All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
rob: I wouldn't say he's wrong I'm not an installer so wouldn't like to say categorically either way.
The principle is that you can improve strength by amplifying. You can't improve quality by amplification quality starts and ends at the aerial.
So if the log is seen as not suitable because it doesn't have enough gain (to provide to one receiver on an average length of cable) then one could say "it's not suitable". Also, a high(er) gain aerial isn't necessarily a suitable alternative to a lower gain one used in conjunction with an amplifier.
As you are using an amplifier (because you want to supply multiple points and because of cable length due to the height of your house) then perhaps signal level from the aerial isn't so much an issue.
jb38 can you confirm whether I'm on the right lines or not?
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Keith Tomlin: There is no indication is to any work at Huntshaw Cross. Digital UK publishes engineering works here:
Digital UK - Planned Engineering Works
I will make one observation and that is that PSB2 multiplex is on UHF channel 59 from Huntshaw Cross. PSB2 is the multiplex you are having difficulty with.
4G mobile services in the 800MHz band operate just above that, on C61 upwards. So any such services are pretty close frequency wise, with PSB2 being the closest meaning that chances are if any will be affected it will be that one.
The mobile operators have set-up a company to deal with interference issues and it will know whether there is a 800MHz 4G base station that has come on air in your area. It is called "at800" and you might like to enquire with them as to whether this could be a possibility: Contact us | Advice or general enquiries | at800
They will send out a free filter should this be thought to be the issue.
As for the question relating to DAB reception, what is the issue you allude to?
With digital reception (TV and radio) there is strength and quality. Strength is what it says it is. Quality is the degree to which the digits that make up the sound/picture are intact. Less than 100% quality may result in breakup of the audio/video.
As far as strength goes, the signal needs to be strong enough so that the receiver can decode the digits and so that any natural slight variances in strength aren't likely to leave it under the threshold required.
You might find, for example, that with a strength of ~70% you get 100% quality all the time. That's fine. The idea of using a percentage for strength is somewhat of a misnomer as it implies to the user that the higher the better when this isn't necessarily the case.
Different frequencies carry differently owing to objects in the space which the signals are carried. Thus, it's not uncommon for different channels to be received at different levels even though they are from the same transmitting station. If you ever used a set-top aerial indoors with analogue TV you would have likely found that out.
In the case of Huntshaw Cross, the power of D1 National DAB is 4kW and that of BBC National DAB is 2.5kW. It's also the case that this isn't the same power in all directions with each multiplex being different in this respect.
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Austin Grant: If you are in Buncrana at the side of Lough Swilly, then I'm amazed you can receive anything from Brougher Mountain! Presumably you can't pick up from Limavady.
Other than the C28 signal from Brougher not reaching you, the reason might be because Malin transmitter also uses C28.
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Barrie: This is the first I've heard of BBC Local Radio being available on Freeview. Digital UK does indeed list some local stations on Freeview, including Bristol:
Digital UK Industry - Channel listings
The assumption must be, therefore, that it is available from Mendip and its relays. If you have Wales then the assumption must be that you are receiving it from a transmitter in Wales, Wenvoe maybe.
Thus the answer to your question is much the same as if you ended up with BBC One Wales or BBC Two Wales. Is this what you have?
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David Reynolds-Moreton: ITV3 is not available from the Bovey Tracey transmitter therefore if you are receiving it sometimes (and you have your aerial directed to Bovey Tracey) you do not have a reception issue.
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Peter Johnson: Different frequencies are affected by onjects in the way and in the surroundings. This is a law of physics. The only way all signals would carry the same is if there was absolutely nothing other than the transmitter so no trees, no ground, no buildings, no air (a vacuum) etc.
You are in fact 2.8 miles from the transmitter. This terrain plotter suggests that the line-sight is close to the ground and therefore could be obstructed:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Obviously the terrain plotter samples ground levels every so often and therefore peaks and troughs may exist which aren't shown.
I do not think it a possibility that you could have too high a signal level as the transmitter is only 15W.
Switchover at Llanrhaeadr ym Mochnant happened in 2009 and the three channels used by the digital services were, and still are, 45, 49 and 42. In September 2011 Sutton Coldfield began to use these three channels for its COM services (those which aren't available from Llanrhaeadr ym Mochnant). While these channels are horizontally polarised, Sutton Coldfield is on about the same bearing as Llanrhaeadr ym Mochnant so the reason for poor reception could conceivably be due to this.
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Ian Glover: Are you aware that, since switchover, the Eastbourne relay transmitter (on the top of South Cliff Tower) uses the same three channels as Hastings for PSB services (BBC, ITV, C4, HD etc)?
It's in roughly the opposite direction to Hastings transmitter, so you could perhaps be picking it up off the back of your aerial. Here is a terrain plot between you and the top of South Cliff Tower:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
As you can see, it's just over 10 miles away with high ground at Little Common and Cooden almost (or just) obstructing line-of-sight.
What's the strength and quality like on UHF channels 25 (BBC) and 28 (ITV)? If it's interference then I think we would expect the strength to stay the same and the quality to go down. That is, the signal would be there but that there's too much unwanted signal from Eastbourne.
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Ian Glover: What am I telling you???!!
It's the COM channels of Hastings (ITV3, Pick, 4Music etc) that are shared with Eastbourne and not the PSBs. So interference from Eastbourne couldn't be a possibility be the issue you report.
Rowridge's COMs, which are vertically polarised are co-channel with Hastings' PSBs and it's in the opposite direction. You're a long way off site from it though, although there's a large expanse of water across a large chunk of the signal path (between you and it). Hastings' COMs don't share with Rowridge.
I would suggest that you "might" be better off using Heathfield instead, although High Woods/Jack O'Boreham's Wood is probably in the way and could therefore perhaps affect reception. Unfortunately, like Hastings, Heathfield doesn't carry the new quasi-national HD channels (BBC Four HD, BBC News HD etc).
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Ian Glover: Silly question:
Have you confirmed that your receiver is indeed tuned to the Hastings transmitter and not the Bexhill transmitter which came on air at switchover and is on the roof of the Hastings Insurance building, Conquest House?
You may have, or not be far off, line-of-sight with it, at just under a mile away and at a power of 400W your receiver could have favoured it over the PSBs of Hastings. The Bexhill transmitter only carries PSB channels.
Bring up the signal strength screen on BBC One. For Hastings it is UHF channel 25 (506MHz) and for ITV it is C28 (530MHz). For Bexhill it is C46 (674MHz) and C40 (626MHz) for BBC and ITV respectively.
As Hastings' signals are all in the first portion of the band and Bexhill is further up, run the scan through and unplug the aerial once it gets past UHF channel 31 or 30%.
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Thursday 5 February 2015 11:12AM
rob: The other thing is that the wind-loading of a logs is lower (and they look neater):
ATV`s Choice Of Aerials for digital TV