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Reorganising channels between the Multiplexes, for example by moving some non-PSB services to the commercial Multiplexes
Switching transmitters from DVB-T to DVB-T2 Phase 1
The current situation
In the UK, digital television though an aerial is provided using six transmission multiplexes that broadcast using a standard called DVB-T. Two of these multiplexes operate in one mode - 64QAM and the other four in 16QAM mode. The former delivers more data - 24Mb/s compared to 16Mb/s, but is more susceptible to interference. The total capacity is 120Mb/s for all six:
As each region switches over, the multiplexes will be all switched to 64QAM mode - as the transmission power can be increased to compensate. This creates 24Mb/s of additional capacity:
Ofcom propose that the non-PSB channels on multiplex PSB2 be moved to the capacity created on the COM2 and COM3 multiplex. These can include ITV2, 3 & 4, E4, More 4. This will result in this configuration:
Now Ofcom propose that the BBC's capacity on PSB3 be moved to PSB2, like this:
Now Ofcom reclaims 7Mb/s from the BBC, making this allocation:
To provide universal coverage for five (or S4C or TeleG), some capacity is reallocated to PSB2 from COM1. This results in:
Now, as COM3 is now clear, it is repurposed for DVB-T2 transmission:
DVB-T2 is a new standard that uses 256QAM transmission mode combined with a new error correction protocol which delivers 30Mb/s, or about 25% more than 64QAM mode.
Also, all the transmissions will be in MPEG-4 (part 10) which offers better compression for standard resolution channels as well as high definition.
So, from 2009 the plan is:
And by 2017 the rest of the multiplexes have transferred to DVB-T2
Is this a good plan?
This plan will deliver three at launch rising to four full-time HDTV services to every home in the country as switchover happens, with reasonable bandwidth for each service.
However, this will be at the cost to those 8.5% of the population of some channels, such as ITV3, 4, More4 and E4 which they may have been expecting after switchover.
DVB-T2 is a draft standard and is not yet beyond the first draft stage.
Regional switchovers are due to start properly in November 2008; it is unlikely that DVB-T2 receivers could be available by then, as the standard is not yet defined.
Some multiplex owners may have been expecting to benefit from the additional capacity created at switchover for their own services.
Also, the BBC has 7Mb/s taken from it for services it is already running, which using statistical multiplexing on BBC One will not compensate for.
For most people the DVB-T2 transmissions should not require a new aerial, but only those wanting the HDTV transmissions would need to get one.
In addition, most current MPEG4 services use more than the 10Mb/s allocated to the DVB-T system, such as on digital satellite where the BBC service is 16Mb/s, Sky Sports 1 HD is 18Mb/s, Sky Box Office HD is 19.5Mb/s and Discovery 16.4Mb/s. However, increasing computing power and technological advancement increase the compression ratio over time, perhaps supplying good quality HDTV at just 10Mb/s will be possible, as MPEG-2 compression ratios have improved over time.
The DVB-T2 specification requirements
The DVB-T2 specification shall be designed for stationary reception. However, it
shall be possible to design DVB-T2 networks for all three receiving conditions, fixed,
portable and mobile.
Transmissions using the DVB-T2 specification shall meet the interference levels
and spectrum mask requirements as defined by GE06 and not cause more
interference than DVB-T would do.
The DVB-T2 specification should target the maximum increase in net payload
capacity over DVB-T with similar or better robustness than DVB-T under similar
The DVB-T2 specification shall provide a minimum increase in net payload capacity of 30% greater than DVB-T for any given channel profile under similar
The characteristics of the DVB-T2 specification shall not impair the ability to
perform, or efficiency of, statistical multiplexing of DTV Services.
The DVB-T2 specification should offer improved robustness against interference
from other transmitters, compared to DVB-T, potentially improving frequency reuse.
The DVB-T2 specification shall offer a choice of various robustness and protection
levels to be applied equally on all data of a transport stream carried by a DVB-T2
signal in a particular channel.
The DVB-T2 specification should offer a choice of various robustness and
protection levels for each service separately, within a transport stream carried by a
DVB-T2 signal in a particular channel. When more than one transport stream is
carried by a DVB-T2 signal in a particular channel the DVB-T2 specification should
offer a choice of various robustness and protection levels for each transport stream
The DVB-T2 specification shall provide a quality of service across the whole
channel that approximates to no more than one corrupted event (to any audio, video
or data services) per hour for HDTV and SDTV services.
Impulsive noise performance of DVB-T2 shall be no worse than the DVB-T
performance and should be substantially improved from that of DVB-T.
The DVB-T2 specification shall enable changes in modulation mode to be detected
automatically within 0,5s. However, the receiver may not be capable of performing
The DVB-T2 specification shall not introduce any more than 0,3s of additional delay
in receiver channel changing and service selection times compared to DVB-T.
The DVB-T2 specification shall be able to provide at least the minimum specified
increase in payload capacity over DVB-T using existing transmitter sites and masts
broadcasting to existing DVB-T domestic antenna and cable installations.
The DVB-T2 specification should be designed to allow lower cost transmitters (in
terms of both capital and operational costs) than currently for DVB-T (for a given
The DVB-T2 specification should enable larger scale SFNs than currently possible
with DVB-T. The maximum distance between adjacent transmitters in the same
SFN should be at least 30% larger than that offered by a comparable DVB-T 8k
mode for the same level of self-interference.
The DVB-T2 specification should enable the development of cheap and regulationcompliant
home gap fillers to ease indoor coverage, for fixed, portable and mobile
The DVB-T2 specification shall provide for local, regional and national coverage
areas in an economical way (i.e. optimising infrastructure costs and spectrum usage
including SFN and/or MFN techniques) whilst also meeting spectrum management
conditions and constraints as defined within the relevant international treaties and
Any changes to the Service Information delivery caused by DVB-T2 specification
shall be incorporated in the common DVB SI specifications.
The DVB-T2 specification shall support direct carriage of MPEG2 transport streams
and shall be capable of carrying all DVB transports including MPEG2 and GSE.
The DVB-T2 specification shall support the carriage of multiple DVB transports
simultaneously on a single channel.
The DVB-T2 specified signal shall be able to be received using existing DVB-T
domestic antenna and cable installations.
Your comments are always welcome. Please use the form below to add your thoughts or questions to this page. We will get back to you as soon as we can.
Dave Thursday 8 November 2007 8:02AM
I believe that only ~70% of the country have the ability to get cable? And absolutely no-one is interested in extending the cable network becos of the unrecoverable costs.
As Leftfield42 has stated the only group who could get it sorted are the Government but they won't commit the cash either.
Can't see BT upgrading old copper wire systems either as they are making no real money from their networks, so that just leaves us with Freeview or the Evil Empire!
One comment on Freeview boxes - I'm on my 3rd box in ~ 5years - can't see many (if any) people using the same box after 10 years!
Dave: Cable passes much less than 70% of UK homes. Virgin Media own ALL of the cable licences in the UK, it is not possible for anyone else to add to them at the moment. BT will upgrade their copper wire systems, and have been doing for a large number of years now. Just because YOU havn't got fibre doesn't mean that it is not in use!
How are Freeview viewers in SW Scotland to receive BBC1 & 2 (Scotland) and Radio Scotland under the above scheme?
My understanding was that an additional PSB1 mux would become available at digital switch over to allow both English & Scottish viewers to be served from Caldbeck transmitter.
Briantist,Don't disagree that BT are upgrading parts of the system - its just that the pace of replacement is of necessity (capital investment availability) slow!
As a non techie (as far as networks are concerned) it seems to me that they are trying to squeeze every last ounce out of the existing infrastructure - laudable but unlikely to allow HDTV to be transmitted to the masses.My exchange hasn't even got enough lines to make it worthwhile for ISPs to unbundle - so fibre??
As for cable - can't see Virgin ever building an economic case to extend the reach of their system (other than new City developments).
So - as I said - that leaves us(me!!) with either Freeview or the Dark Lord!
Dave: Just because it's not going to happen in the next six month's doesn't mean it won't happen before 2017. Virgin, for example, can upgrade all their existing customers to 100Mb/s with almost no effort and certainly no new equipment at their customer's end. You can watch HDTV using a current broadband link - using downloads or BitTorrents!
Ian: You are correct, the money goes to the treasury. One minute the frequencies are for "public good" and the next for a goverment tax.
"I'll tell you what happens with impossible promises. You start with a far-fetched series of resolutions, and these are then pickled into a rigid dogma, a code, and you go through the years sticking to that, misplaced, outdated, irrelevant to the real needs, and you end in the grotesque chaos of a Labour government, a Labour government, hiring consultant to scuttle round the airwaves handing out payment notices to its own voters. I tell you - and you'll listen - you can't play politics with people's jobs and people's homes and people's services" (apologies to Neil Kinnock).
OFComHD TV and DVB-T2:-The closing date for comments (30/01/08) has now passed. As soon as a decision is reached, I'm sure all those contributors to this page would like to know the outcome. Please .... If anyone has information on what was decided we would ALL like to know what is happening.
Ofcom are desperate to find some way to defend the indefensible, namely their decision to hawk off the spectrum currently used by analogue telly to the highest bidder, rather than reallocating it for HD terrestrial TV broadcasts.
Such is their need to deflect criticism on this issue, they are trying to fit a quart into a pint pot, and I can't see how it's going to work - not without disappointing a lot of people who have rightly high expectations of the picturequality we were all promised digital TV - whether SD or HD - would bring. Over compressed, blocky, pixellated telly with artefacts all over it is not what we want.
Charles: To be fair, a very small number of Freeview boxes are effected. DVB-T2 will start in 2009, and will only be used on a single multiplex. There are no plans to move any other multiplexes to DVB-T2 in 2012.
I have a new Panasonic 32inch TV with Vivera latest technology etc and this week the reception of all the BBC programmes is very poor , what is going on? I live in East Yorkshire and have not had this problem before!My old TV worked OK but that was consigned to the scrap yard.
We are going backwards, will reception improve ? 28-05-2009
using the dvb-T2 standard to provide HD means throwing and landfilling tons of freeview boxes/ HD ready tv's already sold irrisponsibly, when they could have axed loads of the crap channels shopping channels/gambling channels/porn channels, that would have made enough space for some good HD ones on the old dvb-t standard, we could all have enjoyed without new purchases required, DVB-t2 adoption has slowed down freeview HD uptake imo, and if nimo is coming in 2012 it seems quite a sad affair the bbc HD content on sky has pushed the sales of sky boxes for the last 3 years, whilst we waited for freeview to get its act together.
Brian : will any of the current HD receivers
not be compatible with the new DVB/T2 standard?
The document implies that the cunning plan is to "encourage" consumers to invest in new equipment so as to receive the interim services and later the all DVB/T2. Whether or not 700MHz is later cleared, consumers should be informed NOW which equipment will become redundant in a few years time. Some will find repeated landfill-and-replace unduly expensiv - and confusing.