All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Adrian Durrant: Digital reception either works or it doesn't; there is very little in the middle, hence people talk about the "cliff-edge".
You may find that sometimes it works and at other times it doesn't, either because the interference from Eastbourne is a little stronger or because the signal isn't quite as good from Hastings or a bit of both.
If you are in an area with good reception of Heathfield, then that might be a better bet. If your Hastings aerial is a Group A one, then it won't really be suitable for Heathfield. However, as Hastings' pre-switchover digital signals were not all in Group A, I suspect that there is a fair chance that you have a wideband aerial, and this will be suitable for Heathfield, so long as it is sensitive on its Group B channels.
Failing that, you may be able to have the aerial mounted where it gets sufficient signal from Hastings, but where it is screened from Eastbourne, for example by mounting it on one side of the house and using the house to block the unwanted signal.
Obviously any changes should only be carried out by someone who is proficient at going up on to the roof in a safe manner.
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Ian: I gather that you're receiving from Dover.
The signals are as they will stay. In some cases the Commercial channels are lower power than the Public Service ones (see below).
See this page for the six multiplexes (those with a bullet in the "E"/England column apply):
DMOL Post-DSO Multiplex Channel Allocations
There are three Public Service Broadcaster (PSB) multiplexes and three Commercial (COM) ones.
Sky News and Yesterday are on COM5 and COM6 respectively. Is COM4 affected?
Do you know what UHF channel you have been picking up TF1 one? This information is usually given on the signal strength screen.
Maybe the problem is interference from another transmitter caused by the lift conditions.
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The plan is to have the PSBs cover the same areas as the former four-channel analogue. The COMs coverage is reported as being 90% of the population, versus 98.5% for the PSBs.
Even for transmitters like Dover which carry the COMs, their reach won't be as good as the PSBs from the same stations.
The COMs use a mode of signal that is less robust than the PSBs and this is so that they can squeeze more services in. By "less robust", think of sending a fragile package and a non-fragile package via a carrier that throws parcels around. Whilst the non-fragile package gets to its destination without damage, the same cannot be said for the bone china in the fragile one.
So where the signal (the carrier) isn't as good, the COMs are more likely to get broken whereas the PSBs aren't.
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Adrian Durrant: If you do decide to realign your aerial to Heathfield, then you could always add attenuation if the signal level received turns out to be too high.
In any case you will probably be able to split the signal to serve multiple rooms using an unpower splitter:
Television Aerial Boosters / Amplifiers, Splitters, Diplexers & Triplexers
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Mike B: For Belmont you may need your old (Group A) aerial replacing with a wideband one because two of the six multiplexes are well out of that Group. A fuller explanation is below.
Whilst the cable might not be the double-screened stuff used for satellite installations, it may well be OK, or you may decide to replace it or have it replaced. It is the aerial the is most likely to be the difficulty.
I would try it and see. Digital reception requires sufficient signal strength to achieve reliable good quality. The objective is NOT to get the strength bar as close to 100% as possible.
Refer to this page for the six multiplexes (those with a bullet in the "E"/England column apply):
DMOL Post-DSO Multiplex Channel Allocations
You may find that COM5 and COM6 are unavailable or poor. The three PSBs and COM4 should be OK as they are all in Group A from Belmont. This means that your current aerial will be expected to receive the HD services.
I suggest that you focus on the first service from each multiplex, ensuring that they are good and tuned in correctly. They are (including UHF channel numbers for Belmont):
PSB1 | BBC One | C22
PSB2 | ITV1 | C25
PSB3 | BBC One HD | C28
COM4 | ITV3 | C30
COM5 | Pick TV | C53
COM6 | Yesterday | C60
For example, ITV3 is the first service carried on COM4. Go to it and bring up the signal strength screen and check that it is tuned to C30. These checks give you confirmation that your receiver is tuned to Belmont and not another transmitter.
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TV frequencies (known as channel numbers 21 to 69) are divided into three main Groups. Group A is the bottom third and the former four-channel analogue signals from Belmont were all in Group A. As a result aerials whose sensitivity was greatest on those channels were installed.
Channel 5 analogue from Belmont was lower power and therefore weaker and was also well out of Group, being on C56 which is the top third (Group C/D). After switchover, COM5 and COM6 are on 53 and 60 which may mean that your aerial isn't sensitive enough to pick them up.
For an explanation of aerial groups, see:
Aerials, TV Aerial and Digital Aerial
If you are looking at DIYing, or just want to be more informed before calling in a professional, see:
Belmont TV Transmitter
The obvious caveat that working on the roof or at height can be dangerous applies and the job should only be attempted by someone who is qualified and has the appropriate ladders.
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Adam: Which transmitter is your aerial pointing to? Is it Bluebell Hill?
If so, check that it is tuned to it for all channels. It could perhaps have tuned to the Faversham transmitter for BBC and ITV1 (this transmitter does not carry the Commercial channels ITV3, Pick TV, Yesterday etc). Or maybe it has tuned to Crystal Palace which is a few degrees off beam of Bluebell Hill.
For each of the following, bring up the signal strength screen and check they are correct (this assumes Bluebell Hill is the desired transmitter):
BBC One = C46
ITV1 = C43
BBC One HD = C40 (if applicable)
ITV3 = C45
Pick TV = C39
Yesterday = C54
BBC One could perhaps be tuned to Faversham on C21, Crystal Palace on C23 or maybe Rouncefall on C44.
If you find that it is tuned to one in the 20s, then the solution is simple; just run the automatic tuning scan with the aerial unplugged for the first 30% of the scan. This is because, as shown above, Bluebell uses those in the 40s and 54.
The scan runs from 21 to 69 so if it only gives a percentage as it progresses, then you can get a rough conversion to find out where to plug in the aerial.
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Sandie: If you are using a separate set-top box, the issue could be because it has its own volume control.
From what you describe, it sounds as if you have the volume set to high or maximum on the TV whilst having the volume of the box very low.
The volume control on the box's remote (if there is one) operates the volume for the box and the volume on the TV's remote operates the volume on the TV. They are independent of one another.
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barry woodward: There is no such thing as a "digital aerial". Aerials work based on frequencies used and don't care whether signals are of analogue or digital form.
In some cases aerials need to be replaced because the signals used for post-switchover digital are different to those use for former analogue.
If you post your location, preferably in the form of post code or nearby post code (e.g. a shop), then we can advise whether you will be likely to be affected. It is generally a good sign that it works now, but knowing which transmitter you are using will help us to be more sure whether your current aerial is likely to work after switchover.
If you know which transmitter you use or which direction your aerial points, that may help, along with the location.
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Dale: See
Why do the six Freeview "multiplexes" have twenty different names? | ukfree.tv - independent free digital TV advice
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Richard: I imagine that it is likely to be the lift conditions. See the page on the inversion effect.
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Friday 29 June 2012 11:26AM
Adrian Durrant: Unfortunately the UK now has a two-tier terrestrial transmitter network.
Those who can only receive from Eastbourne South Cliff Tower will only ever receive the Public Service (PSB) channels, as will around 8.5% of the population. This is because the 1,000 or so small relays like Eastbourne only carry those channels and of the 81 transmitters that do carry a full service, some viewers will only pick up the Public Service channels. The transmission power of the COM channels from Hastings is lower than that of the PSBs.
The general plan is that Public Service channels are receiveable after switchover without need to change aerial. Some people will require a different aerial to receive COM channels as well.
As part of switchover, UHF channels 31 to 37 were ringfenced to be sold off to three more Commercial operators, whose future networks will no doubt mirror those of the current quasi-national Commercial networks.
Had these channels not been set aside, then there would have been more available and hence clashes like which exists in the Eastbourne area with reception of the COM signals from Hastings transmitter would have been less likely.