DCS dCS 904 User Manual

Page of 86
dCS 904 User Manual
 Manual for Software Version 1.5x and 1.36
dCS Ltd 
June 2000
Manual part no: DOC135904 iss 2B2
Page 50
135904ma2b2.pdf file available from website
Contact 
dCS
 on + 44 1799 531 999 
email to: more@dcsltd.co.uk
(inside the UK replace + 44 with 0)
web site: www.dcsltd.co.uk
SDIF-2
PCM Format
-
The SDIF-2 interface is a 4 wire NRZ interface - so the DC level on each signal
line may not be constant.  It contains 20 bits of audio data and has a block
structure of 256 stereo samples, rather than the 192 of AES/EBU.  There are 8
bits of message per channel  per sample - with a further 3 bits being used for an
"illegal code" based sync code. Of the 8 bits per sample, the 8 in the first sample
are reserved for system messaging, and the rest are for User messages.
The 4 wires are:
Ground return
Left Channel
Right Channel
Word Clock
The sync codes can enable data recovery without the word clock, if necessary,
but with the number of data formats in current operation, this method of locking
is strongly discouraged. The waveforms below SDIF-2 waveforms (data and
word clock) at 44.1 kS/s and 96 kS/s.
Figure 31 – SDIF-2 PCM format at 96 kS/s