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Platinum Frames and Modules
103
Installation, Configuration, and Operation Manual
PM-ADC-IB/PT-ADC-IB: Audio A/D Input Modules
Operation
Note: PM- series modules operate in 5RU and 9RU frames only. PT- series modules operate
in 5RU, 9RU, 15RU, and 28RU frames.
Figure 3-23 PM-ADC-IB/PT-ADC-IB Module
The PM-ADC-IB/PT-ADC-IB audio A/D input module provides analog audio to AES digital
audio conversion within the Platinum routing system. Two optional builds (one option with
High Z inputs, the other with 600 terminated inputs) provide 8 stereo channels of
conversion with standard Platinum I/O module features.
To reduce idle channel noise in systems using A/D and D/A converters, audio level sensing
circuitry is included that will mute the output (i.e., set all sample data = 0) when the analog
input is lost. The level at which input signal presence is determined is user adjustable, and
includes a minimal level which effectively disables the function. The duration for which this
minimum amplitude is maintained before muting occurs is also user-defined.
The PM-ADC-IB/PT-ADC-IB can automatically detect an external AES reference signal
(DARS), to derive the required sampling clocks and generate AES streams that are locked in
both frequency and phase to this external reference signal. When this reference signal is
absent, the PM-ADC-IB/PT-ADC-IB generates the necessary sampling clocks at one of
several of the most common AES frame rates. Users will have the ability to adjust these
internally generated sampling clock frequencies within a specified tolerance.
Analog Inputs
The PM-ADC-IB/PT-ADC-IB provides 8 dual channel balanced analog audio inputs via the
PT-A2-BP back module. The standard option provides high impedance inputs; optional
600 terminated inputs are also available. Input signals are received by high-quality, audio
line receivers containing internal laser-trimmed, matched resistors for maximum common
mode rejection. The signals are converted from balanced to single-ended by the receivers,
and are then attenuated and AC-coupled to the second stage attenuators.
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