Power Line Video Transmission

Power Line Video Transmission

Table of ContentsCHAPTER 01

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

1.1 Background to the problem.........................................................................................1

1.2 Problem statement.......................................................................................................1

1.3 Objectives and Scope..................................................................................................2

1.3.1 Objective..............................................................................................................2

1.3.2 Scope....................................................................................................................2

1.4 Methodology................................................................................................................3

1.4.1 Implementation of testing circuit.........................................................................3

1.4.2 Developing the interface between the camera and modulator input....................3

1.4.3 Designing interface between demodulator and the TV........................................3

1.4.4 Developing the modulator....................................................................................4

1.4.5 Developing the demodulator................................................................................4

1.4.6 Developing the transmitter...................................................................................4

1.4.7 Developing the receiver.......................................................................................4

1.4.8 Application of power line communication system...............................................4

1.5 Resources required and tentative budget.....................................................................5

1.6 Time Plan.....................................................................................................................6

CHAPTER 02

Final Year Undergraduate Project i


List of Figure

Figure 1.0 - Testing interface for PLVT………………………………………………………3

Figure 1.1 - Block Diagram of the final implementation……………………………………..4

Final Year Undergraduate Project ii


CHAPTER 01

1 Introduction

1.1 Background to the problem

Power line communication or power line carrier (PLC), also known as Power line Digital Subscriber Line (PDSL), mains communication, power line telecom (PLT), power line networking (PLN), or Broadband over Power Lines (BPL) are systems for carrying data on a conductor also used for electric power transmission. Electrical power is transmitted over high voltage transmission lines, distributed over medium voltage, and used inside buildings at lower voltages. Power line communications can be applied at each stage. Most PLC technologies limit themselves to one set of wires (for example, premises wiring), but some can cross between two levels (for example, both the distribution network and premises wiring). Typically the transformer prevents propagating the signal, which requires multiple PLC technologies to be used to form very large networks

Broadband communications and multimedia applications become increasingly requisite today. Power line communication systems can achieve information by employing the existing alternating current (AC) power wires, which makes PLC Networks being a promising approach for home multimedia applications. These applications, such as streaming video and HDTV (High Definition Television) particularly require higher data rates and demand tighter quality of service (QoS) constraints.

However Frequency and time varying channel conditions, together with burst and heterogeneous traffics, make it very challenging to achieve efficient transmission over PLC channels to satisfy QoS requirements and constraints.

Most of the time wireless transmission is widely used and implemented in communication system. PLC transmission is not much popular compare with the wireless transmission. In grid to grid data communication purposes, PLC is used within the Sri Lanka.

To establish a CCTV network over a vastly spread are most expensive and complicated since new wiring arrangements have to be installed for Data transmission and power supply. But improving a system which transmits data and power through the existing power wiring system is more advance. Because any electronic device connected to an electrical power line can use this technology.

1.2 Problem statement

For an organization existing of a proper communication system within the organization to deliver meetings, speeches, seminars to the remote persons without participating is improve the performance. To establish such a system required new wiring arrangements to transmit data in addition to the power wiring system. This may cause for higher initial cost. But transmit data and video signals through the existing power wiring system is more feasible and cost effective. Major problems inherent to Video and data transmission through indoor wiring system can be solved by applying advanced broadband communication techniques like OFDM (Orthogonal Frequency Division Multi flexing).

Final Year Undergraduate Project 1


In a country like Sri Lanka, Still video surveillance in city areas are still not developed. If a new surveillance system is planned to establish in city areas it will cost high amount. So a method like PLC will be use full in a case like that.

1.3 Objectives and Scope

1.3.1 Objective

The main objective of the project is to implement a system which transmit video signal through the existing power wiring. We also focus to produce Transmitter and Receiver which were capable of transmitting video signals through power line. Final target is to watch a video transfers from a remote camera.

Within the project the following objectives will be achieved. Implement Analog to Digital converter

To convert incoming Analog video signal into Digital Implement Digital to Analog converter

To convert output signal into Analog form Implement modulator and demodulator

To modulate and demodulate the incoming signal Implement an interface

To establish the connection between the incoming video signal and the modulator

1.3.2 Scope

All power line communications systems operate by impressing a modulated carrier signal on the wiring system. Different types of power line communications use different frequency bands, depending on the signal transmission characteristics of the power wiring used. Since the power wiring system was originally intended for transmission of AC power, in conventional use, the power wire circuits have only a limited ability to carry higher frequencies. The propagation problem is a limiting factor for each type of power line communications.

Power line video communication can be implemented on High voltage power lines and also on Low voltage power lines. But some problems like transmitting signals through the transformer may be involved Bluetooth applications or any other advanced techniques. So at this level our scope is limited to low voltage indoor power line video communication. At this stage our aim is limited to do power line video communication within a single wiring circuit of a specific building.

The camera used to take input signal have to be limited to lower pixel rate because higher pixel rate cameras cause to higher output data rate. Further improvements will be associated with them.



1.4 Methodology

Implementation of power line communication system is to be done in the following steps.

1. Implementation of testing circuit2. Developing the interface between the camera and modulator input3. Designing interface between demodulator and the TV4. Developing the modulator5. Developing the demodulator6. Developing the transmitter7. Developing the receiver8. Application of power line communication system

1.4.1 Implementation of testing circuit

As a reliable circuit with no faults is needed for the testing purposes, firstly we have to develop a testing circuit which should be closed to the ideal characteristics as possible. For this purpose we hope to develop a testing circuit which can be considered as almost an ideal circuit as in the following figure. And also we hope to use this circuit as long as we can have a sufficient amount of satisfaction. And also in many buildings there are 3 phase lines. But for testing purposes we prefer to have a single phase line.

Figure 1.0 - Testing interface for PLVT

1.4.2 Developing the interface between the camera and modulator input

The camera output cannot be given directly to the input of the modulator. So another interface between camera and the modulator input have to be created. For this purpose, a microcontroller based circuit can be developed.

1.4.3 Designing interface between demodulator and the TV

The output from the demodulator circuit is a digital signal, but the signal displayed through television must be an analog signal. so a digital to analog converter has to be used between the demodulator and the television.



1.4.4 Developing the modulator

The camera output data signal cannot be transferred through a medium as it is. So an alternative method has to be used. Hence here a modulation method has to be used. For this project it is feasible to use PSK modulation technique because there are many advances in this technique. Some of them are,

1. Higher bit rate2. Less attenuation3. When comparing with ASK, FSK techniques, PSK is very suitable for higher

frequencies.

1.4.5 Developing the demodulator

This module has to be developed according to the modulated circuit. In this process a modulated signal has to be demodulated at the receiver end to visualize the video.

1.4.6 Developing the transmitter

For the signal to be able to transmit trough the power line it have to be transmitted with a suitable frequency range. For this purpose the OFDM technology can be used. In OFDM, the sub-carrier frequencies are chosen so that the sub-carriers are orthogonal to each other, meaning that cross-talk between the sub-channels is eliminated and inter-carrier guard bands are not required. This greatly simplifies the design of both the transmitter and the receiver; unlike conventional FDM, a separate filter for each sub-channel is not required. And also there, the modulated signal is delivered at 2 orthogonal planes. So the bit rate is higher compared to FDM and other techniques. However using this technology affects to the overall cost of the project. So in this project we hope to use this technology to further improve the quality of the video and keep this as an advanced step.

1.4.7 Developing the receiver

The transmitted signal must be decoded at the receiver to see through the television. For this purpose an OFDM de-multiplexer has to be used.

1.4.8 Application of power line communication system

Finally all the components have to be connected together so that the complete operation of the circuit can be analyzed. At there any faults and other troubleshooting operations hope to be done.


Figure 1.1 - Block Diagram of the final implementation


1.5 Resources required and tentative budget

Required Item Description Tentative Cost

Camera 5MP Camera with analog output $12Micro controller unit Programmable plug and play micro controller $31High frequency T/F Two transformer to isolate power line and Tx and Rx cct $17Cables Power cable 3core, Screen cables, Circuit wires $8Electrical outlet (13A) Two electrical out let to access to power line $7Transistors, resisters, Diodes and boards

For building circuits $25



1.6 Time Plan


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CHAPTER 02


Power Line Video Transmission

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