24 Functional Description
CP560 DVB-T2 Gateway User’s Manual Rev. 2.2 (3686) ID: um_t2gateway
5.3 TS output
The CP560 generates a T2-MI output. When using ASI output,the transport stream is presented
on at least one ASI output port. In addition one port is programmed to carry the same signal,
as described in chapter
6.1.2.
The output is always re-clocked, configuring a wanted bitrate for the output stream.
The CP560 can transmit the same transport stream over IP via the extra physical Ethernet data
connector(s) or via an SFP module inserted in the SFP slot.
5.4 SFN adapter
The product is fitted with an SFN adapter that generates an accurate DVB-T2 timestamp. This
enables synchronisation of the output clock to the Network Time Protocol (NTP) or a 1PPS
signal for operation in SFN networks. The 1 PPS signal can be taken from an external source.
5.5 Video over IP
5.5.1 Input and output
The CP560 supports MPEG transport streams over IP, the functionality is protected with a
separate SW licence.
The CP560 has 8 IP inputs, these are modelled to have the same functionality as the ASI input
ports, and content received will be available to the DVB-T2 Gateway generating the output. The
input streams can be either SPTS or MPTS and streams with or without RTP layer are accepted.
The DVB-T2 Gateway can generate one output and the operator chooses whether to transmit
this stream over IP or not.
Two Ethernet interfaces can be used simultaneously for video carriage, the interfaces are bi-
directional. When using the SFP slot, one of the Electrical interfaces will be disabled.
5.5.2 Protocol mapping
Ethernet
14 bytes
[IEEE 802.3/802.3u]
IP
20 bytes
[RFC 769]
Optional
VLAN
4 bytes
[802.1q]
UDP
8 bytes
(RFC 768)
RTP
12 bytes
(RFC 1889)
1-7 MPEG TS packets
188 – 1316 bytes
[ISO/IEC 13818-1]
Figure 5.2 Protocol mapping
When transmitting T2-MI streams over IP, the protocol mapping is according to figure 5.2. The
VLAN framing and RTP encapsulation are optional.
The RTP layer is important for diagnosing network related problems, since it contains a sequence
number that can be used for packet loss detection.
The maximum transfer unit (MTU) for Ethernet is usually 1500 bytes. This limits the number of
transport stream packets to embed into the outgoing Ethernet/IP frames to be between 1 and
7.
5.6 T2-gateway module
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