequency for a particular signal of
interest. Undersampling leads to aliasing and
the original signal cannot be properly
reconstructed
Oversampling is sampling at a rate beyond
twice the highest frequency component of
interest in the signal and is usually desired.
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10. • If the required condition of the sampling theorem that fs
>= 2fmmax is not met, then errors will occur in the
reconstruction.
• When such errors arise due to undersampling, aliasing is
said to occur
• Undersampling: Sampling rate is too low to capture high-
frequency variation
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Aliasing effect
12. 12
For an intuitive example of the Nyquist theorem, let us
sample a simple sine wave at three sampling rates:
a) fs = 2f (Nyquist rate)
b) fs = 4f (2 times the Nyquist rate),
c) fs = f (one-half the Nyquist rate).
Figure shows the sampling and the subsequent recovery of
the signal.
SOLUTION:
It can be seen that sampling at the Nyquist rate can create
a good approximation of the original sine wave (part a).
Oversampling in part b can also create the same
approximation, but it is redundant and unnecessary.
Sampling below the Nyquist rate (part c) does not produce
a signal that looks like the original sine wave.
Example 3
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Recovery of a sampled sine wave for different sampling rates
14. Natural Sampling
• Tops of the sample pulses retain their natural
shape during the sample interval.
• Frequency spectrum of the sampled output is
different from an ideal sample.
• Amplitude of frequency components
produced from narrow, finite-width sample
pulses decreases for the higher harmonics
– Requiring the use of frequency equalizers
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16. Flat-top Sampling
• Common used in PCM systems.
• Accomplish in a sample-and-hold circuit
– To periodically sample the continually changing analog
input voltage & convert to a series of constant-amplitude
PAM voltage levels.
• The input voltage is sampled with a narrow pulse
and then held relatively constant until the next
sample is taken.
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17. Cont’d…
• Sampling process alters the frequency
spectrum & introduces aperture error.
• The amplitude of the sampled signal changes
during the sample pulse time.
• Advantages:
– Introduces less aperture distortion
– Can operate with a slower ADC
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19. • Sampling analog information signal
• Converting samples into discrete pulses
• used to represent an analog signal with digital data
• among the first of the pulse techniques to be utilized
Carrier signal is pulse waveform and the modulated signal
is where one of the carrier signal’s characteristic (either
amplitude, width or position) is changed according to
information signal.
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20. The amplitude of
pulses is varied in
accordance with the
information signal.
Width & position
constant.
2 types –
double polarity
single polarity
Pulse Amplitude Modulation (PAM)
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21. Natural Sampling (PAM)
• A PAM signal is generated by using a pulse train, called the
sampling signal (or clock signal) to operate an electronic
switch or "chopper". This produces samples of the analog
message signal, as shown in Figure
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22. Flat Top Sampling (PAM)
• a sample-and-hold circuit is used in conjunction with the
chopper to hold the amplitude of each pulse at a constant
level during the sampling time
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Flat-top sampling – generation of PAM signals.
23. Cont’d
• Pulse duration (τ) supposed to be very small
compare to the period, Ts between 2 samples
• Lets max frequency of the signal, W
• If ON/OFF time of the pulse is same,
frequency of the PAM pulse is
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Fs >= 2 W
Ts =< 1/2W
T « Ts =< 1/2W
2
1
max f
24. Transmission BW of PAM Signal
• Bandwidth required for transmitter of PAM
signal will be equal to maximum frequency
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2
1
max
fBT
25. Advantages & Disadvantages PAM
• Advantage:
– it allows multiplexing, i.e., the sharing of the same
transmission media by different sources (or users). This
is because a PAM signal only occurs in slots of time,
leaving the idle time for the transmission of other PAM
signals.
• Disadvantage:
– require a larger transmission bandwidth (very large
compare to its maximum frequency)
– Interference of noise is maximum
– Needed for varies transmission power
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26. Pulse Density Modulation (PDM)
• Sometimes called Pulse Duration Modulation/ Pulse Width
Duration (PWM).
• The width of pulses is varied in accordance to information
signal
• Amplitude & position constant.
• PDM is used in a great number of applications
Communications
• The width of the transmitted pulse corresponds to the
encoded data value
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27. PDM
• Immune to noise
• Power Delivery
– Reduce the total amount of power delivered to a load
• Applications: DC Motors, Light Dimmers, Anti-Lock Breaking System
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28. • PWM signal output is generated by comparing summation
result with reference level
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30. Advantages & Disadvantages PDM
• Advantage:
– Noise performance is better compare to PAM.
• Disadvantages:
– require a larger power transmission compare to
PPM
– Require very large bandwidth compare to PAM
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31. Pulse Position Modulation (PPM)
• Modulation in which the temporal positions of the pulses are
varied in accordance with some characteristic of the
information signal.
• Amplitude & width constant.
• The higher the amplitude of the sample, the farther to the
right the pulse is position within the prescribed time slot.
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32. Advantages & Disadvantages PPM
• Advantage:
– The amplitude is held constant thus less noise
interference.
– Signal and noise separation is very easy
– Due to constant pulse widths and amplitudes,
transmission power for each pulse is same.
– Require less power compare to PAM and PDM because
of short duration pulses.
• Disadvantages:
– Require very large bandwidth compare to PAM.
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33. Transmission BW of PDM/PPM Signal
• PPM and PDM need a sharp rise time and fall
time for pulses in order to preserve the message
information.
• Lets rise time, tr
• From formula above, we know that transmission
BW of PPM and PDM is higher than PAM
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tr« Ts
r
T
t
B
2
1
34. Transmission BW of PAM Signal
• Pulse duration (τ) supposed to be very small
compare to the period, Ts between 2 samples
• Lets max frequency of the signal, W
• If ON/OFF time of the pulse is same,
frequency of the PAM pulse is
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Fs >= 2 W
Ts =< 1/2W
T « Ts =< 1/2W
2
1
max f
35. Example 4
• For PAM transmission of voice signal with W =
3kHz. Calculate BT if fs = 8 kHz and τ = 0.1 Ts
• SOLUTION
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sxT
sx
kHzf
T
s
s
s
5
4
1025.11.0
1025.1
8
11
kHzB
WB
W
T
T
40
2
1
2
1
2
1
36. Example 5
For the same information as in example 1, find
minimum transmission BW needed for PPM
and PDM. Given tr= 1% of the width of the
pulse.
SOLUTION
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MHzB
t
B
sxt
T
r
T
r
4
2
1
1025.1
100
1 7
38. PAM PDM PPM
Relation with
modulating signal
Amplitude of the
pulse is
proportional to
amplitude of
modulating signal
Width of the pulse
is proportional to
amplitude of
modulating signal
Relative position of
the pulse is
proportional to
amplitude of
modulating signal
BW of the
transmission
channel
depends on width
of the pulse
Depends of rise
time of the pulse
Depends on rising
time of the pulse
Instantaneous
power
varies varies Remains constant
Noise interference High Minimum Minimum
Complexity of the
system
Complex Simple simple
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39. • PAM, PWM, PPM
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40. Advantages & Drawbacks of Pulse Modulation
• Noise immunity.
• Relatively low cost digital
circuitry.
• Able to be time division
multiplexed with other pulse
modulated signal.
• Storage of digital streams.
• Error detection & correction
• Requires greater BW to transmit
& receive as compared to its
analog counterpart.
• Special encoding & decoding
methods must be used to
increased transmission rates &
more difficult to be recovered.
• Requires precise
synchronization of clocks
between Tx & Rx.
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