Digital Satellite Broadcasting Practical Rules: 1

There are some standards to follow in carrying out digital broadcasting: the Ministerial Ordinances/Notifications and the standards established by the Association of Radio Industries and Businesses (ARIB), based on such governmental guidance. These standards contain a large range of selections that have to be narrowed down for the start of digital satellite broadcasting services in 2000. At the end of September in 1999, the BS-P Consortium, formed by satellite broadcasters, completed an 800 page manual of detailed practical rules with the cooperation of the Electronic Industry Association of Japan (EIAJ). These practical rules were reported to the ARIB and published as a Technical Report ARIB TR-B15.
Starting with this issue, the Broadcast Technology will present a two part report regarding the new digital services broadcasting environment being realized by these practical rules. The following themes will be featured in these issues:

  1. New types of programming services not possible in the analog era.
  2. Electronic Program Guides (EPG) which help a viewer to select programs easily.
  3. Receiver specifications such as for remote controllers and interface with peripherals.

This issue will introduce the first, Programming Services. The next edition of the Broadcast Technology will contain an article developing the latter two themes.

1. Programming Services

Digital satellite broadcasting which is to start in the year 2000 enables new broadcast programming services. This was first made possible by the practical rules which established what exactly each service would provide as well as what their necessary transmission signals and receiver functions would accordingly be. In this article, we will explain "provisional programming service," "multi-view TV," "hierarchical modulation service," and "emergency alert broadcasts."

Provisional Programming Service
The provisional programming service creates a new temporary programming channel while maintaining regular programming but reducing the bit rate. For example, when the time slot for a live Hi-Vision (HDTV) baseball relay is extended due to the game, this service will reduce the HDTV bit rate to create an SDTV channel for the continuation of the baseball game. In this case, while the picture quality of the HDTV program will not be as magnificent as it usually is, the next scheduled program can begin on the HDTV channel without any delay. As Figure 1 shows, selecting the regular HDTV channel or a provisional channel when a second channel is provided is the choice of the viewer. The viewers will be notified by an announcement or closed-captioning during the HDTV program they are currently watching. As the program on the provisional channel ends, the channel will automatically switch back to regular HDTV programming. Moreover, a timer recording selection will make possible a continuous recording (relay recording) of the baseball game which was transferred to the provisional channel during its broadcast.
When this service is provided, the HDTV and SDTV picture quality will depend on the bit rate allocation of each channel. Balancing out the picture quality with data transmission is a problem that is under consideration.

Multi-View TV
The Multi-View TV is an application that divides one regular HDTV channel into a maximum of three SDTV channels. This is to broadcast program related information on multiple channels simultaneously with the main program. Using a broadcast golf game for an example, this function can be used to broadcast three locations at the same time on two additional channels: General channel (main channel), 17th Hole (sub-channel one), and the 18th Hole (sub-channel two). In this case, the multi-view program starts on the General channel, allowing the viewer to freely switch between the main and sub channels during the program. As the multi-view program ends, the screen will automatically return to the next HDTV program on the main channel. Regarding recording of the program, the conventional VCRs will only record the main channel. A future digital video recording system may be equipped with a function enabling the recording of all the multi-view program channels.
The multi-view TV function can be applied to theater relays and dramas, as well as sports programs. This function has a possibility of expanding the viewer's selections and providing new information. On the other hand, because of flexible viewing styles of those watching, program information may not be delivered accurately or as the producers intended. These drawbacks should be considered thoroughly at the time of production.

Figure 1. Provisional programming service example
Figure 2. Multi-view TV example
Figure 3. Hierarchical adjustment example

Hierarchical Modulation Service
On satellite digital broadcasting, radio waves are affected by heavy rain causing abrupt video/audio blackouts (video: freezing, sound: muting, etc.). Broadcasting of a program using the modulation (low hierarchical) which is resistant to interference by multipaths along with the regular modulation (high hierarchical) will enable the transmission of information during rainfalls. Although this low hierarchical modulation is resistant to rain, the amount of information that can be transmitted decreases, which means that only necessary information will be sent on this system. We describe this in Figure 3. A program which is normally in an HDTV video form could be broadcast with reduced sharpness, as reduced size video, or as HDTV still images. A receiver will evaluate reception quality and automatically (or manually) switch between these hierarchies.
Since sound data is smaller, sound service can be sent by means of low hierarchical transmission. However, this low hierarchical transmission is not capable of transmitting numerous data broadcasting programs, resulting in the broadcast of only important programs such as emergency reports.

Emergency Alert Broadcasting
The following two functions are under consideration regarding emergency alert services on digital satellite broadcasting.

  1. A signal of emergency alert broadcasting is able to activate a turned-off (stand-by) receiver for emergency alert broadcasting.
  2. If an emergency broadcast starts while you are watching a program, the screen will automatically switch to the emergency programming.

However, due to the energy saving policy being promoted nationally, it is expected that this function 1 will not be included on a standard receiver. Function 2 will be activated and automatic switching to the emergency channel will occur only when the viewer is watching NHK's HDTV, simultaneous broadcast channel, S1 and S2. In the case the viewer is watching another, commercial, channel when NHK issues an emergency broadcast, the function will not be activated or change the current channel to NHK.