T-VIPS CP560 - 10.5 Seamless SFN operation

Examples of Use 153
ID: um_t2gateway CP560 DVB-T2 Gateway User’s Manual Rev. 2.2 (3686)
DVB-T2
Gateway
DVB-TS
T2-MI
(ASI or IP)
DVB-T2
Modulator
T2-MI network
ASI, IP or a combination
T2-MI
(ASI or IP)
DVB-T2
Modulator
T2-MI
(ASI or IP)
Figure 10.1 Distribution via DVB-T2
Gateway and T2-MI interface
This example briefly gives needed configurations related to SFN operation.
1. Connect 1PPS and enable Clock Regulator if not already enabled.
2. Under the "DVB-T2", "Main configuration" set the "Timestamp type" to a Relative or
Absolute timestamp type.
− Selecting "Relative" will make the gateway stamp the DVB-T2 superframes with a
transmission time, specifying only the sub second part.
− Selecting "Absloute" makes the timestamps contain both sub seconds and a second
count.
3. Specify a "Estimated transition time" in milliseconds. This value should take into ac-
count all delays (buffers) from the CP560 to the transmission time in the modulator.
Current suggestion, 500 ms. (150 ms modulator processing time + 250 ms network
delay + 100 ms extra buffering)
Now connect two or more modulators to the same CP560 ASI or IP output, and have them
transmit in a SFN.
10.5 Seamless SFN operation
The CP560 DVB-T2 Gateway may synchronise it’s T2-Timestamp and internal packet scheduling
such that two different CP560’s will generate identical T2-Timestamps at the same time, given
that they are synchronised properly. There is no need for any direct communication between
the units for this to function, but the units must use the same SNTP and 1PPS references.
This synchronisation is essential when using CP560 in a Seamless SFN system with the T-VIPS
TNS541 TS Seamless Switch. See figure 10.2 for an overview of a Seamless SFN system.
DVB-T2
Gateway
T2-MI
(ASI)
DVB-T2
Modulator
T2-MI
(ASI)
DVB-T2
Gateway
T2-MI
(ASI)
TNS541 TS
Seamless Switch
SNTP & 1PPS
TS
Figure 10.2 Seamless SFN system