The D-Book is the technical specification for UK digital terrestrial television (Freeview and Freeview HD).
The DTG has published and maintained the D-Book for over a decade and the specification is updated annually to keep up with the pace of development in UK DTT.
The D-Book is compiled by DTG working groups comprised of the DTG's staff and membership who continually update and peer-review the specification.
The DTG's test centre: DTG Testing tests digital TV products applying for the Freeview, Freeview + and Freeview HD logos against the D-Book standard. Any manufacturer wishing to use the Freeview HD logo on a product must pass the required DTG Testing Freeview HD tests.
The first edition of the D-Book was written in 1996 when the current UK standard for terrestrial broadcasting (DVB-T) was new and untried. Early editions of the D-Book enabled the publication of the European digital TV specification: the E-Book.
In March 2009, the DTG published the 6th edition of the D-Book—enabling the launch of an initial three free-to-air HD channels on Freeview by late 2009, as well as the introduction of a broadband return path which has the potential to be used for streaming on-demand video content such as BBC iPlayer, ITV Player and 4oD, accessing e-government services and allowing viewers to complete transactions via their television. It also introduced DVB-T2, the modulation scheme that is being used in the UK to deliver these services.
In March 2011 the DTG published D-Book 7 which was split into two parts. Part A was the detailed interoperability specification for digital terrestrial television (Freeview HD) while Part B introduced Connected TV and builds on the European HbbTV and OIPF standards to profile enhanced hybrid services. Connected TV is the convergence of ‘traditional’ broadcast digital television and the Internet to deliver new services, applications and programming (both linear and on-demand). D-Book 7 provided an industry-agreed baseline specification for Connected TV products and services that Sky, Virgin Media, YouView and others could build on for trademark requirements to support their services.
The D-Book 8 was published in March 2015, providing support for the new Freeview Play service, clearance of the 700 MHz band, smart retune to protect user settings during channel changes, over-the-air signalling of software updates via IP, and a standard method for displaying signal strength and quality.
It also removes D-Book 7 Part B, much of which has now been incorporated into HbbTV and is included or referenced in the new edition.