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Do I need to buy a booster?

With analogue television, it has often been necessary to buy an amplifier to improve the quality of the television picture, or to supply a steady on several televisions fed from the same aerial.

With analogue television, it has often been necessary to buy an
published on UK Free TV

With analogue television, it has often been necessary to buy an amplifier to improve the quality of the television picture, or to supply a steady on several televisions fed from the same aerial.

Many people have asked if it necessary to investing in a signal booster for Freeview.

"Analogue television" means is that the sound and pictures are broadcast using signals that are an "analogue" of the input. The sound and picture are transmitted from the source as electrical signals, then as radio waves and then back to sound and picture again.

In an analogue television camera, the image is scanned 25 times a second from side to side, from top to bottom and back. Where a lot of light is scanned, a high voltage is produced. Where no light is scanned, no voltage is produced. The output voltage is the same ratio to amount of light at scanned.

Leaving aside the technically, this signal is sent to the transmitter. The transmitter emits a radio wave on a known frequency, which is varied by the incoming voltage.

A microphone also converts the sound vibrations it picks up into a voltage, which when sent to the transmitter is added to another radio transmission frequency.

The signals are received by a television aerial pointing at the transmitter and converted back to very weak electrical signals. The sound is amplified and sent to a loudspeaker, and a picture created on the TV screen.

So on an analogue television, if the incoming signal is weak then the picture is dull as the background noise (the snow scene seen when an analogue television is not tuned) makes the picture less watchable.

The best analogue television set equipped with a great TV aerial located near to a high powered transmitter will produce brilliant pictures and clear sound. A poor set with an inadequate aerial or substandard cable will not.

If a weak signal is fed to a booster device, this will make the picture appear better on the television set or sets. It is often worth the investment.

Digital television

In a digital studio, the voltages from the cameras and microphones are not sent directly to the transmitter. It is converted into a stream of numbers inside a computer. The input voltage relates directly to the number in the computer. By sampling the input at a regular frequency, it is therefore possible to both store and transmit the information digitally this is what computers are good at.

It is therefore possible to take these numbers and generate a sound and picture output from them. However, the amount of information generated is over 240Mb/s, 30 times the rate of the fastest broadband connection.

Buy using computational techniques on this information the data can be compressed to as low as 2Mb/s, with as little as 6Mb/s being required for a good quality picture. These data compression techniques are called "lossy" because the reconstructed images are not identical to the originals, but look virtually similar to human eyes.

Digital television uses the same transmission frequencies as analogue uses, known as C21 to C68. The digital data is sent using a system called COFDM (Coded Orthogonal Frequency-Division-Multiplexing) which can carry data at a rate of 18Mb/s or 24Mb/s. Several television channels and some radio stations can be multiplexed together to produce exactly this amount of data.

At the receiver, it must be able to decode every single bit from these transmission multiplexes. A single error is impossible to correct for, so the decoder must have no errors.

Until switchover happens, the Freeview signals are being broadcast at very, very low power levels. However the COFDM system and sensitive digital equipment will, as long as the signal can be found and decoded there will be pixel-perfect reconstruction of the television channel. If the signal is drowned out by interference (especially from analogue transmissions) then no picture or sound will be output.

If the TV aerial installation you have provides you with all the Freeview channels, there is nothing to worry about.

If you are missing some channels because the signal is just too weak the best place to start is by improving the aerial, see Freeview reception - All about aerials. A bigger, higher, better designed aerial will always be the most sensible way to get perfect reception.

If you want to supply a signal to several sets, where the incoming signal is being "split" to serve several Freeview boxes, a masthead amplifier will be effective. This is because the signal is already of good quality and is being repeated for several sets.

However, if you are not getting a good signal from your aerial, a booster by the TV set will probably not help as this will simply boost the background interference as much as the Freeview signal.

In circumstances where an amplifier that has improved a picture on an analogue, it may be unsuitable for Freeview reception. Sometimes they will block one or more multiplex, where disconnecting the amplifier will restore the channels.

Help with Television sets?
Why are all TVs on sale not digital?1
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In this section
Loft aerials1
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Indoor aerials3
Whole house digital TV4
Connecting it all up5
Now and Next6

Wednesday, 6 May 2015
Dave Lindsay

6:37 PM

Paul ware: Try manual tuning if available. For PSB1 (BBC One, BBC Two etc) tune to UHF channel 60 and for PSB2 (ITV, Channel 4, Channel 5 etc) tune to UHF channel 57.

What you should do is, on the manual tune screen, enter/select the UHF channel number but hold off pressing the button to scan/add services immediately as in this situation a receiver usually acts like a signal meter, often giving strength and quality readings.

In answer to your question, to feed the main television and bedroom TV from the rooftop aerial then you may well need a powered amplifier (booster) with two outputs at your location because the ground rises up in the direction of the transmitter and therefore you can't see it:

Terrain between ( m a.g.l.) and (antenna m a.g.l.) - Optimising UK DTT Freeview and Radio aerial location

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Dave Lindsay's 5,724 posts GB flag
Tuesday, 17 November 2015
s pocock
8:25 AM

I have a loft aerial feeding a Triax loft box and Triax 304115 wall plate with return link. The return feeds 3 tv's upstaurs with a good signal but I have to boost the signal to the tv downstairs which is also fed by the return link and nearest to it. It seems strange that I have to boost the shortest signal run. The tv is a 65 inch Sony but should it need boosting?

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s pocock's 1 post GB flag
Monday, 18 January 2016
Michelle Davies
12:31 PM

Can someone help please, we have lost some plus channels on our TV. We are currently running 4 TV's from the amplifier in the loft and for some reason have lost these on our TV in our bedroom. Would a booster box help get these back? or do I need to look at a different solution.

Your help would be very much appreciated.


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Michelle Davies's 1 post GB flag
Friday, 29 July 2016
John Hamlyn
9:27 AM

How can sync the sound on 2 digital TVs app 10 Meters apart I get a lot of echo

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John Hamlyn's 1 post GB flag

1:15 PM

John Hamlyn:

Depends on the TV sets. The delay is caused by the signal processing circuitry and software. Some sets have a feature in the settings menu to adjust the sound delay, but not all do.

So look it up in your TV set's User Manual, or find it on-line, and that will tell you how to do it if it is at all possible.

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MikeP's 3,056 posts GB flag

8:58 PM

John Hamlyn: If your sets are all tuned to the same channel, you really shouldn't get much echo. I've just come back from a showroom with at least 20 sets on an aerial feed, with no echo at all. Its true that different sets have slightly diffeerent delays in processing, but that really should be enough for an echo.

However, if one Tv is on the SD channel, and the other on the HD, then there will be a 2 second delay.

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MikeB's 2,579 posts GB flag
Sunday, 21 August 2016
Mike Stevens
2:30 PM

I live on a house boat on the River Medway. I have just installed a new Yagi 18A aerial but cannot get all of the Freeview channels. I have to get a signal from Crystal Palace and I am getting a bit of digital interference.
Would a mast amplifier help?
Any other suggestions.

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Mike Stevens's 2 posts GB flag
Richard Cooper

3:56 PM

Mike Stevens: Hi, Mike. The height of your aerial is an important factor. Is it, for example, as high as it would be if installed on the top of a bungalow on land? Could you have your aerial fixed to a taller pole on your houseboat than you have at the moment? I would experiment with aerial height first before making the financial layout for a masthead amp. Richard, Norwich.

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Richard Cooper's 466 posts GB flag
Monday, 22 August 2016
Mike Stevens
10:24 PM

MikeB: Thank you. My aerial is at about the height of a bungalow but I will put up a temp rig and see if I can get a better reception.

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Mike Stevens's 2 posts GB flag
Mike's: mapM's Freeview map terrainM's terrain plot wavesM's frequency data M's Freeview Detailed Coverage

11:18 PM

Mike Stevens: I think you have to thank the other guys - but I hope it works anyway!

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MikeB's 2,579 posts GB flag
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