TV aerial and cabling system

16 Aug 2010
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United Kingdom
Hello and thank you for reading this post.

Would anyone be able to give a guide to likely price of the following work?

Detached house built 2004 with lots of tv points to the various rooms. So nine rooms have tv aerial points. House on ground floor, first floor, and loft level room. TV aerial on side of house. No signal coming from any of the tv points in the rooms. Am thinking that the following work is required:

1) remove old tv aerial, appears to be analogue
2) install new mountings and new digital tv aerial on side of house
3) replace 8 way amplifier with new unit, and install new unit reconnecting new unit to existing cabling and to new tv aerial
4) test all tv points

Thank you.
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All TV aerials are analogue because the signals they receive are high frequency analogue sine waves ( radio frequency carriers ) that are modulated with signals for picture and/or sound reproduction.

When the switch over from analogue modulation to digital modulation happened extra carriers had to be put into operation used during the change over period to carry the digital services while the analogue service carriers were still operational. For some people this did require a new aerials to be able to receive the addtional radio frequency modulated with the new digitised picture information,
If your old aerial still works well then there's no immediate need to change it. The main difference between the two types of aerial is that the newer ones are 75 Ohm balanced. Although the digital transmission system is pretty robust, it does have a problem that it is more susceptible to picking up noise than the older analogue TV system. This is why cable for digital TV reception has two lots of shielding compared to older generation coax with just one.

When it comes to the aerials, those originally installed for analogue only didn't have any mechanism to help block noise because it wasn't a problem. The newer aerials used for Freeview reception have something called a balun. This acts in a controlled way to break the direct connection between the cable insulation and the aerial. As a result, problems with noise are greatly reduced.

We spend a lt of time looking at- and minimising the effects of noise in aerial installations for digital TV transmissions. Noise affects signal quality. With digital, signal quality is far more important than signal power. It's always possible to increase signal power with some form of amplification. But signal quality can never be improved. It's at its best direct off the back of the aerial connection. Everything else we do either preserves it or reduces it, so we try hard to preserve it and avoid reducing it wherever possible.

The honest answer to your question of "How much....?" is there's no definitive answer. There are just too many variables to be that specific.

Personally, I would replace the aerial for the simple reason that doing it as part of one whole job is cheaper than coming back a second time. The type of aerial you need depends on where you live and also what's happening with TV transmission frequencies from your local transmitter over the next 10 years. The Government is determined to sell off chunks of the TV transmission bands to the mobile phone operators. This means finding an aerial that works well now but will also work well in the future when the TV frequencies have all been shifted.

In my part of the country (N.West England) that means choosing a Log Periodic aerial. For other parts of the country it could mean a Narrow Band Group aerial. There's also the question of whether the aerial needs amplification. This could simply be because the house is on the fringe area of the local transmitter, or you might have trees or a hill in direct line of sight between your property and the transmitter.

The answers to some of these questions come from local knowledge. The rest of the time though it needs direct measurement with a good (read 'expensive') aerial meter to see what the local conditions are like.

Once the aerial is sorted (plus any bracket work if bolts and nuts are rusted to hell), then it's diagnosing what's happening with the amplification in the house. This could be a 10 minute job "Oh, there's no masthead/loft amp power supply or it has failed". Or one could end up inspecting all the cable from the roof to the amp for breaks (more likely, just replacing it), or diagnosing a fault in the supply wiring or a failed masthead/loft amp.
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Thank you very much for the reply. This is very helpful.

There is no signal to the tv points around the house. I asked an engineer to look at it because I am particularly busy at work at present and do not have time to sort it out myself at present. The engineer said I needed all those works doing. BUT, last night I had a go at the system. I tried to find the aerial wire in the loft which I did and connected it directly to a tv. The aerial is fine and the picture was fine on the tv. I then put the aerial directly into the 8 way amplifier, disconnected all the other wiring from it, and tested each output directly to the tv. It worked fine. Then I put the tv aerial back into the original set up which is a booster unit in turn going to the 8 way amplifier. No signal. So its the booster box, that's all. Argos do a cheap new one for £16 although I'm sure there are better ones. The engineer has quoted me £600 plus VAT.

Thank you again for your reply.
It's amazing how a quote of £600 plus VAT makes the time to solve it! Glad you got it sorted and dodged the £720 bill.
Glad you got it sorted.

Note that I have a similar system to you:
Aerial >>> Booster >>>> 8 way Amplified Splitter

This all worked perfected until I got a new BT FreeView box when I stopped getting any TV images.

Thinking that a low signal was the issue I spent a lot of time trying to improve and strengthen the signal, but nothing worked.

In the end I found that the Booster was working perfectly, but it was over amplifying the signal, which was then amplified again by the 8 way Amplified Splitter and amplified again by the internal amplifier of the BT FreeView box (which was presumably better then my old free view box). So my BT FreeView box was getting a over-amplified Saturated signal and hence could not decode.

My solution was to simply remove the "Booster" and it now all works again.

So I am suggesting that your old booster maybe work perfectly, but over-amplifying and already good signal from the Aerial
And so you may not need a new booster, and if you do get one it may again stop you from having a working TV image.

Dear SFK,

Thank you for your helpful reply. If a new booster box doesn't produce a signal on the tv then this will definitely be the explanation. It would have taken a lot of figuring out otherwise.

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