Crystal Vision
Statesman operation in mode 3
TANDEM-200 User Manual R1.7
54
13/02/2008
When two halves of a TANDEM are cascaded, select the final output side to have the
PLL function, unless there are problems with very high jitter in the SDI input signal, in
which case apply the SDI PLL to the input SDI path. If both TANDEM sides are in use
independently choose the side that offers the best influence on the whole system.
Select from the following options:
•
On/Off – Off selects free-run, On allows PLL lock to SDI 1 or 2
•
SDI 1 – PLL locked to SDI 1
•
SDI 2 – PLL locked to SDI 2
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 – GPI Alarms & input status
Using GPI outputs
There are two GPI outputs, GPO5 and GPO6, which may be assigned to eight different
embedded audio 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 9.2 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.
