Freeview modes
Brian Butterworth published on UK Free TV Two of the Freeview multiplexes (collections of channels) broadcast in one mode known as "64QAM mode, FEC=2/3,", and the other three broadcast in another mode called "64QAM mode, FEC=3/4".
The " FEC=2/3" mode provide a more reliable signal than a "FEC=3/4" mode signal at the same power level, but there is a trade-off that means less digital data can be carried.
This diagram shows the current channels carried on the Freeview system. The wider the box, the more bandwidth is used to carry the pictures. The more bandwidth used for a service, the better the picture quality.
Boxes split horizontally denote channels that occupy the bandwidth at different times of the day.
The third line shows the configuration of the BBC "B" multiplex switchover which is used for HD and is in another mode DVB-T2 256QAM.
64 QAM (3/4) mode
In this mode, the digital TV signal is transmitted in groups of 64 symbols. The "forward error correction" is 2/3, and this results in a bitrate of 24M.1b/s (megabits per second). This can be used to carry up to eight simultaneous television channels.64 QAM (2/3) mode
In this mode, the digital TV signal is transmitted in groups of 16 symbols. The "forward error correction" is 3/4, and this results in a bitrate of 27.1Mb/s. This can be used to carry ten simultaneous television channels.Help with Television sets?
Sunday, 11 December 2011
Jon: Have you tried manually tuning the missing multiplexes in on the HDTVs?
Different pieces of equipment are of different sensitivity.
Where is your booster? Does it provide a signal for each outlet?
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Monday, 9 January 2012
Hi,
Great forum. I am trying to get my head around this so bear with me. I have recently moved in , I have a new aerial that comes into my lounge and - plunged directly into the telly or BT Vision box - I can get all channels. However, when I use the Digital compatible Amplifier to link up the aerial boxes in the bedrooms I have managed to get what appears to be 1, B, C & D but not 2 and A - ie. ITV, Channel 4 etc, transmitted on 64QAM according to this forum.
Given that I can get those channels when directly using the aerial can I assume that the problem is interference between the Amp and the other rooms? Should I buy the better connectors I have seen recommended? Or is it more likely a cable problem?
Hope I have explained this sensibly, hope someone can help, thanks,
Paul
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Paul's: mapP's Freeview map terrainP's terrain plot wavesP's frequency data P's Freeview Detailed Coverage
Paul Chapman: If I were you I would connect the incoming aerial directly to the feed to the TV which is unable to show Mux 2 whilst connected via the amplifier.
It may be that the loss is too great in the lead that feeds the socket in the bedroom. You might be able to overcome this by increasing the level of amplification.
If all else fails, you could try tuning the upstairs TV(s) to the equivalent multiplex from Sandy Heath (Ch24) or Sudbury (Ch41). There's obviously no guarantee that it will work, but it may be better than nothing from Crystal Palace.
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Paul Chapman: I would use an analogue TV upstairs and see what quality picture you get and compare it (using the same TV) to the signal that you are putting into your downstairs TV and BT Vision box.
So get an analogue TV, try it downstairs directly from the aerial, then with the amplifier fully connected and the analogue TV connected to what would be fed into the BT Vision box. Then take the same TV upstairs and connect to the bedroom socket.
Whilst it's upstairs (indeed whilst it's downstairs as well) you could compare the signal via the amp (split) and with it directly from the aerial.
Is there more grain on the upstairs picture? Does moving connectors around immediately make a change? If the bedroom has a wall socket with a separate fly lead, then try a different fly lead and see if there is less grain on the analogue picture.
With the analogue with the least grain you can get (e.g. having changed the fly lead), try and tune in the upstairs TV (if you haven't done so already). Indeed, you could perhaps take the upstairs TV downstairs to tune in Mux 2 and then return it to the bedroom.
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J
jb389:45 PM
Jon: If I could just ask for a point of clarification, what type of multi-outlet powered splitter are you using? and forgetting about the bedrooms for the time being, what results do you get if you connect the aerial into the splitter and use "any" of its output sockets to connect back into the TV in the same room?, or is it when you do that problems occur.
The reason I ask is that I cant quite determine if you have tried that or not, or are purely referring to the results observed from TV's in other rooms.
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Saturday, 14 April 2012
L
Lynne Sayers6:36 PM
Hi
I am trying to help an elderly neighbour with her tv in her bedroom. She has bought a digi box for this tv and we have tuned her tv and she gets everything but ITV, Channel 4 and 5. If we plug the tv into the ariel downstairs the digi box and tv picks up all channels. Cannot fathom it, can you help?
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Lynne Sayers: Can you give some more information such as location as it is impossible to be very specific. Is the aerial used for the bedroom the same as used for (I presume) the lounge?
What I will say is that if your neighbour is served by any of the London transmitters, then this will likely right itself on Wednesday.
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Friday, 8 June 2012
T
Terry12:43 PM
Lytham St. Annes
Hi,I live in post code area FY8 2RB and have recently purchased a Sony DVD SVR-HDT500 so that we can record and watch HD programs.The problem is that HD programs are breaking up and sound going out of sync,the shop where it was purchased has said it is a problem with the signal quality and the cable was letting in water,i have had new cable and also a connector was fitted to reduce signal strength which seemed to cure it for a couple of days but the problem is back. This is an intermittent.
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Terry's: mapT's Freeview map terrainT's terrain plot wavesT's frequency data T's Freeview Detailed Coverage
J
jb385:20 PM
Terry: Although you are located at 24 miles away from Winter Hill you could still be receiving a signal thats on the verges of being on the high side, and that will always affect HD transmissions before SD.
I notice you mention that you have an attenuator fitted, is this a variable type or is it fixed, and if the latter what db level is printed on it?
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Tuesday, 12 June 2012
B
Bryn Howells8:48 AM
Hi,
I live in Nottingham, post code NG72PG.
Last night (11/06/12) my icecrypt PVR box suddlenly convinced itself that it had lost all channels. When this has happened before I've simply switched iit of for 10 mins and retuned, and then everything is fine and back to normal.
However on this occasion when retuning, depsite all the channels I normally recive (which is basically all of them) showing up during the scan, when the scan is complete I can now only get the BBC channels to view (the tv guide/channel list show only the bbc channels there). I have tried re-scaning multiple times.
If there is any advice you can give me it would be much appreciated.
Cheers, Bryn
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