Digital Video Noise Generator Computer Science Essay

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This report is based on feasibility studies undertaken on a final year project titled Digital Video Noise Generator. This project involves analysing the effects of noise on digital video signal by virtue of this singular fact a Noise generator has to be developed, the Video source has to be in unison with the noise thereafter both signals will be mixed together in order to achieve the proposed aim.

This document however establishes the possibility of this project within the stipulated time frame. Architecture of the entire circuit has been proposed.

Project based research show that the project is feasible.

At this stage a preliminary design of a noise generator has been implemented and the results obtained seem satisfactory but more research has to be undergone in order to produce a robust architectural design that could be successfully built.

Table of Content

Abstract 2

Table of Content 3

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List of Figures 4

List of Tables 4

Glossary 4

Chapter 1 Introduction 5

1.1 Background Information

1.2 Aims

1.3 Objectives

Chapter 2 Literature Overview 5

2.1 Noise Generator

2.2 Digital Video

2.3 Digital Video and Noise

Chapter 3 Project Specification 6

3.1 Technical Background

3.2 Software Requirement

3.3 Hardware Requirement

Chapter 4 Project Management 7

4.1 Feasibility and Research:

4.2 Project Stages.

4.2.1 Designing, Building and Testing a Noise Generator.

4.2.2 Synchronising The Noise with the Video.

4.2.3 Analysing the Effect of Noise on Digital Signal.

4.3 Project Plan

4.4 List of Resources Required

Chapter 5 Risk Analysis 10

Chapter 6 Conclusion 10

Chapter 7 References 10

APPENDIX A GANTT CHART

APPENDIX B Project Risk, Ethics and Threat Assessment Checklist

APPENDIX C Project Resources Checklist

APPENDIX D Project Registration Form

List of Figures Page

Figure 1 : Digital Video & Noise Comparison 6

Figure 2: A zener Diode Noise Generator 8

Figure 3: Draft Architecture of the Final Circuitry 8

List of Tables

Table 1: Resource Allocation 9

Table 2: Risk Analysis. 10

Glossary

AC - Alternating Current

BNC - Bayonet Neill-Concelman

CCD - Charge-Coupled Devices

CD - Compact Disk

DVD - Digital Video Dics

HD - High Definition

IC - Integrated Circuit

LNA - Low Noise Amplifier

MPEG - Moving Pictures Expert Group

MUX - Multiplexer

Mhz - MegaHertz

NTSC - National Television System Committee

PAL - Phase Alternate Line

SD - Standard Definition

TINA - An Electronic Design Automation Tool

1 INTRODUCTION

1.1 Background Information

The commercial success of digital video transmission is embedded in the quality of the motion picture which must be free from unwanted frame distortion i.e noise, so therefore the world of digital Video signal transmission is rather a complicated but yet interesting industry; which has continually changed our perception of virtual imaging. This effect is evident in most of our daily applications such as Television transmission either in HD or SD, Various definitions of motion pictures as seen in movies and even as little as our daily usage of mobile phones, camcorders or even online podcasting or streaming, these and many more are the present day highlight of Digital video transmission. On the other hand, noise is said to be an unwanted element in the advent of digitization as it scrambles the frames of the signal however Noise could also be used more positively in the analyses of digital stream and also for synthesis of many digital video.

1.2 Aims

This project which is focused on making evident the effects of Noise on digital video signal and will take into context the modalities of constructing a noise generator ensuring that the noise been generated is suitable for transmission and thereafter introducing a digital video signal i.e MPEG-2.

1.3 Objective

This Study will display a range of the following objectives;

The design, construction and testing of a noise generator with variable gain and a selective frequency.

The synchronisation of a digital video signal and noise having the same sync pulses as such a Sync IC is needed.

The Mixing of Both noise and the Sync Video using a Video Mixer in order to analyse the effect of noise over the transmitted video signal

2 LITERATURE REVIEW

2.1 Noise Generator:

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Noise is predominantly seen as a form of distortion the frame of digital video signals but with further applications, noise generations has however been used more positively. White noise, which is defined as noise with constant power spectrum, is useful for measuring and testing wide-band communication circuits. Commercially available white noise generators are usually very expensive. The design idea presented in this article is an inexpensive method that produces white noise up to several hundred MHz. This white noise generator is based on the avalanche noise generated by a zener breakdown phenomenon. It is created when a PN junction is operated in the reverse breakdown mode. The avalanche noise is very similar to shot noise, but much more intense and has a flat frequency spectrum (white). The magnitude of the noise is difficult to predict due to its dependence on the materials.

Basically the circuit has 2 portions: a zener diode, and MAX2611 or any Low Noise Amplifiers (LNA). The diode is reverse biased and noise output is taken from the anode. The MAX2611 is a wide-band Low-Noise-Amplifier with 19dB gain operating from DC to 1GHz. [3]

2.2 Digital Video

Digital video signals are produced by cameras in which the signal is digitized at the CCD array, rather than at the frame grabber. Applications that call for the use of digital video usually include some or all of the following requirements:

High spatial resolution (larger images)

High intensity resolution (bit depth)

High speed

Flexibility in timing or scanning characteristics

Noise immunity

The timing signals for digital video are much simpler than those for analogue video, since the signal is already digitized.[5]

There are two main types of image encoding used for the newer media using compressed digital video such as video CDs and DVDs. These are MPEG1 and MPEG2, where MPEG Stands for Moving Picture Experts Group(the standards body responsible for developing, agreeing on and approving the digital encoding technology).

2.3 Digital Video & Noise

Digital video compression systems achieve bit-rate reduction by exploiting image information correlation within a single frame and between neighbouring frames.

Noise-induced Frame

Original Frame

Figure 1 : Digital Video & Noise Comparison [2]

3 PROJECT SPECIFICATIONS

3.1 Technical Background

A generator is a device that either converts from one form to another or produces a programmable output. Noise generator is a device built by virtue of producing noise from the breakdown of a zener diode or reverse biasing of an NPN transistor, thereafter the few millivolts of noise generated from the output will then need to be amplified for synthesis and this is achieved with two AC coupled non-inverting amplifiers in order to produce a white noise with varied gain and selective frequency.

Both the Synchronisation and the Mixing of both Signals will be achieved using Integrated circuits as this medium is cost-effective to other options.

3.2 Software Requirements

A small fraction of this project will rely on the use of a piece of software called TINA, which is an electronic design automated tool. TINA will be mostly used for the simulation or design of each stage of the circuitry before the actual hardware construction by virtue of this tool components wastage if prevented and it more economical.

3.3 Hardware Requirement

This requirement will cover key area of the circuit construction and part of the list of hardware components requires are as follows; Resistors,capacitors,Breadboad,probes,Operational-amplifiers,transistors/diodes,Intergrated circuits, potential dividers, BNC cables, Voltage Generators, Oscilloscope and multimeters. These and many more are proposed components needed for each category of the project, other additional materials may include soldering iron, long nose pliers, side cutters, anti aliasing mat and wire strippers. Most of the equipments/components if to be purchase in real life scenarios will be out of the budgetary boundaries of this project as such there will be a need to improvise in-house.

4 PROJECT MANAGEMENT.

4.1 Feasibility and Research

A great deal of research is to be done to ascertain the technical and commercial viability of the project to ensure that the scope of the project will meet with the time frame as allocated, this is a very critical stage of the project as it aids in familiarisation with the nature of the work to be done against project time scale. Part of the study will include making findings on the likelihood of developing the product which will include analysing previous work undertaken on similar project and also the cost of both man-power and material.

4.2 Project Stages

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For better clarification and ease in the developmental process of this project, the project will be broken down into stages which includes the following;

4.2.1 Designing, Building and Testing a Noise Generator.

The backbone of this project is the generation of a noise source which will then be used after much optimisation to analyse its effect on video. Noise generation is achieved from reverse biasing of an NPN transistor or avalanche breakdown of zener diode between a supply voltage of 10-15Volts but in order to maximize the output noise for the sake of synthesis, the noise generated which is usually of a few millivolts will be amplified using Two AC couple non-inverting amplifiers. The circuit for the Noise generator will be drawn using TINA[an EDA tool for simulation] thereafter, the circuitry will be laid out in accordance with the schematic on the PCB board for testing to ensure that the output is a noise signal before further implementation on the veroboard/stripboard.

Figure2: A zener Diode Noise Generator[3]

4.2.2 Synchronising the Noise with the Video.

As this project relates to making evident the effect of noise, there would be a need to ensure that both of the signals have the same sync pulses for interoperability. In order to do this, a sync generator has to be built thereafter the digital video file will be fed to the sync generator. However, In order to ensure that we observed a synchronised output from our circuit, it is suggested to bring to bear the use of a multiplexer. This will have the functionality of choosing the correct signal at regular intervals, it is imperative so as not to have an output digital video overridden by noise and if this is the case, therefore the aim is not achieved.

The success of this stage relies on the IC used in the implementation of a sync generator/separator and the Multiplexer, to this effect various Sync IC's and 2-1MUX will be evaluated and the best-fit will be utilized.

4.2.3 Analysing the Effect of Noise on Digital Signal

This is however the final and the main aim of the project, as this involves the mixing of two signals together, it will be imperative that we introduce a MIXER for this to be effectively done.

A MIXER is used to combine signals from external sources in this case a Digital video and a noise source, both will be fed into the input of the MIXER and the corresponding output will be seen on the Screen provided. To this regards the aim of this project will be justified by viewing the effect of noise on digital video signal.

The Entire circuit diagram would take the shape of the Schematic as seen below, however it is very possible for changes to be made during the course of the project therefore the final schematic would be seen in the official report.

SYNC PULSES Video in

A in

Out

SCOPE /TV

MIXER

Circuit

MUX

Noise

Generator

B in

Figure 3: Draft Architecture of the Final Circuitry.

4.3 Project Plan.

A detailed GANTT chart is seen in Appendix A.

4.4 List Of Resources Required.

An Essential Part of Project Management is The Allocation Of key Resources and as such the Foreseeable Resources are seen in Table1 Below.

TINA: An EDA tool which is used for the Drawing and simulation of Circuit Schematic diagrams, this is essential in this project in order to save cost & material also for ease of testing. This software is Available in Project Laboratory.

Hardware Materials: Resistors, Capacitors,Operational Amplifiers,Diodes,Breadboard,Veroboard,soldering bench,wire cutter,Osciloscope,Voltage Generator,BNC cable and other components as listed above. Some of these components are readily available in the laboratory however others may have to be outsourced.

Resources

Type

Use

Availability

Cost [£]

PC With TINA

Hardware

Used for Simulation of the circuitry.

Always [LAB]

0.00

Resistors

Hardware

Used to direct Current flow.

Always

0.06

Capacitors

Hardware

Used to store Electric charge

Always

0.08

Op-Amp

Hardware

As amplifiers for input signal.

Always

0.25

Zener Diode

Hardware

Avalanche Breakdown for noise generation

Always

0.06

Potentiometer

Hardware

Act as a variable resistor and used mostly as volume controller

Always

0.41

Charged Capacitor

Hardware

Used for Blocking direct current and also for smoothing.

Always

0.03

DIL Socket

Hardware

Used as an IC Socket/Holder

Always

0.09

Stripboard

Hardware

As an electronic prototype board

On Request

4.80

Multiplexers

Hardware

Used to select one of two input signals

Always

0.28

Osciloscope

Hardware

Used for signal analysis

Always

0.00

VCO

Hardware

For Voltage Generation

Always

0.00

Total

6.06

Table 1: Resource Allocation

5 Risk Analysis.

Risk

Level

Mitigation

Electrical Shock

Medium

When Using the VCO as a voltage source be sure to handle with care making sure there is no direct contact and also when not in use, keep the Voltage level at Minimum or Switch Off

Soldering

Medium

Never Touch the Tip of the Soldering Iron.

Wear Safety Glass, Work in a Well ventilated Area.

Never solder on a Live Circuit.

Never Leave the Soldering Iron Plugged and Unattended

Powering Op-Amp

Medium

When Powering the Op-Amp, Keep the Voltage Level at minimum to avoid destruction

Handling Op-Am

Medium

Be sure to use the Anti Static Wristband and the Mat when handling Op-amp in order to avoid voltage to leak through

Power Supplies

High

Be Sure not to Connect live wires together for the avoidance of spark explosion

Table 2: Risk Analysis

6 Conclusion.

By Investigating the Background of digital video noise generator, this project can be considered feasible as seen from the feasibility report that the Objectives are possible to achieve within the given time frame and its ability to meet deadlines of each project activity. Finally, it can be concluded that this project "Digital Video Noise Generator" is Technically, Commercially and practicably feasible.