dvb-t measurements with promax tv explorer … measurements with promax tv explorer ii+ and ... i...

DVB-T measurements with PROMAX TV EXPLORER II+ and analysis of DVB

transport streams 1

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CONTENTS

1. Summary…………………………………………………………………………………. 4

2. Preface…………………………………………………………………………………… 5

3. Abbreviations…………………………………………………………………………….. 6

4. Introducing KaHo Sint-Lieven………………………………………………………….. 8

5. Project description……………………………………………………………………….10

6. Action Plan……………………………………………………………………………….. 11

7. Theoretical part………………………………………………………………………….. 13

7.1 Analog television………………………………………………………………. 13

7.1.1 Description of a line in the PAL system…………………………...14

7.2 Transport stream……………………………………………………………….15

7.2.1 Program Specific Information……………………………………………….18

PAT

PMT

CAT

NIT

7.3.1 Descriptors………………………………………………………….. 19

7.3 Elementary Stream…………………………………………………………… 20

7.3.1 Image codification………………………………………………….. 20

Transformation

Quantification

Entropic codification

7.3.2 Video codification…………………………………………………... 22

7.3.3 Audio codification…………………………………………………... 24

7.4 MPEG 2 standard……………………………………………………………... 25

7.4.1 Hierarchy……………………………………………………………. 25

7.4.2 Scalability…………………………………………………………… 26

7.4.3 Levels and profiles………………………………………………..... 27

7.5 DVB-SI…………………………………………………………………………. 28

NIT

SDT

EIT

TDT

TOD

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BAT

ST

RST

DIT

SIT

7.6 Measurements on the digital signal…………………………………………. 30

7.7 Error-correcting algorithms…………………………………………………… 32

Viterbi algorithm

Reed Solomon algorithm

7.8 System used in digital television…………………………………………….. 33

COFDM

QAM

Constellation diagram

8. Practical part…………………………………………………………………………….. 35

8.1 Analog signal tests……………………………………………………………. 35

8.1.1 Test using the STB and an oscilloscope………………… 35

8.1.2 Test using a vectorscope and a TV signal generator….. 38

8.2 Explanation of TsReader software………………………………………….. 41

8.2.1 Available graphs on light version of the TsReader……………... 47

8.2.1.1 Mux usage stacked area………………………………...48

8.2.1.2 PID Usage……………………………………………….. 49

8.2.1.3 Video Bit rate area chart…………………………….….. 50

8.2.1.4 Active PIDs Chart…………………………….…………. 51

8.2.2 Parameters displayed on the TsReader…………………………. 52

TEI errors

Continuity Errors

CRC errors

Section

Example PAT packet……………………………………. 55

Example PMT packet……………………………………. 56

8.3 TV EXPLORER II+ of PROMAX…………………………………………….. 63

8.3.1 Installation of the software………………………………………… 63

8.3.2 Available measurements in the TV Explorer II+ equipment…… 67

Channel Power

C/N

MER


transport streams 3

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MER by carrier

BER

CBER

VBER

8.4 Graphs representations in TV Explorer II+………………………… 72

Constellation Diagram

Spectogram

Merogram

9. Final Conclusion………………………………………………………………………… 75

10. Bibliography……………………………………………………………………………. 76

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1. SUMMARY

In this project ways to study Digital Television (DTV) have been under scrutiny.

DTV has been introduced in the whole world. Analog television has been changed for

digital television because it gives better results. Digital television has a better quality of

the image, the programs are sent using less bandwidth (permitting a bigger number of

channels), etc.

Because of the analog switch off 3rd of November of 2008, in Belgium Digital

Terrestrial Television (DVB-T) has been introduced. The antennas only make it

possible to receive DTV. Therefore it is of capital importance to understand its working

principles and to take into full consideration its characteristics. Besides DVB has not

just been implanted in Belgium but is a universal phenomenon. There are three types

of Digital Television: ISDB-T (Japan and parts of South America), ATSC (USA) and

DVB-T. DVB-T has been chosen for Europe, Russia, Oceania, Africa, etc. To transmit

DVB also cable and satellite is used. Since our laboratory in Kaho Sint-Lieven Gent

has only the possibility to receive DTV with an antenna, the focus of the present project

will be on DVB-T.

Throughout the project, Transport Stream i.e. the way DTV data is transmitted,

is defined. I try to explain how it works and which are its characteristics.

There are many ways to analyze DTV. For the present project I used an

apparatus from Promax, TV Explorer II+, and a computer program, TsReader.

The objective of my project is to show and explain how a Transport Stream is

composed and how it can be analyzed.


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2. PREFACE

First of all, I would like to thank all the people, who have helped me during my

stay in Belgium.

I must thank my parents who gave me the support not only to live through the

Erasmus Experience and who – frankly- have given me careful attention a whole life

long.

I have to thank also my mentors. My supervisor in Ghent, eng. Patrik Debbaut,

and my mentor in Catalonia, eng. Xavier Giró. They where the ones who have guided

me during my entire project. Since the first day I arrived here in Ghent.

I also have to thank Erik Van Achter, who teaches Academic Writing at KaHo-

Sint Lieven, who was always willing to help me in writing my text in a decent English.

Finally I must remember all the people who work on the international relations

areas, in Ghent and Barcelona and who have made this Erasmus programme possible

and helped me in many aspects to adapt to a new country.

6 Anna Arias

3. ABBREVIATIONS

Abbreviattion Meaning

BAT Bouquet Association Table

BER Bit Error Ratio

CAT Conditional Acces Table

CBER BER before viterbi decoder

COFDM Coded Orthogonal Frequency Division Multiplexing

CRC Cyclic Redundancy Check

DAB Digital Audio Broadcasting

DCT Discrete Cosine Transform

DIT Discontinuity Information Table

DPCM Differential Pulse-Code Modulation

DTV Digital Television

DTV Digital Television

DVB Digital Video Broadcasting

DVB-SI Digital Video Broadcasting-Service Information

DVB-T Digital Video Broadcasting Terrestrial

EIT Event Information Table

ES Elementary Stream

IRD Integrated Receiver/decoder

MER Modulation Error Ratio

MN Noise Margin

MPEG Moving Pictures Experts Group

NIT Network Information Table

OFDM Orthogonal Frequency Division Multiplexing

PAL Phased Alternated Line

PAT Program Association Table

PCR Program Clock Reference

PMT Program Map Table

PS Program Stream

PSI Program Specific information

QAM Quadrature Amplitude Modulation

QEF Quasi-Error-Free


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RLE Run Length Encoding

RLE Run-Length Encoding

RST Running Status Table

SDT Service Description Table

SIT Selection Information Table

ST Stuffing Table

STB Set-Top Box

TDT Time of Date Table

TEI Transport Error Indicator

TOT Time Offset Table

TS Transport Stream

TVC Televisió de Catalunya

UTC Coordinated Universal Time

VBER BER after viterbi decoder

VLC Variable Length Code

VLC Variable Length Coding

PID Packet Identifier

TPS Transmission parameters Signalling

VOL Video Object Layer

8 Anna Arias

4. INTRODUCING KAHO SINT-LIEVEN

The Katholieke Hogeschool Sint-Lieven is a young higher education institution in the

East of Flanders with about 4800 students and 500 employees. Although it is a young institution

it has a rich tradition. The history of KaHo Sint- Lieven comes about in the histories of the 8

former higher education institutions, which have merged in 1995.

Since the merger, KaHo Sint-Lieven has reorganized and grouped into 3 campuses in 3

regions in Aalst, Gent and Sint-Niklaas. Each campus has its own traditions and can look back

on a rich – be it shorter or longer – past. Some of the eight founding institutions were

established in the 19th century.

KaHo Sint-Lieven organizes bachelors, masters, posgraduates and short educations

concerning the study-areas of biotechnology, health care, business studies, teacher training,

industrial sciences and technology and nautical sciences.

K.U Leuven association

K.U.Leuven association

In accordance with the ideas of the Sobonne (1999) and Bologna (2000) declarations

about the restructuring of higher education in Europe, the Flemish Minister of Education in going

through a process to reform the Flemish higher education system.

One of the first objectives in this information process is to stimulate co-operation

between institutions of higher education. Therefore universities and hogescholen have drawn up

agreements in order to create “associations”, linking both types of institutions togheter.

KaHo Sint-Lieven has decided to associated with the Catholic University of Leuven (KU

Leuven), Flanders’ largest and oldest university. On 11th July 2002 the association agreement

between the KU Leuven and KaHo Sint-Lieven was signed.

The below institutions constitute the “Association KU Leuven”:

• Katholieke Universiteit Leuven

• Katholieke Universiteit Brussel

• Europese Hogeschool Brussel

• Hogeschool Sint-Lukas Brussel

• Hogeschool voor Wetenschap & Kunst

• Katholieke Hogeschool Brugge-Oostende


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• Katholieke Hogeschool Kempen

• Katholieke Hogeschool Leuven

• Katholieke Hogeschool Limburg

• Katholieke Hogeschool Mechelen

• Katholieke Hogeschool Zuid-Westvlaanderen

• Lessius Hogeschool

• Groep T

• Katholieke Hogeschool Sint-Lieven

10 Anna Arias

5. PROJECT DESCRIPTION

The project is divided in three parts: a study of how DVB is transmitted, options

to analyze TS with TsReader and uses and main functions of the PROMAX TV

Explorer II/+ equipment.

Before I started to analyze Transport Streams, I studied the composition of it.

This was the first part. It’s really necessary to know what information is needed and

important to know how to interpret the results obtained. It also was essential to be able

to explain the results, if they are right and why, and what they mean. At the beginning

of the project I did some tests to know if we were able to receive DTV. The roof

antenna is horizontally polarized, and the DTV in Ghent is transmitted vertically

polarized. The signal is very strong, because the transmitter is close to the university.

So we haven’t had any problems with the polarization. I tried to receive DTV with an

indoor antenna (AVT100 antenna visiosat) and the results were good too.

The second part dealt with software capable of analysing TS. After testing some

computer programs, we decided that the most appropriate for use in this project is the

TsReader. It permits to see what is contained in a TS, the programs and data within a

TS, showing errors, private data, etc. We decided to work with the light version

because it gives enough functions and it’s for free on the net. It is not possible to

record Transport Streams, but this function is available in the PROMAX equipment. I

worked with Transport Streams from Philips and CISCO, that I received from my

supervisor. With those TS, I could do some measurements with TsReader and check if

it was a good tool to use to study DTV.

The last part of the project was to work with the equipment from Promax, the

TV-Explorer II/+. This permits receiving DTV, record TS and perform the most

important measurements.

Another option of the equipment is to connect it to the PC and transfer the files

recorded through a USB, providing us a lot of information. It allows watching the

available channels, shows the constellation diagram, the BER, MER, … Definitely, it

offers a good way to see all the characteristics of the DTV, permitting to choose some

parameters.


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6. ACTION PLAN

Step 1 Duration: one week

I tested the signal received; I made sure that we could receive DTV with the roof

antenna.

I did it using the Set-Top Box. We could receive the radio and video programs.


In that step, the main objective was to record DTV. I was sure that in the lab it was

possible to receive DTV, and because of that I tried to record it. I used an external

hard disk, but there were some problems. Finally I used an USB stick to record.

Step 3 Duration: two weeks

Search information about Transport Stream and Digital Video Broadcasting.

Understand with precision how it works and its composition.


I looked at some TS analyzers and I tried to choose the best. I Saw features of each

one. I downloaded the TS analyzer and I did some test with TS to analyze.

Step 5 Duration: two weeks

I chose TsReader, the light version. It is not possible to record with that version. I

tested the program with some Transport Streams from Cisco and Philips. I started to

try to understand the results.


I worked with two USB STB for the computer to watch DTV in the computer. They

worked correctly. But, the format of the video, that these programs create, has a

incompatible format with TsReader. We therefore couldn’t use this files to study TS,

just to watch DTV in the computer.

I also did some test with an indoor antenna, putting it in different places in the lab to

see the different results.


I studied Vertical Blanking Interval on DTV. How it works, if VBI exists in Digital TV. I

also studied other parameters like SDT, TOT, …

I investigated DTV errors. TsReader gives information about errors. I looked for what

these errors could possible mean.

I made some measurements with an oscilloscope of the output signal of the STB. To

see if the analog signal meets the requirements of the PAL system.

12 Anna Arias

Step 9 Duration: 3 weeks

I received the equipment from PROMAX. I started reading the manual of the PROMAX

equipment and to study the characteristics of the signal. Like e.g. Constellation, BER,

MER, …

Step 10 Duration: 3 weeks

I made some test with the equipment. After that, I tried to connect the equipment with

the PC to be able to download the files saved, the files that contain the information

about the measurements made of the signal received in the lab.



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7. THEORETICAL PART

7.1 ANALOG TELEVISION

In what follows, a brief explanation will be given to understand better the

information explained in the practical part about the output signal of a Set-Top box.

In Europe, the analog colour system used is PAL. In this system, the luminance

signal and the chrominance signal are sent separately, forming together a composite

video baseband signal. The chrominance information is a quadrature amplitude

modulated subcarrier.

The Video signal is made by a set of lines. These lines are grouped in frames.

In their turn, these are divided in two fields.

figure 1: lines in one field

Amplitude signal is 1Vpp (between 0.7v and -0.3v). The part of the signal with

information is above 0v and the part with sync information is below 0v.

The most important specifications of PAL are:

• Aspect ratio: 4:3

• Number of lines: 625

• Active lines: 576

• Active columns: 720

• Erasing vertical: 25 H + 12 microseconds

• Frame rate: 25 Hz

• Field rate: 50 Hz

• Line frequency: 15,625 Hz

14 Anna Arias

• Subcarrier chrominance frequency: 4,4336 MHz

• Line period: 64 microseconds

• Active line period: 52 microseconds

7.1.1Description of a line in the PAL system

The sync pulse is sent to inform the receiver about the fact that a new line is

started. A line with an opposite polarity to luminance is introduced, with an amplitude of

30% of the total level of the sign.

figure 2: PAL line

There are three types of sync: of a line, of a field and the colour sync.

The line sync indicates where a line begins and finishes. It is divided in the front

porch, the back porch and the sync pulse. The burst signal is situated in the back

porch; it has a duration of 2,27 milliseconds. The burst gives a reference of phase

(tone colour) and amplitude (saturation colour) constants. The receiver uses this

reference to demodulate correctly the information of colour that is modulated in the

line.

The field sync indicates where the beginning and the end of each field are

situated. They are made by: the pre-equalization pulses, sync pulses, post-equalization

pulses and guard lines (where teletext and other services are sent).



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7.2 TRANSPORT STREAM

The goal of the project is to analyze transport streams. Throughout the project it

will be explained how this takes place, mentioning the composition and the

characteristics of a transport stream. To be able to fully understand all the results and

the management of the software and equipment a brief explanation is written.

MPEG-2 and DVB specify the workings of Digital Television (in Europe). First MPEG 2

specification is explained.

To generate a TS, the point of departure are the Elementary Streams. A set of

ES forms the program streams of the Transport Stream.

The first step is to split the ES into packets. These packets are called PES packets.

They are composed of the PES header and the payload. The length of the payload is

variable, up to 64 kBytes, and depends on the application. The payload is composed of

a variable number of data of one Elementary Stream and is written in the same order

as the original ES.

In the PES header we can find the Stream_id to be able to know to which ES

they belong. This is a unique number inside the program stream. With that number it is

possible to reconstruct a determined ES. One of the objectives is to give the timing

information and characteristics of the ES that ES is not capable of giving. Like e.g. the

dimensions of the image, image frequency, level, profile, aspect ratio, ...

The second step in the generation of the TS, is to select the PES packets and

insert them within small packets of 188 bytes. If there is less data than 188, because it

is difficult to have all the time the exact data, it contains null data. However, these

packets always have to contain data from only one PES packet.

In the header of the TS packet we can find the PID. The PID indicates to which

Elementary Stream the TS Packet belongs. This number has to be unique for all the

TS. In the header information about transport level and multiplexing is stored. Some of

this information is transport priority, continuity counter and adaptation field control. The

continuity counter is a number that increases each time TS packet is sent, to indicate

16 Anna Arias

the order of the packets with the same number. The adaptation field control indicates if

an adaptation field is present.

figure 3: TS Packet

The adaptation field is an optional field with a variable length (from 2 bytes to

the whole package). Its function is to provide more information about transport level,

multiplexing and synchronization. Among others it contains the PCR, which transports

important information to synchronize the decoder with the time of a selected program,

and a field with variable size to fill a TS packet if this one doesn’t have the necessary

size to do it with the data.

Finally TS packets from Elementary Streams are multiplexed and aligned to

generate the TS. In that multiplexing process the TS packets that contain private or PSI

data are combined. There are no defined restrictions of the order of the TS packets in

multiplexing but the packets of one ES have to be in a sequential order.

The bit rate of TS always has the same value. But the ES that are contained in it can

vary.

Usually one Transport Stream will contain between four and seven programs

(depending on the required quality of them), 2 or 3 audio channels and maybe other

data such as teletext.

In practice there is no equipment to generate TS with 20 audio and video inputs that

will be contained in multiple programs.

To generate the TS, the system used can be divided in two stages. In the first

stage different TS with a single program are generated. Whereas in the second a

remultiplexing of the TS packets of the different Single TS generates a multiple TS.



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The first stage is composed of a set of encoders that digitize, compress and

encode video and audio. And together with other data (like PSI data and PCR) forms

the Single Transport Stream.

The second stage consists of connecting the single transport streams to inputs

of a multiplexor, the function of it is remultiplexing all of the TS packets that belong to

the single TS to generate the Transport Stream. Sometimes the multiplexor has to

change the PCR, and some information in the PSI.

figure 4: Transport Stream

Numbers of inputs are limited and if there are a lot of Programs, it is possible to use

more than one multiplexor to form the TS.

Now the TS is adapted to the network (cable, terrestrial or satellite) and to the

transmission channel. This is specified by DVB.

The DVB defines error prevention techniques and the type of modulation necessary

to transmit the signal through the network.

18 Anna Arias

7.2.1 Program Specific information

With the PSI, MPEG-2 provides a method to describe the contents of a

transport stream with the aim of simplifying processes, guide demultiplexation and

presentation of programs.

There are four PSI data:

• Program Association Table (PAT)

All TS have to contain a valid and complete PAT.

It lists every program in a multiplex transport stream. Each entry in the PAT

points to a PMT. TS packets that contain PAT information always have a PID of

0x0000.

The first entry in the PAT, program 0, is reserved for network data and

contains the PID of Network Information Table (NIT) packets.

Any change inside the transmitted programs has to be described in an updated

PAT version.

PAT is divided in 255 sections to minimize the data loss. Each section

transports part of the totality of PAT. If one packet is lost or there are error bits

in a small section of the PAT, we can decode the other sections.

• Program Map Table (PMT)

The PMT table lists elementary streams making up each program with

its PID's.

MPEG-2 requires at least, an identification of the program: program number,

formats of streams, PID of the PCR, Elementary Streams and PID of the

program.

When more information is needed, it is possible to use descriptors. The

PMT always is without encryption.

• Conditional Access Table (CAT)

CAT is a service that allows the broadcasters to restrict some contents

and to prevent unauthorized use.



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It also denies the access of general users to private content, and

provides the necessary protocols and systems to access users’ ability to play a

program. For example, CAT is used in pay-per-view or interactive features.

MPEG only establishes the data structure; the details will depend on the

encrypted system used.

In any TS with one or more encrypted ES, a detailed CAT table has to be within

the TS.

CAT provides details of the scrambling system in use and provides the

PID values of TS packets that contain the CA information.

The PID 0x0001 is for TS packets that contain CAT information.

• Network Information Table (NIT)

Contents are private, specified by the broadcaster. NIT contains

information about the physical network that carries the TS. Like maps of the

services with TS identifiers, channel frequencies, features of the modulation,

service name, etc.

PID of the TS packets with NIT information is 0x0010. Also this table

contains the private stream information too. For example, TeleText and

subtitles.

Descriptors

If the information conveyed by the PSI tables is not enough descriptors are

used. Descriptors are a set of syntactic structures transmitting the additional data.

There are a lot of descriptors, each directed to one type of information. The location of

them is always within one loop section, although it is used in private sections too.

20 Anna Arias

7.3 ELEMENTARY STREAM

7.3.1 Image codification

To make a video ES starts with the compression of images. Compression of

data is defined as the reducing process of a quantity of necessary data to effectively

represent information, in this case an image.

This is based on the reduction of spatial redundancy and irrelevance of images.

So, images have the common characteristic that the nearest pixels are correlated.

There are three ways to reduce data: elimination of redundant code, elimination

of redundant pixels and elimination of visual redundancy (information that no one can

perceive).

It is possible to compress with loss of data or without loss data. The first one

gives a higher compression factor than the other.

Three steps form a typical schedule of compression:

• Transformation

Reduces redundancy of the input signal. The image is divided in some

blocks trying to have a common content in each one and with the same size for

all of them (normally 8x8 pixels). This signal is transformed into a DCT signal.

DCT has the capacity to concentrate most of the information in a few

transformed coefficients.

figure 5: image divided in blocks

• Quantification

This step permits to reduce precision of DCT coefficients that are

represented when DCT is converted into a whole representation. Here, the

number of coefficients is reduced.



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The Bit rate is controlled by varying the steps of the quantification of the

coefficients of the transformed image. The human eye is more sensitive to low

frequencies than to high frequencies.

figure 6: example of quantification

• Entropic codification

This codification is used to codify quantified coefficients. It is calculated

with the number of bits per used symbol and uses three kinds of codification:

Zig-zag reader + RLE, DPCM and VLC.

The reading method used is zig-zag. This one reads the matrix symbols

in a zig-zag manner.

The zig-zag reading permits that consecutive zeros can be codified

efficiently through Run Length Encoding (RLE).

figure 7: zig zag reader

RLE compression keeps the symbol value and counts how many equal

symbols there are consecutively. It generates a sequence of values where a

number of symbols and symbols are contained.

Example:

Original sequence: (1,1,8,8,8,8,8,2,2,2,4,4,4,1,3)

RLE codification: [(2,1),(5,8)(3,2)(3,4)(1,1)(1,3)]

22 Anna Arias

DPCM codifies the difference between a value and the previous one.

The difference between both is minimum.

VLC assigns code words of variable length of bits for each symbol to

their likelihood of appearing in the sequence to send. Symbols, which are more

likely to appear, they are codified with less numbers of bits and vice verse.

7.3.2 Video codification

Video is a consecution of images. Images are commonly very similar to

previous or next ones. Video sequences present a high temporal redundancy. Video

algorithms of compression do difference operation to try to identify temporal

redundancy to codify just the difference between images.

A simple prediction of pixels to pixels doesn’t give a good result normally,

because it is ineffective.

Therefore movement prediction is used, frame prediction of video sequence

made through partitions of an image that contain several pixels. Estimation of pixels is

based in level treatment of macroblocks.

To get the correct vector movement block matching is used. This gives the

vector to apply to each macroblock of the image to find position that gives the minimum

difference.

Predict movement implies that one macroblock in a predicted image is always

referenced to another image.

Depending on the position of the reference image with a regard to the image to be

encoded, there are three kinds of prediction:

• Backward

Prediction of each macroblock takes reference in the later frame.

• Forward

Prediction of each macroblock takes reference in the previous frame.



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• Bidirectional

Prediction of each macroblock is done using values of the previous and

later frame.

If consecutive frames don’t have any temporal redundancy, the frame to encode

is just processed like an image, looking for space redundancy.

Compression standards of video use type of images to compress data. Instead

of coding each picture that form video, it is possible to codify an image totally and later

codify differences between this one and next ones.

For example, in video sequence with a fixed plane, can be codified just the

parts with movement, winning capacity of compression.

Frames of a sequence can be I, P or B, depending the kind of prediction used in

each case.

• Image I

They are used to decode other images that compose video. Normally

these need more space than the others. Just take profit of the space

redundancy in its codification. Give random access inside the sequence. And

can be used to predict P and B images.

• Images P

They are predicted referenced an image that can be I or P before in

time. Needing previous decoding of the reference image. Accumulates errors.

• Images B

They are predicted with the reference of two images that can be I o P.

Needing the previous decoding of both images.

24 Anna Arias

Example:

figure 8: example of images I,P,B

In the figure 8 is showed an example of a sequence of images. Vectors below

indicate predictive reference between them.

7.3.3 Audio codification

In the project, audio coding is not explained in detail because video is the more

important part to be studied.

Audio codification is a means to translate analog into digital signals, voltage

value into binary system. To get the digital signal, the analog signal has to be

digitalized. The signal has to be quantified and the signal has to be converted into

digits (zeros and ones).

figure 9: audio codification

The audio codification mode used in TVD is the so called component

codification. This codification implies a process that digitalizes analog TV signals; using

the division per components: luminance and chrominance (Y, R-Y, B-Y). This

codification is compatible for all the television standards, using the same sample rate,

digital quantification and codification.



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7.4 MPEG 2 STANDARD

MPEG 2 standardizes several processes related with encoding image:

hierarchy, scalability and levels and profiles.

7.4.1 Hierarchy

Video elementary stream is organized in those hierarchies groups:

• Sequence

Is formed by one or more image groupe. In its header it defines

dimension of images, image frequency, buffer size and ratio aspect of pixels.

• Image Group

Images that can be transmitted in different order than the order have to

be showed. The first one always is an I image.

• Picture

Picture is a unit that contains luminance and the two components of

chrominance.

The header defines if it is an image I, P or B, the value maxim and

minimum of value of movement vectors and its position within the image group.

• Slice

Slice is a basic resynchronization unit of the system, a point to recover

against errors. The decoder can reject a corrupt slice and continue with the next

one. The number of slices can vary between one per picture to one per

macroblock, depending error protection against noise selected.

• Macroblock

Macroblock is the basic unit where movement compensation is made.

The header gives information about the kind of codification used in the

macroblock, scale of quantifier and vector movement.

26 Anna Arias

• Block

Block is a codification unit on which DCT is done.

figure 10: hierarchy

7.4.2 Scalability

Scalability permits a representation by layers of the bit rate of one video source.

The structure of the video is broken into different layers.

Scalability give us the possibility to adapt bit rate to the needs of each

application, the receiver may request the desired resolution. It is implemented using

VOLs (Video Object Layer). These are base layer and enhancement layers.

The bit rate is divided in two layers, called partitions. The Base layer is

transmitted with a higher level of priority data (extra error correction data and less error

bits). This layer has to be has enough data to give a minimum quality. Enhancement

layer has a lower level of priority with a higher probability of loss. This layer contains

high frequency coefficients and other less important information.

MPEG 2 permits four basic methods of scalability of bit rate:

• SNR scalability



27

The different layers are coded at identical sample rates, but with

different picture quality.

• Spatial scalability

This scalability is based on coding base layer in lower sampling

dimensions than enhancement layers.

• Temporal scalability

Video is coded with a lower frame rate. The enhancement layers can do

a reconstruction as prediction, to improve the quality of the video.

• Data Partitioning

This scalability consist of break the block of 64 quantized transform

coefficient into two bit streams: The base layer, with the critical lower

frequencies, and the enhancements layers, with the higher frequency data.

7.4.3 Levels and profiles

To provide a definition of a unique codification standard was impossible; the

majority of the applications should use a little subset of offered possibilities by the

standard. Because of that MPEG took the decision to make a standard of data

transmission composed of a set of profiles and levels so as to satisfy the specific

requirements of the applications.

The profile is basically the degree of complexity expected in the encoder. The

level is a set of parameters, like the size of the image or the bit rate used in this profile.

Levels indicate vertical and horizontal resolution of the image.

28 Anna Arias

figure 11: levels and profiles

7.5 DVB-SI

Digital Video Broadcasting-Service Information is a normatively defined. It is a

standard of data transmission in DTV emissions. This information service gives

facilities about the navigation within DVB to the user.

DVB-SI works on MPEG-2, complementing Program Specific Information. DVB

adds information that helps to tune particular services or to show interesting programs.

Necessary elements to develop Electronic Guide Program are given by DVB-SI.

DVB-SI basically consists of four information service tables and a set of

additional tables. The next four ones are the principals:

• NIT

The Network Information Table is specified by DVB. On MPEG 2, NIT

was defined but the content was not specified. Necessary information is

exposed in NIT to syntonize channels of a service provider.

• SDT

The Service Description Table describes services that are part of a TS.

There is always one SDT per TS. In the SDT, the parameters associated to

every service are listed. Like e.g. name of the service, service identifier and

service status.

• EIT



29

The Event Information Table gives information about the event; grouping

all present and future events that will be contained in MPEG multiplex. EIT

provides information like e.g. starting times.

• TDT

The Time of date and table gives information about present time and

date.

• TOT

The Time offset tables transmit the actual date and hour according to the

UTC. It also transmits information about local time difference. The transmission

of TOT is optional, but if it is transmitted it must happen at least every 30

seconds.

The following tables are the additional ones:

• BAT

The Bouquet Association Table could be helpful for the IRD, to show the

available services in a user friendly way.

• ST

The Stuffing Table is used to invalidate non-existent sections.

• RST

The Running Status Table permits to update the status of an event (if it

is running or not) when there are unexpected problems in the programming.

• DIT

The DIT is used when the bit stream is finite. It is inserted where the SI

information could have discontinuities.

• SIT

The Selection Information Table is just used when the bit streams are

finite. It transports a summary of SI information required to describe the streams

within finite bit streams.

30 Anna Arias

7.6 MEASUREMENTS ON THE DIGITAL SIGNAL

These measurements are used to measure the quality of the signal that arrives to

the receiver.

• BER

Bit Error Ratio is the main parameter describing transmission quality. It

is defined as the ratio between the number of erroneous bits and the number of

total bits transmitted.

• CBER

BER before Reed Solomon decoder. The error bits of a TS packet would

be estimated comparing errors bits before and after Reed Solomon decoding.

If BER value is higher than 10-3, the measurement is no reliable.

Quasi error free corresponds to the value before Viterbi decoder. BER of

7x10-2 to 7x10-3, depending on the convolution code chosen.

• VBER

BER after Viterbi decoder. This measure is made after Viterbi decoder.

These errors must have a value between 7x10-2 and 10-5. Outside these ranges

the measurement has no reliability.

QEF in Viterbi decoder output is 2x10-4.

• MER



31

Measurement done on the symbols of the modulations type QAM to

check that the constellation diagram will have an acceptable form. This is really

useful when it is impossible to show the diagram because it gives a value of the

error number bits.

Graphically, MER can be defined as the difference between the ideal

constellation and the constellation received.

• N (Level Noise)

The received noise power is the total interference power present in a

system, when the information signal of the power is erased.

• C (Power)

To do the measure of the channel power, the bandwidth of the

modulated signal has to be defined. The equipment, which measures the

average received modulated carrier power, integrates the carrier in the whole

bandwidth.

• C/N

The carrier-to-noise ratio is the quotient between the C and the N. C/N

ratio compares the level of a desired signal to the level of background noise.

High C/N ratios provide good quality of reception. The units of C and N are

watts or volts squared.

figure 12: Carrier to Noise Ratio

32 Anna Arias

7.7 ERROR-CORRECTING ALGORITHMS

Viterbi algorithm

Andrew Viterbi designed the Viterbi algorithm in 1967. The Viterbi algorithm is a

technique to decode convolutional codes.

The information is convoluted before it is transmitted by the channel. Because

the messages are convoluted, the messages have redundant information into the

transmitted signal. This redundant information helps correcting errors.

The algorithm can find the most probable sequence of states in a Hidden

Markov Model. From a sample, the algorithm obtains the optimal sequence that best

explains the sequence of samples.

Reed Solomon algorithm

Reed Solomon algorithm is used to correct errors in digital transmissions.

This code forms part of the Forward error codes. This means that the errors are

corrected in the receiver.

The algorithm uses redundancy bits to correct the errors. In DVB the algorithm

introduces 16 bits in each packet of the transport stream (188,204). This permits to

correct 8 error bits of each packet.



33

The Reed Solomon algorithm can correct a specific number of errors “C”. That

number depends on the difference between the total number of symbols (N) and the

total number of unprotected symbols (K).

C = N − K

2

7.8 SYSTEM USED IN DIGITAL TELEVISION

COFDM

Coded Orthogonal Frequency Division Multiplexing is a type of modulation

especially suitable for terrestrial broadcasting channels and DAB.

The terrestrial environment is subject to fading, Doppler effect, etc. In order to

transmit digital signals in these conditions is needed to implement OFDM modulation.

Orthogonal Frequency Division Multiplexing is a transmission system that

consists in sending a set of carriers of different frequencies. Whereby the transmitted

information is modulated in QAM modulation.

The symbol rate of each of these carriers is rather low. This is the cause of the

fact that the length of the symbol is extended. It also gives a protection against echoes

produced for the several paths that the signal crosses before reaching the receiver.

Usually OFDM is made after having passed one channel encoder (to correct

errors produced by the transmission). After that, this modulation is called COFDM.

MPEG-2 signal passes through two systems of error correction. And after these

systems, the signal passes an interleaving process. Then is multiplied by a pseudo

random sequence to disperse the spectrum and reduce the interference effect.

34 Anna Arias

COFDM uses 1536 up to 6817 carriers, spaced depending on the type of the

sent sign. That the information is distributed in a huge number of carriers helps is not

losing much information if one carrier is lost.

The modulated signal has a guard interval, in that period of time is one symbol

constantly sent. The signals that arrive with less delay than this guard interval can be

constructive signals to improve the received signal.

figure 13: COFDM transmission

In Europe DVB-T 8k carriers are used. The modulated data are multiplexed in

each carrier, which is modulated in 64 QAM.

QAM

QAM modulation is a scheme of multi-level modulation. Quadrature amplitude

modulation is the combination of amplitude modulation and phase shift keying.

The information is sent modulating the amplitude of two carrier signals. Both

signals, sinusoids, are out of phase by 90° degrees . QAM modulation sends the

information changing some aspects of the carrier information respecting a data signal.

The possible states of a particular configuration are showed using a

constellation diagram. In this diagram, constellation points are organized in a squared

grid, with equal horizontal and vertical spacing. The 64 is the number of points in DVB-

T used.

Constellation Diagram

A constellation diagram is a graphic representation of a signal modulated by a

digital modulation in a complex plane. The real axis normally is called I (In-phase), and

imaginary axis is called Q (quadrature).



35

A constellation diagram can be used to recognize the type of interference and

distortion in the signal.

The figure 14 is an example of a constellation diagram of a 16 QAM modulation

system.

figure 14: example of 16 QAM constellation diagram

8. PRACTICAL PART

8.1 ANALOG SIGNAL TESTS

8.1.1 Test using the STB and an oscilloscope

Nowadays it is impossible to receive analog television with an antenna.

Currently, in the cable television analog television is transmitted. But it is paid

television.

Therefore, to do analog measurements in the lab of the university, the only way

is analyzing the output signal of the Set-Top Box.

figure 15: Set-Top Box and a oscilloscope

36 Anna Arias

Before using the output signal of the STB (TVT200 DVB-Terrestrial receiver), as we can see in the figure, we had to be sure that the signal meets the PAL requirements.

Figure 16 presents how the output signal has to be part of a PAL line. This

picture shows the sync pulses (pre-equalization pulses, post-equalization pulses) and

the beginning of the odd field.

figure 16: PAL line

figure 17: PAL line

Figure 18 shows how the output signal of the STB is like. A digital signal

received from the roof antenna.

figure 18: signal displayed on the oscilloscope



37

Between figure 17 and figure 18 there is consistency. Figure 17 shows clearly that in the output signal there are the pre-equalization pulses and the post- equalization pulses with the correct measures.

figure 19: PAL line


In figure 20 the horizontal sync and the last teletext lines are contained. The

total amplitude of the signal is 1v approximately and the amplitude of the horizontal sync is -0.3.

In figure 19 is shown how a line has to be. In the part of the horizontal sync is

specified that the horizontal sync is inverted polarized, with an amplitude of the 30% of the signal.

Figure 20 and figure 19 follow the same standards.

38 Anna Arias


In figure 21 in the Vertical Blanking Interval, teletext lines are displayed. Like in

figure 17 after the post-equalization pulses, the teletext lines are present.

After all these tests, the fact that the PAL analog signal and the output signal of the STB have the same parameters is confirmed.

This is necessary because the analog televisions need an analog signal to

display the contents. Because of that the Vertical Blanking Interval also has to be present in the output signal.

VBI is the time between the last line of a frame or field and the beginning of the next. It is expressed as the number of scanned lines in this short period. During this time the data transmitted is not displayed on the screen (for example, teletext).

Another test made to confirm that the teletext can be displayed on the television

by its own decoder. It was just trying to display the teletext signal with the command of the television. This is possible because a signal that meets PAL requirements is received.

The teletext can be displayed in both ways, with the command of the STB or with the command of the television.

The image produced by the STB is weaker than the image made by the

television. This signal is only sent in one field, this image is interlaced. The image produced by the television is harder without flickering, no interlaced.

8.1.2 Test using a vectorscope and a TV signal generator.

In the lab also there is also a vectorscope (it was received from VRT) and a TV

signal generator.



39

figure 22: Vectorscope and TV signal generator

A vectorscope is a measure instrument used in television to see and measure

the colour component of the video signal.

A vectorscope displays an X-Y plot of two signals. That is why it is used to

represent the chrominance of the video signal.

The chrominance has two parameters, the colour saturation and the hue. The

Colour saturation is encoded as the subcarrier’s amplitude and the hue is encoded as

the subcarrier's phase.

The result is a vector, which has the origin in the centre of the screen. The

module as the saturation and the hue as phase represent this vector.

On the other hand, a TV signal generator is used in this test. Different video

signals are generated in this test. The colour bar is the signal used.

The colour bar is a test video signal used in TV production to check the state of

the production systems, which are used to generate and transmit the TV signal.

figure 23: colour bar

If the TV signal generator is connected to the vectorscope the signal received is

displayed in vectorscope as is shown in figure 24.

40 Anna Arias

figure 24: vectorscope displaying the colour bar.

Figure 24 shows in the first screen of the vectorscope two PAL line. First, there

is the colour burst, and then the colour bar with the rainbow colours.

In the second screen, colour information is show. The X-axis represents the B-Y

difference component and the Y-axis the R-Y difference component.

The colour burst is the colour reference. It is sent in each line, between 135 and

225 degrees. That is why colour representation is made two times, one above and one

below the X-axis.

figure 25: vectorscope displaying the green frames.

Figure 25 is interesting to see in an easy way how runs the vectorscope and

how are transmitted the PAL lines.

The signal generated this time is continuously green lines. As it is shown in both

screens of the vectorscope.



41

In the first screen the whole line is only one colour sent, the green colour. And

in the second screen there are just four vectors. The colour burst and the green colour.

8.2 EXPLANATION OF TSREADER SOFTWARE

In figure 26, the interface of TsReader is shown. The TS used to give the

following examples is from The University of Diepenbeek. This TS contains 2 video

programs, and 9 audio programs.

In this picture is shown the easy way to see how a TS is structured and the

values of a lot of parameters using TsReader.

The general items shown are the list of the data contained (in the left part of the

window), the descriptions of the data selected (in the white square showed in the top of

the middle space), all the ES presents sorted by rate or PID (in the middle of the

middle part) and a list of the programs included in the TS (in the right part). Finally, at

the central part, at the bottom of it, there are the quantified results. Like errors and

numbers of sections.

42 Anna Arias

figure 26: TsReader interface

In figure 27, a radio program is selected. When a click is made above the PMT

of it, the composition of it is shown, giving some information: program number, the PID

of the PCR of this Program, PMT version, service name, format of the Streams that it

contains and the PID of the ES contained. When a PMT is selected in the list by rate of

the bit rate from ES contained in this program are selected (they take the blue colour).



43

figure 27: radio program

When you select a PS as is shown in figure 27. The ES contained are listed.

The list shows that the PS contains one radio ES. In the white square next to the list,

details of the PS are displayed. Like the program number, the PID of the PCR, service

name, and descriptions of the ES presents in the PS.

figure 28: video program

1 In figure 28 a video program stream is selected. Video ES, audio ES and

Teletext/VBI are listed with their respective details.

As is explained in the analog practical part. In DVB, within a TS has to be

present the VBI, where teletext data is sent.

44 Anna Arias

When you select the NIT, it is displayed which is showed in figures 29 and 30.

figure 29: NIT information


These figures give information about the network. Like the network name, the

network ID, the TS ID, etc. Services also are described.



45


figure 32: SDT information

In figures 31 and 32 are contained the information about SDT that the

TsReader gives.

46 Anna Arias

figure 33: numeric results

In figure 33, the number of TEI errors, CRC errors, continuity errors and

sections are showed. The red line warns about there is an ES with errors.

These errors are explained later in another section (page 51, headland 8.3).

8.2.1 AVAILABLE GRAPHS ON LIGHT VERSION OF THE TSREADER.



47

The possible graphs on TsReader can be found selecting View-> Chart-> “and

the graph desired”. As it is shown on figure 34.

figure 34 : graph list

8.2.1.1 Mux usage stacked area

48 Anna Arias

If Mux usage stacked area is selected, figure 35 will appear. This graph

indicates the percentage of each present program. The graph is a stacked area graph.

figure 35: Mux Usage Area Chart

As in this case the graph evinces that the NULL packets are the packets with

more presence in the TS. Also it is shown how a video program needs to use a bit rate

higher than a radio program.

8.2.1.2 PID Usage



49

The PID Usage (figure 36) is another option present on TsReader. This graph is

really similar to the previous one. It shows how the transport stream is composed by

percentages, also showing the PID number and the name service.

figure 36: PID Usage

8.2.1.3 Video Bit rate area chart

50 Anna Arias

Figure 37 is a chart just with the video programs. This graphs helps to see

quickly which video has a higher bit rate.

This parameter can help to know what contains the program. Normally if a

higher bit rate is needed it is because the images need to have more definition. Like

when transmitting a football match, where the movements are fast, and to have a good

definition, a higher bit rate is needed.

figure 37: Video Bitrate Area Chart

8.2.1.4 Active PIDs Chart



51

Figure 38 is a table where all the ES are listed, sort by rate.

figure 38: Active PIDs Chart

Specifically this graph gives information just taking a look to the figure. Large

differences between bit rates of the ES are present. Also figure 38 shows how a video

ES is bigger than any other kind of ES.

8.3 EXPLANATIONS ABOUT SOME PARAMETERS DISPLAYED ON THE

TSREADER

52 Anna Arias

TEI errors

The MPEG-2 only permits to correct 8 bits of a TS packet. If this number is

exceeded, Reed Solomon decoder is not able to correct all the errors within one TS

packet.

So the demodulator changes one bit in the TS header to alert the demultiplexor

that this packet can’t be demultiplexed. This flag is the Transport Error Indicator.

Continuity Errors

Each transport stream packet with the same PID carries in the header the

continuity counter, a field composed of four bits, with a range between 0 and 15.

The decoder increases this counter each time one packet is sent, to indicate the order

of the packets with the same PID. The counter continuously increases its number to

reach 15.

The objective of this counter is to ensure that none of the TS packets get lost

and that the PES packet has all of his packets.

If there is one packet lost, the discontinuity indicator, which is in the adaptation field,

indicates it.

If there are more than one or two errors per second there is a problem in the TS

and there will be problems to reproduce it.

CRC errors

The Cyclic Redundancy Check is a function that receives a data stream and like

an output originates a value with a fix length. The term is used to designate the

function and its result. They can be used like a verification sum to detect data

alterations during its transmission or storage.

CRC for Digital TV is used because it is really effective to detect errors caused

by noise in the transmission channels. But this is not safe because if the data have

been modified deliberately and not at random it can't be fully verified.

Section



53

PAT, PMT, CAT and NIT tables have to be serialized and segmented into

sections to insert them within TS packets, which have a fixed length and which provide

a bit stream. Hence sections are just segments of the bit stream.

PSI information is repeated periodically within the TS, so independently of the

moment when the decoder synchronises the multiplex, the decoder will eventually see

it sooner or later.

Without the PAT the demultiplexation is impossible and because of that, these

packets are sent more frequently than others. PAT packets are sent every 0.5

seconds. Despite this, the PAT bit rate is smaller than the PMT bit rate.

The following graphs show bit rates for data tables, which belong to a transport

stream of a Catalan channel, TVC. These graphs are from LABMU program from

EXPERTIA Company. This program is used in the Campus Nord of Barcelona, which

belongs to the UPC (Universitat Politècnica de Barcelona).

Josep Ramon Casas (a professor in the UPC) sent me these graphs and these

examples of PAT and PMT tables.

These are stacked area graph, so the bit rate of one element is accumulated in

the second one. The last curve is the total bit rate. To know how much the bit rate is, it

is needed to take into account only the distance between the two curves.

In figure 39 there are bit rates of PMT (yellow), PAT (red) and EIT (orange).

With figure 39 can be seen the bit rates of them:

• PAT : 15 Kbit/s

• PMT : 30-50 Kbit/s

• EIT : 40 Kbit/s

54 Anna Arias

figure 39: LABMU graph

In the figure 40 it is possible to see bit rates of PAT (red), PMT’s of the

different programs that form the TS (green and yellow), EIT (orange), CAT, NIT,

TDT-TOT, MIP. The last ones are bit rates really low because of that is difficult

to see them. They are almost above the previous one.

figure 40: LABMU graph



55

Example PAT packet

TS sub-decoding (1 packet(s) stored for PID 0x0000): ===================================================== TS contains Section... SI packet (length=32): PID: 0 (0x0000) [= assigned for: ISO 13818-1 Program Association Table (PAT)] Guess table from table id... PAT-decoding.... Table_ID: 0 (0x00) [= Program Association Table (PAT)] section_syntax_indicator: 1 (0x01) (fixed): 0 (0x00) reserved_1: 3 (0x03) Section_length: 29 (0x001d) Transport_Stream_ID: 97 (0x0061) reserved_2: 3 (0x03) Version_number: 4 (0x04) current_next_indicator: 1 (0x01) [= valid now] Section_number: 0 (0x00) Last_Section_number: 0 (0x00) Program_number: 0 (0x0000) reserved: 7 (0x07) Network_PID: 16 (0x0010)

Program_number: 801 (0x0321) reserved: 7 (0x07) Program_map_PID: 110 (0x006e) Program_number: 802 (0x0322) reserved: 7 (0x07) Program_map_PID: 120 (0x0078) Program_number: 803 (0x0323) reserved: 7 (0x07) Program_map_PID: 130 (0x0082) Program_number: 804 (0x0324) reserved: 7 (0x07) Program_map_PID: 140 (0x008c) CRC: 1573623104 (0x5dcb9540)

56 Anna Arias

Example PMT packet

TS sub-decoding (3 packet(s) stored for PID 0x006e): ===================================================== TS contains Section... SI packet (length=380): PID: 110 (0x006e) Guess table from table id... PMT-decoding.... Table_ID: 2 (0x02) [= Program Map Table (PMT)] section_syntax_indicator: 1 (0x01) (fixed '0'): 0 (0x00) reserved_1: 3 (0x03) Section_length: 377 (0x0179) Program_number: 801 (0x0321) reserved_2: 3 (0x03) Version_number: 24 (0x18) current_next_indicator: 1 (0x01) [= valid now] Section_number: 0 (0x00) Last_Section_number: 0 (0x00) reserved_3: 7 (0x07) PCR PID: 111 (0x006f) reserved_4: 15 (0x0f) Program_info_length: 11 (0x000b) MPEG-DescriptorTag: 21 (0x15) [= deferred_association_tag_descriptor] descriptor_length: 9 (0x09) Association_tags_loop_length: 2 (0x0002) Association tag loop: Association_tag: 30 (0x001e) Transport_stream_ID: 97 (0x0061) Program_number: 801 (0x0321) Original_network_ID: 8916 (0x22d4) [= Spanish Digital Terrestrial Television | Spanish Broadcasting Regulator] Stream_type loop:

Stream_type: 2 (0x02) [= ITU-T Rec. H.262 | ISO/IEC 13818-2 Video | ISO/IEC 11172-2 constr. parameter video stream] reserved_1: 7 (0x07) Elementary_PID: 111 (0x006f) reserved_2: 15 (0x0f) ES_info_length: 12 (0x000c) MPEG-DescriptorTag: 17 (0x11) [= STD_descriptor] descriptor_length: 1 (0x01) reserved_1: 127 (0x7f) leak_valid_flag: 1 (0x01) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 11 (0x0b) MPEG-DescriptorTag: 7 (0x07) [= target_background_grid_descriptor] descriptor_length: 4 (0x04) horizontal_size: 720 (0x02d0) [= pixel] vertical_size: 576 (0x0240) [= pixel] aspect_ratio_information: 3 (0x03) [= 9:16] Stream_type: 3 (0x03) [= ISO/IEC 11172 Audio] reserved_1: 7 (0x07) Elementary_PID: 112 (0x0070) reserved_2: 15 (0x0f) ES_info_length: 9 (0x0009) MPEG-DescriptorTag: 10 (0x0a) [= ISO_639_language_descriptor]



57

descriptor_length: 4 (0x04) ISO639_language_code: cat Audio_type: 0 (0x00) [= undefined] DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 12 (0x0c) Stream_type: 3 (0x03) [= ISO/IEC 11172 Audio] reserved_1: 7 (0x07) Elementary_PID: 114 (0x0072) reserved_2: 15 (0x0f) ES_info_length: 9 (0x0009) MPEG-DescriptorTag: 10 (0x0a) [= ISO_639_language_descriptor] descriptor_length: 4 (0x04) ISO639_language_code: v.o Audio_type: 0 (0x00) [= undefined] DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 14 (0x0e) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 115 (0x0073) reserved_2: 15 (0x0f) ES_info_length: 18 (0x0012)

MPEG-DescriptorTag: 10 (0x0a) [= ISO_639_language_descriptor] descriptor_length: 4 (0x04) ISO639_language_code: ac3 Audio_type: 0 (0x00) [= undefined] DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 15 (0x0f) MPEG-DescriptorTag: 5 (0x05) [= registration_descriptor] descriptor_length: 4 (0x04) format_identifier: 1094921523 (0x41432d33) [= see: SC29] AC-3 DVB-DescriptorTag: 106 (0x6a) [= AC3_descriptor] descriptor_length: 1 (0x01) component_type_flag: 0 (0x00) bsid_flag: 0 (0x00) mainid_flag: 0 (0x00) asvc_flag: 0 (0x00) reserved: 0 (0x00) Stream_type: 3 (0x03) [= ISO/IEC 11172 Audio] reserved_1: 7 (0x07) Elementary_PID: 116 (0x0074) reserved_2: 15 (0x0f) ES_info_length: 9 (0x0009) MPEG-DescriptorTag: 10 (0x0a) [= ISO_639_language_descriptor] descriptor_length: 4 (0x04)

58 Anna Arias

ISO639_language_code: ad. Audio_type: 0 (0x00) [= undefined] DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 16 (0x10) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 801 (0x0321) reserved_2: 15 (0x0f) ES_info_length: 10 (0x000a) DVB-DescriptorTag: 89 (0x59) [= subtitling_descriptor] descriptor_length: 8 (0x08) ISO639_language_code: cat Subtitling_type: 16 (0x10) [= DVB subtitles (normal) with no monitor aspect ratio critical] Composition_page_id: 1 (0x0001) Ancillary_page_id: 1 (0x0001) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 811 (0x032b) reserved_2: 15 (0x0f) ES_info_length: 10 (0x000a) DVB-DescriptorTag: 89 (0x59) [= subtitling_descriptor] descriptor_length: 8 (0x08)

ISO639_language_code: eng Subtitling_type: 16 (0x10) [= DVB subtitles (normal) with no monitor aspect ratio critical] Composition_page_id: 1 (0x0001) Ancillary_page_id: 1 (0x0001) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 812 (0x032c) reserved_2: 15 (0x0f) ES_info_length: 10 (0x000a) DVB-DescriptorTag: 89 (0x59) [= subtitling_descriptor] descriptor_length: 8 (0x08) ISO639_language_code: spa Subtitling_type: 16 (0x10) [= DVB subtitles (normal) with no monitor aspect ratio critical] Composition_page_id: 1 (0x0001) Ancillary_page_id: 1 (0x0001) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 813 (0x032d) reserved_2: 15 (0x0f) ES_info_length: 10 (0x000a) DVB-DescriptorTag: 89 (0x59) [= subtitling_descriptor] descriptor_length: 8 (0x08) ISO639_language_code: ara



59

Subtitling_type: 16 (0x10) [= DVB subtitles (normal) with no monitor aspect ratio critical] Composition_page_id: 1 (0x0001) Ancillary_page_id: 1 (0x0001) Stream_type: 6 (0x06) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 PES packets containing private data] reserved_1: 7 (0x07) Elementary_PID: 113 (0x0071) reserved_2: 15 (0x0f) ES_info_length: 45 (0x002d) DVB-DescriptorTag: 86 (0x56) [= teletext_descriptor] descriptor_length: 10 (0x0a) ISO639_language_code: cat Teletext_type: 1 (0x01) [= initial teletext page] Teletext_magazine_number: 1 (0x01) Teletext_page_number: 0 (0x00) ISO639_language_code: txt Teletext_type: 2 (0x02) [= teletext subtitle page] Teletext_magazine_number: 0 (0x00) Teletext_page_number: 136 (0x88) DVB-DescriptorTag: 69 (0x45) [= VBI_data_descriptor] descriptor_length: 31 (0x1f) Data_service_id: 1 (0x01) [= EBU teletext] Data_service_descriptor_length: 26 (0x1a)

reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 7 (0x07) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 8 (0x08) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 9 (0x09) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 10 (0x0a) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 11 (0x0b) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 12 (0x0c) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 13 (0x0d) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 14 (0x0e) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 15 (0x0f) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 19 (0x13) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 20 (0x14) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 21 (0x15) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 22 (0x16)

60 Anna Arias

reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 7 (0x07) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 8 (0x08) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 9 (0x09) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 10 (0x0a) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 11 (0x0b) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 12 (0x0c) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 13 (0x0d) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 14 (0x0e) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 15 (0x0f) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 19 (0x13) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 20 (0x14) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 21 (0x15) reserved_1: 3 (0x03) field_parity: 0 (0x00) line_offset: 22 (0x16)

Data_service_id: 4 (0x04) [= VPS (Video Programming System)] Data_service_descriptor_length: 1 (0x01) reserved_1: 3 (0x03) field_parity: 1 (0x01) line_offset: 16 (0x10) Stream_type: 5 (0x05) [= ITU-T Rec. H.222.0 | ISO/IEC 13818-1 private sections] reserved_1: 7 (0x07) Elementary_PID: 901 (0x0385) reserved_2: 15 (0x0f) ES_info_length: 5 (0x0005) DVB-DescriptorTag: 111 (0x6f) [= application_signalling_descriptor] descriptor_length: 3 (0x03) Application type: 1 (0x0001) reserved: 7 (0x07) AIT version nr.: 0 (0x00) Stream_type: 12 (0x0c) [= ISO/IEC 13818-6 Stream Descriptors] reserved_1: 7 (0x07) Elementary_PID: 601 (0x0259) reserved_2: 15 (0x0f) ES_info_length: 10 (0x000a) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 31 (0x1f) MPEG-DescriptorTag: 20 (0x14) [= association_tag_descriptor] descriptor_length: 5 (0x05) Association_tag: 31 (0x001f) Use: 256 (0x0100)



61

Selector_length: 0 (0x00) Stream_type: 11 (0x0b) [= ISO/IEC 13818-6 DSM-CC U-N Messages] reserved_1: 7 (0x07) Elementary_PID: 701 (0x02bd) reserved_2: 15 (0x0f) ES_info_length: 29 (0x001d) MPEG-DescriptorTag: 19 (0x13) [= carousel_identifier_descriptor] descriptor_length: 5 (0x05) Carousel_id: 1 (0x00000001) format_id: 0 (0x00) MPEG-DescriptorTag: 20 (0x14) [= association_tag_descriptor] descriptor_length: 13 (0x0d) Association_tag: 1 (0x0001) Use: 0 (0x0000) Selector_length: 0 (0x00) Transaction_ID: 4294967295 (0xffffffff) Timeout: 4294967295 (0xffffffff) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 1 (0x01) DVB-DescriptorTag: 102 (0x66) [= data_broadcast_id_descriptor] descriptor_length: 2 (0x02) Data_broadcast_ID: 7 (0x0007) [= Object Carousel] Stream_type: 11 (0x0b) [= ISO/IEC 13818-6 DSM-CC U-N Messages]

reserved_1: 7 (0x07) Elementary_PID: 702 (0x02be) reserved_2: 15 (0x0f) ES_info_length: 29 (0x001d) MPEG-DescriptorTag: 19 (0x13) [= carousel_identifier_descriptor] descriptor_length: 5 (0x05) Carousel_id: 2 (0x00000002) format_id: 0 (0x00) MPEG-DescriptorTag: 20 (0x14) [= association_tag_descriptor] descriptor_length: 13 (0x0d) Association_tag: 2 (0x0002) Use: 0 (0x0000) Selector_length: 0 (0x00) Transaction_ID: 4294967295 (0xffffffff) Timeout: 4294967295 (0xffffffff) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 2 (0x02) DVB-DescriptorTag: 102 (0x66) [= data_broadcast_id_descriptor] descriptor_length: 2 (0x02) Data_broadcast_ID: 7 (0x0007) [= Object Carousel] Stream_type: 11 (0x0b) [= ISO/IEC 13818-6 DSM-CC U-N Messages] reserved_1: 7 (0x07) Elementary_PID: 703 (0x02bf) reserved_2: 15 (0x0f) ES_info_length: 29 (0x001d)

62 Anna Arias

MPEG-DescriptorTag: 19 (0x13) [= carousel_identifier_descriptor] descriptor_length: 5 (0x05) Carousel_id: 3 (0x00000003) format_id: 0 (0x00) MPEG-DescriptorTag: 20 (0x14) [= association_tag_descriptor] descriptor_length: 13 (0x0d) Association_tag: 3 (0x0003) Use: 0 (0x0000) Selector_length: 0 (0x00) Transaction_ID: 4294967295 (0xffffffff) Timeout: 4294967295 (0xffffffff) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 3 (0x03) DVB-DescriptorTag: 102 (0x66) [= data_broadcast_id_descriptor] descriptor_length: 2 (0x02) Data_broadcast_ID: 7 (0x0007) [= Object Carousel] Stream_type: 11 (0x0b) [= ISO/IEC 13818-6 DSM-CC U-N Messages] reserved_1: 7 (0x07) Elementary_PID: 704 (0x02c0) reserved_2: 15 (0x0f) ES_info_length: 29 (0x001d) MPEG-DescriptorTag: 19 (0x13) [= carousel_identifier_descriptor] descriptor_length: 5 (0x05) Carousel_id: 4 (0x00000004)

format_id: 0 (0x00) MPEG-DescriptorTag: 20 (0x14) [= association_tag_descriptor] descriptor_length: 13 (0x0d) Association_tag: 4 (0x0004) Use: 0 (0x0000) Selector_length: 0 (0x00) Transaction_ID: 4294967295 (0xffffffff) Timeout: 4294967295 (0xffffffff) DVB-DescriptorTag: 82 (0x52) [= stream_identifier_descriptor] descriptor_length: 1 (0x01) component_tag: 4 (0x04) DVB-DescriptorTag: 102 (0x66) [= data_broadcast_id_descriptor] descriptor_length: 2 (0x02) Data_broadcast_ID: 7 (0x0007) [= Object Carousel] CRC: 3464519067 (0xce805d9b)



In this figure we can see results obtained with TsReader, analysing a TS obtained from

Philips.

figure 41: bottom part of the central part of TsReader interface

After having shown all the examples and explanations of the analysis of

TsReader, it is shown in figure 41 the results of an analysis of TsReader.

These results are normal. The higher number of PAT sections than PMT

sections its normal because the PAT TS packets are sent more frequently (every 0,5

seconds). Although sections of those will be shorter than PMT sections because they

have to carry less data, as is possible to see in the example of code of PMT and PAT.

64 Anna Arias Fuentes

8.3 TV EXPLORER II+ OF PROMAX

8.3.1 Installation of the software

In the installation process some problems occurred because the computer used

had the Vista Windows installed. The software for the computer obtained from

PROMAX on the other hand was for Windows XP. I tried to download different files for

the computer in the PROMAX website, but no of them resolved the problem. Finally I

explained my problem to the customer services centre of PROMAX Company.

They sent me another setup, which you can find at:

http://home.promax.es/ftp/Zips/USB_driver_XP_VISTA.zip

This setup doesn’t install the program. It just unzips the files in a folder (you can

choose the location of the folder). In this folder you will have all the necessary files to

install the drivers. You have to click in the folder to see the files. Here you will see one

folder called DISK1, click on this folder. Here, click on the setup file.

The installation is rather easy. Follow the steps, accept the terms of the license

agreement and then indicate where you want the location of the folder with the files of

the program.

The next step is to connect the TV Explorer II+ to the PC, using the USB cable.

The computer asks you if you want to install the necessary driver software of the

equipment. Select the option to do it automatically. Follow a few steps and the

installation of the device will be completed.

After that part, Windows displays a new dialog box. Windows has found New

Hardware, USB-Serial-Port. Select again the automatic option and follow the steps.

Now, choose My computer -> Configuratiescherm -> Apparaatbeheer, to see

figure 42 on the screen.



figure 42: apparaatbeheer

PROMAX gave us some files with the equipment. Where you can find some

programs, PkTools and PkUpdate.

The PkUpdate program is there to create channel tables or to modify tables of

existent channels and to recover safe measurements in the Datalogger of the

equipment.

The PkUpdate is used to update the firmware.

I didn’t use neither of them. To get the files, like print shoots, I used the

NetUpdate program. The setup of this program is not in the files obtained from

PROMAX. You can find it at:

http://home.promax.es/ftp/Zips/Netupdate_2v23.zip


The setup is easy, when it is done. The NetUpdate indicates that it has

recognised the equipment. And after that the program appears. In figure 43 the

interface of the program is showed.

figure 43: NetUpdate

If you select the option “Resource Updates” and click on update, figure 44 will

appear.


Here you can choose between three possibilities: server, PC and equipment.

The PC shows the files contained in the computer and the equipment shows the files



contained in the TV Explorer II+. If you click in one of the folders, you will see the files

contained therein, like it is shown in figure 45.


If you press on the folder called PrintScreen. You will see the print shoots

made. If you want to see the video files (program streams) recorded, you can click on

the video folder.

If you want to transfer a file between the computer and the equipment, you just

have to drag the file, from the equipment to the PC, or vice verse.

In the bottom part, on the right, you can see two options, namely Binary and

Text. This is for when you want to choose a file of another folder than PrintScreen.

These folders contain data files (about diagram constellations, spectrums, etc.). If you

want only to safe files you must take them selecting Binary. If on the other hand, you

want to use them (in the extension file .csv), you can do it with some programs like

Excel.


8.3.2 Examples and explanations of available measurements in the TV Explorer

II+ equipment

• C (Channel power)

The channel power is measured in the bandwidth of the measurements

filter. Total power of the channel is estimated assuming spectral density is

uniform in channel bandwidth.

figure 46: Power

In figure 46 appears the value of the power. This measurement is

expressed in dBµV, which is just a tradition as the installers are used of working

with this measure.

It is why traditionally the manufacturers of measure equipments continue

using this measure like a measure of channel power, although it is not correct.

Anyway you can choose the measure used in the equipment. If you

press the 8 key during 3 or 4 seconds, the “preferences menu” will appear.

Here you can select the terrestrial measure. The possibilities are dBµ, dBm,

dBmV.

• C/N

With an average value detector, noise and power carrier values are

quantified. In the figure 47 you can see the ratio between the video carrier and



the noise level (C/N), the power of the video carrier, the selected channel

frequency, etc. that the equipment displays.

figure 47: C/N

In the two following figures you can see the spectrum of the HF-signal.

They are from the spectrum analyzer. The spectrum analyzer permits to check

present signs in frequency bandwidth.

In figures 48 and 49 there are different values. This happens because I

changed the position of the roof antenna (the antenna permits to turn it). The

figure 48 shows the worst result, and figure 49 the best. I could choose the best

one and the worst one using an option of the equipment. The equipment emits

a sound when this option is being used. The better the signal, the higher the

frequency sound.

Figure 48: C/N figure 49: C/N


All the following results are with the antenna in the best position to receive the

signal.

• MER

The ratio between the power of the average DVB signal and the average

power of the present noise in the constellation is represented by the MER

measurement.

MN (Noise Margin) is showed in the figure. It indicates the secure

margin respects the value MER that the signal has. It is the margin to do not

lose the QEF value of the signal.

figure 50: MER

In a 64 QAM system, a MR measurement has to be between 3 or 4 dB.

In this test, it is 15.4 (correct value). The MER has to be higher than 23 dB, It is

30.1 dB.

These measurements give information about the PS received. And they

confirm a good received signal.

o MER by carrier

This function analyzes the MER for each of the carriers that

compose the selected channel and that is shown in a graph. In figure 51



you can see also the standard deviation and the average of the MER by

carrier.

figure 51: MER

• BER

Selection of the parameters of the COFDM signal has to be done before

looking at this parameter. In an absolute value and science notation BER is

expressed.

In a DVB-T reception system, two methods of error correction are

applied. Because of that, different values will be after both methods.

o CBER

Error value, before the Reed Solomon correction method.

figure 52: CBER


The showed CBER measurement is correct. The value is less

than 10-3th, the CBER measurement of the signal is 4x10-4. We have

received a good signal.

o VBER

Error value, after the Viterbi correction method.

figure 53: VBER

The result shown and obtained figure 49 of VBER measurement

is 10-7.

To get a good quality of image, there must be less than an error of transmission

per hour. In the VBER bar, the point with the 2x10-4 value (2 error bits each 10,000 bits)

is called Quasi-Error-Free. If the VBER value is on the left of this point, the result is

acceptable. Therefore, the signal received by the equipment is good.



8.4 Examples and explanations of graphs representations in TV Explorer II+

• Constellation Diagram

If there are no interferences and noise, in the constellation diagram,

concentrated points will represent all the symbols.

When the constellation diagram function is selected in the equipment,

the different impacts of the received symbols will appear in the screen of the

equipment while there is a digital signal transmission.

It is possible to change the channel frequency or the COFDM carrier.

There is also the ZOOM option to see more accurately the diagram

constellation.

The quality of the transmission is visualized through the colour of the

points contained in a region of the constellation. Black, blue, yellow and red

form the gradation of colours. Black is the colour for the worst result, and red

the best.

figure 54: constellation diagram


In figure 54 the results are good enough. The areas have almost all the

points with red colour, and the points are not too separated.

Not always the constellations diagrams have 64 areas with points. For

example, if 34 or 50 carrier is selected, figure 55 is displayed.


This constellation diagram is different because it carries TPS carriers.

The Transmission parameters Signalling carriers are used to send

parameters of the system:

• Type of the modulation of the information carriers.

• Information about hierarchy.

• Guard interval.

• Convolution codification used.

• Transmission mode.

• Cell identification.

The TPS carriers are transmitted in parallel. In 8k mode, into 68 carriers.

• Spectrogram

The spectrogram is a tool to detect anomalies in a frequency range. In

the spectrogram a graphic representation of the signal level of the frequencies



in the time function is made. Each colour represents a different level. In the Y-

axis are the values of the frequency. In the X-axis are the values of time.


• Merogram

This function is designed to detect sporadic and eventual problems

within a DVB-T channel.

A graphic representation of the MER level of the carriers as function of

the time is done by the Merogram.

Every level is represented by a different colour. Carriers are on X-axis

and the time variable are represented on the Y-axis.


9. FINAL CONCLUSION

During my stay in Gent I could learn a lot about how television is transmitted. I did many tests with analog and digital signals. These tests help me understanding the learned knowledge.

To practice with the learned theory is really important. Because I could learn

more, understand and reassert part of different subjects that I have studied during my college in Barcelona.

I also think that this was a good experience to see the differences in television

system used in Belgium than Catalonia. To transmit and receive television there are many specified standards. But all

the countries have their characteristics. As in Belgium cable television is the system picket for the majority of the population. And the terrestrial is not much watched, it has just 3 channels.

In Catalonia analog signal is still transmitted. The next year the DVB will be

launched and analog television will disappear. Nowadays it is possible to receive both, analog and digital television. With the STB it is possible to receive many DVB-T channels (tens). And the cable television is not really used for Catalan citizens.

With my project the study of DVB signals is started in KaHo-Sint Lieven. The

next year surely will be another student continuing the study. Interesting things to study would be how to record transport stream. Because

right now it is only possible to record program streams. And maybe try it through the signals received by the USB receiver is a good idea.

My final conclusion about the Erasmus in general is that I have learned in all the

possible aspects. I studied a lot about important and interesting knowledge about my field, I knew people from the entire world, I learned how to live in a foreign country and I have improved my English and learned a little Dutch. I am really happy for all that I have lived in those months.

Anna Arias



10. BIBLIOGRAPHY

WEBSITES

• http://www.dvb.org/

• http://www.sateliteinfos.com/actu/tp.asp/tp/16472/inicio-de-la-plataforma-

belga-telesat.html

• http://support.microsoft.com/default.aspx?scid=kb;en-us;184006

• http://www.bretl.com/mpeghtml/mpegpsi.HTM

• http://www.tdtzone.com/el-ber-y-su-medida.html

• http://www.etherguidesystems.com/Glossary/Default.aspx

• http://2000newsarchive.broadcastengineering.com/ar/broadcasting_cond

itional_access/

• http://www.etherguidesystems.com/Help/SDOs/MPEG/Syntax/Tablesecti

ons/cats.aspx

• http://www.aero.org/publications/crosslink/winter2002/04.html

• http://74.125.77.132/search?q=cache:W9CQbvAHPcoJ:cva.stanford.edu/

classes/ee482s/projects/group2_proposal.pdf+viterbi+algorithm+applicati

ons&cd=1&hl=ca&ct=clnk&client=firefox-a

• http://www.bbc.co.uk/rd/pubs/papers/paper_15/paper_15.shtml

• http://www.hdtvtotal.com/module-pagesetter-viewpub-tid-1-pid-954.html

DOCUMENTS

• "Sistemas audiovisuales I. Televisión analógica y digital", Edicions UPC 2000

from Francesc Tarrés (UPC Barcelona).

• Information technology — Generic coding of moving pictures and associated audio information: Systems from ISO/IEC 13818-1

• DVB information from Rohde&Schwarz

• Digital Video Broadcasting (DVB); DVB specification for data broadcasting from


ETSI

• MPEG fundamentals and protocol analysis from Tektronix

• AV communications documentation from Xavier Giró (UPC Terrassa-

Barcelona).

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