Primer
Crestron
Surround Sound
DTS-Neo 6
The DTS-Neo 6 derives the surround sound channels from a technique
of advanced sub-band processing by using algorithms. Stereo music
material may be expanded from stereo to 5.1 or 6.1 surround channels.
Users with 5.1 and 6.1 systems derive five and six separate channels,
respectively, corresponding to the standard home-theater speaker
layouts. Bass management in the preamp or receiver generates the
subwoofer channel.
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Neo 6 decodes Extended Surround matrix soundtracks, and
generates a back channel from 5.1 material.
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Neo 6 technology separately steers various sound elements
within a channel or channels in a naturalistic way that follows
the original presentation.
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Neo 6 Music and Neo 6 Cinema have slightly different
characteristics because these are recorded in different types of
sound studios.
Pulse Code Modulation
The representation of sound as a mathematical sum of frequencies
(digital) is just as valid as a linear series of pressure measurements
(analog).
Pulse Code Modulation (PCM) representations of high quality audio is
the industry standard method of digitizing analog audio signals.
An audio signal, recorded as a time varying electrical signal, is a
fluctuating voltage. The amplitude and polarity of this voltage are
directly related to the changes in air pressure. This signal is measured
or sampled at a rate of at least twice the maximum frequency contained
in the audio signal (the Nyquist rate), typically 44.1 kHz for Compact
Discs or 48 kHz for professional audio applications. Each sample is
given a binary number to represent the measured voltage at that instant
in time.
The binary number, representing the original signal, is stored in
memory. This representation of the audio signal must be converted
back to a continuously time varying analog signal.
Typically a 16-bit number is used in PCM, yielding a number range up
to about 32767. For a 1-volt analog signal, a 16-bit number can only
resolve to 1/32767 of a volt. Because the 16-bit number cannot
represent voltages that lie between these 1/32767 steps, the
measurement is rounded off to a discrete number. This loss in precision
creates a slight increase in the background noise during playback.
Generally, small binary numbers generate higher levels of noise or
distortion, and large binary word lengths have such low noise that the
dynamic range can exceed human hearing. The size of the binary
number determines the extent of lost information and determines the
fidelity of the reproduced audio.
One fundamental problem of PCM digital audio recorders is the
recording of all frequencies with equal importance. PCM operates in a
time domain; the binary numbers represent a time-series of sampled
voltages. The frequency domain of all the components of the time-
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Surround Sound
Primer – DOC. 6122
