All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Lexy: Perhaps the upstairs TV is tune to Grassington for BBC and elsewhere (maybe Winter Hill) for other channels.
This could suggest that Grassington has gone off (or went off earlier).
In circumstances such as this, the last thing to do is to wipe the memory and retune as this just creates a second problem which is that the set is now not tuned. When the transmitter comes on air, the signals will be as they were before. If there is something causing interference or a poor connection; then the signals will be as they were before.
For manual tuning to Grassington, BBC is on C23 and ITV1, C4 etc is on C26. HD services are on C29.
You should be able to find out which transmitter your upstairs TV is tuned to for BBC standard definition services by going to BBC One and bringing up the signal strength screen. If it is C23, then it is Grassington. C62 is Winter Hill which is North West regional programming rather than Yorkshire.
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Colin: It's probably always worth trying changing bits that are easy to change, like swapping the aerial lead. If this turns out to be the problem, then you might find you don't need another aerial.
For an explanation of aerial groups, see here: Aerials, TV Aerial and Digital Aerial
Before 9th May, ITV3 was on C31 which is within Group A which might explain why you could pick it up then.
One final thing, some people have two aerials on different transmitters that are connected to one downlead. This allows reception of signals from both, e.g. to allow viewing of different regional programming. If this is the case here, then it probably has a bearing on the problem you are experiencing.
Failing that, you may have a Group A aerial which is not sensitive enough on 48, 51 and 52, hence replacement with a wideband one may be necessary.
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Lexy: If there is someone else you know who uses the Grassington transmitter, you could ask them if they have the same problem.
Do you have ITV1, C4, C5 etc from Grassington? (For these, you need to tune to C26.)
It could be a fault, which by their very nature are unplanned. A local power failure is one reason that a transmitter might go off. Obviously, this might not affect the power at your location.
I checked the websites for BBC Reception and Digital UK and none report issues with Grassington.
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Lexy: I think that you have rather confirmed that there was a power outage to the site.
If not that, then there was engineering works which necessitated the transmitters to be turned off, although the fact that no website advises that works are in progress suggests that this is very unlikely.
The site on Edge Lane, which is home to the TV transmitter, is also home to base stations for O2, Orange and Vodafone, as well as Airwave which is the network used by the emergency services.
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JS: The first thing to check is that the receiver will work after switchover. Some older devices won't work with the signals as they are after switchover. What is the make and model of your receiver?
The Digital UK Tradeview prediction should be regarded more as a guide to likelihood of success than what any individual will actually achieve.
However, for your location I do note that there is a channel clash of BBCA and D3&4 from Heathfield and two of Guildford's channels. BBCA is what is on full power now and which carries BBC standard definition services; D3&4 carries ITV1, Channel 4, Channel 5 etc. "If" this appears to be the problem, then you may be able to adjust or replace your aerial with one that picks up less interference from Guildford.
Before you think about this, if your receiver has manual tuning, then go to it and tune to C52 (this being the UHF channel, equivalent to frequency, of BBCA from Heathfield).
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JS: Out of interest, do you get (or did you get before you retuned yesterday) the full complement of channels before switchover?
In particular do (or did you get) BBC One, BBC Four, ITV1, ITV3, Pick TV and Yesterday?
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JS: The signals after switchover are different to those before switchover.
Before switchover they are transmitted using 2k mode and afterwards they use 8k mode. Some older equipment will not work in 8k mode.
At the first stage of switchover, the standard definition BBC services change to 8k mode. The rest stay in their pre-switchover state (in 2k mode).
Hence after the first stage of switchover, an affected piece of equipment will not be able to receive the new 8k signals. At the second stage of switchover, it will no longer pick up anything because the remaining 2k signals have been turned off.
This is why I asked what the model is so the specifications may be checked on as to whether it will function in 8k mode.
With analogue, one service is carried on one signal. With digital, multiple services (programme channels) are carried on a single signal known as a multiplex or "mux".
There are six multiplexes before switchover and six after switchover. At switchover, some services move multiplex. Consequently, between the first and final stages of switchover, BBC Four and BBC Parliament are carried on two muxes simultaneously.
See this page for the six muxes before switchover and the six after (you may need to press F5 to see the graphics below the headings):
Freeview multiplexes | ukfree.tv - independent free digital TV advice
Each row is a single multiplex.
Prior to yesterday, Heathfield was broadcasting the six muxes that are under the heading "Before switchover configuration" (on the page I've just linked to). You will note that BBC Four and BBC Parliament are carried on Mux B whereas the other BBC services were on Mux 1.
After switchover, BBC Four and BBC Parliament are carried on a multiplex along with other BBC services (BBCA mux).
At the first stage of switchover, pre-switchover Mux 1 is replaced with post-switchover BBCA (in 8k mode). The other five pre-switchover muxes continue as they were (in 2k mode).
At the "end" of switchover in two weeks time, the other five pre-switchover muxes will be replaced by the other five post-switchover muxes.
Hence, between the first and second stage of switchover, BBC Four and BBC Parliament are carried on (post-switchover) BBCA and (pre-switchover) Mux B.
From what you describe, you are missing BBCA. I guess that the BBC Four that you have on number 803 is likely to be that which is carried on Mux B.
Receivers usually give the UHF channel number (equivalent to frequency) that they are tuned to and this is usually given on the signal strength screen. Go to 803 and bring up the signal strength screen and you will probably find that it is tuned to C47, which is Mux B from Heathfield (and not C52 which is BBCA).
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Stu: At the first stage of switchover, only BBC services go on full power (or go on air for the first time from relay transmitters).
If you have your aerial directed to the Newhaven transmitter, then the commercial Public Service channels will come on air in two weeks time. These are ITV1, ITV1+1, ITV2, Channel 4, E4, More 4, Channel 5 and the four HD services.
Only transmitters that carried low-power Freeview before switchover will carry all Freeview channels after switchover. This is because the Commercial (COM) broadcasters do not have a "Public Service" obligation and operate purely on a profit-making basis. They stick to the biggest transmitters to cover the greatest amount of the population and lowest cost.
So the Newhaven transmitter will be a Public Service Broadcaster (PSB) one only.
If you can receive from another transmitter such as Heathfield or Whitehawk Hill, then you may be in with a shot of watching the COMs. If not, then you will only be able to receive the PSBs via terrestrial Freeview.
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Trevor: With your aerial on Marlborough, you can expect to receive the Commercial channels sometime never.
The Commercial broadcasters operate purely on a profit-driven basis. They site their transmitters where it suits them and have no "Public Service" obligation, unlike those that broadcast from Marlborough.
I think that the only way you can get more free to air channels is Freesat.
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Thursday 31 May 2012 11:53AM
Jonathan: What transmitter are you using? If your receiver has manual tuning, then try using it. Knowing which transmitter it is will allow us to find out what channel you need to manually tune to.