Aes asynchronous, Aes sample rate converter (input only), Als. (see – Grass Valley NV5128 v.2.5 User Manual
Page 34: Introduction
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Rev 2.5 • 24 Sep 09
2. Introduction
Active Cards
AES Asynchronous
Incoming and outgoing AES asynchronous signals are received or distributed through passive con-
nectors housed on backplanes: 16 BNC connectors for unbalanced signals or 16 Phoenix connec-
tors for balanced signals. (See
on page 13.) Asynchronous AES input signals can be
routed only to asynchronous AES output cards; they cannot be routed to analog or AES synchro-
nous output cards, nor can they be routed as mono channels.
Asynchronous AES operation is not intended for use with “live” or program audio feeds where
glitches at switch boundaries are unacceptable. Instead, asynchronous input cards and output cards
provide an economical way to select AES signal sources, even ones that are synchronous, for ongo-
ing operations such as editing, monitoring or dubbing.
Input Card
The AES asynchronous input card (EM0387) receives up to 16 stereo signals through backplane
I/O connectors. The architecture of the input card is identical to that of the AES synchronous input
card, except that signals are not synchronized to the systems clock on the control card. (See
Output Card
The AES asynchronous output card (EM0388) receives up to 128 stereo inputs from the mother-
board. The signals are then sent to a crosspoint array (128 inputs x 16 outputs) for switching. The
outgoing AES signals are switched asynchronously (i.e., not synchronous with a system clock) and
then sent to balanced output drivers and backplane I/O connectors for distribution. Be aware that
this may cause possible problems in the output signal stream.
Figure 2-18 shows the asynchronous AES signal path.
Figure 2-18. Asynchronous AES Signal Flow (Balanced or Unbalanced)
AES Sample Rate Converter (Input Only)
The AES Sample Rate Converter (SRC) input card (EM0500) provides additional routing flexibil-
ity. The card accepts up to 16 asynchronous AES inputs with a wide range of sample rates. The sig-
nals are converted into synchronous AES signals locked to the 48
before being forwarded to the motherboard. This means that a wide variety of AES-compatible dig-
ital audio inputs with sample rates from 22
kHz to 108
kHz can be integrated into a synchronous
AES environment or converted to analog audio outputs as desired.
The receivers buffer the input, extracting audio data, sample clock, and applicable channel status
information. The clock and data signals are then processed by an asynchronous SRC and the rate-
converted data reformatted and combined with the appropriate channel status information and user
bits. Reference clock signals from the control card are used to synchronize the data to create an
AES format signal. The signal is then forwarded to the motherboard for distribution to output cards.
I/O
Connectors (up to 16)
Recr
Motherboard
Input Card
Transformer
Coupled
Recr
Output Card
XPT
128x16 stereo
I/O
Connectors (up to 16)