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Why do the six Freeview "multiplexes" have twenty different names?

There are twenty names - 1, 2, A, B, C, D, PSB1, PSB2, PSB3, COM4, COM5, COM6, BBCA, BBCB, D3+4, SDN, ArqA, ArqivaA, ArqB and ArqivaB, given to the six terrestrial digital services... why?

There are twenty names - 1, 2, A, B, C, D, PSB1, PSB2, PSB3, CO
Published on by on UK Free TV
All digital television services - from cable and satellite to terrestrial transmission - were planned and implemented to use the existing "analogue" broadcasting infrastructure.

The engineers who designed the services created digital broadcasting systems that would allow the reliable distribution of bits using the same infrastructure of cables and masts (or satellites) that already carried the analogue services to millions of homes.

Part of the design process allowed for more than one television channel to be carried by the digital system using a long-established data-processing technique called "multiplexing", a word that had, by another route, also come to mean a cinema complex where several films are shown at once on different screens.

It was back in 1996 that Parliament decided that the UK should have a six-multiplex service.

The www.legislation.gov.uk link icon Broadcasting Act 1996 provided that these "multiplex licences" should be issued for 12 years with a one-time right-to-renew.

Independent Television Commission: 1, 2, A, B, C and D

The regulator at the time, the web.archive.org link icon ITC (Independent Television Commission) said:

The current coverage figures range from around 90 per cent of the UK population for the largest of the multiplexes down to around 70 per cent for the smallest.

Of these six multiplexes, two are wholly reserved for existing broadcasters who are guaranteed places on the multiplexes under the Broadcasting Act 1996. The first will be used by the BBC to transmit existing programmes in digital form and develop new digital services. The second is reserved for Channel 3, Channel 4 and Teletext Ltd whose existing services will be reproduced in digital form, and who can use the additional capacity available for new services. This multiplex will be licensed and regulated by the ITC.

Licences to operate the remaining four were advertised and three have now been awarded to British Digital Broadcasting plc (BDB). The fourth multiplex, the third largest in terms of UK coverage, has been awarded to S4C Digital Networks Ltd (SDN). It will carry the new Channel 5, S4C in Wales, and a certain amount of Gaelic programming during peak hours in Scotland.


The ITC named the "wholly reserved" multiplexes 1 and 2, and the others, by the level of coverage: A, B, C and D.

British Digital Broadcasting, ONdigital and ITV Digital

British Digital Broadcasting plc eventually launched their service as ONdigital on 15th November 1998, re-launched as ITV Digital on 11th July 2001 and went out of business on 1st May 2002.

ITV Digital handed back B, C and D multiplex licences to the regulator, who awarded them to the promise of a free-to-air service the BBC and Crown Castle International, a company formed by the privatization of the BBC's transmitter network.

Freeview

When Freeview started on 30th October 2002, the BBC realised that the existing broadcasting "mode" used for the digital services was causing problems for some viewers. For this reason, some multiplexes changed from "mode 1" to "mode 2" (see the diagram at the end of the article), which provided a more stable signal, but with the loss of some channel capacity. See www.ukfree.tv link icon Freeview modes - a simplified explanation for a longer discussion about this.

This was not a problem for the BBC with six full-time television channels to fit onto two whole multiplexes. So, multiplexes 1, B, C and D changed to the robust mode, but 2 and A did not.

Ofcom plans PSBs and COMs

During the planning for the digital switchover, where the existing analogue channels are turned off over several years, Ofcom, now the regulator used the names PSB1, PSB2, COM4, PSB3, COM5 and COM6 to refer to the six multiplexes.

PSB refers to the "public service broadcasters" (BBC, Channel 3 licence holders - ITV plc, STV and UTV, Channel 4 Corporation, S4C - Sianel Pedwar Cymru, Channel 5 and the "public teletext service".

The PSB multiplexes have almost total coverage of UK homes - 98.5%, and are broadcast from all television masts in the UK, including 1,036 smaller ones that only carry the PSB services.

COM is an abbreviation of "commercial", referring to the two multiplexes held by Arqiva, the company that owns and operates all of the UK television transmitters, and SDN, a company owned by ITV plc.

The COM multiplexes have coverage of around 90%, and are broadcast from the main 81 transmitters.

Because this planning required that all multiplexes move to "mode 3" the post-switchover multiplexes these new descriptions have been widely used to represent the "final" multiplexes, even though legally they are named 1, 2, A, B, C and D - see licensing.ofcom.org.uk link icon Ofcom - Multiplex licensees.

The introduction of Freeview HD has seen the BBC change the use of the BBC multiplex to "DVB-T2" mode, and in addition, during 2012 the commercial multiplexes have changed to "mode 8 configuration", which has increased their capacity by another 12.5% - see www.ukfree.tv link icon Changes to commercial multiplex capacity - 2012 timetable .

Eight more names

Digital UK now refers to the multiplex by the name of the ower, usually four letters, but sometimes the written in full, so we now have:

Multiplex 1 is also known as PSB1 and also BBCA


BBCA denotes the first BBC multiplex when in "mode 3", with all the services from "mode 2" multiplexes 1 and B. This multiplex has many regional versions to supply BBC regional news on BBC One.


Multiplex 2 is also known as PSB2 and also D3+4


The legal owner is "Digital 3 and 4 Ltd", which is half-owned by the Channel 3 licensee, and half-owned by the Channel 4 Corporation. This multiplex has more than 20 regional versions to supply regional news on ITV 1/STV/UTV, plus advert regions for that station, Channel 4, Channel 5 and the channels 3 and 4 "plus one" services.


Multiplex A is also known as COM4 and also SDN


SDN, originally "S4C Digital Networks" was sold to ITV plc in April 2005 for £134m. The SDN multiplex has two versions, one for Wales, where it carries E4 and one for the rest of the UK.


Multiplex B is also known as PSB3 and also BBCB


BBCB denotes the first BBC multiplex when in "mode 6" which is used to carry, by arrangement with ITV/STV/UTV, Channel 4/S4C, the Freeview HD service.


Multiplex C is also known as COM5 and also ArqA (or ArqivaA)


The "mode 3" (now "mode 8") post-switchover ArqA/COM5 multiplex carries all the services on "mode 1" Multiplex C, with space for couple of extra TV channels.


Multiplex D is also known as COM6 and also ArqB (or ArqivaB)


The "mode 3" (now "mode 8") post-switchover ArqA/COM5 multiplex carries all the services on "mode 1" Multiplex D, with space for couple of extra TV channels, which include 4seven and two subscription channels, Sky Sports 1 and 2.


Freeview standard transmission "modes"

UK Freeview modes

The above diagram illustrates the capacity of different ONdigital/ITV digital/Freeview transmissions over the years. The longer the bar, the more bits are transmitted per second. Mode 2 is 16QAM, mode 7 is QSPK, the DVB-T2 modes are 256QAM, the rest 64QAM.





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L
Lee
Sunday 6 May 2012 1:38PM

Yea will do , am going to try it, will be later in the week as I don't have a laptop with a com port, and will be getting a local pc shop to do the transfer for me, rather than using a usb to rs232 adaptor.


L
lee
Tuesday 15 May 2012 4:15PM

The update worked ! It is a Digihome DTRO202. Thanks. I'm well pleased.


J
jb38
Tuesday 15 May 2012 6:07PM

lee: Good news then! although I would have liked the serial number associated with your model of box so that I could tag it as being from a serial number onwards that the update works on, as subtle changes to a devices circuitry always takes place during long batch runs, and with this in many cases being why an update will work on some models but not others even although the model to all intents is the same.


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