Question Aerial Help

Discussion in 'Freeview & YouView' started by taylor8, Sep 3, 2017.

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  1. taylor8

    taylor8
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    Thinking on chaining over to BT from Sky, need a new aerial as i cant seem to pic up any HD channels, current aerial is located in the loft, do you think i should go with an outdoor or just stick with indoor?? Thanks in advance
     
  2. jcjefferies

    jcjefferies
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    The obvious first question is will your TV receive Freeview HD? If it is just HD Ready then it wont pick up HD channels! If it dosnt have the "Freeview HD" logo then you will need a set top box to pick up the HD channels.
     
  3. taylor8

    taylor8
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    Thanks, Yes its got hd freeview but with the bt 4k box it dont matter as the aerial goes into the box anyway.
     
  4. winston2010

    winston2010
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    Outdoor is always better.
     
  5. taylor8

    taylor8
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    Thanks, so are all outdoor aerials mostly thr same? Any better than an other? Currently have on fitted in loft but its seen better days
     
  6. Rodders53

    Rodders53
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    ATV`s Choice Of Aerials for digital TV is worth reading (along with other bits of the website).

    First, though, go over all the cables and connections on your existing loft aerial system: re-make any suspect plugs and sockets, replace any crushed or kinked cables. 90% of problems are caused by poor connections and cables.

    If the signal is split to multiple outlets, see if the aerial connected as direct as possible (using cable joiners) gives you the HD channels... If so then an amplified splitter be required?

    A problem with loft aerials is that they can get knocked or moved, so check it is pointing to your transmitter correctly. A compass can help with that. Obviously if the current aerial is physically very damaged it will need replacing. Loft and indoor aerial installations for TV, FM and DAB

    I recall reading that the BT UHD boxes' tuners are fairly 'deaf', needing an above average signal input? They should still pass through the UHF signals to a TV set to allow its internal tuner to work. (RF loop through)
     
  7. TJT1

    TJT1
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    In addition to Rodders' excellent advice above, if you already have an amplified splitter/distribution amp, has it got a power supply connected and switched on.

    Another question that hasn't yet been asked is where are you located and what is your 'local' transmitter.
    If for instance you live 1/2 mile away from a main transmitter, then it is likely that a coat hanger poked into the aerial socket would do the trick.:D If however you live in a weak signal area, an outdoor aerial is pretty much essential.
    Without the aforementioned info, it is only possible to give very general advice.
    As winston said, outdoor aerials are generally 'better', but in a really strong signal area might even produce too much signal and overload the input stages to your TV/box. Whereas, in a moderate signal area, a loft aerial would be sufficient, and some might say, more aesthetically pleasing than an outdoor aerial.
    As you say that you are having a problem with HD, does this imply that the SD is all OK? Does your box/TV have a signal strength/quality readout anywhere in the menus? If so indicate what they are. A nearby postcode to you would help?
     
  8. taylor8

    taylor8
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    Screenshot_2017-09-03-20-35-33.png Thanks guys does this info help?
     
  9. TJT1

    TJT1
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    It doesn't tell us what the signal strength is at your TV/box, other than it should be pretty solid across all MPXs and your primary transmitter should be Durris.
    It also tells us that your your aerial should be pointing about 30 degrees to the West of due South.
    With all greens, it is possible that a horizontally polarised, correctly pointed loft aerial will be adequate.
    Rodders, what's that site that predicts signal strength?
     
  10. taylor8

    taylor8
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    Signal quality on some channels is 0% strength on most channels ranges from 10-38% max
     
  11. TJT1

    TJT1
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    Too low. Presumably the loft aerial has worked at some time or other? Is it pointed in the right direction? Is it horizontally polarised? Is there any sort of amplifier box in the cable? If the latter is present and not powered, this will remove most of the signal.
    Have you fully taken on board Rodders' post (paras 2 and 3) above and acted on it? If so, what were your findings?
     
  12. taylor8

    taylor8
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    Tbh not had aerial in as ive always just had sky, house is a new build well 6 years old now and aerial came installed with house, i did move it the other day with a signal tester so went up a bit and we got more channels, have a powered amp installed
     
  13. TJT1

    TJT1
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    But is it actually powered? What was the signal like on the signal tester? Which side of the amp did you connect it?
     
  14. taylor8

    taylor8
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  15. Rodders53

    Rodders53
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    55 kilometres from Durris 100kW erp PSBs, 50 kW COMs and 14.5/10kW for the temporary HD COMs. (-3dB, -8dB/-10dB). I'd suggest at that distance an outside aerial is most likely to be needed.

    From a guess of the area I got close-ish with Coverage Checker - Detailed View (56km and 209 degrees). For that postcode wolfbane.net predicts 48dBuV and line of sight (I think he calcs for the 50kW erp muxes) at 10 m above the ground outside.

    DTT design ideal for terminated signal level at TV outlets is 45-65 dBuV (50-65 preferably). Digital Signal Level for Engineers

    There will be a loss of at least 6dB for roofing materials. (10 is not atypical and stone tiles could be even worse). Aerial gain of 6dB (log, small contract). Cable and termination losses of say 3-6dB. Aerial height may also reduce the received signal level in some places.

    So do the sums: 48dBuV - 6dB +6db -6dB = 42dBuV at the TV outlet which is far too low.
    The Nikkai amp claims up to 10dB gain (but will add amplifier noise to an already low/noisy signal):

    42dBuV inside loft +6dB aerial +10dB amp -6dB termination/cable losses = 52dB (55 PSB, 52 COM but only 47/45 for the temporary HD muxes). So borderline OK for the main 6 muxes only.

    Television Aerial Boosters / Amplifiers, Splitters, Diplexers & Triplexers may explain why amplifying a poor signal doesn't actually help much.

    That is all 'best case' theory. Trees, taller buildings, if the loft is attached to others and there are extra walls in line to the transmitter then more losses will occur.

    Going outside with an 18-element aerial and maybe even a masthead amplifier may be required? (ATV`s Choice Of Aerials for digital TV recommends their Yagi 18 for build quality/robustness which may be applicable in this part of Scotland? The mounting pole and fixings to the building are equally - if not more - important!) Durris is and seems likely to remain a group A aerial transmitter site. So a group A aerial would be best, rather than a wideband or group K aerial (as the 700MHz clearance is imminent in Scotland).
     

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