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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 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.


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Comments
Saturday, 29 October 2011
A
Alan Hunter
2:08 PM

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

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Alan Hunter's 2 posts GB
A
Alan hunter
9:36 PM

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?

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Alan hunter's 2 posts GB
Sunday, 30 October 2011
R
R walker
10:23 AM
Durham

Just got a freeview hd tv do i need a aieral upgrade for county Durham?

link to this comment
R walker's 1 post GB
J
John Persijn
11:28 AM

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??

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John Persijn's 3 posts GB
D
David Pinfold
sentiment_satisfiedBronze

4:15 PM
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.

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David Pinfold's 42 posts GB
D
dave
9:33 PM
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!

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dave's 1 post GB
Monday, 31 October 2011
Briantist
sentiment_very_satisfiedOwner

9:23 AM

dave: You are not in the official reception area for those services until 14th March 2012. I would have a look at 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.

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Briantist's 38,844 posts GB
Briantist
sentiment_very_satisfiedOwner

9:41 AM

John Persijn: Yes, the information is carried on many pages on this site, see 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.

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Briantist's 38,844 posts GB
Briantist
sentiment_very_satisfiedOwner

9:43 AM

Alan hunter: See 11954 H on Astra 2B at 28.2°E - LyngSat .

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Briantist's 38,844 posts GB
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