JBL CINEMA SOUND SET UP, Руководство пользователя

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100 Hz. This is commonly referred to as a channel system and uses an elaborate perceptual
encoding process known as AC-3.
data
optical
tracks and picture
Figure 3A. Dolby SR-D Figure DTS Figure 3C. SDDS
Figure 3B shows the format used in DTS. Here we see only the stereo optical tracks and a
sync channel for maintaining control of the associated CD ROM player.
Figure 3C shows the format used with SDDS. In addition to the stereo optical tracks, there are
two digital tracks, one at each edge of the film.
Like Dolby SR-D, DTS and SDDS make use of perceptual encoding methods for reducing the
amount of digital data required for system operation. DTS and SDDS support the 5.1 channel format
used in most cinemas, but SDDS also supports as many as 5 screen channels for special
applications.
All digital formats discussed here have a fall-back (failsafe) mode in which the analog tracks
will be used in case of failure of the digital portion of the systems.
C. A- and B-chains
For convenience in defining responsibilities for system specification and alignment, the
playback chain is customarily broken down into the A-chain and the B-chain, as shown in Figure 4.
The A-chain is comprised of the preamplifiers (optical or magnetic), light source (optical), magnetic
heads, solar cells (optical), associated equalization (signal de-emphasis), and noise reduction and
directional decoding required for flat electrical output at the end of that chain. For digital reproduction,
a digital optical reader is used and the digital signal is fed to a digital-to-analog conversion system.
The analog A-chain is shown in Figure
and the digital A-chain is shown at B. The B-chain,
including split surround channels, is shown at C.