AC POWER LINE CARRIER COMMUNICATION - · PDF fileA PROJECT REPORT ON AC POWER LINE CARRIER...

A PROJECT REPORT ON

AC POWER LINE CARRIER COMMUNICATION

BY

Dinesh AutiNikhil Asawadekar

Rohan ShroffRohankumar Samal

Under the guidance of

Prof. Sachin Charbhe

Submitted as a partial fulfillment of

B.E.(Semester VIII), Electronics EngineeringFrom

RIZVI COLLEGE OF ENGINEERINGBANDRA(W), MUMBAI - 400 050.

UNIVERSITY OF MUMBAI.FOR THE ACADEMIC YEAR 2011-2012.

CERTIFICATE

This to certify that the project report certified“AC POWER LINE CARRIER COMMUNICATION”

Submitted by

Dinesh AutiNikhil Asawadekar

Rohan ShroffRohankumar Samal

of Rizvi College of Engineering Electronics Branch has been approved in partial fulfillment of requirement for the degree of Bachelor of Engineering.

Prof. Sachin CharbheInternal Guide

Prof. Nargis Shaikh Dr. Varsha Shah(Head of the Department) (Principal)

Internal Examiner External Examiner

ACKNOWLEDGEMENT

It is with great pleasure that we are submitting this report on “POWER LINE CARRIER

COMMUNICATION”. As in case project, we faced many problems while giving shape to

our ideas and making the project mold into reality.

We take this opportunity to express our sense of gratitude towards our internal guide Prof.

Sachin Charbhe for his valuable suggestions and guidance from time to time. We have

received constant support from Principal Prof. Varsha Shah, who has always encouraged

us to be innovative in our approach. We are also thankful to the head of department, Prof.

Nargis Shaikh and the remaining staff for making facilities available and giving their

support and guidance.

We express our sincere thanks to Prof. Ramkumar Maurya and Prof. Amit Redkar for

their apt advices and their valuable time that helped our project gain the desired form and

bring our ideas to reality. Guidance from Executive Engineer S.S.Lokare (MSEB, Airoli)

and Bhargav Thakkar (Technical Head at ABB Corporation) added to our conceptual

understanding of PLC systems.

Although we have not mentioned each name, we would like to say that we appreciate

every individual who was associated with our project and made experience satisfying and

fulfilling one.

iii

ABSTRACT

Our project aims at introducing an old technology in a new way. As an alternative to

existing communication systems. Traditional Power Line Communication (PLC) is

widely used to provide real-time communications for protection of high voltage

transmission lines. PLC is often the most economical and reliable high-speed dedicated

channel available for protective relaying. PLC system is mainly used for managing the

high voltage link and for communications between different substations.

Our project PLCC, Power Line Carrier Communication, is an approach to utilize the

existing power lines in the house or office for the transmission of information. Every

house and building has properly installed electricity lines. By using the existing AC

power lines as a medium to transfer the information, it becomes easy to connect the

houses with a high speed network access point without installing new wiring.

A power line carrier system includes three basic elements: a transmission line, presenting

a channel for the transmission of carrier signal between two communicating nodes.

Transformers and coupling equipment, providing a means of connection to the high-

voltage transmission line and to provide electrical isolation between power line and

circuitry. Transmitters and receivers circuitry . The simplified functional diagram of a

power line carrier system is shown and explained further in the report.

iv

List Of Figures

Name Of Figure Page No. Illustration No.

PLC Modem 7 1

PLC Modem Circuit 7 2

Block Diagram of PLCC 9 3

RGB VI Block Diagram 13 4

4RGB Front Panel 13 5

Hamming Code Encoder 14 6

G Matrix 15 7

G Matrix Front Panel 16 8

Hamming Code Encoder Output

16 9

XR 2206 Modulator 18 10

FSK Modulator Board Layout

18 11

Modulator Output (f1) 19 12

Modulator Output (f2) 19 13

Basic Coupling Circuit 20 14

Coupling Circuitry 21 15

Output (L=75%) 22 16

Output (L=25%) 22 17

Measuring Impedance Of Power Line

23 18

Impedance vs Frequency 24 19

Attenuation Measurement 24 20

Attenuation Survey 25 21

FSK Demodulator Schematics

29 22

FSK Demodulator Board Layout

29 23

Syndrome Matrix 32 24

Decoding Process 33 25

Parity Matrix 34 27

v

Parity Check Matrix 35 28

P and HT Matrix 35 29

Possible Error Patterns 36 30

Hamming Decoder 36 31

Original Message 37 32

Corrected Output 37 33

Transmitter Side 38 34

No Transmission Error 38 35

Single Bit Transmission Error

39 36

Two Bit Transmission Error 39 37

Multi Bit Transmission Error

39 38

vi

List Of Tables

Table Page No. Table No.

PLCC & Comparison 5 1

Syndrome Table 33 2

Modulator Components 43 3

Demodulator Components 44 4

Miscellaneous 44 5

vii

List Of Symbols & Abbreviations

Symbol Description

k Message bits

q Check Bits

n Code Word Length

M Message Vector

HT Parity Check Matrix

X Code Vector

Y Output Vector

G Generator Matrix

S Syndrome Vector

E Error Vector

C Check Bits Vector

RC Code Rate

IK (Identity Matrix) K * K

P Parity Matrix

SIndex Syndrome Index

CENELEC European Electro Technical Standards Committee

PLC Power Line Communication

PLCC Power Line Carrier Communication

PLL Phase Locked Loop

BPS Bits Per Seconds

ULP User Language Program

viii

Table of Contents

Acknowledgements........................................................................................................iii Abstract.........................................................................................................................iv List of figures.................................................................................................................v List of tables.................................................................................................................vii List of Symbols and abbreviations..............................................................................viii

1. Introduction............................................................................................................1

2. Literature Survey....................................................................................................22.1 PLCC Paper Analysis.......................................................................................22.2 Site Survey........................................................................................................4

3. Market Study.......................................................................................................... 53.1 Need According to Customer Point of View................................................... 5

3.1.1 Advantages Over Other Communication Systems............................63.2 Product Analysis & Study.................................................................................7

4. Block Diagram .........................................................................................................94.1 Block Description.............................................................................................10

5. Circuit Explanation................................................................................................12 5.1 Random bits generator......................................................................................12 5.2 Hamming Block Decoder.................................................................................14

5.3 Modulators........................................................................................................175.4 Coupling Circuitry............................................................................................205.5 Power line Characteristics................................................................................235.6 Receiver Side Coupling....................................................................................265.7 Demodulator.....................................................................................................275.8 Hamming Decoder............................................................................................30

6. Tools Used................................................................................................................406.1 Softwares used................................................................................................406.2 Hardware used................................................................................................44

7. Conclusion...............................................................................................................48

8. PLM v1.0 …............................................................................................................49

9. Applications............................................................................................................50

10. Future Scope.........................................................................................................53

11. References..............................................................................................................54

Index..............................................................................................................................55

Chapter 1 Introduction

1. Introduction

Data Transmission in the twentieth century mainly meant the transmission of

telephonic data over the wires. This had many disadvantages. Telephonic Equipment is

comparatively costlier. Telephone Circuits were often unreliable. Telephone Lines were

found to be unable to sustain the harsh weather conditions in the mountainous terrain and

the extreme weather. In addition the electrical interference between the parallel power

lines and the telephone lines was a case of concern. On the flip side the power Lines were

much more robust and reliable. Since power Lines were already available it made much

more sense to use them rather than investing in the making of new lines. Power Lines

Communication gained a lot of ground in the early twentieth century. The advantages

that were offered by the implementations of this technology and its social and economic

impacts led to many companies investing in this technology and using it in their own grid.

These Companies (GE, WestingHouse and much later AT&T) pioneered the development

of this technology. Today Data Transmission through Power Lines has covered a lot of

ground from its inception. It is available at a much lower cost and in a much compact

design.

1

Chapter 2 Literature Survey

2. Literature Survey

2.1 PLCC Paper Analysis

“ A Power Line Communication Tutorial - Challenges and Technologies ”

The Power Lines available today were built for the purpose of power transmission from

one place to another. The attempt to transmit data over these power lines leads to the

reception of a lot of noise. This noise is due to the numerous devices connected to the

power lines. An analysis of this noise and their characteristics helps us better understand

how to tackle the problem of noise elimination in the Power Lines. The characteristics of

the modulation techniques and their subsequent analysis gives us an idea of the

advantages and disadvantages of each technique. The receiver contains a phase locked

loop. We studied the modulation techniques and compared their performance in the

present of noise. Finally Spread Spectrum technology is reviewed for the use of

communications on Power Lines. Spread Spectrum is a method of signal modulation

where the transmitted signal occupies a bandwidth considerably higher than the minimum

necessary to send the information and some function other than the information being

sent is used to increase this Bandwidth. Spread Spectrum was found to be unsuitable and

rather detrimental for the PLCC system. Inference : After carefully studying the various

technology we infer that Digital Signal Processing is absolutely necessary for the system

to function efficiently. Spread Spectrum is found to be having a negative impact on the

output and hence should be avoided. FSK is found to be the most immune to noise and

hence chosen for our project.

2


“ Design Of Domestic Power Line Communication ”

This report discusses the power-line communication over the low-voltage grid, which has

A very high potential growth in the near future. The main advantage with power-line

communication is the use of an existing infrastructure. Wires exist to every household

connected to the power-line network. This report starts with a general introduction to

power line communication. Then it discusses the application of an existing home

automation system, then communicating over a low-voltage grid is investigated in order

to obtain some knowledge of how the power line acts as a communication channel. The

power-line communication channel can in general be modeled as a system with frequency

dependent signal-to-noise ratio varying with time over the communication bandwidth.

Finally we describe the basic parts of the system that eventually could be used for

information transfer over the power-line communication channel.

3


2.2 Site Survey

The best way to study any technology is to take guidance from the people who are

working in similar field. We came to know that Maharashtra State Electricity Board

(MSEB) and ABB Corporation are the two giants in the industry who use similar

technology. So our first step was to take help of technical experts working there in order

to tackle problems we are going to face.

We went to MSEB (Airoli) where Executive Engineer S.S.Lokare Sir helped us a lot to

make us aware of how PLCC actually works. He gave us examples of different sub-

stations situated near Navi-Mumbai & Mumbai area and explained us how actually power

flows from one sub-station to another via gantries and also how the main station situated

at Airoli controls everything. He also explained us how voice data travels through the

power line and showed us technical aspects of the same. He backed us for our project and

ensured that digital data can be made to flow over power line. By using modulation

techniques.

When we started struggling with coupling and isolation related problems we visited ABB

Corporation to take some help. We had surfed on the net that ABB works with PLCC

Technology. A visit to ABB was indeed of lot of help and support. Technical Head at ABB

Mr. Bhargav Thakkar helped us explaining how PLC Systems work on broader context.

He told us that for coupling purpose Current Voltage Transformer (CVT) which costs in

lakhs and is used to block the AC Power signal coming into the transmitter/receiver

system. Also we came to that Line Matching Unit (LMU) is used in PLCC which is used

to match the impedance of input and output circuitry and building prototype for it is not

possible. But he also ensured that for general prototype as a final year project a coupling

circuitry can be used instead. which consist of capacitors and inductors. This really

boosted our confidence and we started working accordingly.

4

Chapter 3 Market Study

3. Market Study

3.1 Need According to Customers Point of View

PLCC system in the market will have to compete against telephone and intercom

systems. PLCC system has the potential to outperform telephone and intercom systems.

As these systems require additional resources and installations. Which incur a lot of setup

cost. Plus the additional wiring makes system bulky and unportable. Whereas a power

line system does not incur any setup cost has no additional wiring and can perform rather

more efficiently than the conventional telephone and intercom systems. With the help of

PLCC system one can transmit and receive data as well as voice signals. PLCC is a plug

and play kind of system which can be plugged into any electric socket and

communication can be established within a same building or nearby areas. The customers

will be required to buy a PLCC system adapters which is a one time cost and can be used

for lifetime. Also the size of adapters is small which makes it easily portable unlike

telephone or intercom. So the user can take these adapters to a new place or new office

and the system is established within no time. All the user has to do is to plug the adapters

in sockets in the rooms he/she wants. Considering the above stated merits PLCC system

is certainly the best fit in today’s modern age. PLCC systems completely fit the need of

the customers as it eliminates the shortcomings of the conventional system. Now the only

concern according to customer point of view is the cost factor. Lets see the cost wise

analysis of PLCC system with telephone and intercom.

Intercom Telephone PLCC

Cost/unit( in Rs) 1650 500 + service tax* + installation charges

+ monthly rental

1350

Cost after one year/unit(in Rs.)

1650 12 X (service tax* + monthly rental)

1350

5


3.1.1 Advantages Over Other Communication Techniques

PLCC uses existing power line for communication so it provides many advantages over

traditionally used telephone models and other communication systems. The main

advantage of power line carrier communication is cost on infrastructure is reduced to a

large extent. Consider any building or company office as an example. To supply

electricity for the whole structure first Mains cables are dropped throughout the building

and it bears all the load thruster by fridge , fans and all the other equipments or devices

run on electricity. If PLCC modem is used in such an area , no additional wiring or

cabling is required as PLCC uses this power line only. Data is sent on this with

equipotential coupling circuitry using modulator and it's retrieved at the receiver's side

using demodulator. Thus elimination of wiring or cabling is the biggest bliss in

communication system. This is also a flexible type of service which can have different

formulations as per the need or application. Half duplex PLCC or Full Duplex PLCC

modems are available. Thus they are now greatly used in houses and small office

networks. It is also considered asx a replacement to intercom as it doesn't need any extra

cabling.The biggest relief to the customers is when you talk about installation charges and

service tax. Apart from initial installation charges , user doesn't need to pay service tax

and government taxes for it as he's using existing power line only for communication.

With built-in Error Checking and direct interface with uc as an ad-on , it's the biggest

source of Research and Development since last 50 years. With other applications like

Automatic meter reading , Fire & Security Alarm Systems and Lighting Control this

serves as the major Integration for all the tasks that can be computed easily. With the

invention of new modems such as PLC Modem from Sunrom Technologies , care has

been taken that though using a same platform for transmitter and receiver side , high

power side and low power side are isolated so chances of shock hazards are reduced to

large extent and device is made more user friendly.

6


3.2 Product Analysis

The successive step in study of PLCC is to have a glance on devices which are

using this technology. Technical Experts from ABB Corp and MSEB suggested us two

such devices mentioned below.

This device which supports Windows XP/Pro , Linux OS is like a home plug adapter in

the power line network for signal transmission, to achieve any power outlet next to

Internet . With data rate 200Mbps and working temperature range -20 to -60 degrees , this

serves as easy to connect, easy to use, plug and play device for home and small office

networking environment.

The above device has built-in on board AC isolated coupling circuit, which allows direct

and simple connections to mains. Due to isolation on AC part, there is no worry to get

7

Illustration 1: PLC Modem

Illustration 2: PLC Modem Circuit


shock on the low voltage side when working with it. So it's user friendly device. It has

high immunity to electrical noise persistence in the power line and built in error checking

so it never gives out corrupt data. It transmits and receives serial data at 9600 bps.

Transmission is based on byte by byte basis. Once you give one byte to module for

transmission, you will have to wait at least 500ms before a new byte is given to module

again since the module waits for zero crossing of AC mains to transfer a bit. For AC 50Hz

system the zero crossing of AC signals happens every 10ms and modem needs 50 zero

crossings to transmit one byte with error checking data. That is why it takes 500ms for

one byte. As a half duplex system it normally operates in Receiver mode , once your

application gives serial data to transmit on its RX-IN pin, it switches over to transmit and

transmits the data through power line. Due to low cost , built in error checking, it's mainly

used for Home Automation and Process Control.

8

Chapter 4 Block Diagram & Description

4. Block Diagram & Description

4.1 Block Diagram

9

Illustration 3: Block Diagram Of PLCC


4.2 Block Diagram Description

This block diagram explanation will give the basic idea about the flow of data from

one user to another. It will give the general idea about the processing that the data

underwent from one section to another. Following is the end to end jest of the project. We

first generated a sequence of random bits with the use of Labview. This will act as the

data given by the user which is to be transmitted to the receiver. Random bits are

generated for illustration purpose. Random bits generator can generate bits form 4 bit to

as many bits desired. These random bits which is considered as data cannot be directly

sent over the power line because the data is bound to introduce an error due to noise

present on the power line. Noise on the line cannot be curbed but the error introduced can

be detected and corrected. For that Hamming codes are used which is capable of detecting

multiple errors but can correct multiple errors. In hamming code check bits are appended

at the end which will help the receiver to correct the error if any. Now we have a bit

stream of data and check bits. We need an interfacing device will will help us interface

the labview which is on the computer with the FSK modulator. That job is done by

arduino. Arduino takes the bit stream from the computer and generates the same bit

stream from one of its output pin. This stream of bits is now given to FSK modulator

which will convert the digital data to analog form so that it can be sent over a power line.

This is done because if digital data is sent over any channel then it will consume lot of

bandwidth and the signal will also get corrupted very easily. FSK modulator converts

logic 1 to sine wave of 2200Hz and logic 0 to sine wave of 1200Hz We have used XR

2206 as our FSK modulator. Now our information in in the frequency of the sine wave.

Noise on any channel affects frequency the least. So our data is safe But the power line is

of high voltage so care has to be taken so that the high voltage does not enter the

transmitter circuitry. For that coupling is done .Coupling provides the necessary isolation

between low and high voltage.

10


The functioning of the receiver side blocks is the exact opposite as that of transmitter

side. The coupling circuitry on the receiver side not just provides the isolation but also

acts as a tuned circuit will allows only the high frequency in a selected band i.e. between

800Hz to 3000Hz to enter the receiver side. The FSK demodulator doe the exact opposite

of FSK modulator. It decodes the two frequencies into respective 1's and 0's. We have

used XR 2211 as or FSK demodulator. For the FSk demodulator to detect the input signal

it should be greater than 10mV. But not exceeding 3Vrms. Arduino is used for interfacing

the demodulator with the labview. The hamming decoder in Labview will detect and

correct error if any. by using the check bits. The hamming decoder can detect multiple

errors but correct only single bit errors. After the corrected code word is received the

decoder will remove the check bits so that the original data transmitted is extracted from

codeword and displayed.

11

Chapter 5 Circuit Explanation

5. Circuit Explanation

The PLCC system has been shown in the form of a block diagram representation in

illustration 3. The description below provides a flow of data from its origin to its

destination. Each block will be explained but importance will be given to its

implementation in the system above. First, let's take a look at the origin of data i.e.

possible sources of data and the form in which the data is available. The input to the

above system will be in the form of one's & zero's, so the analog counterpart needs to be

converted to its appropriate digital equivalent via suitable methods (not listed in the block

diagram). While doing so care has to taken that the baud rate must remain appropriate so

as to not violate the modulators design constraints.

Before starting it is assumed that the data at the input of the system is digital. Also

the code provided is graphical & is simulated in LabVIEW development environment.

Following is the block by block introduction to the system.

5.1 Random Bits Generator (RBG)

It is purely for simulation purposes that instead of giving any particular data, a

random bits stream is applied at the input of the system. It is based on the principle of

Bernoulli's noise. It generates a pseudo random sequence of one's & zero's depending on

the probability p, which is given as a input. For example if p=0.7 then there is a 70%

probability that the outcome of the Bernoulli's noise generator is 1.

P(X = i) = pi(1 – p)^(1 – i) (i = 0, 1)

Bernoulli noise is a special case of Binomial noise.

12


We will make a RBG in LabVIEW with the Bernoulli's noise VI (Virtual Instrument)

found in the Signal processing Toolkit. Below is the snapshot of the RBG.

The input to the Bernoulli's noise VI is the number of samples, which has a default

value of 128. The value of p is 0.5 (not shown). At the output a not equal to block is used

to convert the output of Bernoulli's noise to one's & zero's.

This the output snapshot of Bernoulli's noise showing a random bits pattern in

binary format. Now the output from the RBG is given to an Hamming coder, which will

provide the required noise immunity to our data. This is called as channel coding.

13

Illustration 4: RBG VI Block Diagram

Illustration 5: RBG Front Panel


5.2 Hamming Block Encoder

Hamming code is a type of linear block code. A block of data has 'k' message bits

and 'q' check bits. A random bits stream enters the hamming block encoder and output is

data packets each of size 'k+q'. This 'k+q' is denoted by 'n' and is called the block size.

Where,

n = 2q - 1 ; n>q

k = n - q

These codes have d min = 3, which means that they can detect up to two errors or correct

one single error. For example, if k=4 & q=3 then n =7. This represents a (7,4) hamming

code [6].

Code rate : It is defined as message length divided by code word length.

Code Rate = Rc = k/n ;

Higher the code rate is better and becomes more efficient

M = message vector = ( m1, m2, m3,....)1xk

C = check bits vector = ( c1, c2, c3,.......)1xq

X = Code vector = (M | C)1xn

14

Illustration 6: Hamming Code Encoder


The input is q & k , which is given to the G matrix generator to produce a G matrix.

The G matrix is then multiplied to a message matrix M which gives the final code words

matrix. Note that proper care is to taken for matrix multiplication [8].

Where,

G = ( Ik | P)kxn

Ik = Identity matrix (kxk)

P = Parity matrix

The P matrix introduced here consists of q bit words with hamming weight at least 2, arranged in any order.

X = MG

Below is the code for G matrix

The inputs to the G matrix is k & n. Below is the output with k =4 & q = 3. Readers

should note the 4x4 identity matrix. The first four coloums consist of an 4x4 identity

matrix and remaining three coloums consists of two or more one's as stated before.

15

Illustration 7: G Matrix


Consider any one of the sixteen 4 bit messages Let's say M = (0110). Then for values of k

= 4 & q = 3, we get the following code word as shown in the snapshot below.

The important thing to note here is that the matrix multiplication between M & G is

a modulo 2 multiplication.

16

Illustration 8: G matrix Front Panel

Illustration 9: Hamming Code Encoder Output


5.3 Modulator

Let’s consider the Modulator. Modulation is the technique of forwarding low frequency

baseband signal to high frequency bandpass signal. The need of modulation here is to

mainly transform digital signal into equivalent analog signal using a form of modulation

known as Frequency Shift Keying (FSK). XR-2206 is a function generator IC which can

produce stabilized modulated FSK waveforms at frequencies ranging from 0.01 Hz to

1MHz.The XR-2206 is comprised of four functional blocks; a voltage-controlled

oscillator (VCO), an analog multiplier and sine-shaper; a unity gain buffer amplifier; and

a set of current switches. It offers output impedance in the range 600Ω + 10% .

The Mark and Space frequencies can be independently set by the choice of timing

resistors R1 and R2 respectively and the capacitor C0. So depending upon our

requirement we can select proper values of design variables [2]. C0 is chosen as 0.1uf and

from this we have evaluated the values needed for Mark and Space frequencies i.e R1 =

8.333KΩ and R2 = 4.545KΩ

17


Below is a schematic of the XR2206 Modulator from Exar.

The PCB Layout of the above modulator schematic is shown below.

18

Illustration 10: XR2206 Modulator

Illustration 11: FSK Modulator Board Layout


Output of the Modulator :

Following are the screen-shots of the DSO which was connected at the output of the

modulator.

19

Illustration 13: Modulator Output (f2)

Illustration12: Modulator output (f1)


5.4 Coupling Circuitry

A coupling circuit is used to connect the communication system to the power-line. The

purpose of the coupling circuits is two-fold. Firstly, it prevents the 50 Hz signal, used for

power distribution, to enter the equipment. Secondly, it certifies that the

receiver/transmitter circuit is tuned to work in a particular band of frequency. This

increases the efficiency of the receiver and makes sure that the receiver does not detect

any unwanted signal. The transformer in the coupling circuitry provides the necessary

impedance matching as well. The output of modulator which is a high frequency

bandpass signal is fed to the coupling circuitry which consist of transistor 2N2222 which

acts as a valve that allows only the high frequency modulated signal from the modulator

to reach the power line and block the 50Hz from entering the modulator circuitry. The

coupling circuit also incorporates a tank circuit which has a precharge capacitor so that

the oscillation amplitude remains steady. The frequency output of the tank circuit can be

tuned to a desired one by varying the inductor value of the slug-tuned IF(Intermediate

frequency ) transformer. The output frequency value depends upon the inductor and

capacitor value. The capacitors in series helps to attenuate the 50Hz signal and allow high

frequency from the tank circuit to pass through retaining its full strength [1].

20

Illustration 14: Basic Coupling Circuit


The circuit shown in illustration14 is explained above. The illustration below is a

snapshot of the simulation the coupling circuit. Illustration13 & 14 are the outputs of this

circuit for different values of inductor. The voltages and current at various nodes are

shown in the figure below.

21

Illustration 15: Coupling circuitry


Illustration 16 shows the condition when the value of the inductor is set to approximately 75% of its value. The attenuation of the sine wave for this value is negligible.

Illustration 17 shows the condition when the value of the inductor is set to approximately 25% of its value. The attenuation of the sine wave for this value is considerably satisfactory.

22

Illustration 16: Output (L = 75%)

Illustration 17: Output (L = 25%)


5.5 Power Line Characteristics

Impedance and attenuation measurements are performed on the loaded power lines

into three categories: rural, urban and the industrial power lines. Impedance of the power

lines looked at a wall receptacle in research building is measured by the circuit shown in

illustration 18. The frequency range of measurement is selected between 10 kHz and 150

kHz because these frequencies belong to the CENELEC bands. The measurements system

is described in illustration 18. A signal generator (SG) is used to simulate PLC carrier

signal and an AC millivoltmeter is used to measure the values of voltages: V1, V2 and V3

are shown in the circuit diagram. In the circuit, a coupling transformer T, and the coupling

capacitor C , are added to the measurements system because of this component should be

used on the PLC. Every modem must consist a coupling transformer and a coupling

capacitor to send or receive carrier from or to power lines. So, T and C are necessary

elements on the power line communications.

Power line impedance is a very important parameter on the design of power line

communications modem architecture. Variations on the impedance of the power line

affect the communications circuit performance. In order to determine impedance of the

power lines, measurements were carried out in Turkey at frequencies ranging from 10 to

170 kHz . Measurements were conducted in three categories: rural, urban and the

industrial power lines. The measured impedances were determined as 4-21 ohms for

urban. Here is a resonance and a local max at 60 kHz for urban power lines and

impedance of 4 to 12 ohms at 60-80 kHz bands at the urban power lines. After 80KHz the

impedance increases.

23

Illustration 18: Measuring Impedance of Power Line


Attenuation measurements are made using the hardware layout shown in illustration 20.

Two transceiver modems are used, one of them is a transmitter, the other one is the

receiver. T1 and C are the coupling transformer and coupling capacitor on the transmitter

modem and the others T2 and C are the same components on the receiver side. An AC

millivoltmeter is used to measure V1 and V2 voltages in order to calculate signal

attenuations on the along the power lines. Experiments on signal attenuations of the

power line are realized at different parts of homes. The parameters of the signal

attenuation measurements are line length, carrier frequency, the numbers of connector

box. The conductors of phase-neutral, phase-ground and neutral-ground may be used as

the communication channels. Normally phase-neutral conductors are used as PLC

channel, but in this study other ground conductor also observed. The reason of the

selection different channel ways is to examine the characteristics of the possible channels

in the PLC[7].

24

Illustration 19: Impedance vs Frequency


Phase-neutral power line channel in rural area has more attenuation with respect to other

phase- ground channels and neutral-ground channels up to frequencies 120 kHz, is shown

in illustration 21. Attenuation measurements in rural power lines are carried out at the

different plugs in the normally loaded homes. Selected homes are similar the each others

with about 120 m2. Attenuations are observed between 4-19 dB. Urban homes are

normally located at the city centers. Illustration 21 shows that power lines attenuations in

the urban decrease versus frequency after 70 kHz. Attenuation value may raise up to 23

dB in urban areas. Attenuation measurements at the all the different PLC channels such as

rural, urban and the industrial power lines are given in illustration 21 Measured o

attenuation values at the industrial power lines are bigger than rural and urban due to

heavy loads in this kind of power lines. These measurements are made inside homes

between different plugs on the wall, so line length is small such as a few ten meters.

These results may be used at the home automation modems via PLC.

25

Illustration 20: Attenuation Measurement

Illustration 21: Attenuation Survey


5.6 Receiver Side Coupling

Coupling at receiver side also performs the same job as that of transmitter side that to

block high voltage 50Hz and allow low voltage, high frequency carrier signal to pass

through. The circuitry and the role of the components in the circuit are exactly the same.

A coupling circuit is used to connect the communication system to the power-line. The

purpose of the coupling circuits is two-fold. Firstly, it prevents the 50 Hz signal, used for

power distribution, to enter the equipment. Secondly, it certifies that the

receiver/transmitter circuit is tuned to work in a particular band of frequency. This

increases the efficiency of the receiver and makes sure that the receiver does not detect

any unwanted signal. The transformer in the coupling circuitry provides the necessary

impedance matching as well.

The output of modulator which is a high frequency bandpass signal is fed to the coupling

circuitry which consist of transistor 2N2222 which acts as a valve that allows only the

high frequency modulated signal from the modulator to reach the power line and block

the 50Hz from entering the modulator circuitry. The coupling circuit also incorporates a

tank circuit which has a precharge capacitor so that the oscillation amplitude remains

steady. The frequency output of the tank circuit can be tuned to a desired one by varying

the inductor value of the slug-tuned IF(Intermediate frequency ) transformer. The output

frequency value depends upon the inductor and capacitor value. The capacitors in series

helps to attenuate the 50Hz signal and allow high frequency from the tank circuit to pass

through retaining its full strength.

26


Receiver Side :

The receiver side starts with a coupling to the power line. This is essential because

we need to separate low voltage circuit from high voltage power line. The coupling part

explained in the above section. After the coupling we need step down transformer to step

down the 230V voltage to 12V required by the receiver circuit to operate. Another main

reason for the transformer is to isolate the low power circuit from the high power circuit.

The low voltage step down signal is then passed to a tuned circuit, which will allow only

a select band of frequencies to pass. Arrangement for the above explanation is shown in

illustration 13. The signal that we get after the above step is then required to be

demodulated and then decoded. The demodulation is done using XR2211 FSK

DEMODULATOR from Exar Corporation. A hamming decoder is used to decode the

message.

Below is a block by block explanation of the receiver side.

5.7 Demodulator :

The XR -2211 is a Phase Locked Loop (PLL) integrated circuit especially designed

for data communication and particularly suited for FSK applications. It operates over a

frequency range of 0.01 Hz to 300KHz and can accommodate analog input signals

between 10mV(RMS) to 3V(RMS) [3]. Frequency shift keyed input signals fed into pin 2

of the XR-2211 must be capacitively coupled through a 0.1uf capacitor. The internal

impedance is 20K and the minimum recommended input signal is 10mV. The first order

of business is to set center frequency of the demodulator passband at the center of

frequency band that we wish to detect. For showing a prototype we have chosen center

frequency 1624 Hz. Mark frequency we have selected is 1200 Hz and space frequency is

2200 Hz. The center frequency of the two frequencies is 1624 Hz. The component values

are computed as follows.

27


f0 = 1/(R0*C0).

where R0 is 15.788K. The value of R0 is adjusted by using a 10K resistor and a variable

pot for fine adjustment. The value of C0 is chosen as 39nf. R1 sets the system bandwidth

and C1 states the loop filter time constant. and damping factor. The value of R1 is

determined by Mark and Space frequencies .

R1 = (R0*f0) / (f1-f2).

The value of C1 is chosen approximately as C0/4. The Resistor Rb provides positive

feedback across the fsk comparator and facilitates rapid transition between output logic

states. Cf and Rf form a single pole post detection filter for FSK data output. Rf is most

often set at 100K and Cf smooths the data output. Its value is roughly calculated [1].

Cf = 3/(Data Rate in Bits per second).

Because this modem is designed for operation at 1200 BPS , a value of 2.2nf is

acceptable.

28


The schematics of the XR2211 is show below.

Illustration 23 is the board layout of Demodulator using XR2211.

29

Illustration22: FSK Demodulator Schematics

Illustration 23: FSK Demodulator Board Layout


The output of the demodulator is in the form of ones & zeros. In order to read the values

of the demodulator we need a micro controller, which would properly interpret the

demodulators output so that it can be further processed & message can be decoded.

5.8 Hamming Decoder :

As shown below the generator matrix is used to generate a Code word from

message. If we use an ideal channel i.e. no transmission errors then the transmitted code

word should be equal to the received code word. But in reality this may not be the case.

There may be single bit or multiple bit errors. Errors are denoted by error vector E as

shown below. Error vector is the list of all possible error patterns that can be introduced

during transmission.

We know that the G matrix is represented as an augmentation of identity matrix and a

parity matrix as shown below

G = ( Ik | P)kxn

Ik = Identity matrix (kxk)

P = Parity matrix

30

Message

Error Vector

Received Code WordM X

E

Y

Code Word

G


The corresponding equivalent in the decoder is the Parity Check Matrix HT . The

parity check matrix is also a combination of an identity matrix and a parity matrix but

they are stacked one below the other as shown below

HT = ( P / Iq )n x q

One of the most important properties of the Parity Check Matrix HT is that modulo

2 multiplication of X and HT is always a zero vector. The only condition that is

required to be fulfilled is that X should be a valid code word.

Symbolically,

( HT )*( X ) = {0,0.........0}

This becomes the basis for error detection. In simple words if X is not a valid

codeword the product is going to be a non zero value.

We next define a matrix called as Syndrome Matrix denoted by 'S'

S = Y * ( HT )

Syndrome Vector is a 1/Q matrix.

Y is a 1/N matrix and H is N/Q matrix.

Consider Y = X+E

E = Vector of error patterns

X = Transmitted code word

Substituting value of Y in above equation , we get

S = (X+E) * ( HT )

S = X*( HT ) + E*( HT )

Note that addition in the above equation is Modulo2 addition.

31


From the above theory we know that X*( HT ) = 0.

Therefore S = E*( HT )

Suppose S = (00....) , this has two possible interpretations.

1. There are no transmission errors in the received codeword. Thus E = 0.

2. Occurrence of an undetectable transmission error that is Y appears to look like a

valid codeword.

Whenever S is not equal to zero , we say that error has been detected.

That error can be single bit error or multiple bit error.

Hamming code is a type of block code in which we can detect up to two bit errors

and correct upto one bit.

Since our syndrome has q bits , there are 2q possible syndromes and 2n possible error

patterns.

For eg. In our case ,

q = 3 for a (7,4) hamming code.

23 = 8 Syndrome patterns and 27 = 128 Error patterns.

Therefore we get 16 (128/8) , different errors produce the same syndrome.

That is not all errors can be corrected.

We adopt a procedure called as Maximum Likelihood Decoding wherein

1. 0 errors is most likely

2. Single bit error is next most likely.

We need to associate each possible syndrome with its most likely error pattern.

32

Illustration 24: Syndrome Matrix


In the above block diagram , we use the received codeword as the input in order to

calculate 'S'. Then we use a notation called as Syndrome Index Si which is used to point

to the suitable error pattern in the table of error pattern. The output of the table of error

patterns is E^. This E^ is our best possible guess of the position where the error has

occurred. Now we perform a modulo2 addition of E^ and the received codeword Y to get

the corrected code word X.

Syndrome (S) Error pattern (E)

000 0000 000

001 0000 001

010 0000 010

011 0010 000

100 0000 100

101 0100 000

110 1000 000

111 0001 000

Above table illustrates the Syndrome tables and the corresponding Error vector values.

33

Illustration 25: Decoding Process


Thus using concept of syndrome and the possible error vector values we are able to

correct the received code word which has up to single bit of error.

Following is a graphical code snapshot of the Parity Check Matrix HT .

As we can see in the illustration above we need the Parity Matrix as the input to

generate the parity check matrix. Consider the Parity matrix shown below

The parity matrix shown above consists of all the three bit values that contain one

or more than one 1's.

34

Illustration 26: Parity Check Matrix

Illustration 26: Parity Matrix


The parity check matrix is a (n x q) matrix as shown below. It is represented as

follows

HT = ( P / Iq )n x q

35

Illustration 28: Parity Check Matrix

Illustration 29: P and HT Matrix


List of all possible error patterns that can occur in a (7,4) hamming block code.

Figure below shows the entire decoder in a graphical form.

36

Illustration 31: Hamming Decoder

Illustration30: Possible Error patterns


Let's say that we send an encoded message shown in illustration 28 via the power line

towards the receiver. The encoded message consists of a 4-bit message and a 3-bit check

bit.

Below is an example of M = 0110 011.

Wherein,

m = 0110 ; message bits (4)

q = 011 ; Check bits (3)

The message that has been encoded i.e. m = 0110 is one of the valid sixteen

message words. Therefore if we assume a error free transmission then the output would

look like as shown in illustration 29.

If a error occurs during transmission then there may be following cases :

1. Single bit error transmission

2. Two bit error transmission

3. Multi bit error transmission

These cases are shown below

37

Illustration 32: Original Message

Illustration 33: Corrected Output


Transmitter side :

The illustration 30 shows the front panel of the transmitter side. The encoded bits section

shows the 7 bits that are to be transmitted serially out of the Power Line Communication

Modem. The figure also shows a boolean representation of the 7 bits encoded message.

The values of k, q and n are as shown in the illustration.

The value of n that is the codeword size depends upon the no. of check bits that are required. In our case, it's k = 4 , q = 3 and n = 7.

Receiver side :

1. No transmission error

38

Illustration 34: Tx side

Illustration 35: No transmission error


2. Single bit transmission error

3. Two bit transmission error

4. Multi bit transmission error

39

Illustration 36: Single bit transmission error

Illustration 37: Two bit transmission error

Illustration 38: Multi bit transmission error

Chapter 6 Tools Used

6. Tools Used

6.1 Softwares Used

1. NI LabVIEW

LabVIEW (short for Laboratory Virtual Instrumentation Engineering Workbench) is a

platform and development environment for a visual programming language from National

Instruments. The purpose of such programming is auto mating the usage of processing

and measuring equipment in any laboratory setup. LabVIEW is a graphical programming

environment used by engineers and scientists to develop sophisticated measurement, test,

and control systems using intuitive graphical icons and wires that resemble a flowchart. It

offers unrivaled integration with thousands of hardware devices and provides hundreds of

built-in libraries for advanced analysis and data visualization – all for creating virtual

instrumentation.

40

LabVIEW


2. Eagle CAD

EAGLE provides quality PCB design software with the features that get the job done. For

over 20 years, EAGLE has been satisfying design engineers around the world, by offering

the same core functionality as expensive commercial software, at the fraction of the cost.

Easy to learn

•Schematic editor, layout editor, library editor modules with identical user interfaces

•Free service support through dedicated experts

•Compatible with Windows®, Linux®, Mac®

Easy to buy

•Purchase and license on-line or with personal support from our distributors

•No maintenance fees or add on contracts

Easy to use

•Flexible User Language Programs (ULPs) enable custom features, such as

individual instruction sequences, simulation, data export and import

•Export Gerber files that can be used at any board house:

•Gerber 274X & Gerber 274D

•Excellon NC Drill Format

•SM1000 and SM3000

•Custom user-defined export formats

•Online import of product & pricing information through DesignLink

•Active customer forums to share files, libraries ULPs, design tips and more

•Parse and paste your data outside of EAGLE (XM datastructure)

41


3. Arduino

Arduino is an open-source electronics prototyping platform based on flexible, easy-to-use

hardware and software. It's intended for artists, designers, hobbyists, and anyone

interested in creating interactive objects or environments. Arduino can sense the

environment by receiving input from a variety of sensors and can affect its surroundings

by controlling lights, motors, and other actuators. The micro controller on the board is

programmed using the Arduino programming language (based on Wiring) and the

Arduino development environment (based on Processing). Arduino projects can be stand-

alone or they can communicate with software running on a computer (e.g. Flash,

Processing, MaxMSP).

42

Arduino IDE

Arduino UNO


4. MultiSim

NI Multisim (formerly MultiSIM) is an electronic schematic capture and simulation

program which is part of a suite of circuit design programs, along with NI Ultiboard.

Multisim is one of the few circuit design programs to employ the original Berkeley

SPICE based software simulation. Multisim was originally created by a company named

Electronics Workbench, which is now a division of National Instruments. Multisim

includes microcontroller simulation (formerly known as MultiMCU), as well as

integrated import and export features to the Printed Circuit Boardlayout software in the

suite, NI Ultiboard.

43


6.2 Hardware Used

Modulator Components

Part Value Package Library Position(inch)

Orientation

C 10uF CPOL-R AD SparkFun (1.6.0.65) R180

C2 10uF CPOL-R AD SparkFun (2.05 1.75) R0

C3 1uF CPOL-R AD SparkFun (0.75 1.6) R90

C4 M01PTH_L CPOL-R AD SparkFun (0.85 0.75) R0

FSKIN M01PTH_L 1X01_L SparkFun (2.35 1.05) R90

FSKOUT M01PTH_L 1X01_L SparkFun (1.1 0.35) R0

Ground M01PTH_L 1X01_L SparkFun (2.35 1.45) R90

Ground 1 M01PTH_L 1X01_L SparkFun (0.5 0.35) R0

JP1 1X01_LS SparkFun (0.3 1.65) R90

R3 200 AXIAL_0.5 SparkFun (1.4 1.6) R0

R4 5.1K AXIAL_0.5 SparkFun (1.8 2.1) R0

R5 5.1K AXIAL_0.5 SparkFun (1.3 1.9) R0

U$1 TRIM_POT SparkFun (2.05 0.35) R90



u1 XR2206 DIL16 SparkFun (1.55 1.15) R0

Total Cost = Rs. 200

44


Demodulator Components

Part Value Package Library Position(Inch)

Orientation

C 0.1uF CPOL_RAD SparkFun (1.1 1.9) R90

C0 27nF CPOL_RAD SparkFun (2 1.8) R90

C1 2.7nF CPOL_RAD SparkFun (2.2 0.4) R0

C2 0.1uF CPOL_RAD SparkFun (1 1.6) R0

C4 0.1uF CPOL_RAD SparkFun (2.6 1.6) R270

CF 1nF CPOL_RAD SparkFun (2.8 1.3) R270

DATAOUT MO1PTH_L 1x01_L SparkFun (0.8 0.5) R0

FSKIN MO1PTH_L 1x01_L SparkFun (0.4 0.8) R90

GND MO1PTH_L 1x01_L SparkFun (1.2 0.5) R0

GND2 MO1PTH_L 1x01_L SparkFun (0.4 1.3) R0

IC1 DIL14 SparkFun (1.55 1.5) R270

R0 5K 1% AXIAL-0.5 SparkFun (2.3 1.5) R90

R1 35.2K 1% AXIAL-0.5 SparkFun (2 1.1) R270

RB 510K AXIAL-0.5 SparkFun (1.5 0.8) R0

RF AXIAL-0.5 SparkFun (2.5 0.9) R180

RL 5.1K 1% AXIAL-0.5 SparkFun (0.7 1.6) R90

RX 20K TRIM_POT SparkFun (1.5 0.5) R0

SUPPLY 1X02_L SparkFun (2 2.2) R0

Total Cost = Rs.210

45


Miscellaneous components

Product Name Product Quantity Price per piece Total(Rs.)

IC HOLDER 2 5 10

Jumpers 2 packs 10 (per pack) 20

Epoxy PCB 1 125 125

Dotted PCB 3 30 90

Transformer 2 35 70

Bug Strip 1 10 10

Total Cost = Rs. 155

46


47

Modulator & Arduino

Modulator & Demodulator

Chapter 7 Conclusion

7. Conclusion

The project has the capability of transforming the information highway in India. In

a way that India has bypassed the land-line telephone revolution, the adaptation of PLCC

can help propel India into an elite group of countries with a very deep Internet

penetration. This would in turn help in dispelling the superstitions and ignorance that

prevails in some of the backward areas of the country. India’s image as a low cost

development country in the world would get a major boost by the implementation of this

technology on a wider scale. Power Lines Communication would result in a very large

scale savings of the tax payers money. Efficiency of the existing infrastructure would be

enhanced thus giving more value for money. It aims to ensure that the PLCC system can

be used as a plug and play device without any major investments on the part of the

consumer. PLCC is a technology that has the potential to revolutionize communication

and to change the lives of the citizens if factors such as cost, effectiveness and security

are carefully handled.

48

Chapter 8 PLM v1.0

8. PLM v1.0

Now as we have been through the practical and thesis sessions of this PLCC

project , our next aim is how to get it in compact form. As it includes many advantages

over other types of communication , it can be constructed or structured into compact form

or portable form. And yes , to get a PLC modem in compact or portable form is possible.

The duplex form of PLC is used now a days which allows the user to transmit and receive

the data from the same platform. This is the biggest revolution in PLCC technology as far

as communication over small houses , office networks and hub communication is

concerned. SMD components are used to build the circuitry which reduces circuit size

and weight of the product and thus restrictions over its portability can be eliminated. Built

in board AC connection circuits with direct connection to AC mains and built in carrier

generation technique can be used to reduce the external periferals which make the product

bulky. At the same time by using LEDs for transmission and receiption , built in error

checking can be implemented so correct data is guaranteed and it never gives corrupt

data. Also High Power circuitry and Low Power circuitry can be isolated on same PCB

thus serving both purposes less space, weight and hazard free device. AC isolated

coupling circuit, allows direct and simple connections to mains. Due to isolation on AC

part, there is no worry to get shock on the low voltage side when working with it. The

total cost of the entire trans-receiver unit does not exceed Rs.1500. Thus an economical

solution has been provided for data communication via PLCC modem by this project.

49

Chapter 9 Applications

9. Applications

Power line networking offers several advantages over other available home networking

technologies; the availability of power outlets in abundance in every home and offices , it

eliminates the need of laying new wiring. PLCC technology can be deployed into

different types of applications in order to provide economic networking solutions. Hence

merging with other technologies it proves useful in different areas.

These are few key areas where PLC communications are utilized:

a. Transmission & Distribution Network: PLCC was first adopted in the electrical

transmission and distribution system to transmit information at a fast rate.

b. Home control and Automation: PLCC technology is used in home control and

automation. This technology can reduce the resources as well as efforts for activities like

power management, energy conservation, etc.

Plug the adapter into any existing power sockets and you can program it to control other

modules over your AC wiring. You can program all the switch modules in the house in a

single unit and you can remotely switch lights, televisions, Audio-visual equipment and

other appliances on and off with a touch of a button --- A handy controller for Home

Automation. The Programmable Controller and the corresponding Switch Modules are

configurable at the host station. An LCD screen shows the operating status of the modules

under control. In modern homes, there is a huge requirement of sending digital

information, audio, and video all over the home. Running new wires to support this will

increase the burden and cost of maintenance. To overcome this, PLCC is the right choice

to implement Home Automation concept. Home automation or also known as Smart

Home technology is a collection of systems and devices in a home that have an ability to

interact with each other or function individually in order to be optimized in best way.

50


Using PLCC technology, existing power wiring of the house is used to connect home

appliances with each other as well as with Internet. Architecture of a PLCC based home

automation system is shown in the above image. Various home appliances are connected

within a loop through the existing power cables. This technology can connect each device

with the network which is connected to an AC outlet. All appliances are also connected

with a centralized control panel which controls them.

c. Entertainment: PLCC is used to distribute the multimedia content throughout the

home.

d. Telecommunication: Data transmission for different types of communications like

telephonic communication, audio, video communication can be made with the use of

PLCC technology.

e. Security Systems: In monitoring houses or businesses through surveillance cameras,

PLCC technology is far useful. The surveillance cameras connected over Power System

in a light bulb is unique; simply screw it into any light socket. Hidden inside the "bulb" is

a sophisticated Low-Light Monochrome Camera, coupled with PLCC circuitry. The video

signal is "encoded" by this circuit and fed directly to the power line. Each Video Over

Power System features a companion Decoder, which plugs into any wall outlet. A typical

homeowner would plug in the decoder at the outlet nearest the TV. A standard video

output connects the decoder to any TV or VCR using line-level RCA-type cables.

51


Once the Decoder is plugged in and connected, live video is delivered to the TV or VCR.

It's simple and easy. There are no wires to run, no holes to drill, and no antennas or

complicated "tuning" is required.

f. Automatic Meter Reading : Automatic Meter reading applications use the PLCC

technology to send the data from home meters to Host Central Station. Automatic Meter

Reading using PLCC technology is quite useful as it saves a lot of human efforts and also

makes the whole system more efficient. The automatic meter reading system consists of

three components, namely, Multifunction Node (MFN), Concentrator & Communication

Node (CCN) and Operation & Management System (OMS). Different components and

their inter-connections are shown in the figure.

MFN is a unit installed in household meters, either incorporated in the meter itself or

externally connected to it. Its function is to take reading of the meter on an hourly basis

and store it in a memory chip. CNN is another part which manages all MFNs within a

particular area and collects meter readings from all MFNs. It is generally installed on

substations and needs a computer. The computer is installed with Operation and

Management System (OMS) which further manages all the data and meter readings from

CNNs.

52

Chapter 10 Future Scope

10. Future Scope

a. Telecommunication: Data transmission for different types of communications like

telephonic communication, audio, video communication can be made with the use of

PLCC technology. The user will be free to choose the necessary mode of communication.

b. Industrial Automation: In an industrial environment the PLC communication

networks can be used to give electric energy related services, such as meter reading,

demand management and remote billing but also to give value added services like remote

control and security, automation or even, education, information and e business

opportunities. On the other hand it can also offer telecommunication services such as

traditional telephony and Internet.

c. System protection: The communication link can be used to transit control signals that

may be used to protect the system. For example, PLC can be successfully used in order to

detect is landing operation of DER units.

d. Telecommunication services: Current PLC networks are able to reach speeds of

200Mbps. Telephony and Internet services can be delivered at high speed through

broadband PLC networks. Traditional telephony uses Plesiochronous Digital Hierarchy,

PDH. PDH uses Time Division Multiplexing, TDM. One possibility is to send the TDM

frame over IP, and the voice over TDM, VoTDM. However, this service should

accomplish the quality and reliability criteria, like Bit Error Rate, timing and latency, and

unfortunately the delay in VoTDM transmissions exceeds 25ms. Nevertheless, it is

possible to give a good telephony service over IP. Over TCP/IP, VoIP and Internet

services can be delivered at a 200Mbps speed, so it can be possible to compete with

technologies such as ADSL.

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Chapter 11 References

11. References

[1] Ciarcia's Circuit Cellar, Volume 7

Build a Power-Line Carrier Current modem.

[2] Designing Reliable Powerline Communications Published in EDN

Ashish Garg and Angad Singh Gill, Cypress Semiconductor -- EDN, Dec 2, 2010

[3] Power Line Communication Modem

Power Line Communication Modem Solutions from Texas Instruments

[4] Data communication and networking - Behrouz A Forouzan.

Hamming Code - page 280.

[5] Measurements and attenuation for power line communication systems.

[6] NI LabVIEW Getting Started

[7] XR2206 Datasheet

[8] XR2211 Datasheet

54

Index

Index

AArduino

BBlock descriptionblock diagram

Ccoupling circuitry

DDemodulator

HHamming block codehamming Decoder

P Power line characteristics

RRandom Bits Generation

MModulatorMultiSim

NNI Labview

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