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Australian DTTB Field Trial

Australian DTTB Field Trial . SMPTE Presentation 29 June 1998 HDTV into the HOME. Compiled by Wayne Dickson SMIREE MIEAust CPEng. Member SMPTE. In comparison with current PAL television In various reception conditions : City Urban Suburban Industrial suburban Hills

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Australian DTTB Field Trial

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  1. Australian DTTB Field Trial SMPTE Presentation 29 June 1998 HDTV into the HOME Compiled by Wayne Dickson SMIREE MIEAust CPEng. Member SMPTE

  2. In comparison with current PAL television In various reception conditions : City Urban Suburban Industrial suburban Hills Harbour - across water Beach areas Rural Translator areas Distribution systems Near Airports Near highways Australian DTTB Field Trial What was it ! A DTTB Field Trial is study of Failure !!

  3. Australian DTTB Field Trial Overall Objectives • Provide, as part of the selection criteria for a choice between 8VSB and COFDM systems, the difference in the reception character of the two systems. • Provide, to the system planners, some of the information for design to allow reliable reception by the viewing public. • Use upmost care to provide credible data.

  4. Australian DTTB Field Trial Overall Objectives • GSM Mobile Telephones are the public’s first example of DIGITAL communications and the characteristic “cliff edge”. • “We” in Australia will plan to minimise the impact of the “cliff edge” by first ignoring the “marketing” and then embarking upon testing and analysing phases to select the best parameters to provide reliable HDTV into the homes of Australia.

  5. Australian DTTB Field Trial Unique Charactercompared to other international Trials • BothATSCandDVB-TSystems @ the SAME TIME AND LOCATION • VHF 7MHz Trial - UHF in Europe and USA • Adjacent Channels - both upper and lower • Reception matching Consumer’s Antenna • Static and Dynamic (Flutter) ECHOES (multipath) • Current Analogue (PAL) character records • Multiple test methods used : • Two Threshold C/N generation methods • Two DTTB power Measurement methods

  6. Australian DTTB Field Trial TechnicalAims • CompareDTTB to Analogue (PAL) for : • COVERAGE study and prediction • ROBUSTNESS study under conditions such as : • Level variations • Static Echoes • Dynamic (varying) Echoes - eg Aircraft • Impulsive noise • Develop reliable field trial techniques for DTTB

  7. Australian DTTB Field Trial TechnicalAims • Analyse to obtain character of the : • ATSC 8VSB system • DVB-T COFDM system • Analyse to provide “Infrastructure” needs • DTTB transmission power requirements • Translator or “Gap filler” requirements • Margins for reliable reception • Requirements for the minimum DTTB receiver

  8. Australian DTTB Field Trial Limitations The Field Trial did not cover : • UHF Bands IV & V (for Regions and translators) • Co-channel interference • Long term level variations (seasonal) • Variable weather conditions eg rain and lightening • Performance in MATV and cabled systems • In-door reception eg via “rabbit ear antennas” • Portable and Mobile reception

  9. ATSC 8VSB modulation 6 MHz nominal bandwidth Useful Bitrate 19.39 Mbps FEC 2/3 RS (207,187) Equaliser range of 23uSec Co-channel comp. off. “Blue racks” decoder DVB-T COFDM modulation 7 MHz nominal bandwidth Useful Bitrate 19.35 Mbps FEC 2/3 RS (204,188) Guard interval 1/8(32uSec) DMV V1.0 Eq. Software DMV V2.0 Sys. Software Australian DTTB Field Trial Systems Tested

  10. Australian Broadcasting Authority (ABA) DCA Communication Laboratory FACTS TEN Network NINE Network SEVEN Network NDS ZENITH Electronics Corp. Harris Corp. RFS NEC Hewlett Packard Rohde & Schartz Australian DTTB Field Trial Contributing Organisations

  11. 13,500 square Km 3.9 million people 1.3 million dwellings 3 Oct. to 14 Nov. 1998 27 days of testing 108 Sites 125 Tests 0.4 Km to 100 Km 4 KW erp DTTB 100 KW erp PAL DTTB F/S’s 30 to 90 dBuV/m PAL F/S’s 40 to 105 dBuV/m DTTB Av. F/S 68 dBuV/m PAL Av. F/S 82 dBuV/m Australian DTTB Field Trial Trial Statistics Field Trail : Sydney statistics * : * approximate

  12. Australian DTTB Field TrialTransmission Spectrums

  13. DTTB Transmission8VSB Spectrum Analyser display : Dependent upon Resolution B/W setting. Vision Carrier D + 11.3 dB CH7 CH8 CH9 Sound Carriers A Chroma DTTB (8VSB) PAL PAL D = DTTB to PAL ratio D = 14 dB for the Trial DTTB power = average heating power PAL power = the equivalent CW power of peak sync Vision Carrier power

  14. DTTB TransmissionCOFDM Spectrum Analyser display : Dependent upon Resolution B/W setting. Vision Carrier CH7 CH8 CH9 Sound Carriers A Chroma DTTB (COFDM) PAL PAL D = DTTB to PAL ratio D = 14 dB for the Trial DTTB power = average heating power PAL power = the equivalent CW power of peak sync Vision Carrier power

  15. Australian DTTB Field Trial Reception Antennas • VHF Band III antenna with a nominal gain of 7 dBd and a front to back ratio of > 20 dB • A folded Dipole with a nomimal gain of 0 dBd The following Antennas were used at heights from 2.5m to 10m determined by the Consumer’s antenna heights at the location.

  16. Australian DTTB Field Trial Observations With DTTB power 1/25th (-14 dB) of PAL, when there was noticeable : • Grain (noise) and some echoes (multipath) on Analogue PAL picture, 8VSB and COFDM failed. • “Flutter” 8VSB reception failed. • Impulsive noise and some grain in picture, COFDM reception failed.

  17. Australian DTTB Field Trial Summary ResultsCOVERAGE • Judgement of the coverage of DTTB compared to PAL is complex, as comparison has to be between a “cliff edge” failure of DTTB to a gradualfailure of PAL. • A margin of safety has to be allowed, for DTTB reliable reception, further complicating decisions on equivalent coverage. • Coverage is also influenced by Receiver performance, especially NF.

  18. Australian DTTB Field Trial Summary ResultsCOVERAGE • The following graphically presented data represents a fraction of the that being studied. Other data is yet to be analysed. • By investigating both the character of PAL “failure” against that of the individual character of the DTTB systems failure, an idea of the required power for reliable “equivalent” coverage can be envisaged. • A brief pointing to the following graphs may help later study.

  19. Australian DTTB Field Trial Summary ResultsPAL Receive Margin

  20. Australian DTTB Field Trial Summary ResultsDTTB compared to PAL

  21. Australian DTTB Field Trial Summary Results8VSB Decoder Margin

  22. Australian DTTB Field Trial Summary ResultsCOFDM Decoder Margin

  23. Australian DTTB Field Trial Summary ResultsCOVERAGERoof antenna DTTB to PAL Ratio System Required F/S Margin of Safety Required F/S for Reliable Coverage Rx. NF 0 dB PAL 55 dBuV/m 0 dB 55 dBuV/m -11 dB 8VSB 41 dBuV/m 3 dB 44 dBuV/m 3 dB -9 dB COFDM 43 dBuV/m 3 dB 46 dBuV/m 5 dB PAL 57 dBuV/m 0 dB 57 dBuV/m 0 dB 8VSB 47 dBuV/m 3 dB 50 dBuV/m -7 dB 9 dB COFDM 45 dBuV/m 3 dB 48 dBuV/m -9 dB 5 dB

  24. Australian DTTB Field Trial Required DTTB Power(VHF roof top Antenna) • To provide approximate equivalent coverage to current FTA transmission (nominal ERP of 100 KW), the DTTB ERP is estimated to be : • Equal Receiver NF : • 8VSB 8 KW ERP • COFDM 12.5 KW ERP • Receivers as expected to be implemented : • 8VSB 20 KW ERP • COFDM 12.5 KW ERP

  25. DTTB Field trialExplanations Multipath Static Conditions Fixed reception

  26. Field Trial Multipath Character (Conditions: Static multipath, Equal Rx NF, No Co-channel or impulse interference) Indoor Antenna Outdoor Antenna 35 8VSB COFDM C/N Threshold (dB) (64QAM,2/3,1/8) Picture (above curve) 19 15 SYDNEY FIELD TRIAL TESTS No Picture 15 0 3 30 (Below curve) Multipath Level ( - dB) (Single Echo) W.T.Dickson 29 March 98

  27. DTTB System Multipath Character - Unequal NF (Conditions: Static multipath,Unequal Rx NF, No Co-channel or impulse interference) Indoor Antenna Outdoor Antenna (31) 35 8VSB With NF=(X+4)dB COFDM With NF=XdB Picture (64QAM,2/3,1/8) C/N Threshold (dB) (above curve) (15) 19 No Picture (Below curve) 15 0 3 30 Multipath Level ( - dB) (Single Echo) W.T.Dickson 29 March 98

  28. DTTB System Multipath Performance Improvement (Conditions: Static multipath, Equal Rx NF, No Co-channel or impulse interference) Indoor Antennas Outdoor Antennas 35 8VSB COFDM (64QAM,2/3,1/8) (Nov. 1997) COFDM Picture C/N Threshold (dB) (above curve) Current implementations (April 1998) 19 15 No Picture (Below curve) 15 0 3 30 Multipath Level ( - dB) (Single Echo) W.T.Dickson 16 April 98

  29. DTTB Field trialExplanations Multipath Dynamic Conditions Fixed reception

  30. Aircraft Flutter Va   Far Das Dar Fas D F Fas = F - F * Cos  * Va / c + F * Cos  * Va / c tg = ( Dar + Das - D ) / 0.3 uSec Doppler shift NOTE : There are competing doppler shifts.

  31. DTTB System Dynamic Multipath Character (Conditions: Dynamic multipath (flutter), Equal Rx NF, No Co-channel or impulse interference) Indoor Antenna Outdoor Antenna 35 8VSB w/o flutter 8VSB with flutter Dependent upon flutter level (amplitude and doppler shift) COFDM C/N Threshold (dB) (64QAM,2/3,1/8) Picture With or without flutter (above curve) 19 15 No Picture 15 0 3 30 (Below curve) Multipath Level ( - dB) (Single Echo) W.T.Dickson 29 March 98

  32. DTTB Systems Doppler Performance Limits for current implementations 300 250 UHF 200 DOPPLERSHIFT(Hz) COFDM 2K, 3dB degrade 140 VHF - Band III COFDM 2K 100 50 0 0 100 200 300 400 500 600 700 800 900 1000 ATSC 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.

  33. ATSC 8-VSB Doppler Performance Limits for current implementations 10 UHF VHF - Band III DOPPLERSHIFT(Hz) 8VSB, “Fast Mode”, 3dB degrade 5 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.

  34. DTTB system Laboratory Doppler Tests Doppler Echo 0 -5 -10 EchoLevel(dB) -15 COFDM -20 8-VSB -25 -500 -400 -300 -200 -100 0 100 300 500 200 400 Doppler Frequency (Hz) 8VSB standard mode (1Hz nom.) Fast mode - not shown (5Hz nom.)

  35. Aircraft Flutter & Doppler Performance Conclusion • The COFDM 2K system is OK for VHF and UHF reception conditions. • The COFDM 8K system is OK for VHF reception conditions. • The 8VSB system is highly susceptible to any flutter from either Aircraft or vehicles. DTTB system performance :

  36. DTTB Field trialExplanations Interference Power Line, Industrial & Home Appliance Fixed reception

  37. DTTB System Impulse Noise Character (Conditions: Static multipath, Equal Rx NF, No Co-channel, but with impulse interference) Indoor Antenna Outdoor Antenna 35 Dependent upon level and character ofimpulsenoise (up to 10 dB higher than 8VSB) 8VSB COFDM With impulse noise Picture C/N Threshold (dB) COFDM (above curve) (64QAM,2/3,1/8) 19 15 No Picture (Below curve) 15 0 3 30 Multipath Level ( - dB) (Single Echo) W.T.Dickson 29 March 98

  38. DTTB system Laboratory Tests Impulse Noise Performance

  39. DTTB Field trialExplanations Powers

  40. Analogue TVPeak & RMS Voltage Peak voltage = 1.414 Black(1.1) RMS voltage = 1 3 dB peak to average That is : For the peak sync region the “peak to average” ratio, like a Sine Wave, is 3 dB and applies to voltage & power.

  41. COFDMPeak to Average ( CDF = 99.99%) Peak voltage = 3 (9.5dB) - COFDM ( for CDF = 95% peak voltage = 1.7 (4.7dB) ) ( “CDF” - Cumultive Distribution Function ) RMS voltage = 1 (0dB) 9.5 dB peak to average DIGITAL TV

  42. 8-VSB Peak to Average (CDF = 99.99%) Peak voltage = 2.5 (7dB) - 8VSB ( for CDF = 95% peak voltage = 1.6 (4dB) ) RMS voltage = 1 (0dB) 7 dB peak to average DIGITAL TV

  43. DTTB Peak Amplitude Distribution

  44. PAL-DTTB @ -14 dB Transmitter Powerin the Field trials Peak 3dB 6 KW(CW) 0dB Average -4.5dB -7dB Analogue (Peak Sync.) 10 KW 400W 400W -14dB -14dB COFDM 8VSB ERP = 100 KW 4 KW 4 KW

  45. PAL-DTTB @ -10 dB Transmitter Powerpossible at DTTB introduction Peak 3dB 6 KW(CW) 0dB Average -0.5dB -3dB Analogue (Peak Sync.) 1KW 1KW 10 KW -10dB -10dB COFDM 8VSB ERP = 100 KW 10 KW 10 KW

  46. Selection of COFDMModulation Parametersa possible Scenariofor a softer cliff edge and extended coverage Use Hierarchical Modulation : - with alpha=1 and guard interval = 1/8 (32uSec) SDTV + SI information Robust level : QPSK, FEC 1/2 = 5 Mbps & C/NT =13dB - SDTV only with SI information on robust level HDTV Less robust level : 64QAM,FEC 2/3 = 13.6 Mps & C/NT=20 dB - all available to HDTV video and sound (Field Trial Scenario : 64QAM,FEC 2/3 = 19.3 Mbps & C/NT=19 dB)

  47. Further Testing to followfor example of : • Set top or indoor Antennas • Transmitters & Translators • Digital receivers as they appear • Portable & Mobile reception • 2 K / 8 K & Hierarchical modes • Planning problems - eg : • DTTB to PAL (eg CH6 & CH8 in Melbourne)

  48. Australian HDTV As you can all see we are not finished !

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