What is DVB-H?

The plethora of options now available on phones, personal digital assistants (PDAs), and other handheld devices now includes television (TV). Incredibly, you can take your TV with you. Whether you're comfortable squinting at that very small screen is something only you can answer.

More and more providers are embracing the idea of mobile television, and more and more manufacturers are following suit. It's not just mobile phones and PDAs that are the prime candidates for mobile TV. Devices designed specifically for mobile television are being built with increasing regularity. These devices look like tablet personal computers (PCs), but with wider screens and built-in antennas.

Companies that broadcast television signals to handheld devices are subject to the same kind of laws and best practices that govern those who broadcast to homebound devices. The industry standard for these regulations is called Digital Video Broadcasting—Handheld (DVB-H).

DVB-H is a relatively new cousin in the DVB family. The Digital Video Broadcasting Project — a group of nearly 300 broadcasters, network operators, and software makers that since 1993 have designed global open standards for digital television transmissions — has created other formats as well. DVB-T, in which the T stands for Terrestrial, deals with signals that are broadcast via aerial antennas to home receivers. DVB-H, in fact, is patterned after DVB-T.

Also used in Europe are DVB-C and DVB-S. The last letters in these acronyms stand for Cable and Satellite. Another well-known protocol is Digital Video Broadcasting–Multimedia Home Platform (DVB-MHP).

DVB-H offers high-speed streaming video that can be used either on its own or as a piggyback signal on existing mobile telecommunication networks. The signals are designed to account for the limited battery life of small handheld devices by employing a technique called time-slicing, in which bursts of data are sent periodically and then stored, avoiding the need for a constant battery drain. The signals are also designed to account for the varied environments in which DVB-H viewers watch those signals. A portable video viewer can be taken many places that cable-bound TVs can't.

The idea of the portable video viewer presents a few challenges. If you've tried to keep listening to a radio station while driving out of its transmission range, you know the feeling. DVB-H, however, is designed to broadcast on a selection of frequencies. If one signal becomes weak, the video viewer switches to a frequency that is stronger. This switching is internal and doesn't apply to the overall transmission of the video signals.

The advent of DVB-H depends largely on what country you live in. If you're an American, you'll begin to see this service more and more in 2007. Launch dates for DVB-H service in other countries will vary.