All posts by Dave Lindsay
Below are all of Dave Lindsay's postings, with the most recent are at the bottom of the page.
Trevor: I write this as someone who isn't an aerial installer. I don't give any guarantee as to what will or won't work; more that I'm making suggestions as to how chances of success might be improved.
I think that it will be best for you to wait until switchover is completed on 13th June.
The Digital UK predictor doesn't give a sparkling result for your area with any transmitter. It isn't fool-proof as obstructions such as trees and buildings will affect the signal as well. Looking by entire post code gives results for the whole area over which there could be variation in what can and cannot be received. For a more accurate prediction, enter house number as well. My advice is to use it as a guide only, particularly due to the surrounding terrain (I will come on to this).
A look at your road on Google Streetview shows that you're on the side of a hill. Some aerials are on Hastings and some on Heathfield.
I used this site to plot the terrain between you and each transmitter:
Terrain - shows radio profile between two UK sites to optimise you DTT, Freeview, DAB or analogue TV reception
The "base station" is your location. I left the height of your aerial at 10m.
The line from your location to Hastings transmitter is here:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
The line from your location to Heathfield transmitter is here:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
As you can see, both transmitters' line of sight is obstructed. This explains why it's not straightforward to receive from Hastings which is only 2.4 miles away.
If the booster you are using is behind your TV, i.e. at the end of the lead from the aerial, then an improvement will be to have one fitted nearer the aerial (so that there is much less cable between the aerial and the booster). Such a booster/amplifier is often called a "masthead-amp" and requires a power supply, usually fitted behind the television. Don't confuse this with being a booster in itself.
Basically, if you amplify (insert a booster) immediately before your television, then you are not only making bigger the signal (which is what you want) but the noise (rubbish) that is picked up in the length of cable. By amplifying at the aerial, you only make what's picked up by your aerial bigger.
Whether this is needed or whether a change of aerial would be better is another matter. I simply provide this as food for thought; that a booster behind the TV isn't as good as one at the aerial.
Also, if your booster does have a variable control on it, it might be worth trying different levels of amplification to see what works best as the highest isn't always the best!
As I say, I think that you're best advised to wait until switchover and see how your current aerial fairs.
If you're after some more information, then I recommend reading ATV Sheffield's site: www.aerialsandtv.com
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John McCann: I found your previous postings (click on the "3 posts" to the left of the Union Flag).
In answer to your question, no you will not simply be able to switch to TW post-switchover. The main reason (which is a definite) is because Heathfield's signal is horizontally polarised and TW's is vertical. So your aerial will need to be changed to vertical (assuming that it's the right type for TW; I'll come on to this). For a picture of vertical and horizontal aerials, see here:
Aerials, TV Aerial and Digital Aerial
The angle between the two transmitters is 40 degrees.
The other thing is that the aerial *might* be one which is designed to work (optimally) with the frequencies used by Heathfield. Do you know what aerial group your aerial is? Is it wideband? See here:
Aerial groups - new feature | ukfree.tv - independent free digital TV advice
I used a website to plot the path of the signal from Heathfield to your location and from TW to your location.
This shows that the terrain acts to block your direct sight of Heathfield:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Whereas TW can apparently be seen:
Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location
Personally I would wait until switchover and see how reception from Heathfield fairs. If the current aerial works OK then, then any work to change it will only be of direct benefit for the period up to switchover.
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John McCann: Adam B put it more succinctly!
I see that Heathfield and TW will act as a signal frequency network (so will use the same frequencies). The only difference is different polarisations (one is horizontal and one vertical).
I repeat what I said above, I would see how you go post-switchover, particularly if you're going to have to pay someone to do it. If it works fine, then leave it as it is. If you can do it yourself (or get a friend to do it), then re-orientate your aerial to TW.
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Richard Watson: Do you have a booster/amplifier connected? If so, get rid of it.
See this page:
Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice
It could be too much signal. What sort of aerial do you have?
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Richard Watson: Certainly if you've got a high-gain antenna, I would suggest it could be too higher signal level. If it's not, I'm not sure I'd rule it out.
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Mark Fletcher: The commercial multiplexes are on lower power than the PSBs.
SDN Ch30 50kW
ArqA Ch53 100kW
ArqB Ch60 100kW
The reason for this is probably because there are other transmitters that are co-channel.
Use the map to see transmitters that use the same channels:
UK TV Frequency map - channel C21 (474.0MHz) before switchover map | ukfree.tv - independent free digital TV advice
Look at the channels used by the three PSBs and then compare Ch53 and Ch60. I don't quite understand the reason for the restriction on power on Ch30 as it is used very little in the UK.
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R Coulter: Alexandra Palace does not (at the moment) broadcast digital terrestrial TV ("Freeview"). It will do so when the London region switches to digital next June.
Are you confusing this with Crystal Palace which is the main London transmitter which does broadcast Freeview now?
In any case, you will not be using a dish, you will be using an aerial. A dish is used for satellite services.
Why have you stopped using the Oxford transmitter?
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Mark: I believe you!
See here for the response I made to someone else in Hunstanton with the same query:
Freeview on Tacolneston TV transmitter | ukfree.tv - independent free digital TV advice
If you have lost Yesterday etc then it could be because you have a Group A aerial on Belmont. The commercial channels are not in Group A and as such that is probably why such an aerial is less sensitive to picking them up.
If you would like a fuller explanation, please let me know. Your post code might help give a more accurate prediction.
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David Kent: It's likely that there will be no need for a new aerial.
The transmitters that operate before digital switchover do not carry HD except for Crystal Palace and a few others.
The Crystal Palace pre-switchover HD multiplex has been shoe-horned in. It's coverage area isn't as big as that for the other digital channels which might explain why you can't pick it up now.
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Friday 2 December 2011 1:34PM
JP Richardson, KMJ,Derby: The point about Belmont ArqA and ArqB using the same frequencies as PSBs from Olivers Mount (albeit different polarisations) probably explains why those two Belmont multiplexes are on lower power than its PSBs. Clearly Belmont's signal (it's former analogue and current PSB digital) can be picked up in Filey and (higher?) parts of Scarborough.
Olivers Mount's digital signal is higher than its analogue one, so will serve some that haven't been able to pick it up before now.