Research and development for digital broadcasting in NHK ...€¦ · 7 CLI canceller for...

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ＤｉＢＥＧDigital Broadcasting

Experts Group

Research and development for digital Research and development for digital broadcasting in NHK STRL / Japanbroadcasting in NHK STRL / Japan

Digital Broadcasting Expert Group (DiBEG)

Masayuki TAKADA

NHK Science and Technical Research Laboratories (STRL)

Presentation 4

Oct. 14, 2004

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ContentsContents

1. Research and development relate to Digital Terrestrial Television Broadcasting transmission technologies

2. Video on HDTV mobile reception (3 minute)

3. New technologies for broadcasting systems and devices under development in STRL

4. Video on STRL Open House 2004 (26 minute)

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ContentsContents





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1. 1. R&D relate to DTTB transmission technologiesR&D relate to DTTB transmission technologies

Transmitter sideCoupling loop interference canceller at broadcast-wave relay station for single frequency network

Receiver sideFixed reception

Long delay multipath equalizer

Mobile receptionHDTV mobile reception

Handheld/portable receptionStudy on prediction of service area

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6

Countrywide transmitter networksCountrywide transmitter networks

To cover the service area all over the country,Broadcasters have to construct relay stations.

DTTB has an ability of constructing SFN.There are 3 delivery methods of DTTB signal from master station to relay station.

Microwave LinkMore frequency bands(limited frequency band)

Optical FiberConstruction and running cost(expensive)

Broadcast-wave relay system(On air relay from master station)

Coupling loop interferenceMerit : low cost

Master station

Relay station

Relay station

f1

f1 f1

f1

SFN : Single Frequency Networks

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CLI canceller for broadcastCLI canceller for broadcast--wave relay systemwave relay system--Toward the Toward the cconstruction of onstruction of ccountrywide ountrywide ddigital igital tterrestrial errestrial bbroadcasting roadcasting nnetworks etworks --

Constructing stable and cost-effective relay networks is important.Broadcast-wave relay system is the most cost-effective signal delivery system.Remaining problem was stability. But we developed Coupling loop interference (CLI) canceller.CLI cancellers can eliminate distortion when signals are relayed in a single frequency network (SFN).

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BroadcastBroadcast--wave relay stationswave relay stations

ReceivingAntenna

TransmittingAntenna

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What is CLI (coupling loop interference) ?What is CLI (coupling loop interference) ?

Frequency of transmitting signal is the same as frequency of receiving signal.If the output of transmitting signal comes to the input receiving antenna, receiving signal is interfered. This is CLI.It is generally said that more than 90dB isolation is needed between transmitting antenna and receiving antenna.

Coupling loop interference

Relay Station

Mountains etc.

NHK

ReceivingAntenna

Transmitting Antenna

f1f1

f1From Master Station

f1

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Principle of CLI cancellerPrinciple of CLI canceller

Loop Canceller

Condition for canceling : W (w) = G (w) C (w)

+_

_W (w)

G (w)

Coupling Loop : C (w)

From Master Station

Transmitting Antenna

Transversalfilter

Receiving Antenna

AMP

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Effect of CLI cancellerEffect of CLI canceller

Transmission signal without CLI canceller

Transmission signalwith CLI canceller

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Performance of CLI cancellerPerformance of CLI canceller (Experimental data)(Experimental data)

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

-15 -10 -5 0 5 10 15 20

Coupling loop D/U (dB)

Deg

rada

tion

of e

quiv

alen

t C/N

(dB

) Without canceller

With canceller

20dB

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Equipment of CLI canceller Equipment of CLI canceller (small type)(small type)

RF/IF, IF/RF freq. transform

Loopcanceller

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Merits / demerits of SFNMerits / demerits of SFN

Merits of SFNFrequency effective use (Frequency is limited)

Demerits of SFNCLI at broadcast-wave relay station

solve by CLI canceller

Appearance of long delay multipathsolve by guard interval of OFDM

How about long delay multipath over guard intervalLong delay mutipath equalizer

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Long delay Long delay multipathmultipath situationsituation

Masterstation

On air relay

station

t1

t2

t3

t1, t2, t3 : transmission time

•Transmission time of desired signal : t1•Transmission time of delayed (undesired) signal : t2+t3•Delay time of undesired signal τx = (t2+t3) - t1•Guard Interval : τGI (for example τGI = 126 usec)•Long delay multipath over guard interval τx > τGI

•IF D>37.8km, t2>126usec, there is possibility to be τx > τGI

Development of long delay multipath equalizer is important.

Distance between stations : D

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Equalizer adapted with long echo over guard interval

(Equalizer in time domain)

Receiver improvementReceiver improvementPrinciple of long delay Principle of long delay mutipathmutipath equalizerequalizer

: DATA : SP

Carrier (frequency)S

ymbol (tim

e)

Distribution of Scattered Pilot symbol

Receiving signal

OFDM demodulator

FFT SPEqualize

Demodulate

＋

Filter coefficient generator

Filter coefficient generator

Adaptivefilter

－

Update of filter coefficient ;

• SP : 4 symbol interval

• All carrier : 1 symbol

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Performance Performance of long delay of long delay multipathmultipath equalizerequalizer

64QAMMod

1/8GI

3Mode

Useful symbol duration (Tu) ： 1008usecGuard interval (GI = Tu/8) : 126usec

0 100 200 300 400 500 600 700 800 900 100010-4

10-3

10-2

10-1

100

2×10-2

7×10-3

Equalize by all carriers

No equalizer

Tu/3

D/U=6dBC/N=30dB

GITu/8

Equalize by SP

Delay time of an echo (usec)

Bit

Err

or R

ate

GuardInterval

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EquipmentEquipmentof long delay of long delay multipathmultipath equalizerequalizer

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HDTV mobile receptionHDTV mobile reception-- background background --

5 10 15 20

1/2 2/3

1/2 2/3

1/2 2/3 3/4 5/6 7/864QAM

16QAM

QPSK

Transmission capacity (Mbit/s)

Fixed reception

Mobilereception

Receiving improvementwith space diversity

Transmission parameterfor mobile reception,

used to be considered

Mod

ulat

ion

DTTB replaces analog TV. Analog TV is mainly for fixed reception service.So, in Japan, main service of DTTB is decided to be HDTV. DTTB has ability to transmit STDV service for mobile reception using QPSK or 16QAM,however, there is no TV channel to be assigned for mobile reception.

It is hopeful that HDTV service for fixed reception can be received by mobile.

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Prototype 4Prototype 4--branch space diversitybranch space diversityfor HDTV mobile receptionfor HDTV mobile reception

NHK’s prototype diversity reception system for HDTV mobile reception

Signal : 6MHz BW 64QAM-OFDM (ISDB-T)Application : HDTV (18.3 Mbps) in a mobile carDiversity : 4-branch space diversity

Implementation and performance evaluationLaboratory test

Maximum Doppler frequency in fading environmentField trial in Tokyo suburban area

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Principle of 4Principle of 4--branch space diversitybranch space diversityfor OFDM signal under mobile reception for OFDM signal under mobile reception

Derived from the frequency response, based on the received Scattered Pilot (SP) signal of OFDM

Spectra ofOFDM signal

Weighting factor

・・・

・・・

FFT#1

D(0)

D(i)

D(k-1)

FFT#2

FFT#3

FFT#4

01 2 3 ･････････ k carrier

#1

#2

#3

#4

Output

Branch

Block diagram of diversity reception system

C1(0)

C1(k-1)

C2(0)

C2(k-1)

C3(0)

C3(k-1)

C4(0)

C4(k-1)

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Results of lab test Results of lab test on 4on 4--branch diversity reception systembranch diversity reception system

Des

ired

inpu

t lev

el[d

Bm

]

Maximum Doppler Frequency fdmax[Hz]0 10 20 30 40 50 60

-100

-90

-80

-70

-60

-50

1234

Number of used branches

GSM Typical urban area modelMode3 GI=1/864QAM 3/4 I=218.255 Mbps

-86 dBm-84 dBm-81 dBm-66 dBm

Desired input level(@ fdmax =20Hz)

63 km/h95 km/h45Hz349 km/h74 km/h35Hz2

63 km/h95 km/h45Hz4

28 km/h42 km/h20Hz1

Velocity@62ch( v = fdmax × λ )

Velocity@19ch( v = fdmax × λ)fdmaxNumber of

Branch

20dBimproved

35km/himproved

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Field trial in Tokyo (suburban area)Field trial in Tokyo (suburban area)

HorizontalPolarization

Tx power

UHF 19ch 509 MHzFrequency

30 W (45dBm)

TX antenna

Experimental station

1000 m

Measured route

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Receiving antennasReceiving antennasfor DTTB mobile receptionfor DTTB mobile reception

Cross dipole antennaGain = 0 dB

4 antennas are mounted on the car roof. Height is 2 m above the ground.

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40 45 50 55 60 65 70 75 800

20

40

60

80

100

Mode3 GI=1/864QAM 3/4 I=2

Number ofused branches

1234

Electric field strength[dBuV/m]

Perc

enta

ge o

f suc

cess

on re

ceiv

ing[

%]

Results of field experimentResults of field experiment

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Effectiveness of diversity receptionEffectiveness of diversity reception

Emin : Minimum usable field strength [dBµV/m]CRR: Correct Reception Rate

48505565Emin at CRR of 90 %46485061Emin at CRR of 50 %4321Number of branch

Required field strength for 50 % and 90 % correct reception rate.

At CRR of 90 %,Emin of 17dB can be reducedby using 4-branch diversity reception.

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Transmitting station (Tokyo tower)Transmitting station (Tokyo tower)

UHF 27ch(557MHz)Channel

HorizontalPolarization267 mAntenna height

570 WERP (Effective radiation power)

300 WTransmission power

Tokyo tower digital transmitter1st stage (NHK Digital GTV)Transmitting

antenna

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Transmission parameters Transmission parameters and receiving sceneryand receiving scenery

B

215ms3/4

64QAM12

A1Number of segments

QPSKCarrier modulation1/2FEC coding rate

215msTime interleaving

3(5617 carriers)Mode

2 layersHierarchical transmission

1/8(126usec)GI (Guard Interval)

Transmission parameters of NHK Digital GTV

HDTVProgram

5.6 MHz

SinpleVideo

Program

AB B

Receiving Antenna

1.5 m

Receiving scenery

Receiving antenna height : 1.5mReceiving antenna : Cross dipole antenna

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Measured points for handheld receptionMeasured points for handheld reception

Tokyo Tower

10km

・7 directions (spokewise)

・1,3,5,10,15,20,25,30 km

100

m

100 m

100 samples / one way

Representative value :medium

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Distribution of measured field strengthDistribution of measured field strength

30

40

50

60

70

80

90

1 10 100

Distance from the transmitter (km)

Rec

eivi

ng f

ield

str

engt

h (d

BuV/

m)

Eo : ideal (free space)

Average : 29dB0

10

20

30

40

501 10 100

Distance from the transmitter (km)

Atte

nuat

ion

from

Eo

(dB)

Average attenuation from Eo (free space electric field strength) = 29dB

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ContentsContents





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ContentsContents





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NHK STRLNHK STRL

NHK (Japan Broadcasting Cooperation)Established in 1925Non-profit public broadcasting organization2 AM radio, 1 FM radio, 2 terrestrial TV, 3 satellite TV

NHK STRL (Science & Technical Research Labs.)Established in 1930

(5 years later science radio broadcasting started)

Research department of NHKMajor research themes

Television, Color television, HDTV, PDP, Broadcasting satellite,Digital broadcasting (ISDB), etc.

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33rdrd generation research complexgeneration research complex

Opened in April 200214 stories high(office tower)6 stories high (experiment building)

STRL areaB2 – 5th floors

STRL employees (’04,3/31)286 personnel(260 research engineers)

Researches based on “Middle and long term research vision(MLRV) of STRL” are conducted

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Organization of STRL (9 research labs.)Organization of STRL (9 research labs.)

Wireless systemsTerrestrial/satellite digital broadcasting, wireless LAN

Networked broadcasting systemsNetworked program production broadcasting systems and services

Advanced television systemsUltra high definition video (super hi-vision), 3D visual systems

Acoustics and audio signal processingHigh definition audio systems, acoustic signal analysis and coding

Visual information technologiesVideo compression and image expression

Intelligent information processingMetadata production and applications, image recognition, media processing

Human scienceServices for visual or hearing impaired, software agents, speech processing

Advanced broadcasting devicesUltrahigh-sensitivity imaging devices, ultrahigh-density recording

Materials scienceMaterials for displays and recording devices

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STRL Open House 2004STRL Open House 2004

58th Open House　from May 27 to May 30, 2004. 40 exhibits presented research results under the catch phrase “Dreams On Air. Welcome to the Future Fantastic.”These included technologies categorized into three groups.

1. Vision exhibits2. Fun exhibits3. Technical exhibits

More than 28,000 attendance visited

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Specific research themesSpecific research themes

Super Hi-VisionUltrahigh-definition, wide-screen system with 4000 scanning line

3-Dimentional Audio Systemfor Super Hi-Vision

Human-friendly Digital TVfor people with visual and hearing impairments

Ultrahigh-sensitivity HDTV handheld camera Ultra-small silicon microphoneFlexible ultra-thin displays

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4320 pixels

7680 pixels

< 4000 scanning lines >Get sensation of immersion

1080 pixels

1920 pixels

< HDTV >Get sensation of presence

Viewing distance:0.75 H Visual angle: 100 degree

Viewing distance: 3HVisual angle: 30 degree

H:screen height

Super HiSuper Hi--VisionVisionUltrahighUltrahigh--definition, definition, wwideide--screen screen ssystem with 4000 ystem with 4000 sscanning canning llinesines

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Comparison of resolutionComparison of resolution

0 20 40 60 80

Resolution in time(frames/sec)

Mill

ion

pixe

ls/fr

ame

　70mmCinescope

35mmStandard HDTV

NTSC

10

1.0

0.1

100 IMAX(48 frames)

Showscan

Movie

Video

4000 Scanning Line Image

IMAX

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UltrahighUltrahigh--definition definition ccamera and amera and pprojectorrojector

• NHK developed an experimental system made up of a camera, display, and recording device.

• The system uses 4 CCD imaging devices and 4 LC (liquid crystal) panel display devices (8 million pixels each). This four-panel color system, in which two panels are for green, has 32 mega pixels.

Ultrahigh-definition camera Ultrahigh-definition projector

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New camera with 4000 scanning linesNew camera with 4000 scanning lines

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UltrahighUltrahigh--definition, definition, wwideide--screen screen ddisplayisplay

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33--Dimentinal Audio System Dimentinal Audio System for 4000 scanning line systemfor 4000 scanning line system

・Recreation of various sound fields・Sound in synchronization with a picture on a large screen・The arrayed loudspeakers help create a sound that a listener perceives popping up from a 3D video image

Features

Middle part ：10ch

Lower part ：3ch

Upper part ：9ch

Seats for gests

＋

Screen

LFE (Low Frequency Effects) ： 2ch

22.2-channelAudio system Array Speaker

(36 small speakers) x 2

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HumanHuman--friendly Digital TVfriendly Digital TV

Combines a simple-operation remote control and a menu display.Visually impaired people can “VIEW” data services through tactile presentation and synthesized voice.Hearing impaired people can “READ” the announcer’s voice by closed captioning system.

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UltrahighUltrahigh--sensitivity HDTV sensitivity HDTV new Supernew Super--HARP handheld cameraHARP handheld camera

Developed for applications such as emergency reporting at nightClear Hi-Vision picture obtained even under moonlit conditions100 times the sensitivity of a CCD camera, 50,000 times for still pictures

Ultrahigh sensitivity HDTV handheld camera

New-Super-HARP image pickup tube

25µm

New-Super-HARPphotoconductive film

LightElectron

beamAvalanche

multiplication

Charges

HARP (High-gain Avalanche Rushing amorphous Photoconductor)

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UltraUltra--small silicon microphonesmall silicon microphone

• First fabrication of single-crystalline silicon microphone with an integrated structure

- Ultra-small, Superior acoustic characteristics, Highly reliable (robust, thermal resistance)

- Mass producible, Applicable to low-voltage operation, broadcasting or consumer use

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Flexible ultraFlexible ultra--thin displays (1)thin displays (1)Organic EL (electroluminescence) displayOrganic EL (electroluminescence) display

An organic EL device using polymer material. A new light-emission mechanism, phosphorescence, may achieve a quantum efficiency that is four times that of conventional (fluorescence) light-emission.

Organic EL display (moving picture)

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A flexible liquid crystal display (LCD) using a film substrate and ferroelectric liquid crystal with a polymer network

A new film structure and fabrication technique that improve flexibility

Flexible ultraFlexible ultra--thin displays (2)thin displays (2)Film Liquid Crystal Display (LCD)Film Liquid Crystal Display (LCD)

Flexible LCD

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ContentsContents





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ＤｉＢＥＧDigital Broadcasting

Experts Group

Thank you for your attention!Thank you for your attention!

DiBEG(Digital Broadcasting Expert Group)

http://www.dibeg.org

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