Crystal Vision
Statesman operation
TANDEM-300 User Manual R1.2
31
14/02/2008
Miscellaneous
The miscellaneous menu provides access to GPO 5 and 6 assignment, silence delay and
AES phase. In addition, video and AES input presence is included.
Miscellaneous – Silence Detect Delay, Error Level Ch1/2, AES Phase Ch1/2 & GPI Alarms
Using GPI outputs
There are two GPI outputs, GPO5 and GPO6, which may be assigned to twelve different
analogue and/or digital input silence alarms. Audio silence is deemed to refer to embedder
audio signals only, unless that embedder is OFF - in which case de-embedder signals are
tested for silence. If silence is sustained for more than the ‘silence detect delay’ the
assigned GPO will be asserted low as an alarm when ‘flag’ is selected.
Visual indication of GPO 5 and 6 status is also provided.
See section 7.3 for further discussion of GPIs and pinout details.
Silence detect delay
Silence detect or threshold delay can be set at the card edge or via Statesman. The left
hand control slider of the Miscellaneous menu sets the silence detect delay from 0 to 128
seconds for the amount of time a signal is allowed to remain below –50dB wrt Full Scale
before a silence error is flagged. Actual values start at 1.5s, 8s and then in increments of
8s to 120s.
Although the slider control sends a controlling message to TANDEM to select the time
delay in one-second increments, TANDEM rounds down the value sent. For example, if a
value of 7 or less, it is rounded down to 1.5 seconds, or for 8 - 128 seconds to the nearest
whole multiple of 8 seconds that fits the selected value, up to a maximum of 120 seconds.
Error level
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.
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.
