Dolby Laboratories DP503 - Manual (Page 9)

SECTION 1
INTRODUCTION
1.1 Introduction
The Dolby Model DP503 is a digital audio encoder supporting up to two channels
of Dolby AC-2, Dolby Digital (AC-3), and MPEG Layer-II digital audio coding
algorithms at data rates from 40 kbps to 448 kbps. Single channel, dual channel,
and joint stereo configurations are selectively available, depending on the chosen
data rate. A front panel menu and directory system provides convenient access to
the desired operating modes and to recall frequently used encoder settings.
This front panel user interface is also able to control an ISDN terminal
adapter/inverse multiplexer when combined with other equipment as part of a
Dolby Fax
• installation. The result is a flexible, multi-unit solution for real-time,
high-quality digital audio transmission on ISDN that does not require a computer,
terminal, or palmtop unit for its control. The built-in directory system, in Dolby
Fax applications, also stores ISDN settings and frequently dialed phone numbers.
For the ultimate in flexibility, the DP503 can be remotely controlled via a Windows
] ]
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based PC for use as a stand-alone encoder or as part of a Dolby Fax system.
Both digital (AES/EBU and S/PDIF) and analog audio inputs are provided. Analog
to digital conversion is performed at 18 bit resolution. Digital inputs include a
built-in sample rate converter.
The encoder will operate in synchronization with an externally provided clock or
from its own internal time base reference. Once converted to a digital data stream
(at an internal sampling rate of 32, 44.1 or 48 kHz), the 18-bit PCM serial input
data representing both audio channels is processed using the selected algorithm and
formatted into a single serial output data stream at the selected bit rate. An
industry-standard RS-449/422 data connection simplifies incorporation into a
variety of digital communications systems, including the Dolby Fax system for real
time transmission over ISDN.
RS-232 ports are provided for remote control via a PC; software download
capability for field-upgrade of the algorithm software; auxiliary data input; and
ISDN terminal adapter/inverse multiplexer control.
The encoder provides front panel system status indicators as well as a rear-panel
connector with TTL logic levels for remote status monitoring. A digitally generated
test signal is provided for system alignment and troubleshooting and can be
activated from the front panel or via a remote control.
Rear panel analog input trimmers are provided, along with calibration LEDs on
both the front and rear panels. Front panel overload LEDs are also provided.
MAIN