This Application shows how the combination of the T-VIPS TNS541 Seamless TS Monitoring Switch and the CP560 DVB-T2 Gateway enables seamless switching for DVB-T2/SFN digital terrestrial networks. Given the importance of DVB-T2 delivered television it is critical that network operators can ensure uninterrupted TV.
- The solution ensures reliable SFN operation and prevents DVB-T2 modulators losing sync.
- The solution is based on 1+1 redundancy between two independent CP560 Gateways and the TNS541 Monitoring Switch. This combination makes it possible to switch between redundant transport streams in such a way that the T2-MI stream structure and time-stamps at the output of the TNS541 are unaffected.
- This will prevent service outages caused by DVB-T2 modulator resynchronization, a process that typically causes the transmitters to power down until modulater operation has been correctly restored. The transmitter power-up can take a number of minutes to complete. This resynchronisation and power down/up will take place at all modulators and transmitters in a SFN region, consequently a large number of customers would be affected.
The TNS541 aligns the two T2-MI streams coming from the Gateways and runs a matching algorithm comparing these streams. The TNS541 selects the best stream as the active source and transmits through its outputs. The switch continuously analyses the streams and ensures the continuity and order of the Time Stamp Frames. When a switch is performed the order and continuity of the SFN information (Time Stamps) is not interrupted nor duplicated. This avoids a re-synchronization that often causes very considerable loss of service. Monitoring of the streams coming from the Gateway, allows the TNS541 to detect a distortion of the streams and perform a switch to the “healthier” source