All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Doug: I wouldn't like to rate your chances too much.
The powers that be won't release the radiation patterns for the large transmitters. A radiation pattern indicates how much signal gets thrown out in each direction which effectively shows whether there are any restrictions in particular directions. Knowledge of this information would allow more accurate coverage maps to be drawn out.
However, in general the coverage of the Commercial (COM) channels (those that don't broadcast from the Channel Islands transmitters) isn't as good as the Public Service (PSB) ones. Not only do the COM channels not broadcast from smaller transmitters, but of those that they do, there will be some viewers who will only receive the PSBs.
See this page for projections of users of full-service transmitters who will be likely to be able to receive PSBs+COMs versus those who will only get the PSBs: The commercial multiplex after switchover: ArqA, ArqB and SDN | ukfree.tv - 10 years of independent, free digital TV advice
Looking at the Rowridge bar, I reckon that around 30% will be expected to be PSB-only. In some cases this will be because another transmitter which uses the same channels will cause interference.
We had a report from someone on the IoW, about five miles south of Rowridge who lives in a bit of a dip and so can't "see" the top of the mast who could receive only the PSB channels. If this is anything to go by, then we must wonder whether there is a greater restriction on them to the south.
I imagine that if there is any transmitter that you might get on Alderney, then it will be Rowridge. It is interesting that the coverage map of Rowridge on this website includes the north-most edge of the Cotentin Peninsula.
Again, this is obviously calculated assuming that the radiation pattern is omnidirectional. If that of the COMs is anything but (i.e. restricted to the south to prevent interference on the Continent), then the chances of reception of them on Alderney must be diminished accordingly.
So all in all, if you could receive the analogue channels from a UK transmitter, then you may be likely to be able to receive the PSB channels now. This is because we assume that they serve at least the same area.
However, the COMs being more restricted is anyone's guess. Obviously the authorities have to get international clearance for the frequencies they use. They may be allowed to use them subject to restrictions on the propagation of the signals in the directions of other nations.
I and perhaps others on here will be interested to learn either way whether you can receive the COMs on Alderney and from which transmitter.
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A.M.Jones: The Tyne Tees region is due to complete switchover tomorrow. Two weeks ago the BBC signal from Bilsdale (which is the sourthern-most Tyne Tees transmitter) switched to full power The other services remain on low pre-switchover power until tonight.
Evidently your receiver has tuned to the Bilsdale transmitter as the main one for BBC. It "may" do likewise for ITV1, C4, C5 etc. from tomorrow when a rescan is carried out.
The Bilsdale multiplexes that carry BBC and ITV are on low UHF channels (frequencies) and Emley Moor's are higher up. So have the aerial unplugged for the first 30% of the scan to miss them out.
From tomorrow, the Commercial multiplexes (those that carry ITV3, Pick TV, Dave, Film4 etc) are interleaved within the UHF channels used by Emley Moor. However, they are on lower power than the other (Public Service) channels, so may be less likely to be picked up.
The best thing is to check that your receivers are tuned correctly. Do this by bringing up the signal strength screen and checking the UHF channel it is tuned to:
PSB1 - BBC One - C47
PSB2 - ITV1 - C44
PSB3 - BBC One HD (if applicable) - C41
COM4 - ITV3 - C51
COM5 - Pick TV - C52
COM6 - Dave - C48
Those above are the channels used by Emley Moor.
From tomorrow, Bilsdale's six channels will be 26, 29, 23, 43, 46, 40. Its PSB1 is already on C26.
Refer to this page for a list of all Freeview services and which multiplex they are carried on (those that have a bullet in the "E"/England column apply):
DTG :: DTT Services by Multiplex
For example, BBC Two is also carried on PSB1. Usually there isn't a need to check other services in the same multiplex are correct.
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Jeepers!: Only the main transmitters and some larger relays carry all Freeview channels. The Commercial broadcasters don't wish to pay for (and have no obligation to) transmit from the small sites like Calne.
At your location, reception from Mendip (which broadcasts all channels) may be a possibility. I had a look at your road on Google Streetview and in the photographs which were taken in May 2009. Whilst there are quite a few aerials on the Calne transmitter, the chimney stack on numbers 46 and 48 has two aerials on both of which face Mendip and the next chimney along also has an aerial on Mendip.
The two-tier terrestrial transmitter network is due to the fact that the Commercial broadcasters are not mandated to mirror the coverage of the Public Service channels.
The cost of broadcasting from the 1,000 plus "filler-in" relays like Calne is roughly the same as that of transmitting from the 81 largest transmitters (largest by viewer population). These relays serve about 8.5% of the population whereas the 81 full-service ones cover 90% of the population. So the Commercial broadcasters have decided that they don't wish to double their cost of transmission in order to increase their potential viewer bases by about 10%.
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Peter Hall: "East Yorkshire & Lincs" is how the Belmont transmitter identifies itself. Emley Moor's network/region ID is "Yorkshire".
Stuart Swaine has reported (above) an issue with reception of BBC channels.
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Clive: The most common cause of this sort of complaint is due to the receiver "deciding", as part of its automatic tuning process, to tune to another transmitter.
Knowledge of your location (preferably postcode or nearby postcode, e.g. a shop) and the transmitter you are (or should be) tuned to would allow us to work out whether this might be a possibility. If you don't know which transmitter it is, then knowledge of your location and direction of your aerial will allow this to be deduced.
Or see which UHF channels (frequencies) one of the other TVs has tuned to and then compare with that of the Samsung. There is, of course, no guarantee that the other set is correct. Knowledge of the transmitter being used would allow provision of UHF channel numbers that it uses.
For each of the following, bring up the signal strength screen and note down the UHF channel number that it is tuned to:
PSB1 - BBC One
PSB2 - ITV1
PSB3 - BBC One HD (if it is a HD receiver only)
COM4 - ITV3
COM5 - Pick TV
COM6 - Dave
Each of these services are carried on a separate signal, known as a multiplex. Each multiplex carries multiple services, e.g. PSB1 carries all BBC standard definition and BBC radio services.
How to proceed depends on what is found.
Some tuners simply opt to go with the first signals they find when they do their scan. So if your transmitter uses higher UHF channels, and a neighbouring transmitter comes in well and it uses lower ones, then it might get selected. Not all tuners are this primative, but no automatic tuning is infallible.
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Gerry: My understanding is that the pre-switchover digital TV networks in the UK and in Ireland are different.
In the UK, digital coverage is patchy before switchover. At switchover, the coverage of the Public Service Broadcaster (PSB) channels increases to match that of the current four-channel analogue (which is about 98.5% of the population). After switchover, 90% of the population can receive the Commercial (COM) multiplexes as well. Limavady will be a full service transmitter, so you should hopefully be able to receive PSBs and COMs.
Before switchover, main transmitters and some larger relays carry Freeview at lower transmission powers than after switchover. Thus, the coverage foot-print isn't as big as the analogue channels from each of these transmitting stations.
In contrast, I understand that the situation in Ireland is that many of the digital (Saorview) transmitters are already broadcasting on full power and therefore it already covers a greater proportion of the population.
The reason for the difference is because in the UK there are more networks and hence every transmitting station requires more UHF channels (frequencies). The pre-switchover UK signals have been shoe-horned in. There are four full analogue networks and six digital ones, meaning that the pre-switchover transmitting stations require 10 UHF channels, yet there are only 48 available in total.
Consequently, whilst there are those who can/could receive Freeview before switchover, there are quite a few who receive it for the first time at switchover. Some may have intermittent reception until switchover.
Switchovers in the UK happen in two stages and these are two weeks apart. At Limavady, on 10th October BBC Two analogue will cease for good. The post-switchover BBC digital multiplex will start on its full final power. The other multiplexes will remain on their pre-switchover (low) power until 24th October and the analogue signals for BBC One, UTV and Channel 4 will continue until that date. Thus, you will need to carry out a retune on 10th and 24th October.
If you have two aerials (one on Moville and one on Limavady), the feeds for which are combined into one downlead, you "may" not be able to receive some multiplexes from Limavady after switchover. I emphasise that this "may" affect you only if the feeds are combined.
The reason for this is because after switchover Limavady will use the following six channels: 50, 59, 55, 54, 58, 49
Currently its four analogue channels are 55, 62, 59, 63 and its digital ones are 67, 58, 53, 60, 63, 57.
Moville's analogue channels are 40, 43, 50 and its digital is 45, with a future serve planned for 42.
If the aerial feeds are combined, the feed from each will be "split" at one channel. This means that one aerial "supplies" the channels below the channel at which the "split" occurs and the other feeds those above.
If the "split" is at C51, your Moville aerial therefore can receive C21 to C50 and the Limavady one C52 to C68. At the present time the channels used by each of those transmitters are within those ranges. However, after switchover Limavady's will go lower, it using 49 and 50 as well, the former carrying BBC standard definition services and the latter carrying Dave, Yesterday and others.
It appears that you are closer to Holywell Hill than Moville, so I wonder if there is something preventing you from receiving from there. If you could receive from Holywell Hill, then this uses lower channels and therefore combining an aerial on it with one on Limavady would be possible.
According to this document, the Highland Radio transmitter at Moville isn't intended to serve a wide area and is simply a filler-in:
http://www.frequencyfinde….pdf
It complements the highest power transmitter which is at Burnfoot.
Therefore it isn't surprising that you can't receive Highland Radio from Moville (which is on 104.7MHz). Its transmission power is 100W whereas your local transmitter which is in Burnfoot is at 5kW and its frequency is 103.3MHz.
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michelle: Freeview is usually available in all areas where the current four-channel analogue is available. A small proportion of those areas will be "Freeview Lite" and will only receive Public Service channels, these being BBC standard and high definition, BBC radio, ITV1, ITV1+1, ITV1HD, Channel 4, Channel 4+1, Channel 4HD, E4, More4 and Channel 5.
Knowledge of your location, preferably in the form of postcode or nearby postcode such as that of a shop would allow an assessment of the likelihood of reception to be made.
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William: The Commercial (COM) channels cover 90% of the population, as against the Public Service (PSB) channels which are available to 98.5%.
The Commercial broadcasters achieve their 90% covergage by transmitting from 81 of the largest transmitters (largest by viewer population). A small fraction of viewers who use one of these transmitters will not be able to receive the COMs.
In the case of Darvel, the COM channels are broadcasting at lower power than the PSBs.
Crucially though, there are over 1,000 small "filler-in" relay transmitters. The cost to the Commercial broadcasters to transmit from these sites is roughly equal to that of the 81 sites they use. As they operate purely for profit by showing advertisements to as many people as possible which they wish to acquire at lowest possible cost, they have decided not to double their cost of transmission to increase their potential viewer-bases by about 10%.
The Licence Fee does not guarantee reception of any signal. In any case, it funds only the BBC and as a Public Service Broadcaster, you have access to the BBC.
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Alex MacMillan: I assume that your aerial is directed to Craigkelly. Ensure that Pick TV is tuned to UHF channel 45 and this is usually shown on the signal strength screen.
Black Hill's is on C44 so you could perhaps be picking up that.
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Monday 24 September 2012 1:00PM
Bill: Ensure that the country setting is set correctly if there is one. A different country setting can produce unexpected results with regards to logical channel numbering.
Perhaps (i.e. if all else fails) you may have to carry a factory reset (or whatever it's called). The thinking being that there "could" be some remnant of a previous tune.
It may be interesting to find out what happens when only PSB2 multiplex (the one that carries ITV1, C4 etc) is tuned. Do the service go onto the correct logical channel numbers? Manual tuning may be useful here.
If there is no manual tuning it may give the UHF channel numbers as it scans them and you may be able to be quick to plug in and unplug the aerial on the target channel. If it only gives a percentage, then the scan runs channels 21 to 69 which means that a rough calculation can be made.
This is something that you might want to try. I'm not sure how likely it might yield success.
I'm not an RF professional, so these are some things that I would be looking to try.
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