Specifications

Prism Media Products Limited AD-2 Dual-rate A/D converter
Operation Manual
Issue 0.2 © Prism Media Products Limited
11 August 1998 Page 46 of 58
Note: Jitter tolerance is a measure of the ability of a receiver to correctly decode a digital interface signal which
has jitter. Like most other jitter parameters it is normally measured in unit intervals. A unit interval (UI)
corresponds to the smallest nominal time interval in the interface signal, for the AES3 or IEC958 interface
formats there are 128 unit intervals per sample. Therefore at a sample frequency of 44.1kHz the unit interval
is 177 ns. References 5 and 6 explain interface jitter in more detail.
7.5. Digital Outputs
7.5.1. Audio resolution on digital outputs
The AES3, AES-3id, SDIF-2 and both IEC958 outputs can provide up to 24 bits of
audio data. The output wordlength is selectable in the menu for the path which is
configured to drive each output (Main or Aux).
Note: To avoid truncation distortion care must always be taken to match the signal word length to the input
word length of following equipment. Often equipment is limited to a 16-bit input resolution and further
truncation will occur at that equipment if the signal is not re-dithered. This can be done by setting the output
word-length of the AD-2 appropriately. The word-length reduction may be achieved in a fully compatible way
by using dither or SNS noise-shaping. Alternatively the DRE coding system may be used to store high
resolution audio onto 16-bit channels. In the latter case DRE de-coding must be used before the signal is
further processed or played back.
7.5.2. Balanced AES3 (AES/EBU) professional outputs
These conform with the professional interface, AES3-1992, with transformers for
improved isolation.
Pin 1 of the XLR connector is connected to the chassis and the signal is output
differentially across pins 2 and 3.
Output impedance: 110S ± 20%
Output level: 4V ± 10% (terminated)
Rise/fall time: 15ns ± 20% (terminated)
This output will always carry professional channel status, see section 7.5.12.
The XLR outputs can be configured to generate 'Split96' format for 88.2kHz and 96kHz
signals with one channel per bearer in accordance with [Ref.8].
7.5.3. Optical consumer format
This output is physically compatible with the Toshiba `TOSLINK' fibre-optic connector.
It carries consumer format channel status, see section 7.5.12.