User's Manual Part 3

Screen Service SDT 501 UB-C ARK 1-T Operations
May, 2010 v 1.0 Page 3 - 161
Appendix A. Seamless input switching
The Ark1-T device provides the functionality of seamless input auto-switching. This switching
occurs between primary and secondary input selected, under the following restrictions:
• The device is working in SFN mode;
• The frequency reference selected is external or GPS;
• The two inputs are both ASI, and contain the identical stream.
Under these conditions, when primary input becomes not locked, the device automatically
switches to the secondary input. No errors in synchronism bytes or in continuity counters can
be observed in output transport stream. If primary input became locked again, the device
would automatically switch to the primary input, with no errors in synchronism or in continuity
counter.
At the status of the art this functionality is implemented only for ASI inputs, so in Java or
SNMP interface only ASI inputs can be selected as secondary input. The SFN mode with
external frequency reference is required in order to allow the device to achieve the
synchronism.
synchronism.