design and development of a power line communication system kim siong

7/23/2019 Design and Development of a Power Line Communication System Kim Siong

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FACULTY OF ENGINEERINGAND BUILT ENVIRONMENT

School of Electrical Engineering

and Computer Science

ELEC 4840B

Project No: JK04

Project Title: Design & Development of a Power Line

Communication System

Student Name : ANG KIM SIONG

Student ID : C3067053

Cohort : EE206 (EE28)

Supervisor :

Dr Jamil Khan (UON supervisor)Mr Lee Kar Heng (PSB supervisor)


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SCHOOL OF ELECTRICAL ENGINEERING

AND COMPUTER SCIENCE

ELEC 4840B

Project No: JK04

Project Title: Design & Development of a PowerLine Communication System

10th DEC 2010


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ABSTRACT

Nowadays, there are many technologies that have been developed for control

applications. Power line communication (PLC) is one of the technologies that have

proved useful for control applications. It is widely use in home automation, automotiveand internet access applications.

The aim of the project is to design a Power Line Communication Modem Circuit to

control the home appliances between a Host PC and a Slave Application Device.

This report will discuss on the required technology and knowledge involved in the

power line modem design. Hence, information on how the concept of modulation

schemes are introduced, how signal will transmit through the power line and eventually

work plan for the practical design of power line modem will be discussed in this paper.Also, academic research and study on the performance of the transmission system

was elaborated in detail, such as, by using the Multisim software to validate the design

and component used in the circuitry prior to the building of actual circuitry.

Lastly, a labview software will be used to demonstrate the two power line modem

interact with each other on this communication system, by controlling a lamp from a

PC.


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TABLE OF CONTENTS1.0 Introduction ............................................................................................................................ 1

1.1 Objectives ........................................................................................................................... 4

1.2 Scopes of Project ................................................................................................................. 4

1.2.1 Project Planning ........................................................................................................... 4

1.2.2 System Design .............................................................................................................. 4

1.2.3 System verification ....................................................................................................... 4

2.0 Literature Review .................................................................................................................... 5

2.1 Source Data and Message Frames ...................................................................................... 5

2.2. Layers, Access Methods and Protocols .............................................................................. 6

2.2.1 Physical Layer and Modulation Techniques ................................................................. 6

2.2.2 The Medium Access MAC Layer ................................................................................... 7

2.2.3 Protocols for MAC Layer in Power Line Modems ........................................................ 7

2.3 Characteristics on the Power Line Communication ............................................................ 8

2.3.1 Modulation and Coding for Narrowband Systems ...................................................... 8

2.3.2 Signal Attenuation........................................................................................................ 9

2.3.3 Signal-to-Noise Ratio .................................................................................................... 9

2.3.4 Coupling the Signal onto the Channel........................................................................ 10

2.4 Homeplug Power Line Modem ......................................................................................... 11

2.4.1 Homeplug Transmission Techniques ......................................................................... 12

2.4.2 HomePlug Standard & Comparison ........................................................................... 13

2.5 Other Power Line Modem Standards ............................................................................... 14

2.6 Frequency Allocation by FCC and CELENEC ...................................................................... 15

3.0 Specification of Power line Modem ...................................................................................... 17

3.1 Power Line Modem Hardware .......................................................................................... 17


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3.2 Power Line Modem ICs ..................................................................................................... 18

4.0 Detail Design of Power Line Modem .................................................................................... 21

4.1 TDA5051A Modem IC Functional Description and Important Design Parameters ........... 22

4.1.1 TDA5051A Transmission Section ............................................................................... 24

4.1.2 TDA5051A Receiving Section ..................................................................................... 26

4.1.3 TDA5051A Clock Section ............................................................................................ 27

4.1.4 TDA5051A Modem Chipset Design ............................................................................ 27

4.2 Interface Circuit Design ..................................................................................................... 28

4.2.1Serial Communication ................................................................................................. 28

4.2.2 Max 232 Level converter ............................................................................................ 29

4.3 Power Supply .................................................................................................................... 30

4.3.1 Power Supply Circuit Analysis .................................................................................... 32

4.3.2 Simulation Test (Power Supply) ................................................................................. 34

4.4 Coupling Circuit Specification ........................................................................................... 37

4.4.1 Coupling Circuit Design .............................................................................................. 39

4.4.2 Coupling Unit Circuit Analysis .................................................................................... 40

4.4.3 Coupling Circuit Simulation Test ................................................................................ 41

5.0 Software Development ......................................................................................................... 43

5.1 Labview Design ................................................................................................................. 43

5.2 Implementing the Power Line Modem Control Message Frame on RS232 COM Port ..... 45

5.2.1 Interface message frame ........................................................................................... 45

5.2.2 Preamble .................................................................................................................... 45

5.2.3 Address Field .............................................................................................................. 46

5.2.4 Data Field ................................................................................................................... 46

5.2.5 Stop Bit ....................................................................................................................... 46


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5.2.6 Baud Rate ................................................................................................................... 46

6.0 Test Result & Verification ..................................................................................................... 47

6.1 Power Supply Test ............................................................................................................. 48

6.2 Modem IC Circuit Test ....................................................................................................... 49

6.2.1 Interfacing Two Modem IC Circuit Test ..................................................................... 51

6.3 Coupling Circuit Test ......................................................................................................... 51

6.3.1 Coupling Circuit Test (With 230VAC) ......................................................................... 52

6.4 Modem & Coupling Circuit Test ........................................................................................ 53

6.5 Serial Comms Test between Two Modem ........................................................................ 54

6.6 Distance Test between Two Modems............................................................................... 55

6.7 Full Integrated System Test (Hardware & Software) ........................................................ 57

6.8 Summary of finding during the test .................................................................................. 57

6.9 A Full complete Power Line communication Modem ....................................................... 58

7.0 Cost Analysis ......................................................................................................................... 59

8.0 Gantt Chart............................................................................................................................ 60

9.0 Conclusion & Future Development ....................................................................................... 61

9.1 Conclusion ......................................................................................................................... 61

9.2 Future Development ......................................................................................................... 62

Appendix A1: TDA5051A Pin Configuration ................................................................................ 66

Appendix A2: TDA5051A Characteristics-Supply & Transmission Mode .................................... 67

Appendix A3:TDA5051A Characteristics- Reception Mode ........................................................ 68

Appendix A4: TDA5051A Carrier Spectrum ................................................................................ 69

Appendix B: Maxim 232 level converter Specification ............................................................... 70


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LIST OF TABLE

Table 1: MAC Layer in Power Line Modems................................................................................. 8

Table 2: Coupling Components [21] ........................................................................................... 11

Table 3: Comparison table for Homeplug 1.0 & Homeplug AV.................................................. 14

Table 4: Five spectrum bands ..................................................................................................... 16

Table 5: Broadband IC Chipsets .................................................................................................. 19

Table 6: Narrowband IC Chipsets................................................................................................ 20

Table 7: Specification of Power Line Modem Circuit.................................................................. 22

Table 8: Transmission Parameter [2].......................................................................................... 25

Table 9: Receiving Parameter [2]................................................................................................ 26

Table 10: Clock Parameter.......................................................................................................... 27

Table 11: RS232/TTL Level Converter......................................................................................... 29

Table 12: Coupling circuit requirement ...................................................................................... 39

Table 13: Address Field .......................................................................................................... 46

Table 14: Data Field ................................................................................................................ 46

Table 15: Cost Analysis ........................................................................................................... 60

LIST OF FIGURE

Figure 1: PLC Enable Electrical Appliance ..................................................................................... 2

Figure 2: Conceptual Block Diagram............................................................................................. 3

Figure 3 : Project Planning ............................................................................................................ 5

Figure 4: Coupling Circuit Requirement...................................................................................... 10

Figure 5: CELENEC Frequency Band Allocation [7] ..................................................................... 16

Figure 6: FCC Frequency Band [8]............................................................................................... 16

Figure 7: Power Line Modem Hardware Design......................................................................... 17


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Figure 8: Typical IC Solution For Power Line Modem [5]............................................................ 18

Figure 9: Signal & Power Connections for Power Line Modem.................................................. 21

Figure 10: Amplitude Shift Keying............................................................................................... 22

Figure 11: TDA5051A Chipset [2]................................................................................................ 23

Figure 12: Relationship between DataIN& TXOUT[2]................................................................... 24

Figure 13: Modem IC Design Circuit [2]...................................................................................... 27

Figure 14: Serial Port Configuration............................................................................................ 28

Figure 15: Logic state assign to Voltage Level ............................................................................ 29

Figure 16: Interface Design Circuit.............................................................................................. 30

Figure 17: Power Supply [2]........................................................................................................ 31

Figure 18: Power Supply Equivalent Circuit (IIN) ......................................................................... 32

Figure 19: : Power Supply circuit (Equivalent Circuit Design Using Multisim............................. 35

Figure 20: Power Supply Simulation Test (Output Voltage) ....................................................... 36

Figure 21: Power Supply Simulation Test (Output Current) ....................................................... 36

Figure 22: Digital Filter................................................................................................................ 38

Figure 23: Coupling Network Curve............................................................................................ 38

Figure 24: Coupling Circuit Design [2]......................................................................................... 39

Figure 25: Coupling Circuit Test (Equivalent Circuit Design Using Multisim) ............................. 41

Figure 26: Coupling Circuit Simulation Test (Output Voltage).................................................... 42

Figure 27: Coupling Circuit Simulation Test (Output Current).................................................... 42

Figure 28: Master Control Panel (Host PC) ................................................................................. 44

Figure 29: Slave Display Panel (Slave PC).................................................................................... 44

Figure 30: Bit Pattern at COM Port for character A (1 stop bit, no parity).............................. 45

Figure 31: Preamble.................................................................................................................... 45

Figure 32: Protection Devices for Testing................................................................................... 48


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Figure 33: Power Supply Testing................................................................................................. 48

Figure 34: DC waveform ............................................................................................................. 49

Figure 35: Modem IC Circuit Test................................................................................................ 49

Figure 36: Modem IC Circuit Test (Test of 115 KHz) ................................................................... 50

Figure 37: Modem IC Circuit Test (Floating Signal)..................................................................... 50

Figure 38: Modem IC circuit Test (Pull up resistor) .................................................................... 50

Figure 39: Two Modem Circuit Test............................................................................................ 51

Figure 40: Coupling Circuit Test .................................................................................................. 52

Figure 41: Coupling Circuit Test (AC 230V) ................................................................................. 52

Figure 42: Modem & Coupling Circuit Test (With 230VAC)........................................................ 53

Figure 43: Serial Comms Test Between Two Modems ............................................................... 54

Figure 44: Serial Comms Test...................................................................................................... 55

Figure 45: Distance Test between Two modems........................................................................ 56

Figure 46: Full Integrated System Test ....................................................................................... 57

Figure 47: Full Complete Power Line Communication Modem (Internal).................................. 58

Figure 48: Full Complete Power Line Communication Modem (External)................................. 58

Figure 49: A Complete setup power line communication modem test...................................... 59

LIST OF ACRONYMS

AcronymsPLC Power Line Communication

FHSS Frequency Hopping Spread Spectrum

MAC Medium Access Control

ASK Amplitude Shift Keying

FSK Frequency Shift Keying

PSK Phase Shift Keying


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QAM Quadrature Modulation

CDMA Code-Division Multiple Access

OFDM Orthogonal Frequency Division Multiplexing

MOV Metal Oxide Varistor

TTL Transistor-transistor level


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Project No JK04 ELEC4840B

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1.0 Introduct ion

A Power Line Communication System is a system whereby communication signals

were sent and received on household and industrial 50Hz current-bearing power line.

Power Line Carrier Communication has recently become a popular technology for

home automation and networking. It is because power line is a relatively cheaper and

more robust communication channel used throughout the world except wireless

channel. It is used more commonly used than any other communication channel.

A simple digital communication system usually consists of an encoder and a modulator

on the transmitting side, and a decoder and a demodulator on the receiving side.

However, to support two ways communication (full duplex or half duplex), modem(modulator/demodulator) devices are designed and used in communication systems

nowadays.

A power line modem is an all-in-one device which consists of an encoder, a decoder, a

modulator, and a demodulator. As the current bearing AC mains power line is used as

a transmission medium, additional coupling circuits are required in power line modems

for better protection, isolation and impedance matching.

Power line modems can be used in various applications; however, the study on the

use of Power Line Modems for this report will mainly be focused on home automation

applications.

The figure 1 below illustrates a typical conceptual view on the use of power line

modem for home automation network.


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Figure 1: PLC Enable Electrical Appliance

A general purpose PC serves as the PLC (Power Line Communication) enabled main

control center or a master Node for home automation network. PLC enabled Lamp, air

conditioner, television, and other electrical devices are slave nodes in the network.

From the point of view of a home user, a PLC enabled TV will look exactly the same as

a normal TV as the communication and control unit is embedded within and no

additional wire is required for communication.

The AC power line acts as the communication medium for all the electrical devices and

master control centre a data acquisition, monitoring, and control software will run on

the PC.


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Switching on/off the electrical lamps, checking room temperature and controlling the

air conditioner and other various automatic applications can be configured through

proper use of developed software running on PC.

The figure below shows the conceptual block diagram of a PLC enabled electricaldevice. It will have a power line modem, a control unit and a normal function unit

internally.

Figure 2: Conceptual Block Diagram

Each node of PLC enabled electrical device will have its own network address. ThePower Line Modem enables the address, command, and data message frames to be

sent over the AC Power Line.

Due to cost constraints, such kind of PLC enabled products could seldom be found in

the consumer market at this moment in time, however, it is likely to see such kind of

systems in the near future.

Function Unit

e.g. a TV, or an Air

Conditioning Device

Control Unit

Power Line

Modem

Power Supply

Power Point

Address/Command/

Data


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1.1 Objectives

The objective of this project is to design and develop a low cost narrowband power

line communication module applies in home automation system to control home

appliances. By using the existing power point socket outlet through power line, tocontrol and regulate the lamp.

1.2 Scopes of Project

The scope of this project consists of three main structure works as shown in figure 3,

which includes project planning, system design and system verification.

1.2.1 Project Planning

Project planning consists of analytical studies and academic research on the existing

technologies of the power line communication system. Conceptual design and also

sourcing for the main component will also be included in this state.

1.2.2 System Design

System design consists of hardware and software design. In hardware design, design

and building of associated circuitry, like coupling circuit, modem IC circuit, level

converter and power supply. These works comprises of derivation of mathematical

model and simulation work. Whereas, the software design, is to design and develop a

Labview application for interfacing between power line modem and PC.

1.2.3 System verification

This will be the last section of the entire project. Full integrated system test of the

power line communication will be conducted and evaluated during the testing, to

validate the performance. Demonstration of the power line communication system will

also be presented.


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Figure 3 : Project Planning

2.0 Literature Review

To design a power line modem, a good background of digital communication

techniques and existing standards for power line communication is required. A

literature review has been carried out as per this requirement and summarized as

follows:

2.1 Source Data and Message Frames

The simplest control scheme on a TV or Air Conditioner from host PC will be sending

either ON or OFF command. A low to high digital pulse will be modulated over the

power line in this case and the receiving side will simply demodulate this pulse back

from the carrier and the trigger circuit will then activate ON or OFF operation. This is

not a practical approach as a noise signal may be wrongly interpreted as ON or OFF

signal by the modem circuit.

To prevent false triggering, addresses are given for the PLC enabled devices in home

control network. The figure below shows an example of a message frame which

consists of four fields, preamble, identifying address, data field, and stop bit. When the

host PC communicates with a PLC enabled device, it will put the address of the PLC

enabled device in the address field. The data field in this case will be the ON or OFF


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command coded in binary form. The message frame will always start with preamble to

signify the devices that a message is coming and always end with a stop bit.

2.2. Layers, Access Methods and Protocols

Practically speaking, design of the power line modem considers two main layers of the

OSI reference Model as follows:

The Physical Layer, and

The Medium Access Control (MAC) Layer.

2.2.1 Physical Layer and Modulation Techniques

The Physical Layer defines the modulation techniques to transmit data over the power

lines. The accuracy of the data coming from the receiver is determined by the

efficiency of the modulation/demodulation process.

The modulation band selected for power line communications must

meet the required data rate

maximize resistance to various noise interferences occurred in Power Lines

There are three main digital modulation schemes as follows:

Amplitude Shift Keying (ASK)

Frequency Shift Keying (FSK)

Phase Shift Keying (PSK)

For higher data transmission rates, narrower bandwidths, Lower error rates at lower

Signal to Noise ratios, and lower power consumption of modem devices, the following

advanced digital modulation schemes as considered:

1. M-ary Modulation

a. M-ASK

b. M-PSK

c. M-ASK

2. Quadrature Modulation (M-QAM)


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3. Spread Spectrum Techniques

a. Frequency Hopping Spread Spectrum (FHSS)

b. Direct Sequence Spread Spectrum (DSSS)

4. Multiplexing Techniques

a. Code Division Multiple Access (CDMA)

b. Orthogonal Frequency Division Multiplexing (OFDM)

Communicating at the power line communication physical layer demands robust

modulation techniques like Frequency Shift Keying (FSK), Code-Division Multiple

Access (CDMA) and Orthogonal Frequency Division Multiplexing (OFDM).

For low cost, low data rate applications, such as power line protection and tele-

metering, FSK is seen as a good solution. For data rates up to 1Mbps, the CDMA

technique may provide an effective solution. However, for high data applications

beyond that, OFDM is the technology of choice for PLC.

2.2.2 The Medium Access MAC Layer

The MAC protocol specifies as resource sharing strategy i.e. the access of multiple

users to the network transmission capacity based on a fixed resource sharing

protocol. There are generally two categories of access:

Fixed Access Scheme and

Dynamic Access Scheme.

2.2.3 Protocols for MAC Layer in Power Line Modems

No Protocol Description

1 Polling.

It is a primary/secondary access method in which the primarystation asks the secondary station if it has any data to send.

Arbitration based polling can handle heavy traffic and doesprovide QoS guarantees

2 AlohaIt is a random access protocol in which a user accesses achannel as soon as it has data to send.

3Tokenpassingschemes.

These schemes, e.g. token ring, token bus, are efficient underheavy symmetric loads. However, they can be expensive toimplement and can cause serious problems with losttokens on noisy unreliable channels such as PLs


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Table 1: MAC Layer in Power Line Modems

2.3 Characteristics on the Power Line Communication

In this section, modulation and coding for narrowband systems will be discussed. Also,

signal attenuation depend on the distance will be briefly describe here. Coupling will

be another important topic for power line communication, will be

2.3.1 Modulation and Coding for Narrowband Systems

The modulation and coding for narrowband (low speed) transmission in the frequency

bands maximum limit will up to 500 kHz. Regulations stated in west Europe

concerning the PLC are described in the EN 50065 standard, an entitled Signaling on

low-voltage electrical installations in the frequency range of 3 kHz to 148.5 kHz. In

this standard guild, it specifies the allowable frequency band and output voltage over

the power lines are used. In accordance to EN50065.1, is also known as CENELEC,

the maximum allowable peak voltage for narrowband signals (i.e. bandwidth of 20dB

less than 5 kHz in width) at 9 kHz will equals to 5V, exponentially decreasing to 1V at

the frequency of 95 kHz . As for the broadband transmitter (i.e. bandwidth of 20dB

more than 5 kHz in width) will be 5 V = 134dB (V).

4

CarrierSenseMultiple

Access(CSMA)

CSMA with overload detection has been proposed for PLC.CSMA is a contention based access method in which eachstation listens to the line before transmitting data. CSMA isefficient under light to medium traffic loads and for many low-duty-cycle busty terminals (e.g. Internet browsing).

i. Collision Detection (CSMA/CD) senses the channel for acollision after transmitting. When it senses a collision, it waits arandom amount of time before retransmitting again. But onpower lines the wide variation of the received signal and noiselevels make collision detection difficult and unreliable.

ii. Collision Avoidance (CSMA/CA). As in the CSMA/CD method,each device listens to the signal level to determine when thechannel is idle. Unlike CSMA/CD, it then waits for a randomamount of time before trying to send a packet. Packet size iskept small due to the PLC' s hostile channel characteristics.Though this means more overhead, overall data rate is

improved since it means less retransmission.


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2.3.2 Signal Attenuation

The signal attenuation in the lower frequency band is assumed to be slowly time

varying. Low transmission frequency less than 500 kHz will not cause standing

waves, thus narrowband fades unlikely to occur. Signal attenuation due to network

loading can be ranging from 40 to 100dB per kilometer.[22] The actual level signal

attenuation is the number of loads connected to the main line which determine the

main parameter. The signal attenuation and distance can considered as approximately

exponential as long as the loads are evenly distributed over the main line. In power

line channel, received signal power can be modeled as a function between transmitter

and receiver with a specify distance.

Signal attenuation for low voltage networks amounts to 100dB/km, including:

Time Dependence - There is strong day/night sensitivity

Frequency Dependence - Frequencies above 100 kHz, an increase of

0.25dB/kHz is reported [13]. Due to transmission line effects, cable longer than

400m, signal attenuation can get very high at certain frequencies. And if above

10 MHz it will be very hard to distinguish the received signal from the

background noise, which ultimately limits the communication distance.

Distance Dependence In practical schemes, a signal attenuation of100dB/km is often considered [13].

Signal Attenuation over Network Phases Attenuation across phases can be

as high as 40 dB [13]. In conclusion, the signal attenuation for the across-

phase RPC channels is considerably higher than for corresponding in-phase

channels.

2.3.3 Signal-to-Noise Ratio

Signal-to-noise ratio (SNR) [14] is a key parameter when determine the efficiency or

measure the performance in the communications system.

The signal-to-noise ration (SNR) is given as:


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SNR =NoisePower

rceivedPoweRe

The result obtain on this parameter is related to the efficiency of a communication

system. The higher the SNR, the better is the communication.

It is often possible to reduce the noise by controlling the environmental. Otherwise,

when the characteristics of the noise are known and are different from the signals, it is

possible to use filters to improve the signal-to-noise ratio. Noise level in the grid can

be reduced, when a filter is installed. This is to block the generated noise from the grid

before entering into the household. However, the cost of implementing such filters is

rather expensive and complex. Select appropriate power communication module with

this capability of improving the signal to noise ratio module is essential for each

household.

2.3.4 Coupl ing the Signal onto the Channel

The basic function of a coupling circuit in a power line modem is to feature an efficient

high-pass behavior in order to damp the 230V AC, 50Hz signal of the mains, without

attenuating the incoming HF signal. Coupling circuit should be designed to match the

modem communication system and power distribution system. In some cases,

consideration for galvanic isolation and over voltage protection are optionally included

in coupling circuit design.

Figure 4: Coupling Circuit Requirement

There are two method of connecting the power line communication module into the

network [13]:

Capacitive Coupling: A capacitor is responsible for the actual coupling and the

signal is modulated onto the networks voltage waveform.

Modem Communication System

Characteristics

Higher frequencies (kHz) and very

low power (mW), current and

voltage levels (mA and mV).

Power System

Characteristics

Low frequency (50Hz)

High power (kW, MW), current

and voltages levels (1~20A,

230V)

Varying impedances, high

amplitudes and time dependent

disturbances

Coupling Circuit

o Conductivecoupling

o High pass filter

o Galvanic

isolation

(optional)

o Over Voltage

protection


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Inductive Coupling: An inductor is used to couple the signal onto the networks

current waveform. Inductive coupling some time is rather noisy, however, the

advantage is, no physical connection to the network has to be made. Thus

make it safer to install as compare to capacitive coupling.

When designing the coupling circuit, two major types of components as described in

the table 10 below should be considered. Another important feature to take notes is

the protective coupler circuitry. Inclusive of varistors, zener diodes and also coupling

transformers need to consider in the circuit, which involving current and voltage

transients might also damage the chipset.

Component Description

Couplingcapacitors

These are extensively used in power line communications, most

commonly to couple the PLC signal to the power line, but also as apart of more sophisticated, higher-order filters. The requirementsand essential characteristics of coupling capacitors have beenstandardized in ANSI C93.1-1972. Coupling capacitors carry thecommunication current and thus have to be high-frequencycapacitors (self resonant frequency has to be higher than themodulation frequency). Conversely, they have to filter the powervoltage (dropped across the component), as well as voltage surgesand therefore need to be high-voltage capacitors. The filteringcharacteristics of the coupling capacitors are quite dependent on theload onto which the waveform terminates.

Couplingtransformers

The main function of the coupling transformers is to provide galvanic

isolation and impedance adaptation, but the coupling transformerhas also to pass the high-frequency communication signal and it hasto be designed as such. The power waveform has a much lowerfrequency and much higher voltage level, and the power waveformhas a saturating influence in the order of at least 100000 comparedto the communication waveform. Therefore, the power waveform istypically first low-pass filtered before entering the couplingtransformer.

Table 2: Coupling Components [21]

2.4 Homeplug Power Line Modem

The Homeplug Power Line Alliance is an alliance with members such as silicon

vendors, networking companies, service providers, utilities and OEM/ODM retailers.

Development of Home Plug Standards has its focus mainly on increasing data rate as

required by emerging technologies like VoIP, HDTV, etc


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Homeplug standards [17] are basically to fulfill the requirement of networking and data

communication in the homes and offices to obsolete the need of extra wiring and

networking. Usually in every home there is power line to run different appliances so

homeplug follow this scenario to control communication between different rooms. The

technology developed in homeplug is able to send data, voice and video within

different rooms.

The challenges faced by the Alliance were the way to combat other electrical noise

[15] that exists due to the use of a power outlet to transfer information. Whenever any

appliance is turned on or off, it creates noise that could possibly disrupt data transfer

through the wiring. Another problem that has also been resolved was the lack of

standardization in the market for the digital networking products and technologies.

With the implementation of the IEEEs 1901 broadband power line standard (due for

approval on September, 2010), Homeplug technology has been validated by both

IEEE and the market and was selected as a baseline technology for the standard

since it is the most widely deployed technology. The three major specification

published by Homeplug (Homeplug AV, Homeplug Green PHY and the developing

Homeplug AV2) are all compliant to IEEE 1901 and the Homeplug Power Line

Alliance will be the certifying body for IEEE 1901 products [17].

2.4.1 Homeplug Transmission Techniques

OFDM was adopted by the Homeplug Power Line Alliance [17] because of its

robustness to noise and the fact that it is a parallel data transmission method using a

number of parallel FDM sub-bands. Due to the absence of moving devices in the

power line network, there are no Doppler effect. The other problem is timing offset,

which can be mitigated by offset estimation and compensation.

Spread spectrum signal modulation is different [18]. Since the useful bandwidth in the

power line channel is under 25 MHz, the effect of spread spectrum modulation is

considered limited. Using single carrier modulation on the power line is possible, butequalizers could be needed to reduce the delay spread effect, but the cost will be

relatively high.

In order to cope with the wide variation in channel conditions, the physical layer

protocol (PHY) for PLC must be adaptive, intelligently using more robust modulation


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and coding schemes, with lower data rates as needed. In addition, critical protocol

management information requires high fidelity forward error correction (FEC) coding to

ensure that the protocol functions correctly in the worst case situations [18].

2.4.2 HomePlug Standard & ComparisonThe homeplug version v1.0 is designed for low bandwidth and cost effective solution

for the power line communication. The homeplug 1.0 uses 84 sub carriers in the

frequency range of 1MHz to 4.5MHz. So the bandwidth of 3.5MHz is used to adjust all

the sub-carriers carrying different data streams [19]. The feature of FEC is also used

in the homeplug version 1.0. Medium access control is TDMA which provides better

quality of service. This feature is used without the major changing in the hardware

architecture. More work need to be done on the physical and MAC layer of the device,

although continuous research is also being done on network, session and transportlayer [15].

I. HOMEPLUG 1.0 Standard

It is the first specification standard for connecting devices via phone

lines. A peak PHY-rate of 14Mbps is provided.

II. HOMEPLUG AV Standard

This standard is designed to provide sufficient bandwidth for HDTV and

VoIP.

III. HOMEPLUG AV2 Standard

It is the current development standard for the next generation. It offers

Gigabit speed at the physical layer and 600Mbs+ at the MAC layer.

IV. HOMEPLUG GREENPHY

It is a subset of Home Plug AV standard and a peak rate of 10 Mbps is

provided for this standard that is designed into smart meter and smaller

appliances.

V. HOMEPLUG ACCESS BPL

A to-the-home broadband access technology is referred to Access

Broadband Power Line (BPL).

VI. HOMEPLUG Command and Control (CC)

It is a low-speed and low-cost technology.


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Homeplug 1.0 Homeplug AV

Bit rate (Mbps) 14 200

M (FFT size) 256 3072

Mc( # carriers) 128 1536Ms ( # usable carriers) 84 1058

Mc ( # unmasked carriers) 56 917

Bandwidth (MHz) 4.3 - 20.9 1.8 30

Modulation (highest order) DQPSK4 1024 - QAM

T0 (useful duration, s) 5.12 40.96

Sampling Frequency ( 50 75

Note: M length of the OFDM symbol

Table 3: Comparison table for Homeplug 1.0 & Homeplug AV

2.5 Other Power Line Modem Standards

(i) X10 Communication Protocol Standards

The X10 protocol code formats are compatible in Home Automation Systems and it is

De Facto standard for PLC transmission. X10 is one of the oldest power line

communications and it is a powerful, flexible and fairly inexpensive technology and

similar to the network protocols such as TCP/IP. X10 protocol works across home

power lines and is extremely low-bandwidth. A form of amplitude shift keying (ASK)

technique is used for transmission of information. The basic limitations of X10 protocol

are speed, collisions and signal strength.

(ii) CEBus

Peer-to-Peer communication is used in the CEBus protocol. The power line physical

layer of the CEBus communication protocol is based on spread spectrum technology.

(iii) LONWorks

LONWorks is a networking platform that is built for networking devices over media.

The protocol provides a set of communication services. Unless the topology of the

network is known, the sending and receiving messages over the network are allowed.


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2.6 Frequency Al location by FCC and CELENEC

Frequencies restricted the limitations imposed by the regulatory agencies over the

power line communicating devices. The frequency restrictions imposed by FCC and

CENELEC are shown in figure 4 and 5.

Federal Communications Commission (FCC) and European 17 Committee for Electro

technical Standardization (CENELEC) govern regulatory rules in North America and

Europe respectively.

Power line communication frequency band used in North America from 0 to 500 KHz.

Regulatory rules in Europe are more stringent. The CENELEC standard only allows

frequencies between 3 kHz and 148.5 kHz. This puts a hard restriction on power linecommunications and might not be enough to support high bit rate applications, such

as real-time video, depending on the performance needed.

According to this standard the spectrum is divided into five bands based on the

regulations.

Frequency Range Descr ipt ion

3 to 9 KHzThe use of this frequency band is limitedto energy provides

9 to 95 KHzThe use of this frequency band is limited to energy provides andtheir concession holders. Using A-band

95 to 125KHzThe use of this frequency band is limited to the energyproviders consumers; no access protocol is defined for this

frequency band. Using B-Band

125 to 140KHz

The use of this frequency band is limited to the energyproviders customers; in order to make simultaneous operationof several systems within this frequency band. 132.5KHz wasthe centre frequency for multiple access protocol


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140 to 148.5KHz

The use of this frequency band is limited to the energyproviders customers; no access protocolis defined for this frequency band. Using"D-Band".

Table 4: Five spectrum bands

Figure 5: CELENEC Frequency Band Allocation [7]

Figure 6: FCC Frequency Band [8]


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3.0 Specification of Power line Modem

3.1 Power Line Modem Hardware

The figure below shows is a general description of a power line modem hardware

design.

Figure 7: Power Line Modem Hardware Design

Along the transmission path, the source digital data input or output from the

Transmit/Receive Buffer of an Embedded Control Unit or a Host PC Communication

Port is first modulated onto a kHz frequency carrier, and then it is again conditioned

(filtered or amplified) and coupled upon 50Hz 230V AC mains line. The reception part

of the modem demodulates the received digital data back from the modulated carrier.

KHz or MHz Frequency Carrier

Sink Digital Data


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3.2 Power Line Modem ICs

The figure below shows a typical IC Solution for power line modem

Figure 8: Typical IC Solution For Power Line Modem [5]

The use of power line modem ICs simplifies the power line modem circuitry. The

modulator, demodulator circuits and interfaces to the Host are now all embedded in

single IC chip set. The host controller or PC may write data bytes to the

communication port of the modem IC chip set with the use of level converter.

With the use of power line modem IC, only level converter ICs such as MAX232, a

power supply circuit, analog front end, coupling circuit and sometimes external

oscillator circuits are required to design in a power line modem device. Some

intelligent modem ICs even have inherent error correction, coding/decoding and the

MAC Layer and Physical Layer Management built in a single chip.

The IC solutions available in the market can be one of the two categories:

Broad band chipsets, operating at 1.6Mhz up to 80 MHz frequency

Narrow band ICs, operation at frequencies less than 1 MHz


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The table 5 below shows a summary on analysis of available broad band IC chipsets

in the market,

Vendor Part Number

Supported

Homeplug

Version/spec

Associated key

Components

Price

Intellon

INT6400/INT1400

chipset

HomePlug

AV/OFDM/200MBps

Ethernet Controller/ PCI

to MII or USB to MII$10.50/chip

Evaluation Board INT6400 $2500

*INT5130 HomePlug

1.0/OFDM/14Mbps


to MII or USB to MIIObsolete

Maxim

*Max2986HomePlug 1.0

/OFDM/14 Mbps

MAX2986EVKIT no

detailed data sheet

avaiable

$9.95/chip

MAX2990EVKITB# HomePlug 1.0/OFDM/14 Mbps

$1500

**CogencyThe Piranha

chipset

(CS1100+AD9875.)

HomePlug

1.0/OFDM/14Mbps


to MII or USB to MII

*Conexant

SystemsCX11647 HomePlug

1.0/OFDM/14Mbpscannot find detailed info

*DS2 DSS9010200 Mbps Home

Network

cannot find detailed

info/ interface

Ethernet(MII),UART,SPI

Note: * Technical data not available, ** No response from supplier

Table 5: Broadband IC Chipsets

The broad band chipsets have complex interfaces to host like MII (Media Independent

Interface) to support higher data rates. The costs of ICs and evaluation boards are

relatively higher than narrow band chipsets. The technical and sale support provided

by these suppliers are relatively poor. This could be that they are not keen to support

student project and they have minimum order quantity of these chip sets. Also, themost important factor is that the technical datasheet is difficult to obtain.

Narrow Band chipset have simpler interfaces to the host. The cost of ICs and

evaluation boards are lower. Most importantly, the technical datasheet is available and


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easy to obtain which simplifies our design work. Table 5 below shows a few narrow

band ICs

Vendor Model

Supported

HomePlug

Version/spec

Cost

ST ST7540 Up to 4.8kbps

using FSK

USD16.32

EVALST7540-2 : BOARD EVAL

ST7540 PWR LINE TXRX

USD157

PLM-1Ariane

Controls

Up to 30kbps

using FSK

USD12.50

AC-EDP6 evaluation kit USD500

Phillips TDA5051AT ASKmodulation, with

data rate of

1.2kbps

USD10.50

YitranIT800

0.625 to

7.5kbps using

DCSK

(Differential

Code Shift

Keying)

USD10.20

IT800(Evaluation Kit) USD1500

*Echelon PL3120FSK modulation

with data rate of

5.4kps

Note: ** No response from supplier

Table 6: Narrowband IC Chipsets

TDA5051A is selected for this power line modem design project as it is a low cost but

efficient IC with convenient UART interfaces. The others advantage is the availability

of technical datasheet and lead time for purchasing the parts which can source locally

easily.


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4.0 Detail Design of Power Line Modem

The design of power line modem is divided into 3 main sub units, which inclusive of

digital unit, power supply and coupling circuit. This is to ease off verification and

troubleshooting during the design process.

These main sub units are as follow:-

1. Digital Unit which consists of:

a. TDA5051A Modem IC Circuit

b. Interface Circuit

2. Power Supply

3. Coupling Circuit

The figure 9 below shows the signal and power connections between three sub-

units:

Figure 9: Signal & Power Connections for Power Line Modem


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Table 7 below summarizes the specifications of power line modem circuit:

Power Line Modem IC TDA5051A

Carrier Frequency 115 kHz (CELENEC B Band) using 7.3728MHz

crystal

Modulation Amplitude Shift Keying (ASK)

Coupling Circuit Direct Connection to mains (capacitive coupling)

Interface Circuit Direct Interface to PC via RS232 COM Port

Range100 meters (to be verified from practicalexperiments)

Table 7: Specification of Power Line Modem Circuit

4.1 TDA5051A Modem IC Functional Description and Important

Design Parameters

TDA5051A is a modem Integration circuit chipset, operates from a 5VDC supply. This

dedicated to transmit data over a power line network by means of any two wire

networks in exchanging information. The modulation scheme is used Amplitude Shift

Keying (ASK) carrier technique with a data baud rate of 600 or maximum of 1200. In

this amplitude modulation technique, the modulation signals for binary 1 is equal to theamplitude of the carrier frequency and is 0 for binary 0 as shown in figure 10.

Amplitude shift keying (ASK) is also called as on & off keying because of this unique

property.

a (t) = { A Cos (2ft) Binary 1 }

0 Binary 0

Figure 10: Amplitude Shift Keying


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With the help of few components connect externally which used for decouple

purposes. Also as a form of protection on the chipset against overvoltage surge and

negative transient signals. A standard quartz crystal will used to connect on-chip

reference oscillator which required set the operating frequency known as carrier

frequency in transmission mode and receiving mode which known as detection

frequency. The chip is based on the automatically tuned filters for transmit and

receive.

All inputs and outputs signal are compatible with TTL/CMOS feature, which provide

easy connection to the interface hardware inputs & outputs port. For more detail on

TDA5051A modem IC specification refer to appendix A1

Figure 11: TDA5051A Chipset [2]

Note: Power-down input (pin PD) is active HIGH; this means that the power consumption is atminimum when pin PD is HIGH. All functions are disabled, except clock generation.

In this TDA5051A chipset, it can divide them into 3 major sections which make up a

complete modem IC. All these 3 major sections will be discussed in the next followingtopic on their functionality and operation.

1. Transmission Section

2. Reception Section

3. Clock Section


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4.1.1 TDA5051A Transmission Section

In this design a 7.3728MHz standard crystal was chosen for the modem IC circuit,

which gives a carrier frequency of 115 KHz.

64

OSC

CR

ff =

KHz11564

103728.7 6

=

=

Transmission Section of the chip is designed in such a way that whenever the data

signal at DataINpin (pin 1) is LOW, a burst of carrier frequency 115KHz is generated at

TXOUTpin (pin 10) as shown in the figure 11 the relationship between DataIN and

TXOUT. TXOUTpin is in a high-impedance state as long as the device is not transmitting.

Modulation is performed internally by control logic, ROM and digital to analog

conversion section. The carrier frequency is generated by scanning the ROM memory.

The power output stage can feed a 120 dBV (RMS) signal on a typical 30 load.

(1) )(min)()( DIWDIW tt >

(2) qCR

SUDIW

f

tt 1

)(min)( +=

(3) SUDIW tt


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Table 8 below shows the parameters of transmission section essential for modem

design:

Parameter Value Remark

VI

(HIGH-level

input voltage @DATAIN

pin 1) 1.9V~5.5V These parameters are calculated at Vcc =5V. This characteristics should beconsidered in the interface circuit design toTDA5051A DATA_IN pin

VIL

(LOW-levelinput voltage @DATA

IN

pin 1)0.5V ~0.9V

tW(DI)(min)[minimum pulsewidth@ DATA

IN

pin 1]

190 us (typical @fosc = 8.48 MHz)

The minimum pulse width of data signal setsthe limit on the baud rate of interface circuitto TDA5051A DATA_IN pin that it should beless than 5263 bits per second. More detailswill be worked out from practicalexperiments

Vo(rms) outputcarrier signal @ pin10(RMS value)

120 - 122 dBVDATA_IN = LOW;ZL = CISPR16

Io(max) poweramplifier maximumoutput current @pin 10 (peak value)

160 mADATA_IN = LOW;ZL = 1

ZOoutput

impedance of thepower amplifier 5 NIL

VOoutput DC levelat pin 10

2.5 V

The output of the power stage (TX_OUT)must always be connected to a decouplingcapacitor, because of a DC level of 0.5VDDat this pin, which is present even when thedevice is not transmitting

Table 8: Transmission Parameter [2]


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4.1.2 TDA5051A Receiving Section

The output of receiving section is the DATAOUTpin (pin 2) which will remain LOW as

long as a burst is received at RX pin (pin 14). The signal pin (RXIN) is a high

impedance input which has to be protected and DC decoupled for the same reasons

as with pin TXOUT. The high sensitivity of (82 dBV) as mention in the datasheet of this

input requires an efficient 50 Hz rejection filter

Table 9 below shows the parameters of receiving section essential for modem design:

Parameter Value Remark

VOH (HIGH-level outputvoltage@ DATAOUTpin,

pin 14)

> 2.4V

IOH = 1.6 mA , IOL= 1.6 mAVOL(LOW-level outputvoltage@ DATAOUTpin,pin 14)


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4.1.3 TDA5051A Clock Section

The table 10 below shows the parameters of clock section essential for modem design

which need to take into consideration when selecting the crystal (clock):

Parameter Value

fOSCoscillator frequency 115KHz

fOSC/fCR ratio betweenoscillator andcarrier frequency

64

fOSC/fCLKOUTratio betweenoscillator andclock output frequency

2

Table 10: Clock Parameter

4.1.4 TDA5051A Modem Chipset Design

In TDA5051A chipset, PD pin (pin 15) should be pulled to ground to disable Power

Down Mode. And because the microcontroller will not be used in this design, thus the

clock output pin (pin 4) can be left out open. Supply voltage +5VDC are connected to

pins 3, 11 and 13 (VDDD, VDDAP, and VDDA) of TDA5051A. Pin 5, 9, and 12 (DGND,

APGND, and AGND) are all connected to Ground.

As per recommendation from TDA5051A datasheet [2], a 2.2 mega ohms resistor are

connected parallel with 7.3728 MHz standard crystal with two 22pF capacitors in

series to the ground to form a clock circuit.

Figure 13: Modem IC Design Circuit [2]


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4.2 Interface Circuit Design

4.2.1Serial Communication

Data transmission from computer using graphical user interface (GUI) to power line

communication modem via the serial communication, and this connection is based on

Electronic Industries Association (EIA232). DTE and DCE should be very familiar from

this EIA232 standard, which represent by Data communication Equipment (DCE) and

Data Terminal Equipment (DTE) respectively. These terms are used to indicate the

pin-out for the connectors on a device and the direction of the signals on the pins. The

computer is a DTE device, while most of other devices are usually DCE devices that

go with the current project, where the power line communication modem is a DCE

device.

1 DCD Received line si nal DTE

5 Gnd Si nal Ground -

6 DSR Data Set Read DTE

8 CTS Clear To Send DTE


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Serial port on the computer generate serial signal voltage level in form of RS232 from

-3V to -25V with respect to signal ground (pin5) will assign as logic 1 (Mark).

Whereas voltages level from +3V to +25V will assign as logic 0 (Space). The

voltages range between -/+3V is considered a transition region for which a signal state

is not assigned.

Figure 15: Logic state assign to Voltage Level

4.2.2 Max 232 Level converter

TDA5051A modem IC chipset will be used for direct interface with RS232/TTL level

converter from the modem to computer serial port. The Max232 from Maxim is used

as the heart of RS232/TTL level converter. This Max232 IC provides the best noise

reduction and also very reliable again discharge and short circuit. Also, its low power

consumption logic can operate in the range of 0V and +3.3V or even lower voltage.

The purpose of using this level converter in this design is to covert TTL logic which

operate between 0V to 5V into RS232 which having the operating voltage from -15V to

+15V.Whereby the voltage level operate for DataIN& DataOUTfrom the modem IC

chipset is about 2.5VDC. By doing that, modem IC chipset will not be damage with

these high level voltage.

RS232 TTL Logic

-15V ..-3V +2V ....+5V High

+3V..+15V 0V...+0.8V Low

Table 11: RS232/TTL Level Converter


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Basically these Max232 provides 2-channel that covert +5V to +/-10V for RS232

operation. Capacitor (C1) will used in the first converter to double the +5V input to

+10V on capacitor (C3) at the V+ output. The second converter uses capacitor (C2) to

invert +10V to -10V on capacitor (C4) at the V- output [23]. For more detail of this

max232 IC chipset, kindly refer to the Appendix B

Figure 16: Interface Design Circuit

4.3 Power Supply

Instead of using a 9V battery pack going into the voltage regulator to obtain the 5VDC

source to power the modem. AC power supply will be designed to power the modem

circuitry. The reason is being, when using a 9V battery pack once the voltage drop

below 6.5VDC, the supply voltage after the voltage regulator drop to below 4.5V. The

modem chipset will not be able to operate when the supply voltage is less than

4.75VDC according to the datasheet [2]. This problem will encounter during the testing

of modem chipset. Also, another disadvantage of using the battery source is there

wont be any indication/notification to the user when voltage fall below the threshold

value, the user will only aware or notify when the modem stop operation

(transmit/receive). Despite it will provide a pure DC source for the modem. On the

other hand, the advantage of using battery pack is, when using the modem it need not

to turn on the power source to power up the modem, thus it help to save some energy.


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However, after considering all this pro & con, having a reliable source is still an

essential for this device to prevent this constraints. After all, the consumption for this

entire device will not exceed 76mA [2], thus the energy usage is very low. AC power

supply would be the most ideal choice instead of battery source.

This AC power supply circuit will be fed in with 230VAC and eventually step down and

covert to 5VDC with the help of voltage regulator and few components act as half

wave rectifier. In this power supply, it consists of primary and secondary protection.

Secondary protection consists of the metal oxide varistor (MOV), rated at 230VAC for

the power line operation. This MOV will be able to limit the overvoltage spikes which

might damage Capacitor (C1). Whereas a primary protection includes an extra fast

fuse connected before the MOV, this is to overcome the long and severe overvoltage,

so that the fuse will be destroyed before the MOV.

Capacitor (C1) is used to discharge high voltage, whereas to R1 & L1 is connected

before the rectifier to prevent current surge during power up. And with D2 and C2 in

place, it provides a minimum voltage 28VDC before entering into the voltage regulator.

Which will eventually generate a +5VDC source after go through a voltage regulator.

Figure 17: Power Supply [2]


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4.3.1 Power Supply Circuit Analysis

Figure 18: Power Supply Equivalent Circuit (IIN)

IINcan be calculated from the equivalent circuit in figure 14, the given formula as

shown in Eq. (5.2.1)

CL IXIXIRV ++= (5.2.1)

( )

+

++

68

10470101

107.4 63

6

jj

jIIN 7.00230 +=

159.314502 == Where

( ) 02306810470159.314

101159.314107.4159.314

6

3

6 +=

+

++

jj

jIIN

( ) 7.00230687726.6314159.025.677 +=++ jjjIIN

( ) 07.23071.68368 = jIIN

( ) 07.23032.841.687 =INI

IIN


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32.841.687

07.230

=INI

32.84335.0 =INI

mAIIN 335=

The equivalent circuit is used to calculate the IOUT, the formula is given in Eq. (5.2.2)

Zth

VIOUT = (5.2.2)

633 10100502,100 == j

XCFC

83.31j=

944 1047502,47

==

jXCFC

5.67725j=

43

43

XCXC

XCXCZth

+=

( ) ( )( ) ( )5.6772583.31

5.6772583.31

jj

jjZth

+

=

5V Zth


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( ) ( )33.67757

905.677259083.31

jZth

=

9033.67757

18067.2155702

=Zth

9081.31 =Zth

81.31

5= OUTI

mAIOUT 157=

From the data sheet of TDA5051A the maximum draw current is 76mA [2]. However,

the MAX232 interface circuit will draw extra 10mA [23], this will add up to 76mA giving

the total current consumption of Power Line Modem circuit to be approximately 86mA.

Despite the total consumption of the power line communication modem is about

86mA. For a safe use of power supply, the total draw current can go up to 157mA.

4.3.2 Simulation Test (Power Supply)

Based on the above mathematical calculation, prior to build/implement the actual

circuit, multisim software will used to verify the result between the ideal calculation and

actual build circuit.

From the simulation test as shown in figure 19, a 230VRMS was fed into the circuit;

the input current is obtained as 336mA which is very close to the calculated value

(335mA) as shown in the Eq. (5.2.1).


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Figure 19: : Power Supply circuit (Equivalent Circuit Design Using Multisim

Multimeter (XSC1) is used for testing the output of the circuit. Looking at the output of

the circuit showing in figure 15, the output of the equivalent circuit shown 5.008VDC

which determines that the designed circuit met the power supply specification. This

simulation work also test the maximum input voltage source which this circuit can

withstand or before the result starts to saturate. This was being done by varying the

input up to some extend of +/- 50V, or in the fluctuation in the input, the output source

of the circuit remains stable and not affected.

An oscilloscope is also used in this simulation test to confirm the DC source level. As

shown from the oscilloscope, a 5VDC source is obtained.


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Figure 20: Power Supply Simulation Test (Output Voltage)

This will be the last simulation test, multimeter is used to test the total output current of

the entire circuit. From figure 21 shown below, the total measure output current of the

circuit is 151.7mA. As compare to the calculated value (157mA) in Eq. 5.2.2 which is

slightly different by 6 mA. This could be due to the tolerant of the components used in

multisim.

Figure 21: Power Supply Simulation Test (Output Current)


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In conclusion, base on calculated value, it was proven by the simulation test that the

circuit it safe and meet all expectation from the design.

4.4 Coupling Circuit Specification

As modem IC chipset usually has maximum voltage ratings of less than 50V, the

operating voltage of AC mains can easily damage the IC chipset. The coupling circuit

has to effectively block this AC mains signal preventing it from reaching the input of

modem communication system [21]. Another main purpose is to block low frequency

power signal which allow high frequency (carrier frequency) to pass into the modem IC

chipset. For more detail on the needs and requirement of the coupling circuit, refer to

the literature review [2.3.4].

A typical 230V AC mains power line can be seen as a 50Hz sine wave signal source,

delivering 167dBVrms to the modem communication system at about 30 ohms line

impedance of load as specify from the datasheet [2].

(20 log10V

Vout

1)

(20 log10 V

V

1

230

) = 167 dBVrms

Since the modem sensitivity of TDA5051A is about 82dBuV as specify from the

datasheet [2], it is mandatory to provide an attenuation of 167-82=85dB of the 50Hz

sine wave component.

However, the coupling network is not only a high-pass filter, the digital filter of the RX

section in TDA5051A needs an anti- aliasing filter in order to function properly.


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Figure 22: Digital Filter

In transmission mode of TDA5051A, the band-pass filter is used to eliminate the

unexpected harmonics digitized carrier and the aliasing components around the

sampling frequency (Fosc/2+Fc, Fosc/2-Fc) as shown in figure22. In general, the main

features of coupling network, is to 50 Hz rejection > 80dB with anti aliasing for the

digital filter >50dB at the sampling frequency of (1/2fOSC) as shown in figure 23.

Figure 23: Coupling Network Curve

With all these aspect, the coupling network behavior is in fact a band pass filter,

featuring a center frequency equal to the chosen carrier frequency for TDA5051A.

Table 12 below summarizes typical requirements which the coupling circuit design for

TDA5051A has to be considered at center frequency (carrier frequency FCR) 115 KHz:


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RECEPTION MODE

Typical input impedance at Fc 35 Ohms

-3dB Bandwidth 100 KHz

50Hz attenuation > 90 dB

Anti-aliasing around Fosc/2 > 50 dB

Input sensitivity 82 dBuVrmsTRANSMISSION MODE

Typical output impedance 7 Ohms

Output voltage on a CISPR16 load 122 dBuVrms

Table 12: Coupling circuit requirement

4.4.1 Coupling Circuit Design

In this coupling circuit a double LC bandpass filter is used to provide efficient rejection

50Hz signal (high pass) and anti-alising (low pass) for digital filter without any

adjustment or tunable from the components. All values on this coupling circuit will be

determine by impedance matching from the calculation as discussed on the circuit

analysis. A unidirectional transient suppressor (SA5.0A, D1) is connected across the

TXOUTand RXINto protect from overvoltage. It also protects the TXOUTfrom negative

transient voltage which also might damage the circuit output amplifier.

Figure 24: Coupling Circuit Design [2]

VAZ1

Z2

Vin


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4.4.2 Coupling Unit Circuit Analysis

Principle of superposition can be used in coupling circuit analysis. Assuming the

230Vrms, 50Hz AC sine wave as a signal source at VIN. Thevenin Equivalent

Output circuit can be calculated as follows:

+=

21

2

ZZ

ZVV INOC

Where 111 LC XXZ +=

232 // LC XXZ =

159.314501416.322 === f

( )1

11

CXC

=

=

91047159.314

1

= 51.67725

51.6772531 == CC XX

014765.01047501416.321 6

1 === LXL

014765.021 == LL XX

49.67725014765.051.677251

jjjZ =+=

014765.051.67725

014765.051.677252

jj

jjZ

+

= =

( ) )(495.67725

90014765.09051.67725

j

=90495.67725

0967.999

495.67725

0967.999

=

j= 90014765.0

014765.0j=

( )014765.049.67725

90014765.090230

jjVOC

+

=


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90230= ( )47.67725

90014765.0

j

= 230 90 ( )

9047.67725

90014765.0

( )1801018.290230 7=

2701050 6=

This ratio will effectively eliminate the 230VRMS signal to 50 uV with attenuation of

133.25dB, effectively exceeding the requirement of 87dB by RX input of

TDA5051A.

)( 25.1331050

230log20

6 =

=

VdBnAttenuatio dB

4.4.3 Coupling Circuit Simulation Test

Multisim software will used in this test, to verify the results between the obtained values by

mathematical calculation versus actual build circuit.

Figure 25: Coupling Circuit Test (Equivalent Circuit Design Using Multisim)


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As shown on the figure 26, input voltage was successfully suppressed to about 50 V. The

obtained result is equal to the calculated values.

Figure 26: Coupling Circuit Simulation Test (Output Voltage)

The output current for the entired coupling circuit as shown in the figure 27. As

specify in the datasheet a typical 50k ohm input impedance which represent the RXIN

on the TDA5051A IC chipset.

Figure 27: Coupling Circuit Simulation Test (Output Current)


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5.0 Software Development

In this chapter, Labview programming methodology and its programming flow chart

will be discussed. The intend of this section is to give a general overview how Labview

was implement to suit the design of the project application.

5.1 Labview Design

Labview Development System from National Instrument has been used to develop the

interface software. Reason for choosing Labview in this project is because of its easy

to use environment, which combines graphical programming with hardware to simplify

the design development work. Most importantly the use of this software is to

practically put into practise all applications that whatever was taught and learnt from

the course ELEC2500.

It is planned to run all the software related processes including some media access

control schemes on personnel computers. COM port from host PC will be connected

to power line modem which will be directly connected to AC Mains. On the receiving

side, there will be another power line modem with identical circuit configuration

connected to another PC COM Port act as slave. A demonstration will be carry out by

controlling a lamp from one PC to another PC.

Commands will send out by activating the LAMP ON, LAMP OFF, LAMP DIMMR

from the master control (host PC) as shown in figure 28, to the slave display (Slave

PC) as shown in figure 29. To control the lamp from one PC to another PC via the

power line communication modem.


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Figure 28: Master Control Panel (Host PC)

Figure 29: Slave Display Panel (Slave PC)


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5.2 Implementing the Power Line Modem Control Message Frame

on RS232 COM Port

The figure below shows the standard bit pattern sending character A (hexadecimal

41 or binary 0100 0001) at serial COM port:

Figure 30: Bit Pattern at COM Port for character A (1 stop bit, no parity)

5.2.1 Interface message frame

The interface message frame which is supposed to be sent out via serial COM port

will have a 16 bits preamble, an 8 bits address field, 8 bits data field and 1 stop bit

fields. Considering 1 start bit and 1 stop bit of COM port communication, it will take

approximately 113 us (1/300 * [16+8+8+1+1] ~ 113 us) to send this message frame at

the baud rate of 300 bits per second.

5.2.2 Preamble

It is planned to use a 16 bit preamble of 8 falling and 8 rising edges. Implementing this

on standard COM Port, the interface software has to send character UU via PC COM

port as a preamble.

Figure 31: Preamble

Lower

NibbleHigher

Nibble

LSB MSB


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5.2.3 Address Field

As demonstration program is planned to support only a few slave units with one

master unit, 8 bits address field is good enough for this implementation. Considering

00 as the address for master unit, this address field is supposed to support up to 255

slave units. This address field will immediately follow the preamble.

UnitAddress(Hex)

Address(binary)

Master 00 0000 0000

Slave 1 01 0000 0001

Slave 2 02 0000 0010

Slave 255 FF 1111 1111

Table 13: Address Field

5.2.4 Data Field

8 bits are catered for data field. First 4 bits are catered for commands and next 4 bits

are catered for levels. Preliminary definition of bit patterns are as follows:

COMMANDHigherNibble Lower Nibble Hex Remark

LIGHT 'xx' ON 0000 bbbb 0X Lamp Number X =1~ALIGHT 'xx' OFF 0111 bbbb 7X

DIM "xx" 1001 bbbb 9X Dim Level X = 1~A

Acknowledge 0100 1011 4B Acknowledge char:

Table 14: Data Field

5.2.5 Stop Bit

RS232 Standard COM port already has 1 stop bit. For simplicity this same stop bit will

be used in interface message frame.

5.2.6 Baud Rate

As mention, the baud rate for TDA5051A power line modem that used to operates was

600 or 1200 respectively. With this specification, the needs for the Universal

Synchronous Asynchronous Receiver Transmitter (USART) for the computer to

operate at the same baud rate as the power line modem. By having the same baud

rate, the power line modem and computer can be synchronized when transmitting

data from computer to modem. In this project, baud rate of 600 will be used. This is


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because of the application of this project, as is just only controlling of appliances and

sending string of data. Also, it will minimize the error occur if the speed is too fast.

6.0 Test Result & Verif ication

Testing for the power line communication modem is divided into 4 mains hardware

and each hardware is tested individually before interface and combining them

together. These 4 hardwares includes, power supply, modem IC circuit, coupling

circuit and level converter. And because this test involves with 230VAC, before

commencement of the test, safety device and safety awareness need to be

considered and put in place.

Safety device includes, MCB, Variable Transformer (Varic), Fuse and isolating

transformer will be used during the test when the present of 230VAC.

Purpose of having those protection devices are as follows:-

Main Circuit Breaker (MCB) To protect from Live to Neutral shorted

Variable Transformer (Varic) Vary the voltage, from 0 V to the respective

nominal value (230VAC). This is to prevent further damage to the component if

any components not function or operating to its respective optimum

performance.

Fuse To protect the circuit from overload

Isolating Transformer Although isolating transformer can eliminates the noise

and blocking of DC signals. However, in this setup is just to eliminates bonding

and it contains the shock hazard within the device where it might be at a

hazardous potential different between the tested devices.


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Figure 32: Protection Devices for Testing

Equipment used for the test as follow:-

Oscilloscope

2 X Multimeter

Signal generator

Power Supply

2 X Computer with Labview software

6.1 Power Supply Test

The equipment test in these test are, oscilloscope, Variable Transformers, isolating

transformer and a 2 X multimeter, one is to measure the incoming AC voltage and the

other is to measure the DC output voltage. An AC voltage will gradually increase from

0 to 230 VAC as shown in figure 33 to obtain a 5 VDC source.

Figure 33: Power Supply Testing

Incoming

230VACOutput

Voltage 5 VDC


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Figure 34 below shown the DC output voltage measure from oscilloscope.

Figure 34: DC waveform

6.2 Modem IC Circuit Test

As shown in figure 35, TDA50551 chip was solder on the PCB with few components

attached on it. A power supply of 5VDC will feed

design and development of a power line communication system kim siong

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