High Definition Television (HDTV)
Digital technology allows public television stations to broadcast programs in much higher resolution and clarity than current analog television. Viewers will be able to receive visually stunning high quality, crystal clear pictures displayed in a wide-screen format. However, public television stations cannot maximize the benefits to viewers of HDTV without a meaningful commitment to the digital conversion being made by television set makers, cable operators and satellite carriers. APTS applauds the FCC decision to compel television set makers to build digital television tuners into new sets over 36 inches. This decision is a significant step forward in the effort to ensure that all viewers will be able to enjoy the benefits of digital television. APTS strongly believes that the next step is to guarantee that public television stations’ digital signals are carried by cable operators and satellite carriers.

Multicasting in Standard Definition Television (SDTV)
New compression techniques enable public television stations to broadcast not only one stream of high definition digital programming, but also multiple streams of standard definition digital television programming with stereo sound and a higher quality picture than we have today. Digital public television stations are able to do this with only one-half of the 6 MHz capacity of a single cable channel. SDTV “multicasting” enables public television stations to deliver more services to diverse and underserved audiences simultaneously. APTS believes “multicasting” is an invaluable tool to enabling a public television station to deliver mission-related services that are vital to their local community.

Datacasting
Whether it is HDTV or multicasting in SDTV, one of the important benefits of digital broadcasting is that digital broadcast streams may be compressed—which creates the opportunity to use that spectrum for other purposes. In addition to programming, digital television stations act as a wireless network capable of broadcasting data – or “datacasting,” information in a digital television signal beyond the pictures and sound needed for a traditional television program. Digital data that is datacast by a public television station can be received in homes, schools and workplaces by a TV tuner card plugged into a computer, a set-top box attached to a television, or a new digital television set, to capture the digital signal. Using advanced compression techniques, digital public television stations can compress their HDTV broadcast stream to 15.8 Mbps and simultaneously datacast up to 3.6 Mbps of data without affecting the quality of the programming stream. When broadcasting in SDTV, the amount of spectrum available is even greater. For example, when broadcasting a single SDTV broadcasting stream at 3.6 Mbps, a public television station can simultaneously datacast up 15.8 Mbps of data. Whatever the form—HDTV or SDTV—the datacast receiver separates the data bits from the television programming stream. This data can then be manipulated and saved to any software program.