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

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

28 June 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.

28 June 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.

28 June Australian DTTB Field Trial Unique Character compared to other international Trials Both ATSC and DVB-T 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

28 June Australian DTTB Field Trial Technical Aims Compare DTTB 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

28 June Australian DTTB Field Trial Technical Aims 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

28 June Australian DTTB Field Trial Limitations 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 The Field Trial did not cover :

28 June Australian DTTB Field Trial Systems Tested ATSC 8VSB modulation 6 MHz nominal bandwidth Useful Bitrate 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 Mbps FEC 2/3 RS (204,188) Guard interval 1/8(32uSec) DMV V1.0 Eq. Software DMV V2.0 Sys. Software

28 June Australian DTTB Field Trial Contributing Organisations 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

28 June Australian DTTB Field Trial Trial Statistics 13,500 square Km 3.9 million people 1.3 million dwellings Sydney statistics * : 3 Oct. to 14 Nov 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 Field Trail : * approximate

28 June Australian DTTB Field Trial Transmission Spectrums

28 June DTTB Transmission 8VSB Spectrum Analyser display : DTTB (8VSB) Vision Carrier Sound Carriers Chroma PAL Dependent upon Resolution B/W setting. A 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 D dB PAL CH7CH9CH8

28 June DTTB Transmission COFDM Spectrum Analyser display : DTTB (COFDM) Vision Carrier Sound Carriers Chroma PAL Dependent upon Resolution B/W setting. A 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 PAL CH7CH9CH8

28 June 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.

28 June Australian DTTB Field Trial Observations 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. With DTTB power 1/25th (-14 dB) of PAL, when there was noticeable :

28 June Australian DTTB Field Trial Summary Results COVERAGE 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 gradual failure 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.

28 June Australian DTTB Field Trial Summary Results COVERAGE 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.

28 June Australian DTTB Field Trial Summary Results PAL Receive Margin

28 June Australian DTTB Field Trial Summary Results DTTB compared to PAL

28 June Australian DTTB Field Trial Summary Results 8VSB Decoder Margin

28 June Australian DTTB Field Trial Summary Results COFDM Decoder Margin

28 June Australian DTTB Field Trial Summary Results COVERAGE Typical F/S of PAL for 30 dB S/N = 55 dBuV/m (30 dB S/N is a noisy -14 dB DTTB to PAL : The worse typical failure of DTTB system occurred when PAL S/N was : –30 dB for 8VSB ie F/S of 41 dBuV/m –32 dB for COFDM ie F/S of 43 dBuV/m For High Gain (7 dB nom.) Antenna and receiver NF = 3.5 dB

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

28 June 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

28 June DTTB Field trial Explanations Multipath Static Conditions Fixed reception

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

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

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

28 June DTTB Field trial Explanations Multipath Dynamic Conditions Fixed reception

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

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

28 June VHF - Band III UHF DOPPLER SHIFT (  Hz) COFDM 2K, 3dB degrade COFDM 2K SPEED (Km/Hr) AIRCRAFT Vehicles Over Cities for current implementations ATSC see separate curves COFDM implementations will inherently handle post and pre-ghosts equally within the selected guard interval. DTTB Systems Doppler Performance Limits

28 June VHF - Band III UHF VSB, “Fast Mode”, 3dB degrade SPEED (Km/Hr) Vehicles 8VSB Aircraft for current implementations 8VSB implementations of equalisers are likely to cater for post ghosts up to 30 uSec and pre-ghosts up to 3 uSec only. DOPPLER SHIFT (  Hz) ATSC 8-VSB Doppler Performance Limits

28 June Doppler Echo DTTB system Laboratory Doppler Tests 8VSB standard mode (1Hz nom.) Fast mode - not shown (5Hz nom.) COFDM 8-VSB Echo Level (dB) Doppler Frequency (Hz)

28 June Aircraft Flutter & Doppler Performance Conclusion DTTB system performance : 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.

28 June DTTB Field trial Explanations Interference Power Line, Industrial & Home Appliance Fixed reception

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

28 June Impulse Noise Performance DTTB system Laboratory Tests

28 June DTTB Field trial Explanations Powers

28 June Analogue TV Peak & RMS Voltage RMS voltage = 1 Peak voltage = 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. Black(1.1)

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

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

28 June DTTB Peak Amplitude Distribution

28 June Transmitter Power in the Field trials -14 dB Transmitter Power in the Field trials 0dB -14dB 3dB -4.5dB -7dB Analogue COFDM8VSB Average Peak (Peak Sync.) 6 KW (CW) 400W 10 KW ERP = 100 KW 4 KW 4 KW

28 June Transmitter Power possible at DTTB introduction -10 dB Transmitter Power possible at DTTB introduction 0dB -10dB 3dB -0.5dB -3dB Analogue COFDM8VSB Average Peak (Peak Sync.) 6 KW (CW) 1KW 10 KW ERP = 100 KW 10 KW 10 KW

28 June Selection of COFDM Modulation Parameters a possible Scenario for 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/N T =13dB - SDTV only with SI information on robust level HDTV Less robust level :64QAM,FEC 2/3 = 13.6 Mps & C/N T =20 dB - all available to HDTV video and sound (Field Trial Scenario : 64QAM,FEC 2/3 = 19.3 Mbps & C/N T =19 dB)

28 June Further Testing to follow for 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)

28 June As you can all see we are not finished ! Australian HDTV