All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
nicola: Be aware that the three commercial (COM) multiplexes are currently on much lower power from Oxford than its Public Service Broadcaster (PSB) ones.
Thus, you will have to ensure that you attenuate enough to make the PSBs watchable without attenuating the COMs too much so as to make them too weak for your machine to show a picture.
On 18th April the COMs will go to their full final power, which will be lower than that of the PSBs (which are already at their full final power). So it is to be expected that there is a difference in signal strength.
The scale on different boxes will differ, so ultimately it is try it and see. As an example, my Sony recorder (HXD-RDR870) gave strengths of around 50 to 60% before switchover and it worked fine. The quality was 100% and therefore the picture wasn't degraded.
If the 70% is on BBC or ITV1/C4 and ITV2+1, Really is breaking up or gone, then you need to reduce your attenuation to let some more of the signals through.
For a full list of Freeview services and what multiplex they are carried on, see here:
DTG :: DTT Services by Multiplex
Basically, I would look at the first service in each multiplex. So check BBC One, ITV1, BBC One HD (if applicable), ITV3, Pick TV and Yesterday. As I say, the trick will be not to attenuate too much so as to loose the last three, but enough to reduce the level of the first three enough.
Come 18th April this will be easier because the COMs won't be so weak with respect to the PSBs.
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Mel P: I guess that you might be receiving (or not as the case may be!) from the Bluebell Hill (it would be helpful if you would say).
There was another report yesterday of someone in Maidstone who was having issues:
Freeview on Bluebell Hill TV transmitter | ukfree.tv - independent free digital TV advice
There was work at the transmitter last week.
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Jeff Lee: You should be able to use your current aerial to receive from Otford.
But you will only get the main Public Service Broadcaster channels (BBC, ITV1, ITV2, C4, E4, More4, C5 and a few others).
If you are to ever get the commercial multiplexes which carry Film4, Dave and many more, then you will need to receive from a transmitter that broadcasts them. Crystal Palace might be your best bet.
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Jeff Lee: I'm not an aerial installer myself, so just giving you my thoughts as a technically-minded person.
Loft aerials are lower down and sited behind a roof. Thus the level of signal they receive is obviously less than if they were outside and if they were higher up. That is not to say that loft aerials never work. Indeed, at 400 to 500 metres, with (presumably) clear line of sight from your roof to Otford you will probably be alright. And you might even get a good signal from it from a set-top aerial (which is lower down), particularly if it's at that side of the building, maybe on the windowsill.
I had a look at you road on Google Streetview and I can see some high-gain aerials on Crystal Palace (most have the 'X' type elements).
Looking at it logically, if that is what is needed at roof-top level (*see note below), then chances of success in the loft will be less and perhaps very low.
There is nothing to be lost by trying it. If you do go for Crystal Palace with your current loft aerial, then you will need to point it at 300 degrees and have it horizontal (as opposed to vertical for Otford).
If you do look at DIYing, then have a look at Aerials and TV in Sheffield. Its website has lots of information and they sell good stuff too:
A.T.V (Aerials And Television) TV Aerial, DAB Aerial, FM Aerial.
The only possible downside to DIYing is that if you buy a particular aerial and it doesn't prove sufficient to do the job, then you might not be able to take it back. In situations where it's cut and dry (e.g. good signal area such as if you were looking at putting up an aerial for Otford), then it should be simple.
* Perhaps neighbours who have had their aerials directed at Crystal Palace were for Freeview reception prior to switchover (i.e. they need such large aerials to pick up the low-power signals).
If they went with Crystal Palace but cannot get pre-switchover digital, then there would seem little point in them having done so as it would give no advantage (no extra channels) over receiving from Otford. If the larger aerials are needed prior to switchover (to pull in enough of the lower power signal), then it follows that the boost in signal strength (probably) won't necessitate such a large aerial. Or, maybe they have had the larger aerials installed in preparation for the higher power Crystal Palace digital signal (i.e. they can't get digital yet).
If you can speak to one (or more) of them (that have aerials on Crystal Palace), then that might be a useful research. They may also be able to recommend an installer.
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Ian Podmore: On the basis that you are so close to a high power station, then the first thing to try must be an attenuator (as shown at the top of this page). I would get a variable one.
The shop you bought your TV from is (I assume) not responsible for your aerial installation. Thus, if someone comes out, then it is not surprising that they will charge if it is found that their product is not at fault.
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Robert: The likely answer is no. See here for an explanation:
Will there ever be more services on the Freeview Light transmitters? | ukfree.tv - independent free digital TV advice
You might get Rosneath if you're lucky, but that's the only way you will ever get the commercial channels on terrestrial.
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M E Moore: The transmitters serving the London area will be switched to digital in April. That has nothing to do with Northern Ireland, even when the programming comes from London.
You haven't stumbled on some big secret to stop those in Northern Ireland from watching the Olympics!
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Ken Collyer: There have been a few reports on here of people having issues with Bluebell Hill following completion of work (apparently last week).
The Anglia region has switched over, thus its transmitters are (mostly) at their full post-switchover power, whereas Meridian is still at the (low) pre-switchover power.
I am assuming here that you are picking up Sudbury or Rouncefell, the latter operating on the same frequency for the PSBs only (it doesn't carry the COMs). I would run the automatic tuning scan with the aerial plugged in up until 25%. This should pick up Mux 2 (ITV1, C4 etc) and Mux A (ITV3 etc) only which are on channels 24 and 27 respectively.
Then manually add the other multiplexes:
Mux 1 BBC Ch59
Mux B BBC Ch45
Mux C Arq Ch42
Mux D Arq Ch39
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Colin: The situation with Rowridge is that after switchover, it will broadcast horizontally and vertically.
The PSBs will be at 200kW for both polarisations.
However, the COMs will be 50kW horizontal and 200kW vertical.
This would explain the reason for the predictor's result.
I would wait and try it, particularly if you're going to have to get someone in to do it. The predictor should be treated as a guide and not gospel. It exists because of the demand for such a system but it's not possible to design such a system with total accuracy.
It's also often the case that a vertical aerial will pick up, to a certain degree, horizontal signals. So it could just be enough to save you having to have your aerial altered.
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Sunday 15 January 2012 5:01PM
jane: This usually happens due to not enough memory to store all the channels. The multiplex you are having issues with is on the highest frequency from Sutton Coldfield, and so is the last one it will get to when you do the scan and hence will be the last one to store (or not as the case may be).
It might be that your box is storing channels from another transmitter(s) which is taking up space. If you can stop it doing this and get it to use the space that is available for Mux 2, then you will solve the problem.
The predictor suggests that you might get The Wrekin where you are. It is on lower channels.
Run the automatic tuning with the aerial unplugged. Then run it again with the aerial unplugged and plug in the aerial when it gets to 25%. That way you will have it unplugged when it scans channels used by The Wrekin.