Interactive Digital Television(iDTV) – Principles and techniques


Interactive digital television (iDTV) is the process of – merging domestic Television with Interactive Digital technologies. The digital technologies are supplied through a back channel. The main attraction in this TV is that, the user can interact with the service provider. This is a revolution in the broadcasting area.

The present domestic televisions, called as diffusive systems, have only one path – from the source provider to the user. With this, the source provider just broad casts the signals to the user. But, the main requirement for this iDTV is – the return channel from user to the source of information, which is called as Interactive systems. With this return channel, the users choices can be send as data bytes to the service provider. The service provider receives this signal through a digital adapter called as set top box or decoder; connected to the normal television set or integrated with the digital television.

Nature of interactions:

The nature of interaction is mainly decided by the bit transfer rate in the return channel from the user to the source provider. It can be of two forms:

One way interactivity or Pulse format interaction

In this, the viewer sends back a signal to the service provider via a return path, but there is no ongoing, continuous, two-way, real-time dialogue, and the user doesn’t receive a personalized response. The signals will be only in the form of simple impulses (Yes or No logic). The most obvious application is direct response advertising.

The viewer clicks on an icon during a TV commercial (if interested in the product), which sends a capsule of information containing the viewer’s details to the advertiser, allowing a brochure or sample to be delivered to the viewer’s home.

Two-Way Interactivity or Multimedia format Interaction

Here, the user can send data to a service provider or other user, which travels along a return path, and the service provider or user sends data back, either via the return path itself or over the air. In this two-way interactivity the senders and receivers must be able to address a specific dataset to another sender or receiver. It is mainly by the digitalization of the television signal.

An example for this is – TV pay-per-view service. Using the remote control, the viewer calls up through an on-screen menu a specific movie or event scheduled for a given time and orders it. The service provider then ensures, by sending back a message to the viewer’s set top box, that the specific channel carrying the movie at the time specified is unscrambled by that particular box, and that particular viewer is billed for it.

Reception from service provider

The viewer’s reception of the digital signal is made possible through a digital adapter (set top box or decoder), which is connected to the normal television set or integrated with the digital television in the latest versions.
The set top box decodes the digital signals in order to make them readable by the conventional analogue television set. The set top box has a memory and decoding capacity that allows it to handle and visualize information. Thus, the viewer can accede to a simple form of interactivity by connecting the device to the domestic telephone line.

In addition, other installation and infrastructure arrangements are required, depending on the particular technology. In particular, a return channel must be activated. This can imply a second dedicated telephone line for return path via modem. The end user can interact with his or her TV set through a special remote control or, in some cases, even with a wireless keyboard.

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