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.
Objective of Pulse Code Modulation
Block Diagram of PCM
Process of PCM
Sampling
Quantization
Encoding
PCM Standards
Bit Rate and Bandwidth in PCM
Advantages and Disadvantages of PCM
Applications of PCM
Objective of Pulse Code Modulation
Block Diagram of PCM
Process of PCM
Sampling
Quantization
Encoding
PCM Standards
Bit Rate and Bandwidth in PCM
Advantages and Disadvantages of PCM
Applications of PCM
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.
Pulse Amplitude (PAM)
Pulse Width (PWM/PLM/PDM)
Pulse Position (PPM)
Comparison of PAM, PWM and PPM
Pulse Code (PCM)
Delta (DM)
Comparison of DM and PCM
Salient Features:
The magnitude response is nearly constant(equal to 1) at lower frequencies
There are no ripples in passband and stop band
The maximum gain occurs at Ω=0 and it is H(Ω)=1
The magnitude response is monotonically decreasing
As the order of the filter ‘N’ increases, the response of the filter is more close to the ideal response
All about the differential pulse code modulation and adaptive pulse code modulation which is one the classification of pulse code modulation(digital communications).
Design and implementation of qpsk modulator using digital subcarrierGongadi Nagaraju
The digitally implemented QPSK modulator is developed for satellite communication for future satellite missions. As we know that for space application power and bandwidth are most important parameters.The size of PCB and component count are also important parameters. To reduce these all parameters we design new approach. The new approach also minimizes the component count and hence reduces the PCB size. In this modulator summation, orthogonal sub-carrier generation and mixing of subcarrier with data are all digitally implemented inside the FPGA
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.
Pulse Amplitude (PAM)
Pulse Width (PWM/PLM/PDM)
Pulse Position (PPM)
Comparison of PAM, PWM and PPM
Pulse Code (PCM)
Delta (DM)
Comparison of DM and PCM
Salient Features:
The magnitude response is nearly constant(equal to 1) at lower frequencies
There are no ripples in passband and stop band
The maximum gain occurs at Ω=0 and it is H(Ω)=1
The magnitude response is monotonically decreasing
As the order of the filter ‘N’ increases, the response of the filter is more close to the ideal response
All about the differential pulse code modulation and adaptive pulse code modulation which is one the classification of pulse code modulation(digital communications).
Design and implementation of qpsk modulator using digital subcarrierGongadi Nagaraju
The digitally implemented QPSK modulator is developed for satellite communication for future satellite missions. As we know that for space application power and bandwidth are most important parameters.The size of PCB and component count are also important parameters. To reduce these all parameters we design new approach. The new approach also minimizes the component count and hence reduces the PCB size. In this modulator summation, orthogonal sub-carrier generation and mixing of subcarrier with data are all digitally implemented inside the FPGA
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.
AC Distribution in Bangladesh (in a nutshell)Ridwanul Hoque
Power System is an integrated network that interconnects the installations for generation, transmission and distribution of electricity. In Bangladesh electricity is generated at 50 Hertz frequency and at a nominal voltage of 11 KV (Kilo Volts) or 15 KV to be stepped up through transformers to 132 kV or 230 kV for feeding to the grid i.e. a high voltage transmission network that transmits the power to grid substation transformers to be stepped down at 33 kV. 11 kV and 0.4 kV for delivery to the consumers of various categories.
In electronics, impedance matching is the practice of designing the input impedance of an electrical load or the output impedance of its corresponding signal source to maximize the power transfer or minimize signal reflection from the load.
Loadability of line is defined as the extent of load which can flow through the line without exceeding the limitations. Line Loadability is expressed in percentage of Surge Impedance Loading of line. The limiting factor for line loading are: thermal limit, voltage drop limit and steady state stability.
Equipment and Stability Constraints : System OperationRidwanul Hoque
There are two types of constraints which limit the capability of a power system: If the overloading exceeds limits, the equipment is tripped out by protection systems. b) Stability Constraints: A power system may not be able to cater to power flows beyond a certain point due to stability constraints.
A power system control is required to maintain a continuous balance between power generation and load demand. Load Frequency Controller and Automatic Voltage Regulator play an important role in maintaining constant frequency and voltage in order to ensure the reliability of electric power.
HVDC stands for high voltage direct current, a well-proven technology used to transmit electricity over long distances by overhead transmission lines or submarine cables. It is also used to interconnect separate power systems, where traditional alternating current (AC) connections cannot be used.
Hydro Power Plants capture the energy of falling water to generate electricity. A turbine converts the kinetic energy of falling water into mechanical energy. Then a generator converts the mechanical energy from the turbine into electrical energy.
There are three main types of conventional hydropower technologies: impoundment (dam), diversion, and pumped storage. Impoundment is the most common type of hydroelectric power plant. An impoundment facility, typically a large hydro-power system, uses a dam to store river water in a reservoir.
The Rankine cycle or Rankine Vapor Cycle is the process widely used by power plants such as coal-fired power plants or nuclear reactors. In this mechanism, a fuel is used to produce heat within a boiler, converting water into steam which then expands through a turbine producing useful work.
The steam-electric power station is a power station in which the electric generator is steam driven.
The steam-electric power station is a power station in which the electric generator is steam driven.
The Rankine cycle or Rankine Vapor Cycle is the process widely used by power plants such as coal-fired power plants or nuclear reactors. In this mechanism, a fuel is used to produce heat within a boiler, converting water into steam which then expands through a turbine producing useful work.
The aim of our presentation is to describe the AC Distribution system in Bangladesh.
Following are the focused points in terms of Bangladesh perspective:
1. Distribution Procedure
2. Primary and Secondary Distribution System
3. Distribution Substation
4. Distribution Companies
5. Distribution in both City and Rural Area
6. Distribution Loss
7. Protective Devices
8. User Variety
8. Billing Procedure
Power system stability is the ability of an electric power system, for a given initial operating condition, to regain a state of operating equilibrium after being subjected to a physical disturbance, with most system variables bounded so that practically the entire system remains intact.
Economic operation of power system. (i) One dealing with minimum cost of power production called Economic dispatch. (ii) Other dealing with minimum loss of the generated power delivery to the loads. For any specified load condition, economic dispatch (i) determines the power output of each plant.
Event Management System Vb Net Project Report.pdfKamal Acharya
In present era, the scopes of information technology growing with a very fast .We do not see any are untouched from this industry. The scope of information technology has become wider includes: Business and industry. Household Business, Communication, Education, Entertainment, Science, Medicine, Engineering, Distance Learning, Weather Forecasting. Carrier Searching and so on.
My project named “Event Management System” is software that store and maintained all events coordinated in college. It also helpful to print related reports. My project will help to record the events coordinated by faculties with their Name, Event subject, date & details in an efficient & effective ways.
In my system we have to make a system by which a user can record all events coordinated by a particular faculty. In our proposed system some more featured are added which differs it from the existing system such as security.
Final project report on grocery store management system..pdfKamal Acharya
In today’s fast-changing business environment, it’s extremely important to be able to respond to client needs in the most effective and timely manner. If your customers wish to see your business online and have instant access to your products or services.
Online Grocery Store is an e-commerce website, which retails various grocery products. This project allows viewing various products available enables registered users to purchase desired products instantly using Paytm, UPI payment processor (Instant Pay) and also can place order by using Cash on Delivery (Pay Later) option. This project provides an easy access to Administrators and Managers to view orders placed using Pay Later and Instant Pay options.
In order to develop an e-commerce website, a number of Technologies must be studied and understood. These include multi-tiered architecture, server and client-side scripting techniques, implementation technologies, programming language (such as PHP, HTML, CSS, JavaScript) and MySQL relational databases. This is a project with the objective to develop a basic website where a consumer is provided with a shopping cart website and also to know about the technologies used to develop such a website.
This document will discuss each of the underlying technologies to create and implement an e- commerce website.
TECHNICAL TRAINING MANUAL GENERAL FAMILIARIZATION COURSEDuvanRamosGarzon1
AIRCRAFT GENERAL
The Single Aisle is the most advanced family aircraft in service today, with fly-by-wire flight controls.
The A318, A319, A320 and A321 are twin-engine subsonic medium range aircraft.
The family offers a choice of engines
Explore the innovative world of trenchless pipe repair with our comprehensive guide, "The Benefits and Techniques of Trenchless Pipe Repair." This document delves into the modern methods of repairing underground pipes without the need for extensive excavation, highlighting the numerous advantages and the latest techniques used in the industry.
Learn about the cost savings, reduced environmental impact, and minimal disruption associated with trenchless technology. Discover detailed explanations of popular techniques such as pipe bursting, cured-in-place pipe (CIPP) lining, and directional drilling. Understand how these methods can be applied to various types of infrastructure, from residential plumbing to large-scale municipal systems.
Ideal for homeowners, contractors, engineers, and anyone interested in modern plumbing solutions, this guide provides valuable insights into why trenchless pipe repair is becoming the preferred choice for pipe rehabilitation. Stay informed about the latest advancements and best practices in the field.
Sachpazis:Terzaghi Bearing Capacity Estimation in simple terms with Calculati...Dr.Costas Sachpazis
Terzaghi's soil bearing capacity theory, developed by Karl Terzaghi, is a fundamental principle in geotechnical engineering used to determine the bearing capacity of shallow foundations. This theory provides a method to calculate the ultimate bearing capacity of soil, which is the maximum load per unit area that the soil can support without undergoing shear failure. The Calculation HTML Code included.
Democratizing Fuzzing at Scale by Abhishek Aryaabh.arya
Presented at NUS: Fuzzing and Software Security Summer School 2024
This keynote talks about the democratization of fuzzing at scale, highlighting the collaboration between open source communities, academia, and industry to advance the field of fuzzing. It delves into the history of fuzzing, the development of scalable fuzzing platforms, and the empowerment of community-driven research. The talk will further discuss recent advancements leveraging AI/ML and offer insights into the future evolution of the fuzzing landscape.
Water scarcity is the lack of fresh water resources to meet the standard water demand. There are two type of water scarcity. One is physical. The other is economic water scarcity.
COLLEGE BUS MANAGEMENT SYSTEM PROJECT REPORT.pdfKamal Acharya
The College Bus Management system is completely developed by Visual Basic .NET Version. The application is connect with most secured database language MS SQL Server. The application is develop by using best combination of front-end and back-end languages. The application is totally design like flat user interface. This flat user interface is more attractive user interface in 2017. The application is gives more important to the system functionality. The application is to manage the student’s details, driver’s details, bus details, bus route details, bus fees details and more. The application has only one unit for admin. The admin can manage the entire application. The admin can login into the application by using username and password of the admin. The application is develop for big and small colleges. It is more user friendly for non-computer person. Even they can easily learn how to manage the application within hours. The application is more secure by the admin. The system will give an effective output for the VB.Net and SQL Server given as input to the system. The compiled java program given as input to the system, after scanning the program will generate different reports. The application generates the report for users. The admin can view and download the report of the data. The application deliver the excel format reports. Because, excel formatted reports is very easy to understand the income and expense of the college bus. This application is mainly develop for windows operating system users. In 2017, 73% of people enterprises are using windows operating system. So the application will easily install for all the windows operating system users. The application-developed size is very low. The application consumes very low space in disk. Therefore, the user can allocate very minimum local disk space for this application.
Saudi Arabia stands as a titan in the global energy landscape, renowned for its abundant oil and gas resources. It's the largest exporter of petroleum and holds some of the world's most significant reserves. Let's delve into the top 10 oil and gas projects shaping Saudi Arabia's energy future in 2024.
Student information management system project report ii.pdfKamal Acharya
Our project explains about the student management. This project mainly explains the various actions related to student details. This project shows some ease in adding, editing and deleting the student details. It also provides a less time consuming process for viewing, adding, editing and deleting the marks of the students.
2. 2
Advantages of Digital Communication
Digital systems are less sensitive to noise and signal distortion. For long transmission line, the signal may
be regenerated effectively error-free at different points along the path.
With digital systems, it is easier to integrate different services, e.g., video and the accompanying
soundtrack, into the same transmission scheme.
The transmission scheme can be relatively independent of the source
Circuitry for digital signals is easier to repeat and digital circuits are less sensitive to physical effects
such as vibration and temperature
Digital signals are simpler to characterize and typically do not have the same amplitude range and
variability as analog signals. This makes the associated hardware design easier.
Various media sharing strategies (known as multiplexing) are more easily implemented with digital
transmission strategies
Source coding techniques can be used for removing redundancy from digital transmission
Error-control coding can be used for adding redundancy, which can be used to detect and correct
errors at the receiver side
Digital communication systems can be made highly secure by exploiting powerful encryption algorithms
Digital communication systems are inherently more efficient than analog communication systems in
the tradeoff between transmission bandwidth and signal-to-noise ratio
Various channel compensation techniques, such as, channel estimation and equalization, are easier to
implement
3. 3
Sampling (1)
Sampling is an operation that is basic to digital signal processing and digital communications
Through the use of sampling process, an analog signal is converted into a corresponding
sequence of samples that are usually spaced uniformly in time
Message
Sampled Signal
Sampling Signal
n
ssT nffffs
7. 7
Sampling Theorem
Sampling theorem is a fundamental bridge between continuous signals (analog
domain) and discrete signals (digital domain)
It only applies to a class of mathematical functions whose Fourier transforms are
zero outside of a finite region of frequencies
Nyquist Sampling Theorem / Nyquist-Shanon Sampling Theorem:
fs = Sampling frequency
fs = 2W: Nyquist frequency / Nyquist rate / Minimum sampling frequency
A signal whose bandwidth is limited to W Hz can be reconstructed exactly
(without any error) from its samples uniformly taken at a rate fs ≥ 2W Hz
8. 8
Antialiasing Filter
All practical signals are time-limited, i.e., non band-limited => Aliasing inevitable
To limit aliasing, use anti-aliasing filter (LPF) before sampling
Original
Signal
Anti-aliasing
filter
Sample
Reconstruction
Filter
Reconstructed
Signal
10. 10
Quantization (1)
Quantizer characteristic:
Here, k = 1, 2, 3, … , L
L = Number of representation levels
(Number of intervals)
It is the process of transforming the sample amplitude m(nTS) of a baseband signal at time t = nTS
into a discrete amplitude v(nTS) taken from a finite set of possible levels
kth interval:
Quantizer output equals to vk if the input signal sample m belongs to the interval Ik
mk: Decision levels / Decision thresholds
vk: Representation levels / Reconstruction levels
Δ=|vk +1 – vk|: Step-size / quantum
kk Imifvv
11. 11
Quantization(2): Two types
Mid-tread quantization Mid-rise quantization
Mid-rise quantizer:
Decision threshold value is exactly zero
Mid-tread quantizer:
Reconstruction value is exactly zero
Reconstruction
levels
13. 13
Quantization Error for Uniform Quantization (1)
Quantization error (noise)
q = m – v => Q = M – V
If mean of M is zero and the quantizer is
symmetric, then V is also a RV of zero mean
Q is also a RV variable of zero mean in the
range [– Δ/2, Δ/2]
If Δ is sufficiently small, Q can be assumed
a uniform RV with zero mean
– Δ/2 0 Δ/2 q
fQ(q)
1/Δ
Quantization noise power
2/
2/
2
22
12
dqqfq QQ
22
12
PP
SNR
Q
Signal-to-nose-ratio (SNR): P = Average power of m(t)
14. 14
Quantization Error for Uniform Quantization (2)
Special case:
m(t) is a sinusoidal signal with amplitude equal to mmax
R
m
L
m
2
22 maxmax
Suppose m(t) of continuous amplitude in the range [-mmax, mmax]:
R
m
P
SNR 2
2
max
2
3
R
SNR 2
2
2
3
2
max
3
log1002.6
m
P
RSNRdB
8.16 RSNRdB
Each additional bit increases the SNR by 6.02 dB and
a corresponding increase in required channel BW
R = Number of bits for presenting each level (bits/sample)
15. 15
Non-Uniform Quantization
SNR of weak signals is much lower than that of strong signal
Instantaneous SNR is also lower for the smaller amplitudes compared to that of the
larger amplitudes
16. 16
Non-Uniform Quantization
- Step size increases as the separation from the origin of the input–output amplitude
characteristic is increased
- First Compression and then uniform quantization
- Achieve more even SNR over the
dynamic range using fewer bits (e.g.,
8 bits instead of 13/14 bits)
Receiver side: Expansion required
Compression + Expansion = Companding
Original
Signal
Compression
Uniform
Quantization
Reconstruction Expansion
Original
Signal
17. 17
Non-Uniform Quantization
Compressor Input Compressor Output
The compression here occurs in the amplitude values
Compression in amplitudes means that the amplitudes of the compressed signal
are more closely spaced in comparison to the original signal
To do so, the compressor boosts the small amplitudes by a large amount. However,
the large amplitude values receive very small gain and the maximum value remains
the same
20. 20
Encoding
Each quantized samples is encoded into a code word
Each element in a code word is called code element
Binary code:
Each code element is either of two distinct
values, customarily denoted as 0 and 1
Binary symbol withstands a relatively high
level of noise and also easy to regenerate
Each binary code word consists of R bits and
hence, this code can represent 2R distinct
numbers (i.e., at best R bit quantizer can be
used)
21. 21
Pulse Code Modulation (PCM)
In PCM, a message signal is represented by a sequence of coded pulses, which is accomplished
by representing the signal in discrete form in both time and amplitude
Three basic operations in a PCM Transmitter:
- Sampling
- Quantization
- Encoding
Transmitter
Receiver
Transmission
Path
22. 22
Differential PCM (DPCM)
Transmitter
When a signal is sampled at a rate slightly higher than the Nyquist rate, there exists a
high degree correlation between adjacent samples, i.e., in an average sense, the signal
does not change rapidly from one sample to the next
When these highly correlated samples are encoded as in a standard PCM system, the
resulting encoded signal contains redundant information implying that symbols that are not
absolutely essential to the transmission of information are generated
DPCM removes this redundancy before encoding by taking the difference between the
actual sample m(nTS) and its predicted value
The quantized version of the prediction error e(nTS) are encoded instead of encoding
the samples of the original signal
This will result in much smaller quantization intervals leading to less quantization noise
and much higher SNR
SSS nTmnTmnTe ˆ
Prediction error
SnTmˆ
23. 23
Predictor for DPCM:
Liner predictor of order p:
Transversal filter (tapped-delay-line filter) used as a linear predictor
p
k
SqkS TknmwnTm
1
ˆ
25. 25
Delta Modulation (DM) … (1)
DM encodes the difference between the current sample and the previous sample using just one bit
Correlation between samples are increased by oversampling (i.e., at a rate much higher, typically 4 times
higher than the Nyquist rate)
DM involves the generation of the staircase approximation of the oversampled version message
The difference between the input and the approximation is quantized into only two levels:
1-bit version of DPCM (i.e., 2-level quantization) requiring less bandwidth than that of DPCM and PCM
27. 27
Predictor for DM
Transmitter
Note:
(1) DPCM uses a higher order filter.
(2) DM uses a 1st order predictor with w1 = 1. Thus, the predicted output is the previous sample.
28. 28
Delta Modulation (DM)…(3)
Two types of quantization error:
(2) Granular noise(1) Slope overload distortion/noise
Comments:
(1) For avoiding slope overload distortion: larger Δ is desired
(2) For avoiding granular noise: smaller Δ is desired
An optimal step size (Δ) has to be chosen for minimum overall noise
mq(t)
eq(nTS)
Example:
s
s
mm f
T
Atm
max|| tAtm mm cos
m
s
m
f
A
max
r
s
Voicem
f
A
max
8002 r
29. 29
Line Coding (1)
PCM, DPCM and DM are different strategies for source
encoding, which converts an analog signal into digital form
Once a binary sequence of 1s and 0s is produced, the
sequence is transformed into electrical pulses or
waveforms for transmission over a channel and this is
known as line coding
Multi-level line coding is possible
Various line coding
(binary) methods:
(0 means transition)
(f) Split-phase
or Manchester
Or RZ-AMI
Or NRZ-L
30. 30
Line Coding (2)
Book:
Digital Communications:
Fundamentals and Applications
- Bernard Sklar
Applications:
Polar NRZ / NRZ-L: Digital logic circuits
NRZ-M/NRZ-S: Magnetic tap recording
RZ line codes: Base band transmission and magnetic recording (e.g., Bipolar RZ / RZ-AMI
is used for telephone system)
Manchester Coding: Magnetic recording, optical communications and satellite telemetry
Polar NRZ /
31. 31
Line Coding (3)
Desired properties (i.e., design criteria) for line coding:
Transmission bandwidth: should be as small as possible
Noise immunity: should be immune to noise
Power efficiency: for a given bandwidth and given error probability, transmission power
requirement should be as small as possible
Error detection and correction capability: should be possible to detect and correct errors
Favorable power spectral density (PSD): should have zero PSD at zero (i.e., DC)
frequency, otherwise the ac coupling and the transformers used in communication systems
would block the DC component
Adequate timing information / self-clocking: should carry the timing or clock information
which can be used for self-synchronization
Transparency: should be possible to transmit a digital signal correctly regardless of the
patterns of 1’s and 0’s (by preventing long string of 0s and 1s)