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2001 / Jul 01
H A R D W A R E
Digital Input Card (AES-2024)
Overview
There are two versions of digital audio input cards for the 2001:
• AES-2024/8 card will accept up to 8, AES-3 formatted stereo sources
(i.e. 16 mono channels);
• AES-2024/16 card will accept up to 16, AES-3 formatted stereo sources
(i.e. 32 mono channels);
A Signal Definitions form in the supplied XPoint software allows the
user to set attributes for the input channels including signal name, type,
circuit #, etc. The 16 (32) input channels may be configured as mono signals
(one channel), stereo signals (two channels), or 5.1 surround sound signals
(six channels) wired in any combination. Signals may span across input
cards (e.g. a surround sound signal may have 2 channels on one input card,
and 4 on a different input card).
Note: While it is possible to split the 8 (16) stereo AES inputs into 16 (32)
mono channels, there are still only 8 (16) physical wires, each containing the
2-channel AES formatted data.
A dedicated sample rate converter for each input re-clocks the incoming
audio data and phase locks it to the system’s master sample rate clock.
Embedded logic routes each channel of audio data into an available time slot
of the input card’s TDM bus. One TDM bus is allocated for each 8 input card,
2 TDM’s are used by the 16 input card.
AES Input Interface
The balanced, digital audio inputs on the AES-2024 card are transformer
coupled. AES receivers strip off the received sample rate clock and audio
data for further processing by sample rate converters. The balanced interface
operates at a nominal peak-peak input voltage of +5V with an input
impedance of 110
Ω
and conforms to the AES-3 1992 electrical specifica-
tion. Note that Channel Status data is not forwarded.
While unbalanced SPDIF formatted input signals may be connected to
the HI and LO inputs of an AES input channel (leave the shield floating), it
is recommended that a BALUN or other external matching device be
inserted to convert the SPDIF impedance to 110
Ω
and signal level to at least
1V p-p. Note that the optional BNC rear panel input impedance is internally
fixed at 75
Ω
.
Internal Programming Options
There are no internal programming options on the AES-2024 input card.
2001 / Oct 03
