Platinum™ IP3
Installation and Operation Manual
Analog/Digital Audio Converter Modules with TDM
© 2016 Imagine Communications Corp.
Proprietary and Confidential.
September 2016 | Page 214
A/D Conversion
Analog-to-digital conversion is provided by quad channel 24-bit oversampling delta-sigma converters
supporting sampling frequencies up to 192 kHz. These converters provide DC bias voltage outputs,
digital decimation and high pass filtering, and audio input clipping detection.
AES Outputs
The FPGA receives the audio samples from the converters where they are formatted into AES data
streams. The FPGA inserts channel status, parity, and CRC bits, and then encodes the data into biphase
AES signals. Two copies of the first eight AES signals are provided as AC coupled LVDS for distribution to
the wideband Platinum crosspoints. The FPGA also provides a TDM version of all sixteen AES signals for
distribution to the audio-specific crosspoint module(s).
Reporting
Each channel will provide standard reporting of signal presence using card-edge mounted LEDs.
The green signal presence LEDs, labeled "Input 1" to "Input 16," are located in a row on the front of
the input module. Each of these LEDs illuminates when a signal is detected on its corresponding input.
The red signal clipping LEDs, labeled "Input 1" to "Input 16," are located in a row on the front of the
input module. Each of these LEDs illuminates when a signal on the input exceeds the maximum input
amplitude or level adjust available through TDM scales the digital signal beyond AES limits.
In addition, the usual three system LEDs are included.
Operating Modes
The PM-ADCT-IB/
PT-ADCT-IB
operates in one of three modes: External, internal, and auto mode:.
In external mode, all necessary sampling clocks are derived from an external AES reference (DARS).
The resulting AES streams generated from the sampled analog audio inputs will be locked in both
frequency and phase to this external reference.
In internal mode, all necessary sampling clocks are derived from internal oscillators. These oscillators
have been chosen to provide for many of the most common AES frame rates (32 kHz, 44.1 kHz, 48
kHz, 88.2 kHz, 96 kHz, and 192 kHz). Voltage-controlled crystal oscillators, or VCXOs, allow adjustment
of these internally generated sampling clocks within a specified tolerance.
In auto mode, the PM-ADCT-IB/
PT-ADCT-IB
detects whether a usable external reference is present or
not. If it is able to lock to the reference, it will operate as described in External mode; however, if the
reference is lost or becomes unusable, the PM-ADCT-IB/
PT-ADCT-IB
will automatically switch over to
operate as described in Internal Mode. If the reference is restored, the board will again automatically
switch over to operate as described in External Mode.
Analog Level Detection
Analog input level detection is provided in two forms:
