Philips DP-IF8000, Руководство по обслуживанию

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3
DP-IF8000
SECTION 2
SERVICING NOTES
DIAT
(DIGITAL INFRARED AUDIO TRANSMISSION)
High quality media such as DVD and digital broadcasts are currently going through a phase of explosive expansion. To convey these kinds
of high quality media to listeners with no loss in sound nuance or quality, a new technology called DIAT has been developed using the MDR-
DS8000 to transmit these digital audio signals by infrared without harmful data compression.
DIAT technology allows transmitting digital audio signals without data compression on a portion of the sub-carrier frequency bandwidth
allotted to distributing high-fidelity audio by the IEC (International Electrotechnical Commission) and JEITA (Japan Electronic Information
Technical Association). The transmission quality is equal to or better than that on compact discs (CD). (Fig. 2-6)
L
2 3 4 6
Hi-Fi audio data transmission bandwidth
(2 to 6 MHz)
Analog transmission
Digital transmission (DIAT)
[MHz]
R
5
Fig. 2-6 Signal spectrum for digital infrared transmission
[Reference Data]
Sub-carrier frequency
: 4.5 MHz
Occupied bandwidth : 2.5 MHz (approx.)
Data rate : 3 Mbps (approx.)
Modulation method : DQPSK
(differential quadrature phase shift keying)
Transmit error correction : Reed Solomon coding
DIGITAL INFRARED AUDIO TRANSMISSION
Along with developing a custom IC, the number of light-emitter elements were doubled (to 16) and light-receiver elements increased 6-fold
(to 24) to achieve a carrier-to-noise signal ratio well capable of transmitting wide-band digital signals. Using digital transmission eliminates
the transmission hiss noise heard in conventional analog broadcasts and allows listeners to enjoy hearing even small sounds.