DATA BROADCAST: NEW OPPORTUNITIES IN THE VBI

David K. Broberg, April 1993

Originally Published at the 47th Annual Broadcast Engineering Conference, Proceedings [Page 439]

INTRODUCTION

EIA/CEMA Involvement:

The EIA (CEMA) became involved in the closed captioning standards processes with the passage of the TV Decoder Circuitry Act of 1990. After a joint industry task force completed its recommendations to the FCC on TV caption decoder display standards, this task force became known as the Television Data Systems Subcommittee (TDSS) and began work on the fun-stuff. This process included the development of an industry standard for interleaving Extended Data Services (XDS) into a captioning signal as well as new and enhanced captioning modes. The new services were developed with the intention of using them exclusively in the previously unused portion of the line. This provides for the additional bandwidth and prevents interference with existing caption decoders.

Table 1 lists the sequence of events in the timeline for the EIA-608 standards process.

FCC Involvement:

On the basis of FCC rules for line-21 (in place at the time this was written), there is the authorization to carry non-program related data within the line-21 waveform. The TEXT services have been an example of this authorization. This authorization would probably allow other new data services within the line-21 waveform including XDS. The catch is, that they must conform to the established data format. Even though it is permissible to do so, it is not practical, due to the limited amount of bandwidth available in the existing data stream.

The FCC rules did not, however, allow full use of the field-2 waveform. Only one-half of the line-21 on field-2 was defined. This limitation restricted the possibility of ever duplicating the full line-21 waveform on both fields. Current line-21 encoding equipment generates these half-line test signals, but they have never been used in any decoding hardware. In reality this entire line has gone to waste.

In July of 1992, the EIA petitioned the FCC to allow full use of line-21 on field-2 for captioning formatted data signals. By authorizing this additional half-line, the FCC will allow a host of new TV data services without any problems of interference to existing services.

This request for changes to the line-21 VBI signal was combined with a simultaneous request for the use of line 19 as the ghost cancellation reference signal when the FCC issued the Notice of Pro-posed Rule Making on December 31, 1992.

It should be emphasized here that if the FCC acts favorably to the EIA request, any use of the field-2 signal is voluntary. There will be no new requirements placed on TV receivers or broadcasters. The success of this standard depends only on its perceived value and support within the industry.

In a separate action, the FCC seeks to update and improve upon the Emergency Broadcast System (EBS). The EIA has responded with comments to the Commission in this matter identifying the aspects of the EIA-608 that could be used as part of a more modern EBS system. It is unknown how the FCC will consider the capabilities of the EIA's XDS specifications in this matter.

EIA-608 CONTENT

The EIA-608 specification is intended to be the complete reference for all line-21 data services. The title of the specification is: LINE-21 DATA SERVICES FOR NTSC. It documents all aspects of line-21 captioning, text and XDS services for service providers, data encoders, and receivers. It covers the (minimum) required captioning services as established by FCC rules, as well as optional and enhanced captioning, text and data services.

The EIA-608 Specification includes the following sections:

• Signal Specifications for Line-21
• Field-Two Data Formats and Protocol
• R.P. for Caption Encoder Manufacturers
• Recommended Practices (R.P) for Caption Service Providers
• Extended Captioning Features
• R.P. for Caption Decoder Manufacturers
• R.P. for Text Mode
• Extended Data Service Packets
• XDS Encoding and Usage Issues
• XDS Encoder Design
• XDS Encoder Usage

XDS PACKET TYPES

The Extended Data Service packets are divided into Classes. These classes provide an organizational grouping of packets based on context. These classes also allow packet definitions to be reused in different contexts. There are six defined classes:

• The Current Class includes all XDS packets that describe the current program.
  
• The Future Class includes only XDS packets that describe future programs.
  
• The Channel Class includes those packets that describe the source or channel.
  
• The Public Service Class contains those packets relating to public service information such as Emergency Broadcast Services (EBS) or weather information.
  
• The Miscellaneous Class includes packets relating to all other areas.
  
• An Undefined Class is included to allow closed loop services to use the data channel in a way that will be ignored by standard decoders.

XDS FOR THE PROGRAM PRODUCERS

One of the first opportunities to benefit from the XDS system will be at the program production or post-production point. A number of caption provider organizations are making improvements to provide for the insertion of the new field-2 data services. When a program is produced, it may only be a small incremental cost to have basic XDS data added at the same point that captions are added. This level of XDS implementation promises to reach the largest possible audience for the lowest possible cost.

When XDS is included at the production stages, there will be no added generation loss. Encoding will be done simultaneous with standard line-21 captioning. The XDS will always remain a part of the program without any further action downstream. (In some cases downstream line-21 encoders will require a one-time modification to pass field-2 data.)

The largest group of XDS packets are best done during the production or post production phase. The Program Name and Program Description packets are the most obvious. Other packets such as Length/Time-in-Show, Program Type, Audio Services, Aspect Ratio and Composite Packet-1 might can also be encoded during production.

These packets can then be carried all the way to the final viewer's TV receiver with no other participation or equipment needed in the video chain.

Even at this simplest level of XDS implementation, consumers and program producers can benefit. Consumers will benefit by being able to quickly identify many important aspects about the program when channel hopping. Program producers will benefit by better recognition of their program. With the use of the XDS packets, more interested viewers are likely to catch a program because they can recognize the program quickly by name. Programmers will be able to capture these viewers, even during commercial breaks, because of this program identification.

XDS FOR THE NETWORKS

The network level is the second level of opportunity for XDS. When XDS is implemented at the network level, it has the potential to impact programming nation wide. There can also be several levels of network participation.

The first and simplest level of participation is passive compatibility. This means the network has taken any steps necessary to ensure that programs previously encoded with field-2 data will pass unaltered. Usually only a periodic system check is all that will be needed so everyone receiving the signals can enjoy the benefits of the field-2 signals.

A higher level of network implementation would involve the creation and encoding of XDS (and other field-2 signals). In this case the network can benefit by being able to provide a large percentage of his programming with XDS. The network can also benefit by adding packets not included during production such as Network Name, and Program ID Number. These packets will benefit the network by creating a higher level of recognition by viewers for both the network and the program.

To the consumer, the inclusion of the Network Name packet gives him the ability to find the familiar programming sources when visiting other towns or when faced with a channel assignment shuffle by the local cable operator. This packet may also eliminate the need for the superimposed on-screen logos used by the networks by making them redundant.

The Program ID packet can be used to control consumer VCRs, assuring complete capture of programs even during unscheduled interruptions, delays or extensions.

XDS FOR THE LOCAL BROADCASTERS

The final point in the distribution of television programming to take advantage of the XDS capabilities is at the local broadcaster level. There are various levels of participation that can give unique benefits the local audiences.

Like the network level, the local broadcaster's first level of support for XDS comes at a passive level. Again the first goal will be to make any system updates that may be necessary to ensure the unaltered passage of the line-21, field-2 data signal. Once this has been accomplished, all upstream XDS will reach the local broadcaster's audience with no further attention needed at the local level.

Also like the network level, there are a number of areas for further participation by the local broadcaster. Only by the use of an active XDS encoder at the local broadcast level, can the full benefits of the XDS system be realized.

Local broadcasters can benefit a number of ways by adding these services. The most basic advantage will be in the competitive advantage for increased audience. The packets that should only be added at this level include the Time-of-Day, Time Zone, Call Letters, Tape Delay and all the Public Service Class.

In some cases, the local broadcaster has the most control over the scheduling of future programs, in this case it would be appropriate to encode all the Future Class packets at this level.

The Time-of-Day, and Time Zone packets can provide a very useful service to the consumer by providing an automatic clock setting feature. The Call Letters packet provides a way for the local broadcaster to identify his station directly on the viewers TV screen. This can benefit the consumer by allowing an easy method of finding his favorite stations. All of these packets will allow TVs and VCRs to achieve a more user-friendly, automated set-up process.

The packets of the Public Service Class can offer unique benefits for consumers not before possible. To achieve this service, the local broadcaster includes a data bridge to couple the National Weather Service's Weather Radio Specific Area Message Encoding (WRSAME) signals directly into the packetized XDS signal. This will allow XDS receivers to capture and display on-screen, any NWS warning messages automatically. These messages are encoded to identify the specific events, the local areas affected and the duration. These warnings can be accomplished without any interaction or attention by the local broadcaster and without interruption to programming or advertisements.

To the consumer, this advanced warning system has the potential to save lives and property. In addition it can be unobtrusive to unattended recordings. Because there will be less need to interrupt the program, viewers will be able to record programs during some of these events without capturing the usual interruptions by newscasters or weatherman.

Some local stations, that due to their format, don't or can't provide weather or news information, will be able to keep their viewers warned, without hiring additional staff.

CONCLUSION

The pending EIA standard for XDS creates opportunities for broadcasters and program producers to provide new services to their viewers. These new services promise to increase awareness, and provide easy identification of encoded programs. Several levels of support will allow a gradual penetration of XDS services to a point where full support for XDS is provided from production through distribution and the full benefits of the system can be achieved.

New XDS services can help achieve simpler and easier to use TVs and VCRs. New products with these capabilities are expected to be introduced in the near future. The first demonstration of broadcast and reception of XDS signals has been planned to coincide with the NAB Convention this year.

Because of the packetized nature of this XDS approach, it is expected to provide an easy migration path to future digital video transmission schemes including HDTV and compressed digital-525 formats.