The Society of Broadcast Engineers wishes to thank the Advanced Television Systems Committee for their help in organizing this webinar.

Transcription

1 The Society of Broadcast Engineers wishes to thank the Advanced Television Systems Committee for their help in organizing this webinar. With these online, self-study courses, you pick the date, time and location to learn. Now that s convenience! The cost for these courses varies from $59 to $99 for SBE Members. Once you register for the course, you immediately receive a link to the course where you can access it again and again as your schedule permits. More Information: Webinars by SBE addresses specific subjects of interest to broadcast engineers. You can view the webinars live, or choose to view the recording on our website. Next Webinar: FCC Self-Inspection Checklist with Dennis Baldridge, Alternative Inspector November 18 More Information: 1

2 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 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 Three Views Layers and sub-layers Processing steps Hardware Partitioning (Jay Adrick s presentation) 2

3 Layers and Sub-Layers ATSC Mobile DTV Layered Design Presentation Layer Audio and Video Codecs Closed Captioning Management Layer Transport 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 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 3

4 Physical Layer - the Sub-Layer View ATSC M/H Layer Stack - Physical Completely New in ATSC Mobile Additional Training Sequences TPC FIC M/H Payload FEC (SCCC) ATSC 8-VSB ATSC M/H Layer Stack - Physical Completely New in ATSC Mobile Acronyms Deciphered Additional Transmission Training Parameter Sequences Channel Fast Information Channel Mobile/Handheld Payload Forward Error Correction (Serial Concatenated Convolutional Coding) 8-Level Vestigial Sideband Modulation 4

5 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 Sequences TPC FIC M/H Payload FEC (SCCC) 8-Level Vestigial Sideband Modulation 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 8-Level Vestigial Sideband Modulation Training sequences ~ 800 per second - known symbols - measure multipath - support reception at vehicular speeds Transmission Parameter Channel extra-robustly coded - tells the mobile receiver how much mobile data is present and where it is hidden in the legacy stream Fast Information Channel extra-robustly coded - carries FIC data that tells the mobile receiver where each mobile program is located in the mobile data stream 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 5

6 Time Multiplexing Parades of Groups Mobile Frame = 968 ms Legend: Parade # 0 Sub-Frame #0 Sub-Frame #1 Sub-Frame #2 Sub-Frame #3 Sub-Frame #4 Parade # 1 Parade # 2 Legacy only 16 Slots - Each Slot contains all legacy data or some legacy data plus a Group of mobile data Receiving: Parade #0 TUNER ON TUNER OFF Slot 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 Processing Steps 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 ) 6

7 ATSC Mobile Physical Layer Steps Make Space for the Mobile Data Add FEC coding bytes Add SCCC Coding (1/2-rate or ¼-rate) Interleave (required by legacy receivers) Add Training signals Comparison: 8-VSB Only vs. With Mobile MPEG Packets Add RS FEC Bytes Interleave Data Segments with Trellis-Coded 8-Level Symbols Frame Sync (Reference Training Signal) and Segment Syncs ATSC 8-VSB Frame Sync Segment Sync 312 DATA SEG- MENTS ATSC Mobile 313 Data Segments ( ~ 25 msec ) 8-VSB PAY- LOAD Reserve Some Packets for M/H Data M/H Data with Add l FEC Bytes Interleave 8-Level SCCC or Trellis Coding M/H Payload Added Training 5 1a Make Space for M/H Slots and Groups ATSC 8-VSB MPEG Packets 1a ATSC M/H Reserve Some Packets for M/H Data Data Field of 312 MPEG-2 Packets MAIN (8-VSB) DATA ~ 24 msec 118 PACKETS M/H or MAIN 38 PACKETS MAIN ONLY 118 PACKETS M/H or MAIN 38 PACKETS MAIN ONLY Slot of 156 packets Group of 118 M/H Packets (if Slot is used) 7

8 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) 1c Per Program: Form Parade of Groups MPH frame Parade #0 MPH Sub-Frame #0 MPH Sub-Frame #1 MPH Sub-Frame #2 MPH Sub-Frame #3 MPH Sub-Frame #4 Parade #1 Parade #2 Symbol domain (after data interleaver) Slot #0 Slot #1 Slot #2 Slot #3 Slot # 4 Slot #5 Slot #6 Slot #7 Slot #8 Slot # 9 Slot #1 0 Slot #11 Slot #12 Slot #1 3 Slot #1 4 Slot #15 Receiving Parade #0 Receiving Parade #1 Power ON Power OFF (or Sleep) 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 2 Add FEC Bytes for M/H Data RS Frame contains all data in one Parade (for 968 msec) 187 N Payload N columns (187+P,187) RS encode column-by-column 187 Rows of Bytes P Payload RS parity Add RS Bytes to Columns P = 24, 36, or 48 Add 2-byte CRC checksum row-by-row Pack left to right and top to bottom with M/H header and IP packets wrap as necessary 187+P Payload RS parity N+ 2 CRC checksum Add Two CRC Bytes per Row (Then add legacy 8-VSB headers and legacy RS bytes) 8

9 3 4 5 SCCC Coding, Interleaving, Training BEFORE interleaving, with Training Signals segmented INING TRAI M/H GROUP #1 DATA + Interleaved Training M/H GROUP #9 DATA + Interleaved Training MAIN DATA M/H Data is SCCC Coded As broadcast AFTER interleaving, with Training Signals aligned 8-V VSB Data Field 313 Data Segments 8-VSB Data Field 312 Data Packets M/H GROUP #5 DATA + Interleaved Training Data Packet of Bytes Main Data is Trellis Coded Data Segment of Symbols Test Experience Lab Results 8-VSB (A/53) M/H (A/153) ½ rate (Regions A+B) M/H (A/153) ½ rate M/H (A/153) mixed rate M/H (A/153) ¼ rate SNR Required (db) Doppler (Hz) ~= max mph, with complex ghosts (TU-6) ~ 10 (depends on receiver) * *Note: 60 Hz is sometimes quoted as minimum adequate rate (DVB, others) 9

10 Multiple Field Tests 2006 Lincolnshire, Illinois Columbus, Ohio 2007 Buenos Aires, Argentina Santiago, Chile 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 Detailed Field Test Results Washington DC 5 different channels Data recorded simultaneously Washington, DC Channel 34 GOOD ERRORS NO DATA FOR THIS CHANNEL 10

11 Washington, DC Channel 35 GOOD ERRORS NO DATA FOR THIS CHANNEL Washington, DC Channel 48 GOOD ERRORS NO DATA FOR THIS CHANNEL Washington, DC Channel 33 GOOD ERRORS NO DATA FOR THIS CHANNEL 11

12 Washington, DC Channel 24 GOOD ERRORS NO DATA FOR THIS CHANNEL Thank You Physical Layer for ATSC Mobile DTV Wayne E. Bretl Zenith Electronics LLC 2000 Millbrook Drive Lincolnshire IL Transport / IP Rich Chernock, CTO Triveni Digital 12

13 Agenda Overview Streaming Content File Content Summary ATSC Mobile DTV Architecture Video Subsystem Video Video Source Coding and Compression MPEG Audio Subsystem Audio Audio Source Coding and Compression Service Multiplex Ancillary Data Control Data MPEG 2 Transport RF/Transmission System ATSC Legacy System M/H Framing Channel Coding Video Subsystem Video Video Source Coding and Compression Audio Subsystem RTP Service Multiplex And IP Transport Modulation Audio Audio Source Coding and Compression IP Encapsulation Ancillary Data Control Data M/H Structure Data TPC/FIC IP/UDP (RTP) ATSC Mobile / Handheld System 13

14 Content delivery DTV (mobile or fixed) is about delivering content to receiving devices Streaming content for example, linear television File content pushed BLOBs ESGs Non-Real Time content Interactive components Content delivery mechanisms for ATSC Mobile are different than for ATSC Fixed (mostly) Aligned with mechanisms used for other mobile distribution systems Key difference IP rather than MPEG-2 TS based RS-Frame Internal Structure N bytes M/H TP header Service #1 datagram 187 row s Service #2 datagram Service #3 datagram Stuffing Data transport is native IP, not MPEG-2 RS-Frame row is called an M/H Transport Packet (TP) IP Datagrams may wrap around from row to row, and from one RS- Frame to the next (except for NTP packets) IP Layer basics IP packets IPv4 currently Can migrate to IPv6 in future No issue with # of IP addresses using v4 in broadcast environment Multicast UDP over IP Key requirement must operate in broadcast mode w/o return channel TCP would not work well (or be necessary) Remainder of stack depends upon content type 14

15 Agenda Overview Streaming Content File Content Summary What s needed for delivering streaming content? Means to identify and segment/reassemble transport sized chunks of content from/to continuous streams Transport Means to synchronize content element streams Timing model Means to ensure sufficient space to hold content elements for decoding Buffer model Streaming Delivery using RTP Real-time Transport Protocol (RTP) is today s standard for delivering media over mobile networks Enables services and content types to be transferred between other standards bodies such as the Open Mobile Alliance (OMA) to ATSC-M/H Utilizes the wide array of encoding and delivery products optimized for the mobile market RTP Packetizes audio and video frames into UDP over IP frames RTP headers have timestamps and Stream ID unique to their streams. Note timestamps have a random offset from wall clock time RTCP (Real Time Control Protocol) used to provide time base information RFC 3550 Replicates necessary functionality of MPEG-2 Transport IP address/port replicates PID functionality For Broadcast Quality a stringent timing/buffer model is necessary 45 15

16 What is RTP: Encapsulation Real-time Transport Protocol encapsulates (RTP) elementary media streams directly into UDP packets with a RTP Header consisting of stream ID, timestamp and a few other fields RTP Header Media Elementary Data UDP Header IP Header MTU: 1500 Bytes IP Datagram 46 How does ATSC-M/H use RTP ATSC-M/H uses Real-time Transport Protocol as specified in RFC 3550 with the following constraints Packets may not be delivered out of order RTP Sender Reports *should* be sent within 100 ms of a video random access point A special ATSC-M/H timing and buffer model for RTP has been defined 47 Core Philosophy of Audio Video Synchronization System Time Presentation Time Frame 0 Presentation Time Frame 1 Presentation Time Frame 2 Presentation Time Frame 3 Video Frame Video Frame Video Frame Video Frame Audio Frame Audio Frame Audio Frame Presentation Time Frame 0 Presentation Time Frame 1 Presentation Time Frame 2 16

17 RTP: Synchronization RTP streams are synchronized via sender reports which relate the payload timestamp to the overall stream timebase Stream timebases correlated by reference to NTP timebase NTP timebase can be thought of as similar to PCR in MPEG-2 Systems Port Video Timestamp Video Elementary Data Port Port Port Video Sender Report: Timebase offset to master clock NTP Timestamp Audio Timestamp Audio Elementary Data NTP Timestamp Port Audio Sender Report: Timebase offset to master clock 49 Timing Model The ATSC-M/H timing model ensures that the timebase of the encoder can be recreated on the receiver NTP Timestamps will be sent in a jitter-free manner as possible in addition to sender reports - Similar to MPEG-2 PCR Port Video Sender Report: Timebase offset to master clock Port Audio Sender Report: Timebase offset to master clock Port NTP timestamp to true client timebase NTP timestamp to true client timebase NTP timestamp to true client timebase 50 A/153 Timing Model Details Physical Clock Decoder Encoder Reference Clock NIC NTP Transmit Timestamps RTCP SR bindings RTP timestamps NIC Elements of timing model Borrowed from MPEG-2 Resolution, jitter, drift of encoder clock Monotonically increasing NTP timeline w/o discontinuities (except rollover) 90KHz resolution for video timestamps (audio at sample rate) 17

18 TB V RB V EB n An TBX An n A/153 Buffer Model Buffer Model TBX V RBX V (i) TS TSX TB An B n Buffer model established Based on MPEG-2 principles Takes into account bursty nature of A/153 Agenda Overview Streaming Content File Content Summary File Delivery The file delivery protocol is used to deliver the following file types: Content (such as audio or video files) Service Guide Service Protection keys The file delivery protocol does not specify how the files are used, that is up to the application. 18

19 What is needed for file delivery Means to segment/reassemble large BLOBs Means to distinguish between delivery sessions Allows multiplexing deliveries on single transport Means to manage objects What s contained in session? What version Other directory type information Notions of carousels, updates, timing File Delivery Specification IETF has standardized FLUTE for scalable delivery of files over a multicast IP link (RFC 3926) OMA BCAST has specified a set of restrictions and clarifications to improve interoperability A/153 Part 3 directly references the OMA BCAST File Delivery specification With constraints applied FLUTE FiLe Delivery over Unidirectional Transport Generally refers to a set of protocols including FLUTE, ALC (RFC- 3450) and LCT (RFC-3451) FLUTE is used to deliver files over unidirectional network. Feedback is not required, therefore Suitable for broadcast Scales well FLUTE is the file delivery mechanism in OMA-BCAST DVB-IPDC MBMS 19

20 ALC / LCT FLUTE builds on top of ALC/LCT carried on UDP ALC = Asynchronous Layer Coding LCT = Layered Coding Transport ALC / LCT provide the concept of Objects and Sessions Can multiplex FLUTE sessions Transmission Session Identifier (TSI) Can support multiple objects per FLUTE Session Transmission Object Identifier Table of Contents called FDT (TOI==0) FDT describes each file Content location (URI) TOI Content-Length Transfer-Length (may be the same if no FEC) Content-Type (mime-type) Overview Streaming Content File Content Summary Agenda Summary Streaming Content RTP/UDP/IP Specified timing model including use of NTP stream Specified buffer model File Content FLUTE/ALC/LCT/UDP/IP Support for sessions Support for objects NRT standard specifies functionality for things other than ESG, SP keys 20

21 Thanks Rich Chernock ATSC Mobile DTV Broadcast System Implementation ti Jay Adrick VP Broadcast Technology Harris Corporation, Broadcast Communication Division ATSC A/153 System Architecture ATSC A/153 standardizes the characteristics of the emitted Mobile DTV signal and describes the functionality that resides within the signal. A/153 does not standardize the method of implementation It does guarantee transmission to receiver interoperability The following description of ATSC Mobile DTV station implementation reflects the product architecture that is being developed by Harris and our team partners. Other manufacturers may implement their products using another method. Currently, there is limited interoperability between some manufacturers Interface interoperability is under development in ATSC S5 activity Harris equipment design reflects that activity 21

22 Transmission System Pre-Processing Legacy 8VSB Processing A/153 Transmission System Mobile Network Adaptor Studio STL Exciter Transmitter Legacy 8VSB Processing System Architecture - ATSC Only PSIP Generator IP ATSC Main Channel Encoder(s) & Service Multiplexer Studio ATSC STL MPEG-2 TS Transmitter Existing ATSC Exciter ATSC Transmitter 22

23 System Architecture with Basic ATSC Mobile DTV PSIP Generator IP Studio ATSC STL MPEG-2 TS Transmitter ATSC Main Channel Encoder(s) & Service Multiplexer MPEG-2 TS Synchronous Mobile Network Adaptor Mobile Multiplexer System Time Generator Mobile Preprocessor SFN Processor M2X Exciter w/ M/H Preprocessor ATSC Transmitter Mobile Channel Encoder(s) IP IP IP Switch IP Station Metadata Signaling Generator Electronic Service Guide (optional) NRT Content Manager/Server (optional) Products Key Transmission Products Networking Products Partner Products Third Party Supplied System Architecture with Advanced ATSC Mobile DTV PSIP Generator IP Studio ATSC STL MPEG-2 TS Transmitter ATSC Main Channel Encoder(s) & Service Multiplexer MPEG-2 TS Synchronous Mobile Network Adaptor Mobile Multiplexer ATSC Time Generator Mobile Preprocessor SFN Processor M2X Exciter w/ M/H Preprocessor ATSC Transmitter Mobile Channel Encoder(s) IP IP IP Switch IP Station Metadata Signaling Generator Electronic Service Guide (optional) NRT Content Manager/Server (optional) Products Key Transmission Products Networking Products Partner Products Third Party Supplied System Architecture with Advanced ATSC Mobile DTV PSIP Generator IP Studio ATSC STL MPEG-2 TS Transmitter ATSC Main Channel Encoder(s) & Service Multiplexer MPEG-2 TS Synchronous Mobile Network Adaptor Mobile Multiplexer ATSC Time Generator Mobile Preprocessor SFN Processor M2X Exciter w/ M/H Preprocessor ATSC Transmitter Mobile Channel Encoder(s) IP IP IP Switch IP Station Metadata Signaling Generator Electronic Service Guide (optional) NRT Content Manager/Server (optional) Products Key Transmission Products Networking Products Partner Products Third Party Supplied 23

24 System Architecture with Advanced ATSC M/H & SFN PSIP Generator IP Studio ATSC STL MPEG-2 TS Transmitter ATSC Main Channel Encoder(s) & Service Multiplexer Mobile Channel Encoder(s) IP MPEG-2 TS Synchronous Mobile Network Adaptor Mobile Multiplexer ATSC Time Generator Mobile Preprocessor SFN Processor IP IP Switch IP M2X Exciter w/ M/H Preprocessor M2X Exciter w/ M/H Preprocessor ATSC Transmitter ATSC Transmitter Station Metadata Signaling Generator Electronic Service Guide (optional) NRT Content Manager/Server (optional) Products Key Transmission Products Networking Products Partner Products Third Party Supplied System Architecture with Full ATSC M/H & SFN PSIP Generator IP Studio ATSC STL MPEG-2 TS Transmitter ATSC Main Channel Encoder(s) & Service Multiplexer Mobile Channel Encoder(s) IP MPEG-2 TS Synchronous Mobile Network Adaptor Mobile Multiplexer ATSC Time Generator Mobile Preprocessor SFN Processor IP IP Switch IP M2X Exciter w/ M/H Preprocessor M2X Exciter w/ M/H Preprocessor ATSC Transmitter ATSC Transmitter Subscription Manager Service Protection Server/Encryptor (optional) Station Metadata Signaling Generator Electronic Service Guide (optional) NRT Content Manager/Server (optional) Products Key Transmission Products Networking Products Partner Products Third Party Supplied ATSC Mobile DTV Encoder Function: Compresses and encodes audio/video program content into low bit rate IP packetized data streams for transmission to ATSC Mobile enabled receiving devices Requirement: One encoder for each real time program stream that is to be transmitted over the ATSC Mobile DTV system. Redundancy should be considered at N:1 level Detailed Specifications: Video Encoding format MPEG4 h.264 base profile v1.3 Resolution 416 x 240 Progressive scanning Aspect ratio 16 x 9 (Wide Screen) Source video Could be 1080I, 720P, 480P (ws) or 480I (ws) Recommended to start with 16 x 9 format or convert prior to encoding Encoder should respond to AFD (Automatic Format Descriptor) Closed captioning CEA 708 format 24

25 ATSC Mobile DTV Encoder Detailed Specifications cont d: Audio Encoding format HE AAC v2.0 (High Efficiency Advanced Audio Codec version 2.0) Sampling Frequency 16, 22.05, 24 KHz. with SBR & 32, 44.1, 48 KHz. w/o SBR SBR = Spectral Band Replication Audio format Mono or Stereo (capable of supporting parametric surround) Source audio AES digital Discrete or imbedded Output Packetized IP over UDP (User Datagram Protocol) with RTP (Realtime Transport Protocol) RTP supports: Payload-type identification - Indication of what kind of content is being carried Sequence numbering - PDU sequence number Time stamping - allow synchronization and jitter calculations NetVX ATSC Mobile Encoder PC NetVX platform incorporates modules for: Mobile real-time stream encoding Mobile IP encapsulation Up to 4 encoders and encapsulator per frame Video encoder includes 2 independent audio coders enables additional audio only services Also capable of ATSC encoding and multiplexing SynchronyMNA Synchronous Mobile Networking Adaptor Function: Multi function platform that supports preprocessing of the Mobile DTV data, multiplexing of the processed Mobile data into the ATSC transport stream, generation of FIC,TPC and Service ID signals, transmission of signaling tables, generation of ATSC system time and synchronization/timing adjustment of the ATSC transport for distributed transmission networking. The ATSC Mobile DTV processing and distributed transmission timing are each treated as an application. Three functional configurations are available: ATSC Mobile Processing only Distributed Transmission only ATSC Mobile Processing with Distributed Transmission The SynchronyMNA is a dedicated hardware platform using FPGA signal processing technology under the control of a microprocessor. It s architecture allows for easy firmware and software updates. 25

26 SynchronyMNA Synchronous Mobile Networking Adaptor Requirement: One system per station. Redundancy should be considered on a 1:1 level. Application options to be selected depending on system architecture Detailed Specifications: Inputs SMPTE 310M/ASI (selectable) for ATSC Transport Input Ethernet port for ESG, Signaling Generator, Content protection and NRT system Ethernet ports for system configuration, monitoring and control Internal GPS reference requiring an antenna Outputs SMPTE 310M/ASI selectable X 4 PC APEX M2X ATSC Mobile Exciter Function: Generates ATSC 8VSB main service signal modulation while post-processing Mobile DTV content with RS coding, trellis coding, serial concantinated coding and training signals for enhanced Mobile DTV reception. Requirement: One exciter per transmitter is required. Redundancy should be considered on a 1:1 level. Detailed Specifications: Inputs SMPTE 310M or ASI Transport stream (selectable) Internal GPS reference used for precise frequency, ATSC mobile and DTS (SFN) operation External 10 MHz and 1 PPS reference (optional) RF samples for RTAC adaptive correction Ethernet for configuration, monitoring and control Output PC 8VSB modulated RF signal on assigned channel.100 Watt maximum output power APEX M2X ATSC Mobile Exciter 26

27 ATSC Mobile DTV Signaling, Announcement and Beyond Service and Content Discovery Signaling A/153 Part 3 Fast Information Channel (embedded) Service Signaling Channel (IP) Essential information, required to display services to the receiver user play audio/video content Announcement A/153 Part 4 Optional OMA BCAST Service Guide (IP) Additional metadata for services and programs Springboard for advanced services Signaling 27

28 Service Signaling Channel Collection of binary tables Transmitted as a well-known multicast UDP/IP stream Different data is encapsulated in each ensemble Service Map Table (SMT) MANDATORY Describes services type, IP addresses, codecs May include current program information Service Labeling Table (SLT) Adds human-readable names to fast frequency scan Guide Access Table (GAT) How to acquire Service Guide, if present Cell Info Table (CIT) Supports service hand-off when roaming Rating Region Table (RRT) As in A/65 Media Plays! Channel Info Major, minor number Short name Service category (TV, Radio) Typically scanned and cached What s On Now Title Genre, Rating, Duration Available once tuned to ensemble Others may not be populated or up to date Signaling - User Experience Signaling Generator Integration System element responsible for constructing SSC tables Tables (SMT) are dynamic with current program Tables (SMT, SLT) must be sent once per M/H frame A/153 does not standardize signaling to mux interface Architectural choices for integration: Monolithic integration with mobile mux/preprocessor External IP stream generator - encapsulation in mux External table loader - SSC carousel and scheduler in mux E.g., approach used by Roundbox Broadcast Server and Harris SMNA 28

29 Signaling Generator Functions Service Provisioning Ensemble IDs Service IDs and types Component configuration Metadata Collector Program listings TitanTV, Tribune, Program editor Main channel PSIP ingest PMCP integration Table Generator Creates tables and future schedule for upload to MNA FIC built from data by MNA Announcement (Service Guide) Announcement OMA BCAST Service Guide (SG/ESG/EPG) SG provides metadata for the broadcaster s content that can be incorporated into a richer program guide Basic features include Delivery of channel icons Complete program titles and descriptions, genre, ratings Information for upcoming as well as current programs Set of files delivered as FLUTE/UDP/IP streams Signaled as a (hidden) non-a/v service Discovery bootstrapped by FIC, GAT and SMT 29

30 Announcement Relationship with Signaling Some overlap with Signaling layer: IP multicast parameters Title Start time/duration Genre category Content advisory When there s conflicting info, receiver shall use Signaling g Service Signaling Channel always takes precedence over Announcement Signaling is mandatory, Announcement is optional When used, it must be compliant with the following: M/H Service Guide is compliant OMA BCAST Service Guide, as further constrained by A/153 Part 4 More than one ESG is permitted Receiver technology will support aggregation of guides Basic SG - User Experience Signaling experience enhanced Richer channel info Icon, URL, description Richer program info Description What s Coming Up Future programming for all channels on a broadcast Amount may be tuned by broadcaster Receiver aggregation May be cached for all broadcasts Announcement Server Integration Element responsible for SG delivery Architecture need not be as coupled to mux as signaling External generation of FLUTE streams IP streams encapsulated by mux Common config and data with signaling generator Service and component details Program metadata Typically shares hardware with signaling E.g., Upgrade to Roundbox Server 30

31 Announcement Server Functions Service Provisioning Enhancement of signaling SG Delivery Provisioning FLUTE and IP parameters Partitioning of guide data Data type Time window Bitrate (per partition) One or more SGs Metadata Collector Enhancement of signaling Additional media delivery Channel logos Broadcast Guide Configuration Strongly influenced by assumptions about receiver SG acquisition behavior Acquisition of long-term guides (e.g., 7 days) Second receiver? Offline or manual scan and download? Interaction channel? Many receivers/apps have none of the above Announcement server must be able to provide partitioned guide Short-term to support now and soon programming Long-term acquired during viewing (or scans, by more capable receivers) Additional Guide Scenarios A/153 supports signaling of SGs outside the current broadcast Receiver can aggregate Classical time grid views may only be realistic with market guide SG from interactive channel Likely the only common mechanism for market guide SG from external broadcast Requires multi-receiver or offline download device 31

32 Richer information means the user spends more time in the guide or mobile TV application Broadcaster opportunity for Advertising and co-promotion Interstitial content Adjunct content delivery Links to additional content Interactivity Broadcast SG can be a key enabler of additional content, if provided in a standardized way Advanced SG Features Mobile DTV Widgets Mobile DTV initial focus: Television services Widgets add broadcast data services to the mix Types: Global or Synchronized Global: Not associated with a TV/radio service, e.g. news Synchronized: Associated with and synchronized to TV channel/program, e.g. merchandising Non-Real-Time Content Delivery A familiar idea whose time has come? Convergence of multiple factors: Evolution of existing ATSC broadcast data standards New classes of devices that are DTVs Mobile DTV infrastructure relies on file delivery for SG Similar efforts such as OMA DCD ATSC NRT Standard Applies to fixed and mobile ATSC V1.0 in development in S13-1 AHG Set of modes for push data Extensible set of content types: media files, RSS, web bundles, Mobile: SG extensions to provide content guide Standalone services - synchronized proposed in

33 NRT Server Integration Element responsible for NRT Service Delivery Service management Service type, data source, Bandwidth configuration Content ingest (e.g., RSS) From local provisioning, broadcaster source or service bureau Stream generation FLUTE/UDP/IP streams Dynamic bandwidth management Co-resident/co-located with Announcement Server Planning for ATSC Mobile DTV Implementation ti Bandwidth Requirements Planning for Implementation Studio Facility Requirements Transmitter Requirements Optimizing Mobile Coverage 33

34 Main Channel Basics Bandwidth Requirements ATSC A/53 has Mbps payload capability The FCC requires all digital broadcasters to provide at a minimum 1 SD NTSC quality free-to-air program service ATSC program guide (PSIP) requires about 0.5 Mbps Typical SD service in MPEG2 requires 2-4 Mbps Typical HD service in MPEG2 requires Mbps Mobile DTV Basics Bandwidth Requirements ATSC Mobile DTV channels are scaleable in number and level of robustness Robustness is a function of coding level and it also drives payload efficiency Half rate = 37%, Mixed rate = 26%, Quarter rate=17% Streams with the same level of robustness (coding) can be assembled into an ensemble Main channel contribution is made in increments.917mbps, 1.83mbps, 2.750mbps, 3.667mbps, 4.584mbps 5.501mbps, 6.418mbps, 7.334mbps Mobile DTV Basics Bandwidth Requirements Full details of bandwidth allocation for ATSC A/153 Mobile DTV can be found in the ATSC A/153 standards documents, Section 2 Page 63 The following are some sample use cases that were detailed by OMVC members: 34

35 ATSC Mobile Broadcast Scenarios Assumptions VIDEO Three Options High Quality 500 kbps Medium Quality 400 kbps Lower Quality 256 kbps AUDIO Three Options High Quality 32 kbps CODING Two Options Medium Quality 24 kbps Lower Quality 16 kbps SCCC Outer Code 1/4, 1/4, 1/4, 1/4 Efficiency = 17.1% SCCC Outer Code 1/2, 1/4, 1/4, 1/4 Efficiency = 26.4% Notes: A range of 0 to 200 kbps is reserved for overhead (ESG, null bits, etc.), this value has been adjusted to try to optimize scenarios The bit rate of still images is negligible for purposes of this document NRT and other data delivery via M/H is not considered in this document Refer to ATSC A/153 Section 2 Chart 6.1 for complete details Case 1 - One max-quality program One max-quality program - 1/2, 1/4, 1/4, 1/4 Video bit rate 768 kbps Audio bitrate 24 kbps Overhead 176 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps One max-quality program - 1/4, 1/4, 1/4, 1/4 Video bit rate 768 kbps Audio bitrate 24 kbps Overhead 148 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Case 2 - One mid-quality program One mid-quality program - 1/2, 1/4, 1/4, 1/4 Video bit rate 400 kbps Audio bitrate 24 kbps Overhead 60 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps One mid-quality program - 1/4, 1/4, 1/4, 1/4 Video bit rate 400 kbps Audio bitrate 24 kbps Overhead 46 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps 35

36 Case 3 - Two mid-quality programs Two mid-quality programs - 1/2, 1/4, 1/4, 1/4 Video bit rate 800 kbps Audio bitrate 48 kbps Overhead 120 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Two mid-quality programs - 1/4, 1/4, 1/4, 1/4 Video bit rate 800 kbps Audio bitrate 48 kbps Overhead 92 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Case 4 - Two high-quality programs Two high-quality programs - 1/2, 1/4, 1/4, 1/4 Video bit rate 1100 kbps Audio bitrate 48 kbps Overhead 62 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Two high-quality programs - 1/4, 1/4, 1/4, 1/4 Video bit rate 1100 kbps Audio bitrate 48 kbps Overhead 106 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Case 5 - Four mid-quality programs Four mid-quality programs - 1/2, 1/4, 1/4, 1/4 Video bit rate 1600 kbps Audio bitrate 96 kbps Overhead 240 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Four mid-quality programs - 1/4, 1/4, 1/4, 1/4 Video bit rate 1600 kbps Audio bitrate 96 kbps Overhead 185 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps 36

37 Case 6 - Two mid-quality programs + ten high & medium quality audio services Two mid-quality programs and ten high-quality audio services - 1/2, 1/4, 1/4, 1/4 Video bit rate 800 kbps Audio bitrate of program 48 kbps Audio bitrate of audio services 320 kbps Overhead 284 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Two mid-quality programs and ten high-quality audio services - 1/4, 1/4, 1/4, 1/4 Video bit rate 800 kbps Audio bitrate of program 48 kbps Audio bitrate of audio services 320 kbps Overhead 86 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Case 7 - High number of medium quality audio services Reasonable upper limit of medium-quality audio services - 1/2, 1/4, 1/4, 1/4 = 155 Audio bitrate of audio services (32 kbps) 3720 kbps Overhead 153 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Reasonable upper limit of medium-quality audio services - 1/4, 1/4, 1/4, 1/4 = 98 Audio bitrate of audio services (32 kbps) 2352 kbps Overhead 156 kbps Total MH bandwidth Mbps Remaining Legacy DTV Bandwidth Mbps Studio & Transmitter System Requirements 37

38 Mobile System - Studio Equipment at Studio NetVX Mobile Encoder System 1 RU 3 Slot Frame or 5 RU 17 Slot Frame Signaling Server 1 RU Dell Server ChassisRoundBox ESG Server Also supports ESG option IP Hub (Customer Supplied) RoundBox ESG Server SynchronyMNA Mobile Networking Adapter 1 RU Transport Stream From ATSC main multiplexer to SynchronyMNA input From SynchronyMNA to STL input SMPTE 310M preferred but will also support ASI Video SD Widescreen SDI interface per mobile stream IF HD down convert to SD-WS Audio AES 48 KHz sample rate locked to video Discrete or imbedded Signal I/O at Studio RF GPS Antenna to SynchronyMNA Harris offers as option could be central antenna with DA IP Networks Mobile Program Content Must be isolated network Encoder output(s) Up to 5 per frame Signaling Server output NRT Server (optional) External IP delivered services Configuration & Control IP port on each device Preferred to support external access by permission Mobile DTV System Drawing 38

39 Where in the transport stream The mobile system must be installed as the last item in the chain of equipment prior to the STL. No additional multiplexing can be inserted after the mobile stream Common sources of problems are Nielsen NAVE encoders, rate shaping devices, transport processors (DTP), transport format converters (ASI to 310M) and some multichannel STL s if installed down stream of the mobile system STL Considerations Stable Mbps STL link is essential No drop or add of MPEG-2 packets allowed SMPTE 310M interface is highly desirable between MNA output and exciter input System has been tested over RF Microwave, Fiber and Copper links Network to ASI or SMPTE 310M converters are known sources of stability problems Some early digital RF link systems have known stability issues Mobile System - Transmitter Equipment at Transmitter APEX M2X Exciter Replaces existing ATSC exciter Ideal configuration is transmitter with exciter change over system Allows mobile installation without interrupting operations 2 RU configuration is smaller than previous Harris ATSC exciters Exciter requires external PC or lap top PC for configuration Web GUI support remote configuration and monitoring (TBD) 39

40 Signal I/O at Transmitter Transport Stream From STL or TS DA to exciter input SMPTE 310M preferred but will also support ASI RF GPS Antenna to M2X input Harris offers as option could be central antenna with DA RTAC RF Samples Same as APEX Sample ports to M2X inputs 10 MHz Frequency Reference Output available to support other plant requirements IP Network Configuration & Control IP port on M2X Preferred to support external access by permission Local PC or Laptop to configure IP Management ATSC MDTV is a combination of transport stream, RF and IP technologies Encoding, signaling, ESG, service protection, NRT delivery and multiplexing all require management of the IP domain MAC and IP address management is essential and air critical External access to Synchrony, Roundbox Data Server, NetVX and the M2X is very desirable and enables rapid troubleshooting and configuration Access can be on a supervised basis Optimizing Mobile DTV Reception 40

41 Understanding Mobile Coverage & Reception ATSC Mobile DTV reception is based on different planning factors than terrestrial DTV reception Receive antenna height 45 vs. 30 ft. Receive antenna gain -20db to -3db vs. 0db System SNR db vs. 15db Field testing has shown that the radio horizon is the limit to reliable mobile/handheld coverage Typically line of sight from TX antenna to receiver Limitations typically are terrain and buildings Flat terrain + tall towers + H&V pol + max power = mile coverage Targeted MDTV Coverage Broadcasters have indicated that they are most concerned with delivering coverage to: Urban canyon areas Interiors of large buildings Urban areas that are terrain shielded Signal Saturation vs Coverage Contours will become the principal criteria for successful performance Circular polarization Discussion to follow Achieving Signal Saturation Maximized Power from main TX site Achieved by low antenna gain and high transmitter power output Gap fillers and Repeaters Synchronized or OTA 41

42 Why Circular Polarization is Important Polarization Mismatch Loss (Depolarization) Caused by misalignment between the transmit and receive antenna 9 PML db Why Circular Polarization is Important Small scale fading occurs when multiple signals arrive at the receiver from nearby reflecting objects The vector addition of all multipath components create variations in the received signal strength Signal Power Receiver Displacement CP results in improved signal availability Mean 98 % Service 18.7dB Mean 98 % Service 98 % Service 19.7dB Mean 14.8dB Signal Power db Signal Powe er db Signal Power db Horizontal polarization 0 Receiver Displacement Vertical polarization 0 Receiver Displacement Circular polarization 0 Receiver Displacement MHz 42

43 Test Results Summary - UHF in Improvement (db) Marg O P E N A R E A W O O D E D A R E A O F F I C E B U I L D I N G H O U S E S M A L L V E H I C L E Circular Polarization Horizontal Polarization Vertical Polarization On average, circular polarization offers 5 db margin improvement over horizontal polarization On average, circular polarization offers 7.5 db margin improvement over vertical polarization Test Results Summary - UHF Greatest Margin Occurs at 33% Vertical Component 6 Full CP Margin Impro ovement (db) Optimum Range Horizontal Polarization Baseline Vertical Polarization Baseline % Vertical Polarization More than 4 db of margin improvement with 20% < Vpol < 50% What about VHF? 43

44 Results Summary - VHF in Improvement (db) CPOL VPOL O P E N A R E W O O D E D A R O F F I C E B U I L H O U S E S M A L L V E H I Circular Polarization Horizontal Polarization Vertical Polarization Marg -6-8 A E A D I N G C L E -10 On average, circular polarization offers 3.5 db margin improvement over horizontal polarization On average, circular polarization offers 4.5 db margin improvement over vertical polarization Frequency 210 MHz 130 VHF Observations On a small handheld receiver, VHF provides: Less polarization discrimination Greater orientational immunity Omni Polarized On average circular polarization provided 3.5 db of margin improvement over horizontal polarization Great news for VHF.right? VHF Observations Average Received Signal Strength UHF vs. VHF Link Budget Differences Average Field Strength VHF UHF UHF VHF Adjusted VHF Antenna Gain 3.1 db 0.0 db Tx Power 4.0 db 0.0 db Tx Cable 3.6 db 0.0 db Rx Cable 0.5 db 0.0 db Rx Ant. VSWR 9.5 db 0.0 db Free space loss 9.8 db 0.0 db Open 31.8 dbm 56.0 dbm 53.3 dbm Woods 38.2 dbm 55.7 dbm 53.0 dbm Office dbm dbm dbm House 57.9 dbm 75.2 dbm 72.5 dbm Vehicle 40.6 dbm 64.9 dbm 62.2 dbm Adjustment Factor 2.7 db 0.0 db Avg 42.7 dbm 64.8 dbm 62.1 dbm VHF had 19.4 db less average signal strength than UHF 44

45 Small Receive Antennas Harold Wheeler defined the fundamental limitations of electrically small antennas based on their size Electrically small antenna max dimension λ/2π ~3 UHF ~8.5 VHF a Max power factor: P max = (ka) 3 a = antenna volume radius k = 2π/λ Wheeler Limit Solve for the max power ratio difference between 210 MHz and 700 MHz 3 2 a 3 v v u 10log 10log 15dB 3 u 2 v a u Wheeler Limit dictates the best VHF/UHF receive ratio of an electrically small antenna will be -15 db ATSC MDTV Repeater and Gap Filler Solutions Repeater Applications On Channel rebroadcast of main station signal Targeted coverage area is typically terrain isolated from main transmission point Repeater coverage area is typically medium to large area Signal source may be STL or off air depending on synchronization requirements 45

46 ATSC MDTV Repeater and Gap Filler Solutions Gap Filler Applications On Channel rebroadcast of main station signal Targeted coverage area is typically terrain or structure isolated from main transmission point Gap Filler coverage area is typically a small area and may be just the interior of a building or tunnel Signal source is typically off air ATSC MDTV Repeaters ATSC Repeater Solutions Synchronized Non Synchronized Non Synchronized SFN-Repeater Transmitter MPEG-TS RF1 + Performance 5 + Coverage 4 - Cost 5 + Error free output signal + Cascade/repeater possible + Same channel - Requires STL input - Coverage limited by interference from or to main TX Analog RF Gap Filler RF1 Filter RF1 - Performance 1 - Coverage 1 + Cost 1 - Output limited by input SNR - Requires very high I/O isolation - Limited to very low power - Adjacent channel issues + Good bit replication Analog IF Gap Filler RF1 IF-A RF1 - Performance 2 - Coverage 1 + Cost 2 - Output limited by input SNR - Requires very high I/O isolation - Limited to very low power - Adjacent channel issues + Good bit replication ATSC MDTV Repeaters ATSC Repeater ATSC Repeater Solutions Solutions - On Channel Non Synchronized Non Synchronized Non Synchronized Digital IF Gap Filler RF1 IF-D AEC RF1 + Performance 3 + Coverage 3 Cost 3+ - Output limited by input SNR + Able to run higher power + Good bit replication Full Decode Gap Filler RF1 MPEG-TS RF1 - Performance 1 - Coverage 2 - Cost 4 - Requires very high I/O isolation - Limited to very low power - Poor bit replication limits use for MDTV + Not SNR limited Partial Decode Gap Filler RF1 Data RF1 + Performance Coverage 3 - Cost 4 + Error free output signal + repeater chain possible + Not SNR limited - Requires high I/O isolation -Limited to low power - 46

47 SFN Repeater Transmitter ATSC Modulator Up-Converter Amplifier RF1 out MDTV/SFN Transmission Adapter ATSC Modulator Up-Converter Amplifier RF1 out Mode selection synchronization & Trellis state RS Coding Convolutional Coding 100% ATSC Compliant Error Free Signal Analog RF-Gap Filler RF1 in RF Level RF Level RF1 out RF Pre- Amplifier RF Filtering RF Amplifier RF Pre-amplifacation Single Channel RF Filter Post filter RF Amplification Analog IF Gap Fill RF1 in IF Level IF Level RF1 out Down- Converter Amplifier IF Unit Filtering Up-Converter Amplifier RF IF conversion Analog IF Processing IF RF conversion 47

48 Digital IF Gap Filler RF1 in Digital IF Level Digital IF Level RF1 out Down- Converter Amplifier IF Unit Filtering AEC Up-Converter Amplifier RF IF conversion Digital IF Processing Adaptive Echo Cancellation IF RF conversion Full Decode Gap Filler RF1 in MPEG-TS RF1 out ATSC A/53 Demodulator ATSC Modulator Up-Converter Amplifier RF IF TS RS Coding Convolutional Coding ATSC Signal lacking synchronization between VSB & MH frames Partial Decode Gap Filler RF1 in MPEG-TS w/partial MH data RF1 out ATSC A/53 Demodulator w/ partial MH ATSC Modulator Up-Converter Amplifier RF IF TS RS Coding Convolutional Coding 100% ATSC Compliant A/153 Error Free Signal 48

49 Adaptive Echo Cancellation Adaptive Echo Cancellation (AEC): Compensation of unwanted echos due to feedback paths Antenna isolation Gap-filler gain Gain Margin = Difference between the Antenna isolation and the Gap-filler gain Off Air Fed Gap-Filler for ATSC MDTV Problem: Feedback from TX- to RX-Antenna System may become unstable Degradation of output t signal (MER high) h) Ripple in spectrum of output signal Definition of Gain Margin Antenna decoupling (A d ) Echo Level (P E ) Output Level (P O ) Input Level (P I ) Amplification (a = P O - Advanced Television Systems P I ) Committee 49

50 Definition of Gain Margin Input Level (P I ) Echo Level (P E = P O Output Level A d ) (P O = P I + a) Antenna decoupling (A d ) Amplification (a = P O P I ) Gain Margin = P I P E Gain Margin = P I (P O A d ) Gain Margin = P I (P I + a A d ) = A d -a Gain Margin Example P O1 10W = 40 dbm P O2 40W = 46 dbm A D : 60-80dB P I : -40dBm nominal Harris ATSC AEC up to 0dB Gain Margin vs. +20 db w/o AEC 10W Example best case Antenna decoupling: OK Gain Margin = P I (P O1 A D ) = -40dBm (+40dBm 80dB) = 0dB 40W Example best case Antenna decoupling: NO Gain Margin = P I (P O2 A D ) = -40dBm (+46dBm 80dB) = -6dB Gap Fillers Main Transmitter High input to output isolation is required Signal in non synchronous to main station Interference can occur if signals overlap Ideal for shielded building coverage using leaky coax for antenna Gap Filler TX is usually very low power under 10 watts Booster Transmitter Main Site Coverage Booster Site Coverage Interference Zone Main Site Coverage 50

51 Redundancy = Reliability Don t Forget Redundancy Plan for system redundancy from the beginning of ATSC Mobile DTV operation Why: ATSC Mobile DTV service is truly a wireless business. If you are off the air or limited in power, your mobile viewers will be lost. No cable TV distribution will support your wireless viewer base. ATSC Mobile DTV Station Implementation Jay Adrick, VP Broadcast Technology Harris Corporation Broadcast Communication Division Questions? 51