Crystal Vision
Statesman operation in mode 1
TANDEM-200 User Manual R1.7
34
13/02/2008
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.
Adjusting AES phase
The phase of the digital audio output may be adjusted with respect to the AES reference,
providing an AES reference is applied and the appropriate jumper link is set on the
DOP2-75 or DOP2-110 sub-board.
The AES output phase may be varied over a range of just over 360 degrees. The slider
readout display shows a reading of 0 to 127 for indication purposes only.
The AES output frequency is set by the frequency of the video signal carried by the SDI
signal. The AES output clock is synthesised at a fixed rate derived internally from the
TRS sync signals.
The AES reference input signal must be the same as that of the incoming video to be
useable, otherwise it will not work correctly. This is normally the case as the AES
reference signal and the embedded SDI audio data will have been locked to the station
master video source, so that the 48kHz sample rate and AES word rate are both
considered synchronous with the video signal.
