DVB-T2 (Second Generation Terrestrial) - Guidelines
Implementation guidelines for a second generation digital terrestrial television broadcasting system (DVB-T2)
Introduction
DVB-T2 is a standard for digital terrestrial television broadcasting, offering significant benefits compared to DVB-T (EN 300 744 [i.18]).
The present document is intended to serve a number of purposes.
DVB-T2 includes many new techniques not previously used in the DVB family of standards. Some, such as the P1 preamble, are completely novel, having been invented specifically for DVB-T2 and therefore are not yet discussed in the wider literature. The present document gives further information about these techniques.
The physical layer specification ( [i.1]) was written to be precise, rather than descriptive, and the present document aims to give a more extended explanation of the various elements together with some of the reasons behind the design of the DVB-T2 system. It attempts to capture as much as possible of the common understanding arrived at by the working group developing EN 302 755 [i.1]. It also gives additional information intended to make implementation easier, to act as a cross-check, and to help implementers to avoid some of the more common pitfalls.
As is conventional, [i.1] only describes the generation of the signal on the air, and the present document explains how the features of this signal are intended to be used in the receiver.
On the signal generation side, [i.1] is not always prescriptive: operations such as scheduling may be performed in any manner provided certain constraints or conditions are met. The present document suggests some methods by which these operations can be carried out.
The set of processing blocks described in [i.1] do not correspond directly to a piece of equipment, instead including elements of both a T2-gateway and a modulator. This expected topology is not obvious from [i.1] but is described in the present document.
Finally, EN 302 755 [i.1] allows a large number of options and combinations. Flexibility has been deliberately retained in [i.1] to allow optimisation as more experience and expertise is gained. However, initial implementations are expected to use a small subset of the possible combinations and the present document gives some guidance on the choice of parameters.
Readers who are new to DVB-T2 should begin with clause 4, which gives an introduction to DVB-T2, including a summary of the benefits compared to DVB-T [i.18] and an overview of the key new technologies included.
Broadcasters and other users of the DVB-T2 system requiring some guidance on the choice of parameters should see clause 5. The simulated performance results given in clause 14 will also be of interest to such readers, as will clause 12 which will describe aspects of network planning.
Readers requiring a deeper understanding of the structure of the DVB-T2 signal should see clause 6, which explains the key concepts and framing structures used in EN 302 755 [i.1]. This clause should also be studied before the clauses relating to detailed implementation, since those later clauses assume a working knowledge of the concepts described in clause 6. Many of the concepts, particularly the Interleaving Frame, are crucial to an understanding of the rest of the system.
Clause 7 describes some typical network topologies and also introduces the DVB-T2 modulator interface (T2-MI), which is designed to form the backbone of such networks; this is addressed both to network operators and also to implementers of T2-gateways and modulators.
Most of the remaining clauses are each aimed at implementers of a particular piece of equipment: the T2-gateway (clause 8), modulator (clause 9), receiver (clause 10), transmitter (clause 11), or tuner (clause 13). Whilst implementers should pay most attention to the relevant clause, receiver implementers in particular should consult clauses 8 and 9 in addition to clause 10 since some aspects of the signal that are addressed in connection with the generation of the signal are equally applicable to the corresponding demodulation process but are not repeated in the receiver clause.
Clause 16 discusses the T2-Lite profile and is a good starting point for readers who are familiar with DVB-T2 and would like to know about this new profile.
Clause 17 gives an overview of the transmitter signature specification and how it might be used.
Scope
The present document gives guidelines for the implementation of all aspects of the DVB-T2 end-to-end chain. This includes:
- the parts of the system defined by the physical layer system specification [i.1];
- aspects of the input pre-processing, which is outside the scope of [i.1];
- the modulator interface (or T2-MI) specification;
- future developments including a possible Transmitter Identification (TxID) standard.
The scope includes guidance relevant to implementers of T2-gateways, modulators, transmitters, receivers and tuners;network planners or operators; and broadcasters.
