outline of isdb-t(nhk takada).pdf

5/22/2018 Outline of ISDB-T(NHK Takada).pdf

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Dec. 8, 2009

Masayuki TAKADANHK Science and Technology Research Laboratories

Digital Terrestrial Television Broadcasting

ISDB-T,outline and transmission scheme


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Contents

1. Introduction2. Transmission scheme of ISDB-T

Digital modulation

OFDM

Interleaving

Hierarchical transmission

3. Comparison of 3 DTTB systems

4. Current services of ISDB-T in Japan5. ISDB-T receivers on the market

6. Summary


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1. Introduction

Requirements for DTTB, and features of ISDB-T

History and schedule of ISDB-T

DTTB(Digital Terrestrial Television Broadcasting)

ISDB-T(Integrated Services Digital Broadcasting - Terrestrial)


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Requirements for DTTB

For success of DTTB introduct ion

Requirements fo r DTTB

Attract ive broadcast ing serv ice High quality TV and sound (HDTV, 5.1 surround)

Anytime information access (Data, Internet)

Robustness against interference

Mob i le and portable recept ionAnytime, anywhere TV service (HD mobile and One-Seg)

Effect ive Frequency Uti l izat ion SFN (Single Frequency Network)


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What is ISDB-T ?

One of the DTTB systems in the wo rld

There are 3 systems recommended in ITU-R BT1306.

ISDB-T, DVB-T and ATSC

The mos t f lex ible system HDTV, multi-SDTV, EPG, data-casting, internet-access,

mobile reception, Cellular phone TV, etc.

The most robu st system

OFDM, time-interleaving, etc.

Brazilian comparison test results proved it.

Developed in Japan

ISDB-T is ...


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ISDB-T transmissionfrom the broadcaster to the receivers

One TV channel

13 Segments

Fixed

Reception

1 segment 13 or 1 segment

Handheld

Reception

Handheld terminal

Home Receiver

Support 3 reception typesby one channel

13 segment

Receiver in Vehicle

TV station

diversity

reception

Mobile

Reception

Internet / Telephone modem

6


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ISDB-T realizes these services

HDTV

Merits

Multiple programs

2

Mobility

Data broadcasting

Interactive TVAdvanced caption etc.


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History and schedule of DTTB in Japan

1994 Technical requirements for DTTB studied at Council

1999 ISDB-T technical standard established in Japan

Dec. 2003 ISDB-T launched! (Tokyo, Nagoya, Osaka)

Apr. 2006 One-Seg service started

Dec. 2006 ISDB-T started(at main cities of the whole country)

Jul. 2011 Analog TV Switched off

End of 1980' OFDM study started in NHK Labs.

2000 ISDB-T recommended in ITU-R


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2. Transmission scheme of ISDB-T

Features and key technologies of ISDB-T

Digital modulation

OFDM

Interleaving Hierarchical transmission

ISDB-T (Integrated Services Digital Broadcasting- Terrestrial)


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Channel coding

Outline of digital transmission

Source coding

Video/AudioSource

(Analog)

Digita-

lization

Com-

pression

Errorcorrection

coding

Digitalmodulation

Trans-mission

Digitaldemodulation

Errorcorrection

decoding

Source decodingVideo/Audio

Signal

(Analog)

Noise, Multipath,

Fading, etc


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Receiving environmentfor terrestrial TV broadcasting

Fixed reception

Multipath interference

Fading interference

Impulse, manmade noise

Shadowing

Handheld reception

Mobile reception

Receiving environment is very severe.


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Key technologies of ISDB-T

Key technologies adopted in ISDB-T

To overcome the terrestrial severe receiving

environment

OFDM

Time-interleaving (Freq.&Time interleave)

To realize the effective and smart transmissionHierarch ical transm issionby segmented OFDM

Realization of One-Seg service for handheld reception


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Digital modulation

In the case of digital modulation, amplitude,frequency or phase of carrier changes

digitally depend on digital data

ASK (Amplitude Shift Keying)

modulate carrier amplitude

FSK (Frequency Shift Keying)

modulate carrier frequency

PSK (Phase Shift Keying)

modulate carrier phase

0 011


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PSK and QAM

BPSK (Binary Phase Shift Keying)

uses two phases of carrier

QPSK (Quadrature Phase Shift Keying)

uses four phases of carrier

8PSK (8 Phase Shift Keying) uses eight phases of carrier

16QAM (16 Quadrature Amplitude Modulation)

uses 4 levels in orthogonal phases (in-phase andquadrature phase)

64QAM (16 Quadrature Amplitude Modulation)

uses 8 levels in orthogonal phases (in-phase and

quadrature phase)


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Constellations

I

Q

[0][1]

[ C ]

-A A I

Q

[00][01]

[11] [10]

[C1 C0]A

A-A

-A

I

Q

[000]

[001]

[011]

[010]

[100]

[101]

[111]

[110]

[C2 C1 C0]

A

-A

-A A

BPSK QPSK 8PSK

1bit/symbol 2bits/symbol 3bits/symbol

16QAM

4bits/s mbol

Q

I

64QAM

6bits/s mbol

I

Q

19


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BPSK modulation

input

pulses

cosine

BPSK

signal

=0 = ==0 =0

= =0

Signal space diagram

input data 0 1 0 0 1

20


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QPSK modulation

010100011010010101

binary input

QPSK out (I+Q)

Modulated : I

Modulated : Q

0 0 0 0 1 1 0 0 0

1 1 0 1 0 0 1 1 1

I data

Q data

-A

+A

-A

+A

Level Conv.

01 01 00 01 10 10 01 01 01 11

=5/4 = 7/4

=3/4 = /4

(00)(01)

(11) (10)

I

Q


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QPSK 8PSKBPSK

Comparison of PSK modulations

-2 -1 0 1 2

-1

0

1

I

Q

(10)(11)

(01) (00)

-2 -1 0 1 2-2

-1

0

1

2

I

Q

(011)

(001)

(111)

(010)

(000)(100)

(101) (110)

overlap

-2 -1 0 1 2-2

-1

0

1

2

I

Q (0)(1)

Noise

Transmission capacity HighLow

RobustnessStrong Weak

22


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Bit Error Rate / Carrier-to-Noise Ratio

10-1

5 10 15 2010-7

10-5

10-3

BER

C/N (Nyquist)

QPSKBPSK

Good

Good

8PSK 16QAM


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OFDM

Orthogonal Frequency Division Multiplexing Multicarrier modulation method

500 8000 carriers

Modulation method of each carrier is

BPSK, QPSK, 16QAM, 64QAM, etc.


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Features of OFDM

Robustnessagainst multipath interference

symbol duration is longer than single carrier modulation

guard interval is provided

Robustnessagainst frequency-selective fading

OFDM uses many carriers

SFN (Single Frequency Network)

frequency effective usage

Signal process using IFFT/FFT Poor against non-linearity


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OFDM waveform and spectrum

Frequency domain signalTime domain signal

+

+

+

=

+

+

+

+

+

=

GI Effective symbol duration

transmitting symbol S t)

Transmitting

Signal

FFT/IFFT

Carrier #k

Carrier #2

Carrier #1

1

0

))(2()(N

n

tfnj

n

nectS

Addition ofvarious carriers !!Frequency


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Fast Fourier Transform

Time Domain Frequency Domain

1KHzwave (1KHz)

FFT

IFFT

FFT

IFFT

wave (containing

various frequency)

Enables Frequency Analysis


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Overview of OFDM modulation

FFT

TransmissionTime domain

freqn=N

n=N-1

n=n=2

IFFT

freq

n=Nn=N-1

n=n=2

ModulationFrequency domain

DemodulationFrequency domain

QAM Mapping QAM Demapping

time


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Multipath Echo Interferences

NHKMain path

Multipath echo

= Delayed wave

Multipath echo interferes the receiving performance


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Signal Distortion by Multipath Echo

Transmitted signal

10MHz 10MHz

Received signal= includes Main path andMultipath Echo


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Why signal distorted ?

: / /

Frequency

PowerCarrier combined with same phase

C/N=large

Carrier combined with opposite phaseC/N=small


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Why Signal Distorted ?

Case of same phase composition

Main path

Looking onone carrier

Delay path

ReceivedSignal

=Main path

+Delay path

Freq

Power

Amplitude increase


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Why Signal Distorted ?

Case of opposite phase composition

Main path


Delay path

ReceivedSignal

=Main path

+Delay path

Freq

Power

Amplitude decrease


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Guard Interval

In transmittingAdd partial copy of Effective Symbol

In demodulation extract only effective symbol duration

length from transmitting symbol and execute FFT

Able to eliminate the effects of multipath echo interference

within delay time of Tg [sec]

GuardInterval Tg Ts

ISDB-T Signal

Time Domain

EffectiveSymbol

copy signal copy signal

1008ms (*)126ms (*)

(*) figure of NHK

actually its flexible

Transmitting Symbol


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Effect of Guard Interval

Main path


Delay path

Received

Signal

=Main path

+Delay path

Transmitting symbol

Symbol #NSymbol #N-1 Symbol #N+1

Time

Effective symbolGuard

Interval

Only use here for

demodulation (FFT)Non Continuous !!

Delay time

Able to eliminatenon continuous part

Performance of OFDM


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Performance of OFDMunder multipath distortion

10-5

10-4

10-3

10-2

10-1

Delay time [usec]

B

itErrorRate

50 1000 150

D/U = 0 dB

6 dB

10 dB 64QAM-OFDM

C/N = 30 dBguard interval

1

D/U Ratio of Desired wave (mainpath)

and Undesired wave(echo)


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Interleaving

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InterleavingRandomization of data symbols

Carrier arrangement

time-sequence of symbols

An order is randomly changed.


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What is interleaving ?

Error

Correction

Transmit after interleaving

Deinterleave after receiving

Mass Data errorin specified area or frequency

Data

Frequency or time duration

Error

Correction

Error

Correction

Error

Correction

Data 1 Data 2 Data 3 Data k

Able to fix the mass data error

by Interleaving !!

Shuffle order of data

Transmitting

data

Actual

data

Received

data

Reorder

Data after

error

correction


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Effect of frequency interleaving

Good

10-2

10-1

90

92

94

96

98

100

Bit error rate

Cumu

lativecorrectreceptionrate(%)

3.5MHz

500kHz

1.5MHz 100kHz

Time interleave length : 48msec

Maximum Doppler frequency : 15Hz

Spectrum(Multipath distorted)


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Effect of time interleaving

flat fading,DQPSK,Mode=1,GI=1/8,FEC=1/2,RS=OFF

1.00E-06

1.00E-05

1.00E-04

1.00E-03

1.00E-02

1.00E-01

1.00E+00

5 10 15 20 25 30 35 40

C/N[dB]

BER

Fd = 70 Hz

Fd = 20 Hz

Fd = 7 HzWithout

time interleaver

Fd = 7 Hz

Fd = 20 Hz

Fd = 70 Hz

With time interleaver

of 440 ms

Laboratory test resul ts

Witho ut time-interleaver

(Error remains even in

high C/N)

Better

Far from Tx Near to Tx

With tim e-interleaver

(No erro r at mo re than C/N=20dB )


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Hierarchical transmission

ISDB-T adopts hierarchical transmission system

by FDM (frequency division multiplexing) of Segment

Hierarchical transmission is realized by changing following

parameters

Modulation : QPSK, 16QAM, 64QAM, (DQPSK)

Error correction : Coding rate of convolutional code (1/2 - 7/8)

1/2 2/3 3/4 5/6 7/8

More robust

Higher capacity

QPSK 16QAM 64QAM

More robust

Higher capacity

Flexible hierarchical transmission


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Flexible hierarchical transmissionby segmented OFDM

Examples

1 layer

ISDB-T

- Consists of 13 OFDM segments

- Hierarchical transmission

by segmented OFDM

- Up to 3 layers For fixed receivers

For mobile receivers

For handheld receivers

frequency

6MHz(13 segments)

2 layers

3 layers


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Example of hierarchical transmission

Example

(2 layers transmission)

frequency

1 channel(13 segments)

LDTV, Audio, DataLayer A

Handheld reception

(One-Seg service)

Layer A

QPSKFEC=2/3

For handheld

service

Robust

transmission

mode

Fixed reception, Mobile

reception (HDTV,etc)

Layer B

64QAM

FEC=3/4

For HDTV

or Multi-SDTV

service

High capacity

transmission

mode

Layer B

HDTV or

Multi-SDTV

programs with Data


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RS(204,188)

20.1 dB

16.85 Mbps

215 ms

3/4

64 QAM

12

B1/8 (126 s)

1008 s

0.992 kHz

5.572 MHz5617 (8k FFT)

Transmission parameters used in Japan

6.6 dBRequired CN ratio for AWGN

416 kbpsInformation bit rate

430 msTime interleaving length

RS(204,188)Outer error correction code2/3Coding rate of inner code (convolutional code)

QPSKCarrier modulation

1Number of segments

AHierarchical transmissionGuard interval ratio (length)

Usable symbol duration

Carrier spacing

Used bandwidthNumber of carriers


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Features of ISDB-T transmission system

1. Robustnessagainst interference(1)Adopt OFDM transmission system

(2)Adopt time interleaving; very effective for various kinds of interference

(3)Adopt concatenated error correction with plural interleaver

2. HDTVfor fixed/mobile and One-Segfor portable/handheld

can be transmitted simultaneously in one TV channel(1)Hierarchical transmission by segmented OFDM

(2)Partial reception of center one-segment for handheld service

3. Efficient frequency utilization(1)Adopt OFDM transmission system; SFN operation

(2)Adopt hierarchical transmission; service for different type of reception in one

frequency channel

4. Flexibility for several type of service/reception style


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3. Comparison of 3 DTTB systems

Features of 3 DTTB systems

Results of comparison tests

Summary of comparison

f 3


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Key parameters of 3 DTTB systems

3.65 -23.2 Mbps3.69 -23.5Mbps19.39 MbpsInformation bit rate

time

Frequency

Bit/Symbol

TMCCTPS-Configuration

6 / 7 / 8 MHz6 / 7 / 8 MHz6 / 7 / 8 MHzChannelbandwidth

1/4, 1/8,1/16,1/321/4,1/8,1/16,1/3211.5%Excess Bandwidth/

Guard Interval

0s, 0.1s,0.2s,0.4s--

YesYesYesInter-

leaving YesYes-

SegmentedOFDM

(DQPSK,QPSK,16QAM,64QAM)

OFDM(QPSK,

16QAM,64QAM)

8VSBModulation

ISDB-TDVB-TATSCSystem


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Results of Brazilian Tests

Comparison tests for three DTTB systems

- ATSC, DVB-T, ISDB-T

Carried out from Aug. 1999 to April 2000

Selected transmission parameters

- Almost same transmission bit rateATSC

Fixed, 8VSB FEC=2/3 (19,39 Mbit/s)

DVB-T

DVB-2K : 64QAM FEC=3/4 GI=1/16 2K (19,75 Mbit/s)

ISDB-T ISDB-4k : 64QAM FEC=3/4 GI=1/16 4K 0,1s (19,33 Mbit/s)

(From the presentation of the Brazilian SET/ABERT study group at NAB2000)


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Impulse noise

Better performance of the ISDB-T system, by introducing

time interleaving

(From the presentation of Brazilian SET/ABERT study group at NAB2000)

Relation between the noise pulse width & interference to signal ratio

-15

-10

-5

0

5

10

15

20

25

30

0 100 200 300 400

Pulse width (us)

"I"/C

(dB)

ATSC - Chip A

DVB - NDS - 3/4 1/16 2K

ISDB - NEC - 3/4 1/16 4K 0,1s

Bette

r

ISDB-T

ATSC

DVB-T


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Outdoor : Coverage

(From the presentation of Brazilian SET/ABERT study group at NAB2000)

Success on Receiving - Cumulative Function

Criterion: Number of Errors < 5

60%

70%

80%

90%

100%

0 5 10 15 20 25 30 35 40

Distance (km)

Percentage

ofSites

ATSC DVB-2k ISDB-T

Better

ISDB-T

DVB-T

ATSC

E f i t t lt


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Essence of comparison test results

The OFDM modulation scheme is suitablefor DTTB in real broadcast circumstances.

Time interleaving scheme, adopted in ISDB-

T, is a key technology for mobile digitaltransmission and is also effective to copewith impulse noise degradation.

ISDB-T showed the best resultsin Brazils

comparison tests, and other countries suchas Chile, Peru, Philippine, etc.


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4. Current services of ISDB-T in Japan

HDTV, SDTV multi-program,

EPG (Electric Program Guide)

Data broadcasting, Interactive

One-Seg (Handheld)

EWS (Emergency Warning System)


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Powerful applications of ISDB-T

HDTV

High quality image on wide

screen and CD quality sound.

Multi-channel program

Standard qualitymulti-channel service

Local news and weather forecast

for viewers at any time.

Data broadcasting

Interactive service

Offers Interactive service

One-Seg service

Anytime, anywhere,

TV service

Stable reception service

Mobile reception


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HDTV

High Definition Television Program The high quality images on a 169 wide screen and

CD-quality sound make you feel as if you were at thetheater.

European broadcasters have opted for multi-channel strategy, but Japanese broadcasters havechosen to take advantages of high definitionpictures.

HDTV is a killer application.


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Multi channel program (SDTV)

ISDB-T can transmit multiple SDTVprogramssimultaneously in oneTV channel.

SD-1 SD-2 SD-8 -----


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EPG

EPG (Electronic Program Guide)

An Electronic Program Guide (EPG) isan interactive schedule of current andupcoming programs that a viewer can

display on-screen simply by pressing abutton on a remote control unit.

O S i f h dh ld i


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One-Seg service for handheld receiver

Example parameterTransmission Mode 3Guard Interval 1/8Modulation QPSKCode Ratio 2/3Bit Rate 416 Kbps

Display Image

Data service

On-air program Video (H.264)

180-256kbps

Audio (AAC-SBR)32-64kbps

Data-cast (BML)20-80kbps

Eme genc Wa ning S stem


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Emergency Warning System

Schematic diagram for disaster prevention service

TextPossibility of a flood inthe xxx river hasincreased.Residents in thesurrounding areas

should evacuate. Areasaffected are as follows.

Image

Emergencyevacuation

areas

Test Server

TV station Evacuationrecommenda

tion order

Transmission without congestion

On-air wavesStart signal

+Screen

BML automatic converter

Master room

EMG-button

Screendisplay

TunerpowerON

Mobile base station

Application to Disaster Prevention


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5. ISDB-T Receivers on the Market

TV set (PDP, LCD, CRT)(fixed reception home receiver)

STB (Set Top Box)

HDD/DVD recorder with digital tuner One-Seg receiver (Cellular phone)

HDTV mobile receiver for car TV

Portable player

Wide variety of ISDB T receivers


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Wide variety of ISDB-T receivers

TV set STB HDD/DVDrecorder

Cell phone

PCCar TV

Laptop

/ handheld PC Handheld

TV

ISDB T receivers for fixed reception
http://121ware.com/psp/PA121/LEARN/ENTP/h/?tab=LRN_Z_PC_0604_VSW_ST


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ISDB-T receivers for fixed reception

Panasonic SONY Toshiba Hitachi

SANYO PioneerSharp

Mitsubishi NANAOEPSON

Victor

Types of fixed reception digital receivers (HDTV)


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Types of fixed reception digital receivers (HDTV)

(Plasma Display type) (LCD type)

(CRT type)

(Rear Projection type)

PCs with ISDB T tuner (HDTV)


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PCs with ISDB-T tuner (HDTV)

Set Top Box (DTTB Tuners)
http://www.nec.co.jp/http://121ware.com/psp/PA121/LEARN/ENTP/h/?tab=LRN_Z_PC_0604_VSW_SThttp://www.fmworld.net/common/fj/index.htmlhttp://www.fmworld.net/common/fj/index.html


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Set Top Box (DTTB Tuners)

SHARP TU-HD200

SONY DST-TX1 PANASONIC TU-MHD500

HDD/DVD recorders with DTTB tuner


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SHARP

TOSHIBA

Panasonic

SANYO

HITACHI

SONY

Pioneer

Victor

HDD/DVD recorders with DTTB tuner

Cellular Phones for One-Seg


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Cellular Phones for One-Seg

PCs with ISDB-T tuner (One-Seg)


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PCs with ISDB-T tuner (One-Seg)

Tune

r

USB type ISDB-T Tuners for One-Seg
http://www.fmworld.net/common/fj/index.html


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USB type ISDB-T Tuners for One-Seg

Portable DVD Playersi h ISDB T (O S )
http://www.pctv-hiwasa.com/http://www.logitec.co.jp/http://buffalo.jp/http://www.logitec.co.jp/press/photo/photo_350/ldt1s100u.jpghttp://www.sanwa.co.jp/index.html


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with ISDB-T tuner (One-Seg)

Other Portable One-Seg devices
http://panasonic.jp/http://www.toshiba.co.jp/


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Other Portable One Seg devices

Portable Audio Player

Portable Navigator

Portable Electronic Dictionary

Portable TV

Mobile receivers for car TV system(HDTV / O S )


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(HDTV / One-Seg)

Pioneer GEX-P7DTV

Alpine TUE-T300Fujitsu Ten DTV105

Panasonic TU-DTV100, TU-DTV20

Mitsubishi TU-100DSANYO NVP-DTA10


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6. Summary

Summary


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Summary

ISDB-Tis the most robusttransmission system

Adopting OFDM and time-interleaving

Brazil, Chile, Peru, Philippine, etc. confirmed

ISDB-T performance is the best.

HDTV(orSDTV multi-channel) and One-Seg

(handheld TV service) can be transmitted

simultaneously in a channel ISDB-T enables both digital TV service for fixed and

mobile (handheld) by just one transmission facility

HDTV and mobile TV (One-Seg) us ing ISDB-Tis

successfully progressing in Japan.


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Muchas Gracias!

Thank You for Your Attention!

outline of isdb-t(nhk takada).pdf

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