Miranda NV5100MC Master Control, Справочное руководство

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NV5100MC Master Control • Reference Man ual 33
3. Frames
Input (and Output) Cards
Analog Audio
Master control and the MFR route only AES format audio, at 48 kHz with 24-bit sample values.
Each analog audio card (and its backplane) converts analog audio to AES format and processes 16
stereo (or 32 mono) signals.
Analog Audio Input Module
The NV5000-AA-IN is designed for balanced analog audio signals. Differential receivers buffer
incoming signals. Precision components in the input stages provide very high common mode rejec-
tion and gain stability. Additional stages provide low-pass filtering. Signal levels are scaled to
accommodate the d24 dBu maximum input level. On-board DIP switches allow the gain of
each channel to be 6dB to accommodate low-level or single-ended input channels.
Each analog-to-digital converter accepts two analog signals — either left and right channels of a
stereo pair or two independent mono channels — and output the sampled data in multiplexed bit
streams. System clocks are supplied by the frame’s control card. The conversion rate is nominally
48kHz, locked to an external reference. FPGAs format the audio data and re-time it to a common
sample point. The resulting synchronous AES bit stream(s) feed the frame’s motherboard where
they are delivered either to the MCPMs (or to MFR output modules).
Figure 3-8 shows the signal flow for a single stereo channel:
Figure 3 -8. Analog Audio Signal Flow
Analog Audio Input Backplane
The EM0381 is the backplane module for analog audio input. It has 4 DB25 connectors. Each con-
nector handles 4 stereo pairs or 8 mono signals.
Each connector requires a DB25 breakout cable (NV5000-CABLE1, or your own).
Synchronous AES
AES input cards provide 16 AES channels of input.
AES backplanes are available in two types: BNC, for unbalanced signals on coaxial cable, and
Phoenix 3-pin pluggable screw terminal connectors for balanced, twisted-pair signals.
Synchronous AES Input Module
AES signals, balanced or unbalanced, arrive at the input module from the appropriate backplane
module. These signals are transformer-coupled to balanced input receivers. The module extracts
timing information from the signals on the input receivers. The module uses the timing information
to format the data and to correct timing errors. The module can accommodate nearly synchronous
input signals by either deleting or repeating samples to bring the signal into synchronization. Bal-
anced drivers feed the signal to the internal motherboard.
Gain
&
LPF
ADC
Timing
and
Control
Bus
Tx
L
I N
R
I N
Backp la ne
Rx
M otherboard