User guide

Setting up the SFN Functionality
H.1 SFN Adapter Functionality [MX8400/SWO/SFN]
H.1.1 Overview
The addition of SFN adapter functionality within the MX8400 allows SFN head-end
architectures to be designed without the need for third-party SFN adapters. The
SFN adapter produces an output transport stream which complies with to TS 101
191 V1.4.1.
Figure H.1 shows a basic representation of an SFN network.
Sync
system
Sync
system
SFN
Adapter
GPS
10 MHz 1 PPS
GPS
10 MHz
1 PPS
GPS
10 MHz
1 PPS
T
S
T
S
T
S
Distribution
network
Multiplexer
modulator
DVB-T
modulator
DVB-T
Figure H.1 Basic SFN Network
The SFN adapter provides the information within the outgoing transport stream to
allow all Modulators operating within the same SFN network to broadcast in a
synchronized manner. The synchronization of the data broadcast from each
Modulator is achieved by having a common framing structure. That is a common
mapping of transport stream packets to COFDM modulation frames on all
Modulators within the network by using a mega-frame
1
.
H.1.2 Mega-frame Initialization Packet (MIP)
The SFN adapter dictates the start of the each mega-frame, and the DVB-T
modulation mode determines the mega-frame length. The SFN adapter inserts a
mega-frame initialization packet (MIP) into the outgoing transport stream. One MIP
is inserted in each mega-frame.
1
Mega-frame: A group of transport stream packets that correspond to 8 DVB-T frames in 8K mode or 32 frames in 2K modes, and
containing a single MIP.
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