The old analogue television services, for example 鶹Լ 1 or 鶹Լ 2, were broadcast from a transmitter using separate frequencies. Digital television allows us to bundle a number of televisionservices into what is known as a multiplex and to broadcast them all on one frequency from a transmitter.Your television, or set- top box, then pulls out each individual service inthe multiplex and allows you to watch it.
Anumber of multiplexes can betransmitted from each transmitter site, allowing a wider range of stations to be broadcast.
Freeview multiplexes
There are three public service broadcast (PSB) multiplexes.The 鶹Լ runs two of them and they are known as PSB1 and PSB3 or sometimes 鶹ԼA and 鶹ԼB. There isalso a set of commercially-operated multiplexes, known as COM4, COM5, COM6 andCOM7. Plus,in some areas, there are local television multiplexeswhich usually start with LTV.
Since the 鶹Լ has more services that can fit into PSB1 and PSB3, it has leased asmall amount of capacity on the commercial multiplexCOM7.
We keep anupdated list of all our services on the various multiplexes
Why do we use multiplexes?
Using a multiplex enables us to broadcast a number of televisionchannels at once using just a single frequency.This allows broadcasters to use the spectrum allocated to televisionto the maximum, giving you more stations to choose from.We are able to do this using technology that allows the television channels to be compressed together into a multiplex and thenfed to the distribution network for transmission.
We can also add in radiostations, Red Button data services, subtitles and audio description into a multiplex. Each multiplex also carries the service information which includes the data needed for EPGs.
Digital transmission needs less power than analogue, so it is more cost-effective and environmentally friendly.
How many multiplexes can I get where I live?
The 鶹Լ’s two multiplexes (PSB1 and PSB3) are broadcast from over a thousandtransmitters across the UK, along with PSB2, which carries services such as ITV, Channel 4 and FIVE. Between them they cover over 98.5% of the population. Only PSB1 and PSB3 are funded by the licence fee.
The commercial multiplexes (COM4, COM5 and COM6) are broadcast from a much smaller number of transmitters and cover 90% of the population.There is also COM7multiplexwhichbroadcasts from even fewersites and cover about 63% of the population.
In some cities and surrounding areas, one or more Local TV multiplexes may be available. These carry a channel dedicated to the local area, plus some additional commercial services.
Use ourtransmitter checker tool to find outwhich transmitters you can tune toand the multiplexes available on those transmitters.
Reception Problems
If you have a reception problemwith one service in a multiplex, youwill also have problems with all the other services in that multiplex. It is also possible for the signal strength and quality of one multiplex to be different from another. This could be due to the different frequencies used, the power of the transmitter andthat not all multiplexes are broadcast from the same antenna on the site.
The ourtransmitter checker tool can give you an indication of the expected quality of the multiplex signal you can receive at your location.
