Albalá Ingenieros DAT3000C01, Manual, Page: 27 / 38

Albalá Ingenieros | Manual DAT3000C01
4.2.8. Description of the synchronization
The DAT3000C01 includes a bank of switches for selection of the three
synchronization modes. The first is Automatic Mode, where the modules selects the
sampling frequency and the reference input automatically. The second is Manual
Mode, where the user sets the reference input and the sampling frequency. The third
is variable sampling rate or varispeed mode, where the sampling frequency is obtained
exclusively from the AES/EBU reference input.
The DAT3000C01 can operate without an external reference. To operate in this
manner, Manual Mode should be selected and the desired sampling frequency
selected for the output signals. In this case selection of the reference input makes no
difference.
The DAT3000C01 can generate streams of AES/EBU audio synchronized to video
signals with 525 or 625 lines. The sampling frequency of the output signal can be
48kHz or any other of the standard frequencies.
4.2.8.1. Selection of the variable speed, (varispeed ) operating mode
The variable speed (varispeed) mode allows the module to operate with any
sampling frequency in the range from 32 to 96kHz. This mode is employed with
non-standard sampling rates, meaning frequencies other than 32, 44.1, 48, 64, 88.2
or 96kHz.
The variable speed mode only functions when the reference input is digital audio in
AES/EBU format as per (AES11).
4.2.8.2. Operation in Automatic Mode
When the DAT3000C01 functions in Automatic Mode, selection of the reference
input and the sampling frequency is performed automatically.
The reference input signal is chosen based upon the following set of priorities:
- The highest priority reference is AES/EBU digital audio.
- If no digital audio reference is available, the module selects the video input
(black burst or word-clock) depending upon the position of program jumper J7.
- If no reference signal is present then the sampling frequency generated is
48kHz.
The AES/EBU digital audio reference input admits signals with or without audio.
The signal received is used to synchronize the audio samples. Using an internal
quartz crystal oscillator, all of the standard frequencies can be generated: 32kHz,
44.1kHz, 48kHz, 64kHz, 88.2kHz and 96kHz. If the sampling frequency of the
digital audio reference does not correspond to any of these values then the
DAT3000C01's oscillator will not be able to sync.
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