Crystal Vision
The card edge display
TANDEM-110 User Manual R1.8
62
07/07/2010
Error handling
The following table summarises the error handling options. To enter this menu, ensure
that only MENU dip switch 5 is down.
SEL
no
Display
Description
ADJ
funct
0
SD1erlevnn
Error masking on channel A audio outputs
Level 0 provides minimal error masking, 15 is
maximum (default)
ADJ=nn
1
SD2erlevnn
As 0 for channel B
ADJ=nn
Error masking cannot be completely disabled. Level 0 to level 15 provide progressively
more and more advanced error handling capability with level 0 providing basic error
handling and level 15 providing full error handling.
Note:
This setting should be left in the default position of 15. However lower values may be
useful in fault finding. For example changing the error masking to 0 may be useful when
attempting to listen to faults in the input data stream, or if the faults are so bad that the
error masking simply mutes the channel.
Embedding formats and vertical switching
When upstream input switching occurs or when input drop-out occurs the embedded
digital audio can suffer degradation and loss of synchronisation. The result could be
audible defects.
Repeating samples from a buffer during the disturbance can ease the problem or in the
case of upstream switching, lines around the standard switching point can simply be
avoided and not used for digital audio.
SMPTE standards 272M and 291M and SMPTE recommendation RP168 suggests the use
of a single line gap, but larger gaps are sometimes required to provide sufficient
robustness. In addition, there is equipment already in the market place manufactured by
Sony before the SMPTE recommendation was implemented that embeds on all lines. For
these reason both SMPTE and proprietary embedded formats need to be supported.
The two basic embedded audio formats supported by TANDEM-110 are as follows:
SMPTE: no data on lines around the preferred switching point e.g. lines 5,6,7,8
in 625 and lines 9,10,11,12 in 525 and corresponding lines in the alternate fields
SONY: data on every line
TANDEM modules provide a range of embedding and de-embedding formats that
provide a trade off between robustness and processing delay.
The de-embedding and embedding formats do not have to be the same. De-embedding
can be set to look at all lines for embedded audio whilst embedding can be done
according to SMPTE recommendations with a switch-point gap.
This allows TANDEM-110 to convert material from SONY formats to SMPTE. It is also
possible to convert SMPTE to SONY format, however, in this case the de-embed mode
should be placed in the special setting of ‘ALL’ rather than SONY.
