Topfield channels awol: is it just signal strength?

Discussion in 'Digital TV & Video Players & Recorders' started by teabelly, Mar 7, 2006.

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  1. teabelly

    teabelly
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    For some reason on itv & c4 and the associated muxes I can't get any of the channels properly. The signal quality and signal strength are below 50%. I don't understand why this has suddenly happened and why the dtt usb tuner I have upstairs picks up the same channels off the same aerial without bother. I have noticed the signal strength dropping slowly on some of the channels since I got the box, it has mostly dropped then settled into a lower region. I am using a signal booster to get two aerial signals for the dual tuners rather than having one and using that short lead thing. Doing it this way leads to better signal strength but slightly poorer signal quality. Without it Channel 5 can be marginal. Annoyingly channel 5 and that mux is fine but the c4 one with more4 is black. The missing channels came back briefly but typically when I wanted to record from them they had gone again. Both tuners seem to be afflicted as far as I can tell.

    Is there something wrong with the tuners in the topfield or is it atmospherics? If the latter than it is pretty useless that weather stops you watching most of the channels altogether. At least with analogue even when it was a dreadful picture you could still follow the programme!

    I have tried to make sure the connections are sound and they seem ok. The dtt box upstairs is showing full signal (or 90%) for the affected channels even though the topfield is showing 60% strength and no picture at all.

    Any ideas as to the best course of action? Is it likely to be a faulty box? I hope not as being without it will be hell and I can't imagine empire direct will do the decent thing and offer an immediate replacement or a loan unit. I don't think I want to do cold turkey :)
     
  2. chrise

    chrise
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    Teabelly

    Having just got a Topfield myself I cannot claim to be an expert but where I would start is checking that you have picked up the correct channel for that MUX. ITV and Channel 4 are on MUX 2 This site lists the frequencies used by transmitters http://www.dtg.org.uk/retailer/transmitters.html. Check that the Topfield is correctly tuned. It might have picked up a weaker signal from another transmitter.

    It seems unlikely that the tuner is faulty if it is picking up the other MUXs correctly. My money would be on an aerial problem. Perhaps in the wiring to downstairs as my Topfield is very much more sensitive than the Hauppauge USB tuner I was using before.

    Best of luck
    Chris
     
  3. LV426

    LV426
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    My first suspicion would be either:

    a) whatever it is you use to split signal between the upstairs kit and the Topfield or
    b) the cabling between the above splitter and the Topfield

    so you could try taking the Topfield upstairs and connecting it to the same cable/outlet/whatever that your DTT USB tuner uses to see if things change. If they improve, you have your answer.

    I was also interested in your statement: Doing it this way leads to better signal strength but slightly poorer signal quality. If this is true then you are not doing the right thing. Signal quality is the only thing of importance. Strength is only one potential route to better quality. If you get better quality without the splitter, then do away with it.
     
  4. ROYOLD

    ROYOLD
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    Well Multiplex 2 (ITV & Ch.4 channels etc) has been terrible with this continuous rain and its affecting all my PVR's Topfield, Digifusions and Humax.
    All useless reception on two separate aerials. Given up on all mux 2 channels until the weather improves.

    http://www.dtg.org.uk/retailer/dtt_channels.html
     
  5. teabelly

    teabelly
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    I don't think it is the aerial arrangement as each line to the front and the back of the house are separate as from the aerial itself. The downstairs one goes over the front of the house and the upstairs one over the back.

    The signal quality difference (assuming the bottom bar is quality) is 98-99% without the booster and about 96-97 with the booster. The signal strength with the booster is about 10% more minimum, sometimes 20%.

    I have taken off the booster (it's an ordinary labgear one) from the topfield but at the moment it isn't raining so I can't tell whether that was the problem for certain.

    I have checked I am tuned to the right muxes. Ta for the link :) The only possible cause could be interference from the wrekin tranmsitter during certain weather conditions as the broadcast channels are quite close. Sometimes there is ghosting on itv channels which I thought was impossible with digital. The other alternative is that next door have some aerial extender or uhf transmitter which interferes with my signal somehow.
     
  6. LV426

    LV426
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    OK but it could be the "downstairs" cable itself. As I say, why not first check to see it's still misbehaving, and then transport the Toppy up and use the downlead that's currently feeding your PC with clean results. That way you'll be able to narrow down the cause to either the downstairs cable, or your Toppy.
     
  7. teabelly

    teabelly
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    I'll try that the next time it plays up. It is behaving at the moment so I'm going to leave it well alone :)

    The weather forecast says rain for the rest of the week so I should have plenty of opportunity to mess around with it....
     

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