All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Jan Gibson: It is a possibility that your aerial needs replacing in order to pick up some or all of the Commercial (COM) multiplexes.
Refer to this page for the six multiplexes which are groups of services, each carried on a single signal:
DMOL Post-DSO Multiplex Channel Allocations
ITV4 is carried on COM6 multiplex (known as "ArqB") which is on UHF channel (equivalent to frequency) 56 from Sudbury. Aerials fitted during the days of four-channel analogue (or even three-channel analogue !) will probably be less sensitive at frequencies used by the COMs. This may or may not prove to be an issue.
Assess which of the multiplexes are missing and which you have by referring to the above page and checking to see if the services on each are present.
If your receiver has manual tuning, then it is worth attempting to manually tune them. Depending on the design of the device, it may indicate whether there is a signal there, but just not strong enough.
For Sudbury:
COM4 (SDN) | ITV3 etc | C58
COM5 (ArqA) | Pick TV etc | C60
COM6 (ArqB) | Yesterday, ITV4 etc | C56
The "C" numbers are UHF channel numbers that you need to input whilst on the manual tuning screen.
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Your aerial will probably be a Group B one which means that it is most sensitive on the middle third of the band of frequencies used for TV. Sensitivity drops off outside this; it doesn't stop totally, but may be noticeably lower.
Whilst the Public Service channels (BBC, ITV1, C4 etc) are within Group B, the COMs are above it (top third known as Group C/D).
For this reason you may need your aerial replacing with a wideband one which is suitable for the whole band, or a Group E one which is the top two thirds of the band (which are Groups B and C/D combined).
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peter bingham: Assuming that you are receiving from Winter Hill, then there is a retune scheduled for next April when PSB1 (BBC standard definition services) changes from C62 to C50 and COM5 (Pick TV etc) changes from C61 to C49.
This is connected with the clearing of channels 61 to 69 for 4G mobile services. I don't know whether there will be likely to be any further changes necessary.
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Katharine: See the posting I've just made to Jan Gibson who is also using Sudbury:
Freeview reception - all about aerials | ukfree.tv - independent free digital TV advice
Your aerial may need replacing if it is a Group B one. Before Wednesday, the COM4/SDN multiplex which carries ITV3 was on a frequency within Group B and now it is not, so that could be your problem.
Try manually tuning if your set allows. I've covered this in the posting linked to above.
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kaz: It could be that your mother has a Group C/D aerial which was the type usually installed in the days of four-channel analogue, particularly before digital came along during the previous decade.
Group C/D is the top third of the band of channels used for TV. 41, 42 and 44 (and 47[HD]) are in the middle band, which is Group B. PSB1 and PSB2 are on channels where B and C/D overlap.
Refer to this page for channel numbers of each Group:
Aerials, TV Aerial and Digital Aerial
(I haven't directed you to that page to read all the wordy explanation!)
Aerials are sensitive outside of their Groups to a degree. They don't receive "nothing" outside of group.
Further down that page is a graph with some gain curves. The green one is C/D and you can see that it slopes downwards. The gain is the sensitivity or the amount it can "hear" signals. This is just an example curve of one particular aerial to illustrate the point.
With this in mind, I suggest that you compare signal strengths of each UHF channel on the same device. Signal strength meters vary between receivers, so don't compare between different ones (only compare different multiplexes on the same receiver).
Digital reception requires the signal level to be above a threshold level. If it is, then it will work.
So it could be that the level of C44 is just below that which the receiver needs to show a picture. Depending on its design, it may indicate signal level when you manually tune. (Some receivers give more clues than others.)
Compare the levels of BBC One (C52) and ITV1 (C49) with those of the two COM channels you have which are ITV3 (C42) and Yesterday (C41). If the latter two are markedly lower then perhaps it is a C/D aerial.
If you can see that the tip of the aerial is green, then this indicates that it is a C/D one.
Do these checks with the receiver in question connected directly to the aerial socket (and not via the Sky box). If there is a wall socket with an aerial fly lead from that to the receiver, then try swapping it. Maybe you have one that you can try.
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Arnold Hague: I found the manual for it here:
http://www.sony.co.uk/sup…x653
However, it doesn't go into much detail about tuning.
If there is manual tune, then try manually tuning to the HD channel of your transmitter. HD services are broadcast using DVB-T2 standard whereas standard definition services use DVB-T. Therefore, there "may" be an option to select this when manually tuning.
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Pete: The Viera model may not have a HD tuner built-in. In the specification it will say that it is capable of receiving DVB-T2 signals (as well as DVB-T ones).
Freeview HD uses DVB-T2.
Earlier HD sets were HD Ready, meaning that they can show HD pictures, but don't have the means to receive them off the air.
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kaz: I had a look on Streetview at the road of the postcode associated with your postings.
I can see the distant horizon inbetween the bungalows to the east.
The Streetview photographs are dated April 2009, so they were before switchover and therefore pre-date the existance of the Bexhill transmitter, as it was only introduced at switchover.
At that location, the Bexhill and Hastings transmitters are in the same direction (to within one degree). Most of the bungalows on the right (as you enter the close) and some on the left and those at the end have their aerials vertical and directed at Hastings.
A terrain plot suggests that there is line of sight to the Hastings and Bexhill transmitters (so nothing in the way). Because I can see the horizon, I can well believe it.
jb38 has suggested that the aerial could be directed to Bexhill, which in view of the fact that it is has only been in service for a few weeks isn't likely.
So if the aerial is vertical and pointing at what might appear to be Bexhill, it is actually pointing at Hastings (owing to the fact that they are in the same direction).
The view in the direction of Heathfield doesn't look quite as good (I, of course, am only giving my opinion based on the Streetview photos). There are some trees behind the end bungalows that in the photos don't have any leaves on and these "could" be reducing the signal from Heathfield. Perhaps replacing the out of group aerial (if it is so) may make C44 available.
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Hilary: It's possible that the communal aerial system if fitted with a filter that only allows through (from the aerial) frequencies that are used by the transmitter. As the frequency used by COM6 has not been used before switchover, the system could require some adjustment.
Could you receive all Freeview channels before switchover? Did you get BBC One, BBC Two etc?
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Deeque: It depends on which transmitter is being received from!
There is a retune event scheduled for next May when ArqB (Yesterday etc) from Oliver's Mount will move from C61 to C49.
This is to clear channels 61 to 69 so the spectrum can be sold off to 4G operators.
D3&4 (ITV1, C4 etc) uses C60- which is obviously close, but I've no idea whether this might be a problem.
If you receive Tyne Tees from Bilsdale Moor, then the 4G services shouldn't affect it because it uses lower frequencies (and will continue to do so after it has switched).
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Saturday 30 June 2012 1:07PM
Les Beynon: The reason is because ITV4 is carried on one of the Commercial multiplexes. A multiplex is a digital signal that carries multiple services.
The operators of the Commercial multiplexes (known as the "COMs") can choose where to transmit from. As they are run purely for profit the have opted to invest in 81 of the largest transmitter sites (largest by viewer population). This gives them a 90% coverage of the population.
For them to transmit from the 1,000 or so small relays like Newhaven would roughly double their cost of transmission whilst only adding 8.5% of the population to their potential viewer-bases. When the objective is to sell advertising which they show to as many viewers as possible at lowest possible cost, it is easy to see why they aren't interested in the relays.
The multiplexes that Newhaven carries are the Public Service Broadcaster (PSB) ones. The Commercial broadcasters have no "Public Service" obligation which is why the UK now has this two-tier terrestrial transmitter network.
Freesat is probably your best bet for additional services, including ITV4.
See here for a comparison of full Freeview vs Freesat:
Compare TV | ukfree.tv - independent free digital TV advice
ITV3 IS on Freesat, despite its logo appearing on that page.