Improvements to Freeview transmission mode information
Brian Butterworth 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.
Alan hunter: See 11954 H on Astra 2B at 28.2°E - LyngSat .
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12:58 PM
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.
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Trevor's: mapT's Freeview map terrainT's terrain plot wavesT's frequency data T's Freeview Detailed Coverage
10:07 PM
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.
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Len's: mapL's Freeview map terrainL's terrain plot wavesL's frequency data L's Freeview Detailed Coverage
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.
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Dave's: mapD's Freeview map terrainD's terrain plot wavesD's frequency data D's Freeview Detailed Coverage
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)
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9:16 PM
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
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brian's: mapB's Freeview map terrainB's terrain plot wavesB's frequency data B's Freeview Detailed Coverage
7:25 PM
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.
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9:45 PM
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?
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