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Digital Television Talk v3

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Digital Television Talk v3 Powered By Docstoc
					    Communications Laboratory

      DTTB Lab Tests
      Methodology &
      Results Summary
      http://www.commslab.gov.au
             Presentation by: Neil Pickford
1
                    Overview
     Digital Television Objectives & Technology
     DTTB Transmission Technology
     The Australian Test Program
     Laboratory Tests - Test Rig
     Laboratory Tests - Main Results
     Field Test Objectives & Equipment
     Summary Field Test Results
     Selection Process & Criteria
     Selection Result & Future
2
Digital Television
             Why digital?
       Noise free pictures
       Higher resolution images
        Widescreen / HDTV
       No ghosting
       Multi-channel sound
       Other services.




3
Broad Objectives of DTB
 Overcome     limitations of the existing
    analog television system
   Improved picture
     High quality (no interference)
     Resolution (HDTV)
     Format (16:9)
   Enhanced Audio services
   Data capacity available for other value

4
    added services
Enabling Technologies
     Source digitisation (Rec 601 digital studio)
     Compression technology (MPEG, AC-3)
     Data multiplexing (MPEG)
     Display technology (large wide screens)

    Transmission        technology
                        (modulation)

5
Transmission Technology
     The transmission system is used to transport the
      information to the consumer.
     The system protects the information being
      carried from the transmission environment
     Current Australian analog television uses the
      PAL-B AM modulation system




6
          Digital TV Transmission
                Technology
     The transmission
      system is a
       “data pipe”
     Transports data rates
      of around 20 Mb/s
     Transports data in
      individual containers
      called packets

7
DTTB Transmission Systems
       3 systems are being developed at present.

        USA          ATSC       8-VSB

        Europe       DVB-T      COFDM

        Japan        ISDB       Band Segmented
                                 Transmission OFDM

8
8-VSB - USA
       Developed by the advance television systems
        committee - ATSC
       Developed for use in a 6 MHz channel
        A   7 MHz variant is possible.
       Uses a single carrier with pilot tone
       8 level amplitude modulation system
       Single Payload data rate of 19.39 Mb/s
       Relies on adaptive equalisation
       Existing AM technology highly developed

9
COFDM - Europe
        Developed by the digital video
         broadcasting project group - DVB
        Uses similar technology to DRB
        Uses 1705 or 6817 carriers
        Variable carrier modulation types are defined allowing
         Payload data rates of 5-27 Mb/s in 7 MHz
        Developed for 8 MHz channels
         A   7 MHz variant has been produced and tested
        Can use single frequency networks - SFNs
        New technology with scope for continued
         improvement & development
10
The Australian DTTB Test Program
      Australia is interested in a Digital HDTV Future
      Australia has a Unique Broadcasting
       Environment
      Overseas Digital TV Developments were
       interesting but the results could not be directly
       related to Australia.
      To make informed decisions we needed to
       collect information relevant to our situation.
      We had a few Questions.
11
Aims of Australian DTTB Testing-1
     Australia needed to know:
      How does DTTB perform with VHF PAL-B?
      What Protection does PAL require from the
       DTTB service for:
        Co-Channel?
        Adjacent  Channel?          Subjective Assessment
        Is Signal level a factor?




12
Aims of Australian DTTB Testing-2
      How Quickly does the system degrade?
      What are the real system thresholds?
          Signal Level
          Carrier to Noise
          Payload Data Rate in 7 MHz

        How does DTTB cope with Interference?




13
Aims of Australian DTTB Testing-3
        What Protection does DTTB require from the
         PAL-B service for:
          Co-Channel?
          Adjacent  Channel?
          Is Signal level a factor?



        What Protection does DTTB require from other
         DTTB services?


14
Aims of Australian DTTB Testing-4
      How does DTTB perform in a 7 MHz
       Channel Environment?
      How sensitive is DTTB to practical
       Transmission Equipment?
         How important is:
          Transmitter Linearity?
          Transmitter Precorrection?
          Transmitter Output Filtering?
          Combined Feeder/Antenna Systems?



15
Aims of Australian DTTB Testing-5
        Is DTTB affected by Multipath Echoes?
          ArePre-Echoes a Problem?
          What happens past the Guard interval?

      Is DTTB affected by Doppler Shift?
      Is DTTB affected by Dynamic Flutter?
      Is DTTB affected by Impulsive Interference?
      How does DTTB perform in the Field cw PAL


         Lots of Questions but
         Few Definitive Answers!
16
Scope of Tests
      The test program began with the aim of
       answering these questions for DVB-T
      During the early stages of testing ATSC was
       floated as a Candidate Digital TV System
      The test program’s scope was increased and a
       comparative focus adopted.
      All tests were designed to be as generally
       applicable as possible to any Digital TV
       Modulation System.
17
Order of Measurements
      FACTS Advanced TV Specialists Group
       directed the priority of Testing
      Laboratory Tests First
         DTTB into PAL protection
         DTTB System Parameters
         PAL into DTTB protection
         Other Interferers & Degradations
      Field Tests Later

18
                                                                                                                                                                                                                                                                                                  Tv Ant
                                                                                                           MUF2-Z2
                    e        S -271 PAL
                   T ktronixT G                S DW 500P
                                                ony V -A        PAL
                                                                            Plisch SBUF
                                                                                                PAL IF                 PAL RF          Uwn dS n l P th
                                                                                                                                        n a te ig a a
                   P LT s Gne tor
                    A e t e ra                 D ita B ta m
                                                 ig l e ca
                                                                           PAL Stereo IF
                                                                             Modulator                                                                   +21.7 dB          +10.2 dB
                                                                                                                                                                                                                     O Air 7 & 9 Test
                                                                                                                                                                                                                      ff                                                                                                         All Equipment within Da
                                                                                                                       ZSC-2-4
                                                                                                                                      PAL/ CW    P
                                                                                                                                                H 8447E                  A 2098
                                                                                                                                                                          R
                                                                                                                                                                                           +8.0 dBm
                                                                                                                                                                                                                                                                                                                                 Box is in Separate Shie
                                                                                                                                                 m
                                                                                                                                      -23.8 dBm A p               -2.4
                                                                                                                                                                          m
                                                                                                                                                                         Ap
                                                                                                                                                                                                                                             HP-436A
                                    SDI                                                                                                                           dBm                                                                      Power Meter
                                                                                                                                                                                                                                                                                                                                 Room with DTTB R   eceiv
                                                                                                         PAL LO                                                                                                                                                        x ontrol
                                                                                                                                                                                                                                                                       RC
                                                                                                                            CW/ SCM                                                             h
                                                                                                                                                                                               C 7-9                                                                     PC
                                                                                                                                                                                              BW 13MHz                 0 dB C Level for D
                                                                                                                                                                                                                             al          TTB R -23.75 dBm
                                                                                                                                                                                                                                               x                                                                                                     Ethernet
                                              VT-100               226.800 MHz              235.150 MHz                                191.500 MH z                                                                          al                 x
                                                                                                                                                                                                                       0 dB C Level for Pal TV R -27.6 dBm
                                                                                                                                                                                              +6.8 dBm
                                                                   +0 dBm                     -13 dBm                                   -20.1 dBm
                                                                   DTTB LO                     PAL LO                                      M/ W
                                                                                                                                         SC C
                                                                                                                                                                            PAL/ CW
                                                                                                                                                                             Signal          -22.8 dB                      -23.8 dBm
                                                                                                                                                                             Level                                                                                    Spectrum
                                                                                                                                                                                                                       Measure                                        Analyser
                                                                                                                                                                                             -16.5 dBm                 Port
                                                                                                   ll e q ipm n ith is
                                                                                                  A th Eu e t W inth                                                           /
                                                                                                                                                                              DU                                          Test
                                                                                                                                                                                                                                                                        HPIB                                                                             R S232
                                                                                                                                                                                                                                                                                                                                                        19.2 Kb/ s
                    D VMPEG
                     M                           R 232
                                                  S                                                                                                                                          PAL/ CW+DTTB                                    H 70000
                                                                                                                                                                                                                                              P
          DMV         Coder                       9600     ig O
                                                          R L                                    a e ox sid h ld d
                                                                                                Dsh dB isin eS ie e room                                                    Combiner
                                                                                                                                                                            ZSC  -2-4
                                                                                                                                                                                                                          Splitter
                                                                                                                                                                                                                          ZSC -2-4
                                                                                                                                                                                                                                         Spectrum Analyser
          MCC                                      a
                                                  B ud
                           R 422
                            S
                                                                                                     ith e T B od la
                                                                                                    w th DT M u tor                                                          D TTB
                                                                                                                                                                                             -16.4 dBm                  U
                                                                                                                                                                                                                       DT
                                                                                                                                                                                                                       Port
                             T xi
                              a                                                                                                                                              Signal          0 dB
                                                                                  h
                                                                                 C 7-9                                                                                       Level                                           C ombined DTTB Signal         G able Loss 3.85 dB
                                                                                                                                                                                                                                                          R -6 C
                                                                                                 D TTB C al                                                                                                                                                                                                                        DTTB Receiver
                                                                                BW 13MHz                                                                                                                                -23.8 dBm                                                                           -27.6 dBm
         sT
    10ba e                                                                                      Level Adjust             +17.9 dB              ig/
                                                                                                                                              R Tx -15.3
     th rne
    Ee t                                     MV
                                            D 2k                                                                                              Select dBm             HP3708
                                                                       Ch8              -21.4                                       -14.7                                         -15.9                                                     Yellow Shaded Items are under Control of HP9836 via HPIB                                     TTL Clock
                 D Multiplexer
                  MV                        C FD
                                             O M                                                                       H-1A m
                                                                                                                       ZL A p                                    Carrier to Noise
                                                                      Cofdm              dBm                                         dBm                                           dBm                                  -27.6 dBm                                                                                                          & data
                                            Modulator                                                          -32.6                                                Test Set
                                                                      -16.5                                                                      w
                                                                                                                                                S itch
                                                                                                  -10 dB        dBm                                                                                                                       HP9836
                                                                       dBm                                                                                                                                                                Controller                                                                               Anritsu ME520B
                                                                                 Tx Drive                                                                     -23 dBm                 HPIB                      Pal TV Under                                                                                                                                    H P5383A
                           R 422
                            S                            -13.4 dBm                                                         50 Ohm                                                                                                                                                                                                           ate
                                                                                                                                                                                                                                                                                                                                 Bit Error R Meter
                                                                                  Level                                                                                                                              Test                                                                                                                                       Frequency
                              a
                             T xi                                                            -10 dB
                                                               35.3 MHz
                                                                                                                                                                                                                                                                                                                                                                  Meter
                                     a -D ine      te
                                    Dsh ot L Indica s          Cofdm IF                        Min               Dsire S n l P th
                                                                                                                  e d ig a a                                                                                                                                                                                                                HPIB
                   D MPEG
                    MV                                                                          -23.8 dBm
                     Coder           odu tion q ipm nt
                                    M la Eu e                                             P
                                                                                         H 8447C
                                         nde e
                                        U r T st                                           Ap
                                                                                            m
                                                                                                +29.3 dB
                                                                                                                                                                                                             PIB
                                                                                                                                                                                                            H To/ From Other Yellow Shaded Equipment                HP37204                                  H C
                                                                                                                                                                                                                                                                                                               PIB oax               HP37204
                                                                                                                                                                                                                                                                   PIB
                                                                                                                                                                                                                                                                  H Extender                                 Comms Link             PIB
                                                                                                                                                                                                                                                                                                                                   H Extender


                                                                                                 +5.4 dBm                                                                          3 Element VHF                                        ills h
                                                                                                                                                                                                                                       H C 8-11TV antenna
                                                                                                                                                                                      h
                                                                                                                                                                                     C 8 Beam
                                                                                                                                                                                                   ~3 W
                                      ra sm    q ipm n
                                     T n issionEu e t                             Manual
                                                                                 Tx Drive         20.4 dB Link                                                                                                  2 km VH Link
                                                                                                                                                                                                                       F                                                              10 MHz
                                                                                                                                                                                                                                                                                                        GPS
                                                                                                                                                                                                                                                                                                                                                       L-Band
                                                                                                   7.0 dB Coax                    Tx Filter                                                                                                                                                         Frequency
    O air PAL
     ff              Pal             oca d a a ora
                                    L te inMinL b tory                                                                            VH C 8
                                                                                                                                    F h                                  -22 dBm                                                                                                                    R eference                                          G PS
        Video                                     H P8663A                                                          D irect                          Direct                                                                                                                                          10 MH  z
                                                                                                                                  BW 7MH  z                                                                                                                           450 MH z
                                             C FD 226.800 MH
                                              O M
                                             8-VSB 235.500 MH
                                                               z
                                                               z                       Transmitter
                                                                                                                   Calibrate                         Signal              ZFSC-2-4                                                                                      +7 dBm                                                    T n tor L kEu e t
                                                                                                                                                                                                                                                                                                                                  ra sla in q ipm n
                                                                           Tx                       Test                                                                                                                                                                   p
                                                                                                                                                                                                                                                                      Mix U LO
                                                 EC
                                                N +6.2 dBm                 LO             Under
                                                                                                   -14 dBm                                                                                                                               -48.6 dBm
                                                                                                                                                                                                                                                                                                                                   t ne
                                                                                                                                                                                                                                                                                                                                 A Uiv rsityof Cn e
                                                                                                                                                                                                                                                                                                                                                a b rra
                                               Harris +7.0 dBm                            Test                                                                                                                                                                                      +7 dBm                            H h
                                                                                                                                                                                                                                                                                                                     U F C 44
                                                 DTTB Tx LO                                        -0.8 dBm 2.1 dB -17                      -18.5
                                                                                                                                                     0 dB
                                                                                                                                                              -19
                                                                                                                                                                  Direct/ Echo
                                                                                                                                                                                                                                                                                                     +27 dB          641.5 MHz
                                                                                                                                dBm                                C ombiner                                                                                     +12 dB                                                                                  +22 dB             +4
                                                                                             /
                                                                                            OP                                              dBm               dBm                                                                                                                                                                     -16 dB
     Power Levels for two Test Modes Shown                                                         3 W Input          Link                                                                                                           191.5 MHz                                                                                                                          AR
                                                                                                                                                                                                                                                              MV
                                                                                                                                                                                                                                                               A-11                               H 8447C
                                                                                                                                                                                                                                                                                                   P                                                  P
                                                                                                                                                                                                                                                                                                                                                     H 8447E
                                                                                                                                                                                                                                     BW 7 MH z                                                                                                                          10W100
     3 W+33 dBm for Link Echo Tests                                                                               Echo/ Doppler
                                                                                                                                                                                                                                                        -50
                                                                                                                                                                                                                                                              m
                                                                                                                                                                                                                                                              Ap
                                                                                                                                                                                                                                                                       -38 dBm           -50      m
                                                                                                                                                                                                                                                                                                  Ap
                                                                                                                                                                                                                                                                                                            -23 dBm            -27 dBm       -42.8
                                                                                                                                                                                                                                                                                                                                                     Ap
                                                                                                                                                                                                                                                                                                                                                     m            -19    m
                                                                                                                                                                                                                                                                                                                                                                        Ap
     75 W+48.6 dBm for C Echo Tests
                           oax                                                                                                                       0 dB                                                                                                                         ZFM-11 dBm                                                                      dBm
                                                                                                                                                                                                                                                        dBm                                                                                  dBm
                                                                           Coax                                                       -18 dBm                        -19 dBm
                                                  75 W Input
                                                                       Echo/ Doppler
                                                                                                                                                      Echo
                                                                                              Power
          RG-213 Coaxial Delay O Laboratory Roof
                                n                                                                                                                    Signal
                                                                                                +48.55 dBm

                                                                                                                                                                                                                            z PS
                                                                                                                                                                                                                      10 MH G                                                                                                                                               GPS
                                                                                                    500W
                           900 m                                                                                                                                                                                       Reference
                                                                                                    30dB
                                                                                                                                                                                                                                                                                                                                       GPS
                                                                                                    Attenuator                                                                               228..150 MHz                                                                                                             10 MHz                               L-Band
                                                                                                                                              VH C 8
                                                                                                                                                F h                                                                                                                                                                                Frequency
                                                                                                                                                                                               +7 dBm                                                                                                                              R eference               G PS
                                                                                                                                              191.500 MHz
                                                                                                                                                                                               Echo LO                                                                                                                              10 MH  z
                +30 dB                                                                          +18.55 dBm                                    BW 7MH z                                                                                        Doppler LO228.150 MHz                      10 MH z
           P
          H 8447C                                                                                                                                                                                                                                h
                                                                                                                                                                                                                                               C 44 LO678.150 MH  z
          m
          Ap           0 dBm
                                                                                         HP-436A
                                                                                                                                                                                          Echo
                                                                                                                                                                                            LO                                                        +7 dBm
                                                                                                                                                                                                                                                                                        Reference                L kU FRce eEu e t Na R A
                                                                                                                                                                                                                                                                                                                  in H e iv q ipm n e r oof
-30 dBm                                                                                                                                                                                                                                                                                                               H h
                                                                                                                                                                                                                                                                                                                     U F C 44
                                    300 m                                                Power                                                                                                                                                                           +7 dBm
                                                                                                                                                                                                                                                                                                                     641.5 MHz
                                                                                          Meter                                                                                                                                          IF=36.15 MHz
                                                                                                                                                              C 8
                                                                                                                                                               h                                                DTTB IF                                           IF               -35 dBm
                                                                                                                                                                                                                                                                                                                                                 A-11
                                                                                                                                                                                                                                                                                                                                                MV
                                                                                                                                                                                                                                                                                              Pm
                                                                                                                                                                                                                                                                                             H Ap
                                                                                                                                                              DTTB       -17 dBm                 -10 dBm       36.65 MHz        -8 dBm                          -41                                        -60 dBm                -57 dBm         m
                                                                                                                                                                                                                                                                                                                                                  Ap                 -69 dBm
               +30 dB                                                                                                             C Echo
                                                                                                                                   oax                                                                                                    IF amp                dBm ZFM-11
           P
          H 8447C          +11 dBm               200 m                                                                                                                                  ZFM-11                                                       z
                                                                                                                                                                                                                                                 8 MH IF Filter                          -20 dB
          m
          Ap                                                                                                                                                                                                                               Plisch TV Receiver
-18 dBm
                              19                                                                                            -24.5 dBm
                                                                                                                                                          D
                                                                                                                                                           Coax
                                                                                                                                                           oppler
                                                                                                                                                                                                                                                                                       -20 dBm
    Laboratory Tests - Test Rig
           C/N Set & Attenuators   EUT       PAL & CW




 Control Domestic     Modulator      Spectrum Analysers    Plot &
Computer Television    Control                            Printing
          Receiver    Computers
    20
Test Rig - Modulation Equipment
      Power Meter       PAL & CW
         RF LO          Interference
                         Generators
        COFDM
        Modulator

       MPEG Mux
       MPEG Mux
     MPEG Encoder        8-VSB
                        Modulator
     MPEG Encoder

21
Laboratory Tests - Transmitters
                                  Loads

Echo Combiner
                                  Harris
     Power Meter                  1 kW
     Digital CRO                  Tx
          Tx LO
                                  Harris
        Spectrum                  Exciter
        Analyser




                   NEC 200 W Tx
22
Digital Transmitters TCN-9 Sydney




23
 Lab Tests - VHF/UHF Transposer
                        Level Adjust

                        UHF Amps
  Power Supply
VHF Input Filter        UHF BPF Filter
       RF Amp
                        Mixer
           RF LO

      10 Watt UHF
       Amplifier



 24
COFDM - Commercial Receiver
        News Data Systems - System 3000




25
COFDM - Test Rx Hardware




26
27
Main Results - Lab Tests
      C/N ATSC 4 dB better than DVB-T.
       This Advantage offset by Poor Noise Figure
      DVB-T is better than ATSC for Multipath
      ATSC is better than DVB-T for Impulse Noise
      ATSC cannot handle Flutter or Doppler Echoes
      ATSC is very sensitive to Transmission system
       impairments and IF translation
      DVB-T is better at handling Co-channel PAL
      DVB-T is better rejecting on channel
       interference (CW)
28
8-VSB & COFDM - Spectrum


                    8-VSB
                   COFDM




29
          Digital Modulation - 8-AM
                                +7
                                +5
                                +3
                                +1
                                -1
                                -3
                                -5
                                -7


       Before Equaliser                      After Equaliser
     8-VSB - Coaxial Direct Feed through Tuner on Channel 8 VHF
30                        3 Bits/Symbol
Spectrum of COFDM DTTB
     7 MHz Carrier Spacing
       2k Mode 3.91 kHz
       8k Mode 0.98 kHz



       Almost
     Rectangular
       Shape

                    1705 or 6817 Carriers

                   6.67 MHz in 7 MHz Channel
                   5.71 MHz in 6 MHz Channel
31
     64-QAM - Perfect & Failure




32
General Parameters - Aust Tests
Parameter                DVB-T     ATSC

Data Payload             19.35 Mb/s 19.39 Mb/s

Carriers                 1705      1

Symbol Time              256 us    93 ns

Time Interleaving        1 Symbol 4 ms

Reed Solomon code rate   188/204   187/207

IF Bandwidth (3 dB)      6.67 MHz 5.38 MHz
33
General Parameters
     Parameter                DVB-T       ATSC

     IF centre Frequency      35.3 MHz 44.0 MHz

     Receiver AFC range       11.5 kHz    359 kHz

     Latency including MPEG
       coding SDTV 8 Mb/s     37 Frames




34
                                               Payload Bitrate Mb/s
COFDM FEC        Sys Min Sig      Calc    Guard Guard Guard Guard
  MOD     Code C/N       Level   Rx NF      1/4    1/8     1/16   1/32
 TYPE     Rate (dB) (dBuV)        (dB)    (Mb/s) (Mb/s) (Mb/s) (Mb/s)
 QPSK      1/2    5.4    11.7      4.8      4.35    4.84    5.12    5.28
 QPSK      2/3    6.6    13.2      5.1      5.81    6.45    6.83    7.04
 QPSK      3/4    7.6    14.8      5.7      6.53    7.26    7.68    7.92
 QPSK      5/6    8.7    16.8      6.6      7.26    8.06    8.54    8.80
 QPSK      7/8    9.5    19.2      8.2      7.62    8.47    8.96    9.24
16-QAM     1/2   11.2    17.7      5.0      8.71    9.68 10.25 10.56
16-QAM     2/3   13.0    19.6      5.1     11.61 12.90 13.66 14.07
16-QAM     3/4   14.1    20.9      5.3     13.06 14.51 15.37 15.83
16-QAM     5/6   15.5    22.9      5.9     14.51 16.13 17.08 17.59
16-QAM     7/8   16.3    24.9      7.1     15.24 16.93 17.93 18.47
64-QAM     1/2   16.8    23.3      5.0     13.06 14.51 15.37 15.83
64-QAM     2/3   19.1    25.2      4.6     17.42 19.35 20.49 21.11
64-QAM     3/4   20.6    27.5      5.4     19.59 21.77 23.05 23.75
64-QAM     5/6   22.2    30.0      6.3     21.77 24.19 25.61 26.39
64-QAM     7/8   23.7    32.4      7.2     22.86 25.40 26.89 27.71
 8-VSB     2/3   15.1    27.2     11.2       -      -        -    19.39
Blue Payload Figures are 188/204 scaled from actual measurement
Red Figures are calculated from the 1/32 Guard interval data

35
AWGN Receiver Performance
     Parameter                    DVB-T     ATSC

     Carrier to Noise Threshold
      (in native system BW)       19.1 dB   15.1 dB

     Simulated Theoretical C/N
       for optimum system         16.5 dB   14.9 dB

     Minimum Signal Level         25.2 dBuV 27.2 dBuV

     Receiver noise figure        4.6 dB    11.2 dB

     Rx Level for 1 dB C/N Loss 34 dBuV     35 dBuV
36
Receiver Parameters
        Guard interval
                 payload data rate and echo performance
          Affects
          No impact on general receiver parameters such as
           C/N & Signal level.
        COFDM Transmission Parameter Signalling
         (TPS) - receiver automatically determines
         the modulation type, FEC

        Currently Guard interval needs to be
         entered into the receiver.
37
DTTB System Multipath Character
                               Indoor Antenna            Outdoor Antenna


                      35
 C/N Threshold (dB)


                                                   8VSB

                                                            COFDM
                                                            (64QAM,2/3,1/8)




                      19
                      15

                           0      3                        15                 25
                                         Multipath Level ( - dB)
                       (Conditions: Static multipath, Equal Rx NF,
38                     No Co-channel or impulse interference)
AWGN Performance
        C/N 4 dB more power required for DVB-T to
         achieve the same coverage as ATSC.

        Better C/N performance ATSC offset by
         poor receiver noise figure

        ATSC C/N is very close to the theoretical
         DVB-T implementation is still over 2.5 dB
         higher than the simulated margin.

        Other DVB-T modes have different C/N
40
         Thresholds and Data Rates
Multipath & Flutter Measurements
Parameter                  DVB-T     ATSC

7.2 us Coax pre ghost      0 dB      -13.5 dB

7.2 us Coax post ghost     0 dB      -2.2 dB

Echo correction range      32 us     +3 to -20 us

Doppler single echo performance
 (-3 dB echoes)             140 Hz   1 Hz




41
                                                     Doppler Echo - 7.5 us Coax
                                                                             DTTB 7.5 us Single Coax Doppler Echo
                                    0        0

                                                                                                                           COFDM COFDM Post Echo


                                                                                                                            8-VSB8-VSB Post Echo

                       -5                    -5
Echo Level E/D (dB)
                       Echo Level E/D (dB)




                      -10           -10




                      -15           -15




                      -20           -20




                      -25           -25

                        -500                  -500     -400   -300
                                                                     -200
                                                                      -200
                                                                                      0
                                                                                   -100          0
                                                                                                   200         100
                                                                                     Frequency Offset of Echo (Hz)
                                                                                                                     200   300            400
                                                                                                                                                   500
                                                                                                                                                    500


                                                                             Frequency Offset (Hz)
                                                  42
Multipath & Flutter - Overview
        ATSC system 2 Equaliser modes
          RxEq switches to fast mode when short variable
          echoes are detected.
          Lab Tests - slow equalisation mode.

        8 VSB degrades more rapidly when
         multipath echo exceeds -7 dB

        COFDM works up to 0 dB in a white noise
         environment but in this condition is very
         fragile.
43
Transmitter Performance Sensitivity
     Parameter                   DVB-T   ATSC

     Transmitter/Translator Linearity
        & Inter-mod Sensitivity   Low    High

     Group Delay / Combiner /
       Filter Sensitivity        Low     < 50 ns




44
Transmission Strategies
     Suggested Transmission System performance
       maintenance strategy

        DVB-T - Manual Maintenance same as PAL

        ATSC - Automatic Dynamic pre-corrector

     Gap Fill coverage - System Strategy

        DVB-T - IF Translator, Digital Repeater or SFN

        ATSC - Digital Repeater

45
Transmission Performance - 1
        ATSC very sensitive to transmission
         impairments as it uses up correction
         capacity in the receiver equaliser.

        ATSC equaliser has to correct the response
         characteristic of the whole channel.

        DVB-T equaliser uses pilot carriers spread
         throughout the spectrum to equalise the
         channel in small 16-50 kHz sections.
46
Transmission Performance - 2
        ATSC Dynamic Pre-corrector will be difficult
         to apply in the combined antenna systems
         used in Australia

        Zenith suggest transmission without using a
         transmitter output filter to avoid group delay
         problems with 8-VSB.

        ATSC 6 MHz system operating in a 7 MHz
         channel helps this situation.
47
Transmission Performance - 3
        If using existing PAL vision transmitters:
          Recalibrationof metering will be necessary
           (Peak to Average)
          AGC / AFC and protection systems
           may require modification




48
Impulse Noise - Results
        Impulse Sensitivity
          (Differential to PAL grade 4)
          DVB-T       9 -14 dB
          ATSC        17-25 dB
        Difficult to measure & characterise.

        Mainly affects the lower VHF frequencies

        ATSC is 8 to 11 dB better at handling
         impulsive noise than DVB-T
49
Impulse Noise - Plot




50
Impulse Noise - Overview
        ATSC only has a few data symbols affected
         by any normal impulsive phenomenon

        The DVB-T COFDM demodulation (FFT)
         spreads the energy from a broad spectrum
         impulse across all carriers leading to
         massive data loss when the impulse is
         large enough.



51
DTTB into PAL - Subjective
                DTTB into PAL B Protection D/U (dB)
          System Test Description            Mean StdDev   Num   Min     Median   Max
 DVB-T 7 MHz       Ch 7 lower adj. ch.        -9.5  3.3     12   -14.0    -10.0   -4.0
 Tropospheric      Ch 8 Co-Channel            35.8  1.4     12    33.5    36.0    38.5
  Interference     Ch 9 upper adj. ch.       -10.6  4.9     12   -20.0    -10.0   -3.0
 DVB-T 7 MHz       Ch 7 lower adj. ch.        -5.3  3.8     12    -9.5     -6.5    2.5
  Continuous       Ch 8 Co-Channel            41.1  2.0     12    38.5    40.8    45.0
  Interference     Ch 9 upper adj. ch.        -6.4  4.3     12   -14.0     -6.8    1.0
 DVB-T 7 MHz       Ch 7 lower adj. ch.         3.5  3.8     12    -2.5      2.8   10.0
    Limit of       Ch 8 Co-Channel            50.4  0.9     14    48.5    50.3    52.0
 Perceptibility    Ch 9 upper adj. ch.         5.1  5.8     16    -1.0      3.8   20.0
 ATSC 6 MHz        Ch 7 lower adj. ch.        -7.0  3.4     15   -12.5     -7.0   -2.0
 Tropospheric      Ch 8 Co-Channel            38.7  2.6     41    34.5    38.5    44.0
  Interference     Ch 9 upper adj. ch.        -7.1  3.5     17   -14.0     -6.0   -3.5
 ATSC 6 MHz        Ch 7 lower adj. ch.        -0.9  4.3     15    -5.5     -2.0    8.0
  Continuous       Ch 8 Co-Channel            45.5  2.2     41    41.0    45.0    50.5
  Interference     Ch 9 upper adj. ch.        -0.3  2.9     17    -5.5      0.0    3.0
 ATSC 6 MHz        Ch 7 lower adj. ch.         5.0  4.4     15     0.0      4.0   13.0
    Limit of       Ch 8 Co-Channel            51.4  2.5     41    47.0    51.5    56.5
 Perceptibility    Ch 9 upper adj. ch.         5.4  3.1     17     0.0      4.5   10.5

52
DTTB into PAL - Overview
        DVB-T marginally less interference to PAL

        DTTB Co channel signals need to be kept
         at least 46 dB on average below the
         Wanted PAL level to ensure Grade 4
         reception

        DTTB Adjacent channel signals need to be
         kept on average at or below the Wanted
         PAL level to ensure Grade 4 reception
53
PAL into DTTB - Results
           DTTB System Parameters                 PAL into DTTB Protection (D/U)
DTTB TYPE    CONSTELLATION      FEC      Code Ch 7 Lower Co Channel     Ch 9 Upper
              MODULATION              Rate    Adj Ch (dB)   (dB)        Adj Ch (dB)
 DVB-T-7       COFDM QPSK             1/2        -44.8       -13.0         -49.2
 DVB-T-7       COFDM QPSK             2/3        -44.5        -8.4         -47.0
 DVB-T-7       COFDM QPSK             3/4        -43.7        -4.0         -45.3
 DVB-T-7       COFDM QPSK             5/6        -42.3         3.1         -43.3
 DVB-T-7       COFDM QPSK             7/8        -40.8         9.7         -42.0
 DVB-T-7      COFDM 16-QAM            1/2        -43.5        -8.8         -46.1
 DVB-T-7      COFDM 16-QAM            2/3        -42.1        -2.3         -43.3
 DVB-T-7      COFDM 16-QAM            3/4        -40.2         3.3         -41.2
 DVB-T-7      COFDM 16-QAM            5/6        -37.0         9.9         -39.1
 DVB-T-7      COFDM 16-QAM            7/8        -35.2        16.9         -37.3
 DVB-T-7      COFDM 64-QAM            1/2        -41.2        -3.1         -41.7
 DVB-T-7      COFDM 64-QAM            2/3        -35.4        1.4          -37.5
 DVB-T-7      COFDM 64-QAM            3/4        -35.0        10.8         -35.9
 DVB-T-7      COFDM 64-QAM            5/6        -31.2        17.1         -33.1
 DVB-T-7      COFDM 64-QAM            7/8        -28.9        22.6         -30.8
 ATSC-6         8-VSB 8-AM            2/3        -38.6        9.1          -38.7


54
                                      PAL into DTTB - Plot
                                                     Pal into DTTB Protection Ratio Comparison for 50 dBuV DTTB Signals
                            10


                            5


                            0


                            -5
Protection Ratio D/U (dB)




                      -10


                      -15


                      -20

                                                                                        8-VSB
                      -25
                                                                                        COFDM
                      -30


                      -35


                      -40


                      -45
                                 -8        -7   -6   -5    -4     -3     -2     -1      0        1      2   3      4      5   6   7   8
                                                                               Frequency Offset (MHz)


                                      55
                   15
                                       Co Channel PAL into DTTB - Plot
                                              DTTB Small Frequency Offset Co-channel Pal protection for 50 dBuV DTTB Signals




                   10
Protection Ratio D/U (dB)




                                                                              8-VSB Pal Co-Channel Protection
                            5
                                                                              COFDM V2.1 EQ Pal Interference




                            0




                            -5
                                 -40        -30           -20           -10              0                 10     20           30   40
                                                                                 Frequency Offset (kHz)


                                       56
                                 Off Air PAL into DTTB - Plot
                                                         Pal into DTTB Protection with real Off Air Pal signals either side of DTTB Channel 8
                            5



                            0



                            -5
                                                                                                                  7 MHz COFDM
                                                                                                                  6 MHz 8VSB
                      -10
Protection Ratio D/U (dB)




                                      Note: Channel 7 only has a
                      -15              single monophonic Sound
                                      carrier which is 10 dB below
                                         the Vision carrier level
                      -20



                      -25



                      -30



                      -35



                      -40
                            -2000           -1500             -1000             -500             0              500                  1000       1500   2000
                                                                                  Channel 8 DTTB Frequency Offset (kHz)

                                 57
DTTB & PAL - 0 dB Spectrum




58
PAL into DTTB - Overview 1
        The narrower ATSC system achieves very
         similar out of band / adjacent channel
         performance to DVB-T.

        ATSC is nearly 8 dB worse than DVB-T
         when subjected to interference from Co-
         Channel PAL transmissions




59
PAL into DTTB - Overview 2
        In situations where Co-Channel DTTB and
         PAL signals exist the DTTB into PAL
         interference will be the dominant factor,
         providing directional antennas are used.

        If a DTTB frequency offset was being
         considered for use, the data indicates that
         moving up in frequency is preferable to
         moving down.

60
                                      CW into DTTB - Plot
                                                     CW Interferer into DTTB Protection Ratio Comparison for 50 dBuV DTTB Signals
                            15

                            10

                            5

                            0

                            -5
Protection Ratio D/U (dB)




                      -10

                      -15

                      -20

                      -25                                                                    8-VSB

                                                                                             COFDM
                      -30

                      -35

                      -40

                      -45

                      -50
                                 -8        -7   -6       -5     -4     -3     -2     -1      0        1      2    3      4      5   6   7   8
                                                                                    Frequency Offset (MHz)

                                      61
CW into DTTB - Summary
        DVB-T is on average 15.5 dB less sensitive
         across the channel to general CW type
         interferers than ATSC

        The DVB-T orthogonal carrier spacing is
         evident for DVB-T in this measurement with
         a variation of over 8 dB. If known CW
         interferers are likely then a frequency offset
         of less than 4 kHz may assist system
         performance.
62
                            15
                                       CW into DTTB centre channel
                                            DTTB Small Frequency Offset Co-channel CW Interference protection for 50 dBuV Signal




                            10

                                                                              8-VSB CW Interference Protection
                                                                              COFDM V2.1 EQ CW Interference
Protection Ratio D/U (dB)




                             5




                             0




                            -5




                   -10
                                 -40        -30           -20           -10              0                 10      20              30   40
                                                                                 Frequency Offset (kHz)


                                       63
CW into DTTB - Comment
        ATSC has occasional peaks due to critical
         equaliser responses.

        The DVB-T response above was obtained
         from the improved equaliser which was
         provided near the end of the tests.




64
DTTB into DTTB - Overview
 DTTB   Ch 7 Lower       Co Channel Ch 9 Upper
 TYPE   Adj Ch (dB)         (dB)    Adj Ch (dB)
DVB-T-7    -28.3             20        -28.5
ATSC-6     -30.4            14.6       -32.2

      Adjacent channel performance of ATSC is
       better than DVB-T
      The Co-channel protection of both digital
       systems approximates to the system carrier
       to noise threshold.
65
                                   DTTB into DTTB - Plot             DTTB into DTTB Protection
                        25


                        20


                        15


                        10


                         5
Protection Ratio (dB)




                                                                                      COFDM
                         0
                                                                                      8-VSB

                         -5


                        -10


                        -15


                        -20


                        -25


                        -30


                        -35
                              -8        -7   -6   -5   -4   -3        -2       -1       0       1      2        3   4   5   6   7   8
                                                                 Frequency offset of Unwanted DTTB signal (MHz)

                                   66
 DTTB Field Testing Objectives

A DTTB Field Trial is study of Failure !!
  In comparison with current PAL television
       In various reception conditions :
       Investigate the difference in reception character
        for the two DTTB modulation systems.
       Provide information to DTTB system planners
       To provide Credible data.


 67
Field Testing - Van
        A field test vehicle was built in a small van.




68
Field Testing - On the Streets
        Over 115 sites were measured




69
         Field Test Vehicle Block Diagram
Ch 6-11 VHF
 Antenna on                             Spectrum        VM-700
a 10 m Mast                             Analyser
                                         Plisch PAL
        11.5 dB    NF 3.6 dB                             PAL
                                        Demodulator
        11.5 dB
                                 5                      Monitor
                        -20dB
                                way      DVB-T
                Input           split    Receiver       BER
                level           -7 dB     ATSC          Meter
                                         Receiver
                                                         CRO
                Noise                   Vector Signal
              Injection                   Analyser

                    Noise
                    Source
         70
Field Testing - Method
      Field tests were conducted in Sydney over a
       1 month period on VHF channel 8.
      Some simultaneous tests were conducted on
       VHF channel 6
      Power level for the field test was 14 dB below
       adjacent analog television channels 7 & 9
      Analog and digital television performance for
       both systems were evaluated at each site.
      Conducted by Independent Consultant & Mr
       Wayne Dickson of TEN
71
Field Test - Data Collected each Site
      Common Masthead Amp used (NF ~ 3.6 dB)
      Analog PAL transmission character (7,9 & 10)
      Measure level, multipath, quality & Video S/N
      Measure DVB & ATSC reception (Ch 8)
      Record DTTB & Analog Spectrum
      Measure Noise Margin (C/N Margin)
      Measure Level Threshold (Signal Margin)
      Measure antenna off pointing sensitivity

72
                                          Australian DTTB Field Trial
    ( d B )
    A R G IN
                                             PAL Receive Margin
                                                                 PAL - SITE RECEIVE MARGIN
                                                                              Facts DTTB Trial Sites
        40

                                                                       for HIGH GAIN ANTENNA
        35
    M
    R E C E I V E




        30                           Minimum F/S = 55dBuV/m
                                                                                                                 Receiver limitations
        25
                                                Margin to minimum acceptable
                                                picture w/o multipath

        20


        15
    S i t e




        10


             5                                                                                                       PAL on CH9


             0
                    45        50        55        60        65        70          75        80         85   90          95        100      105                        110
                                                                           Site Field Strenght (dBuV/m)
                    MINIMUM A CCEPTABLE PICTURE
                                                                                                                              Plisch Receiver
Nominal conditions :               7 dB gain Antenna + 2 dB leed loss @ CH9
                                       Effective decoder Noise Figure (NF) = 5 dB
                                                                                                                                           W .T. D. 5 J UNE 1 9 9 8




                         73
T H R E S H O L D
                                         Australian DTTB Field Trial
                                          DTTB compared to PAL
                                                                  PAL VIDEO S/N @ DTTB THRESHOLD
                                                                               @ 14dB nominal DTTB to PAL ratio
D T T B




     -15



                                                                                                                                               8VSB
     -20
@
P A L




     -25
o f




     -30
S /N




     -35
                                                                                                                                    COFDM (64QAM,2/3,1/8)
V id e o




                                 Average S/N @ Threshold of :                              8VSB = -24.2dB unwtd (PAL)
     -40
                                                                                        COFDM = -28.7dB unwtd (PAL)

                                                           Note : 8VSB Launch power on average was 0.8dB higher than COFDM Launch power
     -45
                    0        5      10    15    20    25     30     35    40      45    50    55    60       65   70    75     80    85   90    95    100   105              110   115
                                                                                               TEST #
                                                                                                                                          FACTS DTTB Trial Sites


                                                                                       System Noise Method
                                                                                                                                                             W.T. D. 15 Jan 1998




                        74
                    Australian DTTB Field Trial
                      8VSB Decoder Margin
     ( d B )
                                                         8VSB SITE DECODE MARGIN
                                                                       FACTS DTTB Trial Sites
     I N


      60
     A R G




                                                               for a HIGH GAIN ANTENNA

      50
                          Minimum F/S = 37 dBuV/m                                      Margin @ Threshold C/N
     M




                              without multipath                                        w/o multipath
                              and 3 dB margin
     D E




      40
     D E C O




                                       Minimum F/S = 47 dBuV/m
      30                               with multipath allowance
                                          and 3 dB margin
                                                                                                                Margin @ threshold C/N
                                                                                                                with multipath
     S it e




      20


                                                                                                                    8VSB

      10

                                                                                                                Decoder NF = 9 dB

         0
               25    30         35        40        45         50          55          60          65     70         75         80       85                            90
        NO PICTURE                                                  Site Field Strenght (dBuV/m)
                                                                                                                          System Noise Method
                    Nominal conditions : 7 dB gain Antenna + 2 dB leed loss
                                        Effective decoder Noise Figure (NF) = 9 dB
                                                                                                                                                W .T. D. 7 J UNE 1 9 9 8




75
                 Australian DTTB Field Trial
                  COFDM Decoder Margin
      ( d B )
                                                        COFDM SITE DECODE MARGIN

      I N
                                                                     FACTS DTTB Trial Sites

        60
      A R G

                                                                 for a HIGH GAIN ANTENNA
        50
                                                                                         Margin @Threshold C/N
      M




                           Minimum F/S = 37 dBuV/m
                                                                                         w/o multipath
                               without mutipath
      D E




        40                     and 3 dB margin
      D E C O




                                     Minimum F/S = 45 dBuV/m
        30                           with multipath allowance
                                         and 3 dB margin
                                                                                                          Margin @ Threshold C/N
                                                                                                          with Multipath
      S i t e




        20



                                                                                                          COFDM (64QAM,2/3,1/8)
        10


                                                                                                          Decoder NF = 5 dB

          0

                25   30       35        40        45        50           55            60        65       70       75         80    85                90
     NO PICTURE                                                  Site Field Strenght (dBuV/m)
                                                                                                                   System Noise Method
        Nominal conditions : 7 dB gain Antenna + 2 dB leed loss @ CH8
                                     Effective decoder Noise Figure (NF) = 5 dB                                                              . .   NE
                                                                                                                                         W. T D 5 JU 1998




76
                DTTB Systems Doppler
                Performance Limits
                                         for current implementations
                      300

                  250                                    UHF

                  200                                                                         VHF - Band III
DOPPLER
 SHIFT                                              COFDM 2K, 3dB degrade
                  140
  (Hz)                                      COFDM 2K
                  100

                      50
                       0
       ATSC                 0    100   200   300   400   500   600   700   800   900   1000
see separate curves                    SPEED (Km/Hr)
                            Vehicles                      AIRCRAFT
                                         Over Cities
                            COFDM implementations will inherently handle post and
                            pre-ghosts equally within the selected guard interval.
           77
      ATSC 8-VSB
      Doppler Performance Limits
                               for current implementations
          10

                        UHF                   VHF - Band III


DOPPLER
                                                8VSB, “Fast Mode”, 3dB degrade
 SHIFT     5
  (Hz)


                                                8VSB
           1
           0
               0 2 6 10          23   30                                      100
                              SPEED (Km/Hr)
                                          Vehicles                                  Aircraft
                8VSB implementations of equalisers are likely to cater for
                post ghosts up to 30 uSec and pre-ghosts up to 3 uSec only.
     78
Field Test - Observations
      At -14 dB DTTB power when there was a
       reasonable PAL picture both 8-VSB & COFDM
       worked at the vast majority of Sites
      When PAL had:
          Grain  (noise) and some echoes (multipath),
           both 8-VSB & COFDM failed
          Flutter, caused by aircraft or vehicles, 8-VSB failed
          Impulsive noise & some grain, COFDM failed



79
Results Conclusion
        The assessment of the results presented in
         this summary depends largely on the
         specific system requirements of the
         broadcaster and the viewers.

        The implementation and performance of
         both digital terrestrial transmission systems
         are still being improved, however the
         DVB-T system shows more scope for
         achieving future advances.
80
The Selection Committee
        A selection committee was formed
         from FACTS ATV specialists group
         Representing:
          National broadcasters (ABC and SBS)
          The commercial networks (7,9 & 10)
          The regional commercial broadcasters
          The Department of Communications
           and the Arts
          The Australian Broadcasting Authority


81
Selection Panel - Responsibility
        Analysing the comparative tests and other
         available factual information

        Establishing the relevance of the
         performance differences to Australian
         broadcasting

        Recommending the system to be used

82
Selection Criteria
      Derived  a set of 50 selection criteria
       relevant to the Australian transmission
       environment
      Criteria were reduced to final 29 which
       could impact on the final decision
      The criteria were weighted and an
       overall average used to rank the
       selection criteria
83
Selection Criteria - Groups
      Most   Important Criteria Groupings
       Coverage
       System  Design Elements
       Operational Modes Supported
       Overall System
       Receivers




84
Selection Criteria - Analysis
      Assessed   each of the selection criteria
      elements for each modulation system
     Some criteria were put aside as it was
      felt there was not enough information
      to factually score those criteria




85
Criteria - Coverage
 Inner and outer service areas
 Performance with Roof top antennas
 Performance with Set top antennas *
 Co-channel & Adjacent channel protection
 Mobile Reception
 Multipath (Ghosting, Doppler & Flutter)
 Immunity to impulse noise

86
Criteria - System Design Elements
      Combining    & use of common Tx Antenna
      Requirements for implementing translators
      Suitability for co-channel translators
      Ability to use existing transmitters




87
Criteria - Operational Modes Support
      HDTV   Support
      Support for closed captioning
      Multiple languages Audio
      Surround Sound Audio System




88
Criteria - Overall System
      Accepted   HDTV system
      Performance within 7 MHz channel
      Number useful Mb/s in 7 MHz
      Ability to fit in existing infrastructure
      Overall Modulation System Delay
      System Flexibility, Upgrade Capacity &
       Future Development Capacity

89
Selection Criteria - Receivers
      Availability(for HDTV) MP@HL
      Receiver Features & Cost
      PAL and DTTB capability
      Degree of customizing for Australia
      Receiver Applications Software
      Lock up time
      Australian channel selection

90
                              DTTB Choice Assessment Sheet
                                         GROUP1 – COVERAGE                                  ATSC DVB      IMPORTANCE
                                                                                                       Element  Group
     Element    Group 1
          1.1   Percentage of A coverage pop. served
          1.2   Percentage of B coverage pop. served
          1.3   Set top antennas
          1.4   Mobile reception
          1.5   Co-channel performance
          1.6   Adjacent channel performance
          1.7   Multipath Performance
          1.8   Immunity to electrical interference
          1.9   Ability to be conveyed in MATV and cabled systems

                               GROUP 2 - SYSTEM DESIGN ELEMENTS                             ATSC DVB      IMPORTANCE
                                                                                                       Element  Group
     Element    Group 2
          2.1   Combining to use common transmit antennas
          2.2   Ease of use and cost of implementing translators
          2.3   Common channel translator capability
          2.4   Ability to use existing transmitters

                          GROUP3 - OPERATIONAL MODES SUPPORTED                              ATSC DVB      IMPORTANCE
                                                                                                       Element  Group
     Element    Group 3
          3.1   HDTV support
          3.2   Support for closed captions
          3.3   Support for multilingual audio
          3.4   Audio System

                                     GROUP 4 - OVERALL SYSTEM                               ATSC DVB      IMPORTANCE
                                                                                                       Element  Group
     Element    Group 4
          4.1   Adoption of an accepted rather than unique (HDTV) system
     4.2        Performance within 7 MHz channel
     4.3        Number of useful Mbs/7MHz
     4.4        Overall encode/decode delay
     4.5        System upgrade & further development capability

                                  GROUP 5 - RECEIVER ELEMENTS                               ATSC DVB      IMPORTANCE
                                                                                                       Element  Group
     Element    Group 5
     5.1        Receiver availability, features & cost
     5.2        Receiver and STB MP @ HL
     5.3        Receivers with both PAL and DTTB capability
     5.4        Receivers not specific design for Australia
     5.5        Receiver applications software
     5.6        Receiver lock-up time
91   5.7        Ability to provide automatic channel selection for Australian channelling
                            DTTB Choice Assessment Sheet
                                        GROUP1 – COVERAGE        ATSC DVB      IMPORTANCE
                                                                            Element  Group
 Element     Group 1
       1.1   Percentage of A coverage pop. served
       1.2   Percentage of B coverage pop. served
       1.3   Set top antennas
       1.4   Mobile reception
       1.5   Co-channel performance
       1.6   Adjacent channel performance
       1.7   Multipath Performance
       1.8   Immunity to electrical interference
       1.9   Ability to be conveyed in MATV and cabled systems

                             GROUP 2 - SYSTEM DESIGN ELEMENTS    ATSC DVB      IMPORTANCE
                                                                            Element  Group
 Element     Group 2
       2.1   Combining to use common transmit antennas
       2.2   Ease of use and cost of implementing translators
       2.3   Common channel translator capability
       2.4   Ability to use existing transmitters



92
Selection Result - June 1998

      The   selection committee
         unanimously selected the
         7 MHz DVB-T modulation
         system for use in Australia
        The criteria that were set aside would,
         however, not have changed the selection
         decision
93
Overall Selection Influences
  A single system for All Free to Air Broadcasters
 Ability to meet Governments objectives for
   coverage
 Able to deliver the HDTV quality objective
 Availability of consumer products at acceptable
   costs
 Solid support from proponent
 Interoperability with other digital video platforms
 Confidence in the system meeting the business

94
   objectives
More Selections
        Sub-committees formed to investigate:
          Service information data standard
          Multichannel audio system
          HDTV video production format

        July 1998 3 further recommendations
          SI data standard be based on DVB-SI
          AC3 multichannel audio is the
           preferred audio encoding format
          1920/1080/50 Hz interlaced 1125 lines is the
           preferred video production format
95
DTTB Implementation Notes:
      Although SFNs are of interest in Australia they
       will be of little use during the simulcast period.
      Use may be made of Dual Frequency Networks
       during this period to increase spectrum
       efficiency
      The channel frequency matrix will be adjusted
       when Analog services cease. Digital provides
       the capacity to repack the television spectrum.

96
 A Future Digital System Concept
              MMDS

                      Hypermedia
Satellite
                  Integrated Receiver
                    Decoder (IRD)

Terrestrial

 Cable
  Broadcast       Interactivity


              B-ISDN
               XDSL                 CD, DVD
97                                   DVC
The End


     Thank you for your attention

           Any questions?



98

				
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