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Freeview coverage

Discussion in 'Freeview & YouView' started by HAB, Aug 29, 2005.

  1. HAB

    HAB
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    From where I live I can receive 4 of the 6 Freeview multiplexes available at my nearest transmitter (Crystal Palace), which is about 50 km distant. This is precisely what the DTG postcode checker predicts.

    Each multiplex appears to have the same power, they are all on very similar frequencies and I assume that they each use the same type of aerial. The only other factor I can think of which would affect propagation is the height of the aerial up the tower. Since my village is probably partially obscured by a nearby "hill", I could believe that this is the case, especially since a friend who lives on top of that hill (about 50m higher up than me) can receive all six multiplexes.

    Can anyone shed any light on this and/or provide me with a better explanation. Thanks in advance for your help.
     
  2. nigelbb

    nigelbb
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    When we got Freeview for my Mum in Chelmsford Essex we had to get a new aerial that looked like a death ray plus a signal booster. With this gear she received all the multiplexes from Crystal Palace which must be more than 50km away. In fact she got good reception on analogue from TVS broadcasting from Hampshire the other side of London from Essex!
     
  3. SamRadford

    SamRadford
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    A typical aerial does not have linear gain. The gain tends to be lower at the top and bottom end of the frequency spectrum. Apart from that, you may be using aerial and cable that was installed for analogue reception on frequencies higher or lower than those used for digital. The only way to find out is to install the proper aerial and cable.
     
  4. Heinz

    Heinz
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    Strange one this. The UHF channels used for analogue from CP and Croydon range from 23 to 37 and haven't changed recently (five on 37 was the last to be added but, until then, BBC2 on 33 was the highest). A Group A - H aerial has been needed for years.

    The UHF channels used for analogue from CP and Croydon range from 22 to 34 - so the same aerial group (A - H) is required.
     
  5. HAB

    HAB
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    Thanks for the replies.

    You can probably understand that I'm not too keen on spending lots of money on a new aerial and cable when a) the signals I can see have good strength and picture quality and b) DTG predicts that there is no coverage for the multiplexes I can't see. It seems to me like it would be a waste of time, effort and money to try.

    I'm still puzzled that two signals in the same fairly narrow band coming from the same tower should have such different outcomes. I suppose if one aerial were omni-directional and the other fairly strongly directional, that might make sufficient difference, but I find it hard to believe that variation in aerial gain between channels 22 and 25 could account for the (I guess) 10 dB difference between good reception and none at all.

    Given that the area has a well-established cable service, what is the likelihood that ITV, C4, C5 et al will ever provide DTT coverage ? Anyone ?
     
  6. ED_UK

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    Hab, sounds to me like a similar situation to my own(although my problem is in Yorkshire, receiving from Emley Moor).

    I've put my problem down to the transmission mode on the 2 MUX's (2 and A) that I get problems with. MUX's 1, B, C and D are all QAM16, MUX's 2 and A are QAM64. Basically, this means more data is crammed in the bandwidth, which reduces the error tolerance.

    Look at point 10. on this link...
    http://www.digitalspy.co.uk/terrestrial/faq/

    I'm still in the process of deciding how to remedy my situation - several postings seem to suggest that whatever I do could be a waste. If the signal I receive is too poor in the first place then amplification will also increase any 'noise' received.

    I've already installed a highgain antenna with reasonable improvement but I dont want to waste money on a hopeless cause so will read your responses with interest.
     

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