All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Michael McCann: What is the strength on? Is this on the NIMM?
An aerial's gain (in one direction) is at the expense of greater "loss" in other directions. Therefore, a higher gain aerial (if used for transmission) focuses the signal on a narrower beam. Grid aerials have a very wide acceptance angle (over which they are sensitive) and therefore have much lower gain than something which is directional: a yagi or a log periodic.
Thus, whilst you can obviously try, the wide angle of sensitivity would lead me to think, at this stage, that the direction of the aerial won't be that critical.
Another reason I asked you about manual tuning and seeing if it gave a reading is because it could be that you have a signal that is strong enough, but which doesn't have the quality, perhaps due to another transmitter broadcasting on C39. If that were the case, then perhaps the wide acceptance angle of your aerial is contributing to the reception of interfering signal. And so, re-orientating your aerial might help reduce interference.
These are just possibilities I'm throwing your way. The nearest and most likely interfering C39 transmitter would appear to be Larne at 400W which is vertically polarised (as opposed to Divis/Black Mountain NIMM which are horizontally polarised).
Black Mountain is only six degrees anti-clockwise of Divis. However, Larne is clockwise so turning it anti-clockwise might reduce interference from Larne "if" that is what it is, and I'm not that sure that it is.
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Briantist: That was my initial thought when I read Michael's posting, at 8:25AM. However, on looking at his location, it became clear that he isn't going to be receiving Freeview from the Black Mountain relay.
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Michael McCann: There is an explanation of how a grid aerial works here:
Aerials, TV Aerial and Digital Aerial
The typical gain curve for a grid is interesting:
Gain (curves), Again
It suggests that the gain, like a wideband yagi, is higher when you get to the mid-30s. Maybe turning it a bit anti-clockwise might be worth a shot.
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Colin Appleyard: Never. See:
Londonderry (Northern Ireland) digital TV transmitter | ukfree.tv - 10 years of independent, free digital TV advice
Perhaps you may be able to receive the Commercial (COM) channels from Crystal Palace, if you're lucky. If you're unlucky, there will be too much interference from Rowridge transmitter which also broadcasts on those channels.
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janet huyton: Potentially, they can affect TV reception because the blades are reflective.
Perhaps small comfort, but in such situations the company has a responsibility to rectify any issues with reception, or else provide an alternative means of watching TV.
When (technically it's "if") they are built, it may depend on which way they are facing as to whether they cause you grief, or they may do it all the time, perhaps to differing degrees.
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HOWIE: I should imagine that there will be some viewers within the South Glasgow area that will be affected.
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Roy Williams: Have you confirmed that ITV is tuned to UHF channel 44 and therefore to Wenvoe (by checking the signal strength screen)?
If it is, then see:
Freeview signals: too much of a good thing is bad for you | Digital switchover | ukfree.tv - 10 years of independent, free digital TV advice
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Graham: If you can receive from Belmont, then you may have a separate aerial fed into a separate tuner. I assume here that you wish to still be able to watch BBC East/ITV Anglia when there are regional differences.
Combining the two feeds will be more tricky as one of Belmont's COMs (those that don't broadcast from West Runton) is on C30 and West Runton uses 23, 26 and 29. The other two Belmont COMs are 53 and 60, so you could combine using a proper (filtered) diplexer, or you could take your chance with a non-filtered diplexer in an effort to be able to watch C30 (COM4 - ITV3 etc).
If you have a separate Belmont aerial installed then you could have a separate downlead to your lounge and then combine it there. That way you can change it easily if it doesn't work (rather than having to climb on the roof).
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Sunday 17 February 2013 10:35AM
Don Barber; Brian: There is a "Transmission Problem" form on Digital One's website:
ukdigitalradio: Stay in Touch
It might be worth dropping them a line and providing a link to this page where two people in the same area have an issue.