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Next Webinar: FCC Self-Inspection Checklist with Dennis Baldridge, Alternative Inspector November 18 More Information: www.sbe.org 1 Additional upcoming ATSC events… ATSC Mobile DTV Seminar October 7th, 2010 Wiley Rein Conference Center – Washington, DC ATSC Next Generation Broadcast Technology Symposium October 19th, 2010 Westin Hotel – Alexandria, VA For more information on these events and to register to attend, visit www.atsc.org Thank you to the Society of Broadcast Engineers for inviting us to participate in today’s webinar! Physical Layer for ATSC Mobile DTV Wayne E. Bretl Zenith Electronics LLC Advanced Television Systems Committee Three Views… • Layers and sub-layers • Processing steps • Hardware Partitioning (Jay Adrick’s presentation) Advanced Television Systems Committee 2 Layers and Sub-Layers Advanced Television Systems Committee ATSC Mobile DTV Layered Design Presentation Layer Audio and Video Codecs Closed Captioning Management Layer TtTransport Streaming and Non-Real Time File Transfer Electronic Service Guide Physical Layer RF Transmission and Forward Error Correction; Compatibility with Legacy 8-VSB Receivers/Decoders Advanced Television Systems Committee Physical Layer Primary Requirements • Mobile reception – Receivable under high speed mobile conditions (rapidly changing multipath) – Bursted transmission (receiver power saving) • Threshold – Low S/N threshold (for rapid fading conditions) • Backwards compatibility – Divide the broadcaster’s bandwidth flexibly into a variable-size Mobile DTV part and a complementary legacy DTV part, without disturbing the legacy reception – Versioning mechanisms Advanced Television Systems Committee 3 Physical Layer - the Sub-Layer View Advanced Television Systems Committee ATSC M/H Layer Stack - Physical Completely New in ATSC Mobile Additional Training TPC FIC M/H Payload FEC (SCCC) Sequences ATSC 8-VSB Advanced Television Systems Committee ATSC M/H Layer Stack - Physical Completely New Acronyms Deciphered in ATSC Mobile Additional Transmission Fast Mobile/Handheld Payload Training Parameter Information Forward Error Correction Sequences Channel Channel (Serial Concatenated Convolutional Coding) Advanced Television Systems Committee 8-Level Vestigial Sideband Modulation Advanced Television Systems Committee 4 Backwards Compatibility •Legacy receivers must not see the new mobile signal as anything but normal (although unrecognized) data •New signal features for mobile that are logically stacked above 8-VSB, must be physically embedded inside the 8-VSB signal via concatenated coding Completely New in ATSC Mobile, but Hidden Inside Legacy 8-VSB symbols Additional Training TPC FIC M/H Payload FEC (SCCC) Sequences Advanced Television Systems Committee 8-Level Vestigial Sideband Modulation Advanced Television Systems Committee New Features Serial Concatenated Convolutional Coding - improved error correction and S/N ratio for mobile data Additional Training TPC FIC M/H Payload FEC (SCCC) Sequences Advanced Television Systems Committee 8-Level Vestigial Sideband Modulation FtIfFast Informa tion Training sequences Transmission Parameter Channel ~ 800 per second Channel – extra-robustly coded - known symbols – extra-robustly coded - carries FIC data that - measure multipath - tells the mobile receiver tells the mobile receiver - support reception how much mobile data where each mobile at vehicular speeds is present and where it is program is located hidden in the legacy stream in the mobile data stream Advanced Television Systems Committee Time Multiplexing - Bursted Transmission •The hidden mobile data is not constantly present. •Each mobile service/program has a series of time Slots within a mobile DTV Frame (968 ms) where it appears •The mobile receiver front end may be turned on only for the desired service Advanced Television Systems Committee 5 Time Multiplexing – “Parades” of “Groups” Legend: Mobile “Frame” = 968 ms Parade # 0 Parade # 1 Sub-Frame Sub-Frame Sub-Frame Sub-Frame Sub-Frame Parade # 2 #0 #1 #2 #3 #4 Legacy only 16 “Slots” - Each Slot contains all legacy data or some legacy data plus a Group of mobile data TUNER Slot ON TUNER Receiving: OFF Parade #0 Parade #1 Parade #2 Each Parade carries an “Ensemble” of programs with the same FEC code. The receiver tuner turns on only for the Parades it needs for a service Advanced Television Systems Committee Processing Steps Advanced Television Systems Committee Improvements … Required for Mobile • Response to rapidly changing ghosts – 8-VSB reception fails above a few miles per hour in terrestrial vehicles – need highway speed • Signal-to-Noise Ratio – Improve resistance to signal fading • Do this while maintaining backwards compatibility and providing new features (higher layers) to support the mobile service (e.g., power saving, IP carriage, service guide…) Advanced Television Systems Committee 6 ATSC Mobile Physical Layer Steps 1 Make Space for the Mobile Data 2 Add FEC coding bytes 3 Add SCCC Coding (1/2-rate or ¼-rate) 4 Interleave ((qrequired by ygy legacy receivers) 5 Add Training signals Advanced Television Systems Committee Comparison: 8-VSB Only vs. With Mobile ATSC 8-VSB ATSC Mobile MPEG Reserve Some Packets 1 Packets for M/H Data Add RS 2 M/H Data with FEC Bytes Add’l FEC Bytes Interleave 3 Interleave Data Segments 8-Level with Trellis -Coded 4 SCCC or 8-Level Symbols Frame Trellis Coding Sync 313 M/H Frame Sync Data Payload (Reference Segment 312 Seg- DATA Training Sync ments SEG- Added Signal) ( ~ 25 8-VSB 5 and Segment MENTS msec ) PAY- Training Syncs LOAD Advanced Television Systems Committee 1a Make Space for M/H “Slots” and “Groups” ATSC 8-VSB ATSC M/H MPEG 1a Reserve Some Packets Packets for M/H Data 118 PACKETS ~ M/H or MAIN “Slot” of 24 msec 156 packets Data Field of 38 PACKETS “MAIN” MAIN ONLY 312 MPEG-2 (8-VSB) Packets DATA 118 PACKETS “Group” of M/H or MAIN 118 M/H Packets 38 PACKETS (if Slot is used) MAIN ONLY Advanced Television Systems Committee 7 1b Organize into “M/H Frames” TIME 1 M/H Slot = 156 TS Packets (approx 12.1 ms) 1 M/H Frame = 80 Slots (approx 968 ms) Advanced Television Systems Committee 1c Per Program: Form “Parade” of “Groups” MP H frame Parade #0 MP H Su b-Fra me MP H Sub -Frame MPH Su b-Frame MPH S ub-Fra me MP H Su b-Fra me Parade #1 #0 #1 #2 #3 #4 Parade #2 Symbol domain (after data interleaver) Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot Slot #0 #1 #2 #3 # 4 #5 #6 #7 #8 # 9 #1 0 #11 #12 #1 3 #1 4 #15 Power ON Receiving Power OFF Parade #0 (o r S lee p) Receiving Parade #1 Receivinga Parade #2 Each Parade carries an “Ensemble” of programs with the same FEC code. The receiver tuner turns on only for the Parades it needs for a service Advanced Television Systems Committee 2 Add FEC Bytes for M/H Data “RS Frame” contains N all data in one Parade (for 968 msec) 187 Payload “N” columns (187+P,187) RS encode column-by-column 187 Add RS Bytes Payload Rows to Columns of Bytes P RS parity P = 24, 36, or 48 Add 2-byte CRC checksum row-by-row Pack left to right and checksum CRC Payload Add Two CRC top to bottom with 187+P Bytes M/H header and IP RS parity per Row packets – wrap as necessary N+ 2 (Then add legacy 8-VSB headers and legacy RS bytes) Advanced Television Systems Committee 8 3 4 5 SCCC Coding, Interleaving, Training As broadcast BEFORE interleaving, with AFTER interleaving, with Training Signals segmented Training Signals aligned MAIN DATA M/H GROUP #1 DATA + Interleaved Training SB Data Field SB Data Data Segments NING M/H Data I M/H GROUP #9 V is 8- DATA 313 TRA + Interleaved Training SCCC Coded M/H GROUP #5 DATA + Interleaved Training Main Data is 8-VSB Data Field Data 8-VSB 312 Data 312 Data Packets Trellis Data Packet of Bytes Coded Data Segment of Symbols Advanced Television Systems Committee Test Experience Advanced Television Systems Committee Lab Results 8-VSB M/H M/H M/H M/H (A/53) (A/153) (A/153) (A/153) (A/153) ½ rate ½ rate mixed rate ¼ rate (Regions A+B) SNR 15 7.4 7.9 7.3 3.4 Required (dB) Doppler (Hz) ~= ~ 10 150 80* 140 180 max mph, with (depends on complex ghosts receiver) (TU-6) *Note: 60 Hz is sometimes quoted as minimum adequate rate (DVB, others) Advanced Television Systems Committee 9 Multiple Field Tests • 2006 Lincolnshire, Illinois • Columbus, Ohio • 2007 Buenos Aires, Argentina • Santiago, Chile • 2007-09 Chicago, Illinois – two different broadcasters • 2008 Las Vegas, Nevada – four different broadcasters • San Francisco / San Jose, California – four different broadcasters • Raleigh, North Carolina • Dallas, Texas • 2009 Baltimore, Maryland • Denver, Colorado • Mexico City, Mexico • Milwaukee, Wisconsin – UHF and VHF • Atlanta, Georgia – two different broadcasters • Seattle, Washington – two different broadcasters • Washington, DC – six different broadcasters Advanced Television Systems Committee Detailed Field Test Results Washington DC 5 different channels Data recorded simultaneously Advanced Television Systems Committee Washington, DC Channel 34 GOOD ERRORS NO DATA FOR THIS CHANNEL Advanced Television Systems Committee 10 Washington, DC Channel 35 GOOD ERRORS NO DATA FOR THIS CHANNEL Advanced Television Systems Committee Washington, DC Channel 48 GOOD ERRORS NO DATA FOR THIS CHANNEL Advanced Television Systems Committee Washington, DC Channel 33 GOOD ERRORS NO DATA FOR THIS CHANNEL Advanced Television Systems Committee 11 Washington, DC Channel 24 GOOD ERRORS NO DATA FOR THIS CHANNEL Advanced Television Systems Committee Thank You Physical Layer for ATSC Mobile DTV Wayne E.