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Improvements to Freeview transmission mode information

Following the changes to the commercial multiplexes that are now being rolled out over the main 80 transmitters, I have improved the information shown on the site.

Following the changes to the commercial multiplexes that are no
Published on by on UK Free TV

On each transmitter information page, there is a three-line description for each multiplex that lists the configuration used.

The first example shown here shows the new mode being used for the commercial multiplexes:



64QAM shows the number of "symbols" that are transmitted within each subcarrier, in effect in 8x8 positions. 8K is the number of subcarriers (which is actually 6817) used within the 8MHz UHF signal. 3/4 (three quarters, or 0.75) in this example is the amount of "forward error correction" used.

The second line shows the bitrates provided - in this example 27.1 megabits (million bits) per second.

The third line indicates the transmission standard used - DVB-T and the type of video encoding used, in this case MPEG-2.

The second example is from the Winter Hill transmitter, where a local television multiplex is broadcast:



Here the QSPK is a 2x2 position system, and results in only 6.0 megabits per second.

The third example shows the standard post-switchover configuration for the public service transmitters.



PSB1 and PSB2 use 64QAM, 8K (6817) but with forward error correction of 2/3 (two thirds, or 0.67). The use of this form of error correction provides 24.1 megabits per second.

PSB3 is used for Freeview HD, this showing on the third line as DVB-T2 MPEG4. DVB-T2 is a more advanced transmission system, with a number of enhancements over DVB-T. MPEG4 is also a newer, more efficient video encoding system.

The use of a 256QAM (16x16) symbol positions and 32KE (that's 27841) subcarriers results in a broadcast of 40.2 megabits per second.

The final example is from Rowridge, a transmitter in a pre-switchover state:



The low power digital transmissions use 2K (1705) subcarriers with a 16QAM (4x4), which results in 18.1 megabits per second per multiplex.

Bitrate comparisons

Compared to pre-switchover multiplexes 1, B, C and D:

  • Pre-switchover 2 and A: 33% more
  • Post-switchover PSB1. PSB2: 33% more
  • Post-switchover PSB3: 122% more.
  • Local TV: 67% less
  • Post-switchover COMs after changes: 50% more.






Your comments: most recent posts are at the bottom


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.

Alan Hunter
Saturday 29 October 2011 2:08PM
What has happened to the BBC Streaming channels on Freesat? They have disappeared from my box, and no amount of retuning will bring them back
Briantist
Saturday 29 October 2011 2:38PM
Alan Hunter: The have moved transponder, see www.ukfree.tv link icon BBC to reduce satellite transponders from seven to six on 7 October 2011 | ukfree.tv - independent free digital TV advice . I can confirm that they are working right now.
Alan hunter
Saturday 29 October 2011 9:36PM
So, how do I get the channels back, given that I have tried retuning the box, and that the information about the new transponder frequencies does not tie-in with anything I have on my sat box, which lists everything with PID's. Anyway of translating the new style into what is obviously the prehistoric style?
R walker
Sunday 30 October 2011 10:23AM Durham
Just got a freeview hd tv do i need a aieral upgrade for county Durham?
John Persijn
Sunday 30 October 2011 11:28AM

My broadband areal is pointed to the Malvern transmitter, with signals relayed from Sutton Coldfield. Due to engineering work on the latter, my signals suddenly dropped to below the normal receiving level. This caused some of the channels to disappear. My request is, is it possible to warn people when the main transmitter will loose power for periods on end??
David Pinfold
Sunday 30 October 2011 4:15PM Banbury
R Walker - It depends whether your aerial is pointing to Pontop Pike Or Bilsdale. Pontop Pike is broadcasting Freeview HD at low power but Bilsdale will not be until DSO next Septemner (according to data on these pages).After DSO both transmitters will have it a high power. Very good it is too.
dave
Sunday 30 October 2011 9:33PM Horsham
Whats happen to Film4 and challenge in the Horsham area? I can't get either of them anymore and no amount of re-tuning has bought them back. Especially frustrating regarding challenge as I can't watch TNA anymore!
Briantist
Monday 31 October 2011 9:23AM
dave: You are not in the official reception area for those services until 14th March 2012. I would have a look at www.ukfree.tv link icon Freeview reception has changed? | ukfree.tv - independent free digital TV advice but if that won't fix it you will have to wait for next March.
Briantist
Monday 31 October 2011 9:41AM
John Persijn: Yes, the information is carried on many pages on this site, see www.ukfree.tv link icon All transmitters with faults and engineering map | ukfree.tv - independent free digital TV advice .

However, your superstition is wrong, Malvern is line-fed by fibre optics and does not take signals from Sutton Coldfield over-the-air.
Briantist
Monday 31 October 2011 9:43AM
Alan hunter: See 11954 H on Astra 2B at 28.2°E - LyngSat .
Trevor Dores
Thursday 3 November 2011 12:58PM Bury St. Edmunds
Sir, On Tuesday 1Nov I tried to get my usual freeview station up, this happened to be 12 Yesterday, and got no signal. On checking other freeview channels I found I had lost a number of others. I have retuned the tv and the situation is the same. What has changed is I can now get ITV1,CH4, CH5 on freeview whereas before we had to change to freesat.Altogether I have lost ch11,12,15,18,19,20,21 etc. I live 12.5 miles from Sudbury in the Bury St Edmunds direction. Everything was working ok prior to this. Could you please advise mr on what the problem is? Thank you.
Len Beeton
Tuesday 8 November 2011 10:07PM Hull
I live in the Bransholme area of Hull. After the switchover fully to digital I found that I'd lost a few stations i.e. Yesterday, Film4 and ITV4 to name just a few.

I'm using a Goodmans set top box,
model no. GDB6

My reception for all other channels is very good but no amount of rescanning will bring the lost channels back. I just want to find out whether I have to buy a new box.
Dave Lindsay
Tuesday 8 November 2011 10:43PM Doncaster
Len Beeton: Those channels aren't at the same power (strength) from the transmitter which is probably why you aren't picking them up. On 23rd November they will be increased to their full power, so re-tune then.
Dave Lindsay
Tuesday 8 November 2011 11:03PM
Len Beeton: I found the instructions for your receiver here:

http://www.remote-control….pdf

You can try to add them manually now. There's no guarantee it'll work. It might say that they can't be picked up or it might get them but they keep breaking up, or you might be lucky and they work.

Press Menu, go to Installation and press Select. Go to Manual Search and press Select. It should ask for a UHF channel number (frequency).

For Pick TV/Dave/Really etc it is UHF channel 53.
For Yesterday/Film4/4Music etc it is 60.

As I say, the worst that can happen when you try it is that it says there is no signal, in which case you will have to wait until 23 November. (DN31NJ)
brian
Wednesday 16 November 2011 9:16PM Skipton
using the dvb signal strength and quality guide built into tv freeveiw tuner what is the minimum quality & strength on scale 1 to 10 to maintain consistant stable pic ie no freezing or pixalating
Greebo
Friday 18 November 2011 7:25PM
Brian - sorry no one can really answer your signal/quality question. Every receiver is different, there is no standard that the strength/quality scales adhere to. The only thing you can really do with these figures is compare your own system with itself as you make external changes - e.g. adjusting aerial position or replacing a dodgy cable. You can't even be certain that the values will be consistent across a firmware/software update on your receiver- though on most occasions they will be.
Glanville Carleton
Thursday 1 December 2011 9:45PM
I live just North of Cambridge (March)
Since the latest re-tune I can no longer receive "Look East" but only "Look North"
I have no interest in events in Grimsby or Hull.so how and when can I get my Anglian programmes back?

More to the point, how and who can I complain to?
Dave Lindsay
Thursday 1 December 2011 10:58PM
Glanville Carleton: The reason for this is because your receiver is picking up the signal from Belmont (whose principle service area is Lincolnshire and East Yorkshire) and it has decided to go with this instead of that from Sandy Heath.

What is the make and model of your receiver (TV or set-top box)? I will see if I can find the instructions for it and suggest how you might get it to do what you want it to do.
sheila macey
Sunday 15 July 2012 10:14AM
i have just purchased a panasonic television after having a freeview box but i cannot watch bbc 1 or 2 and some other channels what is the problem can youhelp please
jb38
Sunday 15 July 2012 1:47PM
sheila macey: With any question involving a reception issue its essential for a location to be given, and with this being in the form of a post code or at least one from nearby, as this will then enable the signal levels predicted for your area to be assessed.

Also, on the basis of what you have said it would be of assistance to know the model of Panasonic TV in question.
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