Pace Twin Signal Strength...Whats Yours?

Discussion in 'Digital TV & Video Players & Recorders' started by Skiddins, Jan 24, 2004.

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  1. Skiddins

    Skiddins
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    I have found the section that mentions the signal strength in the menu's and I'm getting 46% on both tuners.
    I am using an old dektop awrial on the window sill that I bought from Argos about 8 years ago, and an analogue booster.

    I get the odd dropout which is worse on some channels than others, but they are all easily watchable.

    What is a good reception percentage?
    I will be upgrading the rooftop aerial soon, what difference will it make?

    Thanks
    Skiddins
     
  2. idhutt

    idhutt
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    As long as you get a picture without dropouts, signal strength appears to make no difference at all. I've run with signal strength for in the 40's, 60's and 90's and the only thing that make a difference is the quality of the signal.

    I went from 40ish% to 60ish% when I added a booster to distrubute the signal through the house and it made no difference to the picture. Dropouts were the same, possibly slightly worse.

    However, an RF filter (Maplin about £10) in the downlead dramatically reduces the number of dropouts although I do still suffer some - especially when some teenager (how I remember those days) revs his moped up. On a non digital picture, this is seen as snow on the picture.

    -Ian
     
  3. LV426

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    The important factor is not signal strength - it is signal cleanliness.

    A weak, but very clean, signal will give few or no bit errors and therefore good reception. Conversely, a strong signal but affected by what causes ghosting on analog, may well suffer a high error rate and present many glitches.

    The only benefit of a strong (but clean) signal is that it is less likely to suffer from interference (eg from momentary electrical stuff - thermostats and crappy cars' ignition, etc).
     
  4. Skiddins

    Skiddins
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    If the strength makes no diffeence, how can I tell if I'm getting a clean signal?

    I thought that the higher the percentage the fewer dropouts etc.

    How can I clean up the signal?

    Skiddins
     
  5. LV426

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    I didn't say it made no difference. What I said was that it is the cleanliness of the signal that is important. Strength has this effect: A strong, clean signal is more likely to remain clean (i.e., remain unaffected by local electrical interferences, say) than a weak one.

    But a weak signal that IS clean will give good results.

    You can (on some hardware) see an indication of the 'bit error rate'. This is what affects the level of 'glitches' you experience.

    Cleaning up an inherently dirty signal (i.e. one which is dirty because of your reception conditions) is difficult. (By which I mean - if you have a strong signal but plagued with stuff like multipath errors - these cause ghosting on analog signals). Only a respositioned and/or better aerial may cure this.

    If the aerial is picking up a weak, but clean signal, you can try to keep it that way by

    a) adding a masthead amplifier to increase its strength in your local wiring, which will improve its resilence to local interference

    b) use new, properly screened cable (say, like satellite cable - with an additional foil screen).

    My Pace Twin shows signal strength varying between high 40's and low 60s. It shows a bit error rate of 1.00000E-9 which is as low as it gets. Hence I get largely glitch-free reception.
     
  6. breszh

    breszh
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    I was getting between 41 and 44 but at the weekend it started dropping on some channels to 37 ish. Bit error rates also increased up to 4 or 5 on occasion, tying in with the picture freezes.

    I removed a spare coax splitter and cable which I'd rather stupidly left in between the aerial point and the Pace, this dramatically increased signal strength (55-65). I haven't watched it long enough to see if it has improved the pricture freeze problem but from what Nigel was saying I don't think it will.
     
  7. idhutt

    idhutt
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    Maplin sell a TVI RF Filter for 9.99 (QT25C) and it works very well for me. I've two, one connected immediately before the RF input of the twin, and one on the point of entry to my distribution amplifier uplink. Its dramatically decreased the amount of dropouts and completely cured a problem that I was having with a low voltage lighting transformer in close proximity. It is critical to place it correctly though. The instructions mention that it must not be used low signal area (it attenuates the signal) or on an amplified signal ~ I've got a mast head amplifier and it works ok (actually the mast head amplifier made no difference to my signal quality so is largely redundant).

    -Ian

    From the blurb:

    This high pass filter is designed to reject aerial-borne interference. It connects straight to the back of your TV or video recorder in line with your antenna to stop those unwanted signals.
    · Hi-pass filter
    · Commercial grade
    · For use with UHF TVs, VCRs etc
     
  8. steev

    steev
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    I've currently got a loft aerial and get signal strength in the 30s. Picture on the Pace is fine with a very occaisional freeze, but the analogue signal is rubbish. I'm debating whether to remount it outside, but we don't really miss the analogue.

    My cable comes down to a cupboard and is currently just joined to the one from the lounge with a female-female connector. I tried a passive splitter, but the signal went too low. I probably need an active one to send the signal around the house. Maybe that will help the analogue.
     
  9. Skiddins

    Skiddins
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    My signal was 46% for both tuners, I then replaced the aerial lead for a Monster Cable 4m item.
    Both tuners are now at 50%

    The error rates are normally 1.00000E-9 as well, but occasionally it goes up.

    I will be replacing the aerial on the chimney shortly, but not until the weather clears up a bit.
    But what sort of digital aerial? Medium gain, high gain?

    Skiddins
     
  10. LV426

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    Depends on your transmitter. Important to get an aerial of the right 'grouping'. Check your transmitter details out on the DTG website to find the grouping that's appropriate for you.

    http://www.dtg.org.uk/retailer/tx_details/_tx_index.htm

    And, the higher the gain, the better.
     
  11. Tom Destry

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    Nigel, can you explain what these groupings mean? For example my local transmitter is Sandy Heath, which has an existing group of 'A' and a new group of 'W'.
     
  12. Skiddins

    Skiddins
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    I think my nearest would be Crystal Palace, Guildford is 5Km closer but is much lower power, Crystal Palace is 20kW

    Either way, it's group A H or B V.

    What do these groupings mean?

    Skiddins
     
  13. LV426

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    The aerial groupings refer to the range of frequencies used for a given set of channels. A is one group, B another, and C/D a third. Depending on these frequencies, different sizes and spacings of the elements on the aerial would be optimal. So, for example, for the low frequencies (channel numbers) group A aerial is required.

    Historically, all analog channels would be positioned fairly close together so as to all fit inside of one 'group'.

    With the introduction of more channels to carry digital 'muxes' many transmitters have had to widen this 'spread'. The analog channels are unchanged, fairly close together, and all fit inside one frequency (and hence aerial) group. But in your case the digital channels are in another group.

    For this reason, aerial group W (which stands for wideband) is needed. A wideband (group W) aerial is optimised for the full spread of frequencies - all channels from 21 to 69.

    H or V refers to the orientation of the aerial elements. Most 'main' transmitters are H, meaning that the aerial elements should be positioned Horizontally. Repeaters are more often V (meaning Vertical).
     
  14. Skiddins

    Skiddins
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    Would an Ultra High Gain aerial be OK.
    I believe I am about 20 miles from the Crystal Palace transmitter, which has a group A channels, and would appear from the DTT lists as the most powerfull in the country.

    Should I get something with a high Feedback rating?

    I notice from the list of CIA certified aerials on the DTT pages that they haven't found an aerial above Standard 2, does anyone know of any.

    THanks
    Skiddins
     
  15. shyewei

    shyewei
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    Just to add my tuppence worth. Just bought the TVI filter from Maplins also expecting great things. Interestingly enough both my signal strength and bit rate errors actually got much worse!!!! Strength went from 50s to 40s and low errors to 4 - 5!!!!
    I also bought a screened RF socket to see if this improved things and this may have also dropped the signal strength - go figure I was using a 10 year old plastic socket before!!!
    I guess this just adds strength to the addage "if it ain't broke don't fix it!!!"
     
  16. Skiddins

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    I have now fitted the aerial on it's cranked aluminium mast (this was a mistake, the aerial moves a bit too much in the wind, my advice, a straight steel one!)

    The signal has now improved from my 48% ish to the low 70's, I have the aerial going into an old booster, then a cheap splitter fitted on the output of the booster, If I remove the splitter my signal goes up by about 10%.

    I have to use the cheap splitter as the signal is then sent back outside and then downstairs to supply the analogue TV in the front room.
    Does anyone know of a site that has some reviews of boosters and exactly how well they perform. I can read up on the boost and noise levels etc, but the limited experience I have of things like this shows, that even if the figures are good, the performance can still be crap.

    Skiddins
     

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