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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.
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.
Our home is in a valley and as consequence the signal from P.P. is reduced. This has been improved in the past by installing a mains powered signal booster to the aerial where it enters the house, maximum gain 17 Db
Subsequent to changeover the reception across all channels has remained at pre-changeover quality with he exception of the newly consolidated BBC channels ( Chan 58 ).
If I remove the booster the situation deteriorates, ( more vision pauses and less audio ), but improves once it is reinstated but still to an unacceptable level.
The same deterioration occurs if the booster gain is reduced.
Channels other than the newly consolidated BBC Mux are not affected.
The aerial has not changed since pre-changeover and we are no further away from P.P. yet the changeover help line are advising that an attenuator be fitted into the aerial lead.
I have been unable to find any viable technical query route into the faceless transmission services industry and the BBC questionaire service is not fit for purpose as they advise that it is not monitored and that they do not reply to all queries as a matter of policy.
Is there any service I can access to unravel this situation and get my service back to its pre-change-over performance
I have just removed my sky system and installed BT vision to my main tv and also 6 others around the house. The signal to the main TV is ok however the signal to the rest being feed of an amplifier in the roof space ( main one then split between 6 tv leads) has led to no reception at all . Could the amplifier (Booster) be broken or unsuitable for purpose ? Any suggestions would be most helpful before i go to purchase various componenets.
e. roberts: Well the advice that was given to you by the changeover helpline regarding an attenuator would under normal circumstances be correct, as at your distance from the transmitter your TV or boxes tuner could be completely swamped by the signal thereby seriously affecting reception, or indeed even blocking it altogether.
But though being located too close to a high mast can put you in am umbrella type situation whereby you are in effect being shielded from the signal, and by you being located in a dip makes matters worse.
You say that your TV has its own dedicated aerial but where is it located? and have you tried some tests using a simple (emphasise on simple!) set top aerial and moved it around at various angles whilst observing the signal quality as shown on the signal strength / quality test screen? even try a short piece of wire (about 3 feet or so max) connected into the aerial socket and see what results you get using that.
My daughter has just moved into a flat which has a tv aerial point but tv shows no signal being received. Neighbour says there is a communal loft aerial but we need a signal booster as adjoining building blocks the signal. Are there different types of boosters? Any advice welcomed.
farmgirlj: If the post code that's been entered is that of your daughters, then unfortunately the signal levels expected at wherever she might be located cannot be assessed as the entry made in the box has contained disallowed characters, likewise DUK's checker rejecting them.
However as far as boosters are concerned, its sometimes a safer bet to purchase a variable gain type such as sold by Argos. link to same below.
Argos item number: 534 / 4235 (Â£11.99)
If though you provide a proper post code, or one from nearby e.g: a shop, then further advice can be given.
hi we have a external arial and a 6 way booster with only 2 tv on it on bbc 2and 2 we get defragmataions to the picture our some times no picture at allmost of the other programes are ok we live high up on dartmoor , devon could you give me so me some
advice how to inprove this situation thanks
jeff cane: On the basis that you live high up I assume that you may well have line of sight to your transmitter. You may also have good signals from other transmitters. For this reason, the first thing I would do is check that your TV is tuned to the transmitter you are using for all its five standard definition and one HD channel.
It is the case that too high a signal strength can cause poor or no signal which is exactly the same as too little a signal.
You "may" be able to turn down the amplifier (assuming that it has such a control), or even remove it and replace with an unpowered splitter, and still get all channels. Before you do any of this though, check that you are tuned to the correct transmitter.
There are six signals known as multiplexes. Each carries a number of services and you just need to check one service from each.
I live in Portsmouth; we get our Freeview from the Isle of Wight transmitter. We get good reception of all Freeview channels but not 11-Pick TV, Dave-12, 29-E4+1 and 32-Movie Mix. All these come from Portsdown hill xmitter. On the bad channels we show 100% signal and almost 0 signal quality. The good channels show 100% level and quality. We use a common aerial for 12 flats. The aerial feeds a 6 output (fixed gain) 8db gain per output into the six 8 output SLX (12db fixed gain) per output. That is 48 feeds to the flats.
Hi, I live in Faringdon Oxfordshire, we get our signal from the transmitter near Oxford. We have 2 TV's an old CRT and a brand new digital Samsung. When I tuned the new TV, none of the Com 6 channels such as Yesterday where displayed and I have tried retuning several times but still missing these channels. But on the old CRT TV which used a Humax box to receive the digital channels I was able to get these. In fact our other TV which an old CRT which uses a freeview box can still get them. What should I do???
Hi I live in Altrincham,Cheshire (near Manchester) within the last two weeks instead of normally receiving ITV local news Manchester I now receive ITV local news Wales. Checked the system retuned freeview, nothing in the immediate area has changed (new buildings etc). I have two TV systems connected to one aerial picture and sound quality OK. Please Advise. Regards
I am new to FreeView and aerials. My signal strength on all channels varies from 26 to 45%, signal quality always 100%.
Is this a reasonable situation?
Advice from the experts will be gratefully received.
One. Aerial feeds 3tv,s main tv in lounge has signal Booster fitted, no problem, tv in kitchen no online. Booster fitted no problem, tv in bedroom no booster fitted keeps losing the signal and freezing. Will it be the tv or will a booster help and if so what type of booster will be best..advice will be appreciated. Thanks
Gil: What method are you using to connect the three TV's to the aerial? as going by what you have said would suggest that you are already using two boosters, but with the signal being fed to the bedroom TV also requiring one.
The normal way of doing things is to have the aerial going straight into a three way booster / splitter and with each of its three outputs being used to feed the TV's in each of the three locations.
Advice regarding boosters / splitters can only be given if you indicate your location, this in the form of a post code or one from nearby, e.g: a shop or post office, as this will enable the signal strength expected at your location to assessed.
My postcode is PO31 7SJ and I live in Cowes on the Isle of Wight.
I have an aerial on the roof (-attached the the chimney) and a booster splitter up in he loft. This was all fitted by TV/electricity specialists a few years ago at the same time as they installed several TV sockets around the house, including basement, living room and bedrooms. The signal was never great and used to be affected by cruise liners passing along the Solent. Boat passage no longer has any impact but the TV signal has got worse and a TV specialist came to check things and said the booster splitter needed replacing which he did a year or so ago.
Things seemed to work again fairly well, but never brilliantly and sometimes unplugging and plugging the aerial would fix things temporarily. Recently things have deteriorated so often there is not any signal. The picture flickers all the time since The big change and digital was introduced and most often there is the "weak or no signal" notice on e screen while trying to watch the BBC channels, while other times it is only the other channels and sometimes no channels work at all.
What should I do? Get the aerial adjusted, the booster fixed, change the cables or just throw my TV out the window?
Angie: Which transmitter is the aerial pointing to? Hannington is North, Midhurst (roughly)NE and Rowridge SSW. Check that the TV is tuned to the correct frequencies for the chosen transmitter. It is worth mentioning that if Midhurst was chosen, this is not predicted to give particularly good reception. If Rowridge, there is an additional vertically polarised signal transmitted from this mast since switchover. Changing the aerial to vertical polarisation could improve reliability of reception from Rowridge. When doing an automatic scan for channels signals for Rowridge are found first in the scan. If you intend to receive from Hannington (or Midhurst) do a manual tune for each of the correct frequencies after first clearing the channel list, or alternatively start the scan with the aerial unplugged, then plug it in at C38 after the scan has gone past the Rowridge frequencies.
Angie: Just purely out of curiosity, although things might well have been altered by now as the street view imagery I am looking at is not bang up to date, but most of the aerials seen on the roofs of the Beckford Road properties are pointing towards either the Midhurst or Hannington transmitters, this making me wonder where your aerial is facing? Rowridge being on a bearing of 207 degrees, you can use the Sky dishes seen as roughly facing towards 152 degrees.
A terrain check of your area indicates that the signal from Rowridge is being obstructed from about 1.5 miles from your location, but considering that the 200Kw Rowridge transmitter is located at only 6.5 miles away I feel that the chances are that you could being receiving a better level of signal than you are doing by having your aerial system checked out by an installer, provided that is if its someone of the "open minded" type meaning a person who is prepared to try a few tests using such as a log periodic aerial which is perfect for applications such as yours.
I do realise that your aerial has already been checked out by a TV / electrical company, but I am inclined to agree with Mazbar's inference with regards to a spark, because (and without wishing to appear offensive) but electricians are generally not compatible with frequencies higher than 50Hz or so albeit that they might well be top people in their own field.
Thanks so much fr coming back t me. TV still behaving bady and picture gets white lines and freezes all the time if it works at all.
It looks like I need to get a specialist in as I am struggling to even answer your questions, I will try to find out and let you know, My house is on the RHS of the road going up the hill from the sea. Would itnhelp if I check the compas bearing of the aerial?
The original installation of coax, booster and TV sockets was done by an electrical firm who claimed TV expertise. The booster was replaced by a TV specialist.
Angie: Getting back to the basics, have you as yet made any local enquiries with regards to the standard of reception being experienced by others around your area? as this would at least give you an idea if the problem is widespread or is possibly solely confined to your own installation.
The other thing being, that its essential to find out which transmitter your TV is tuned to, this normally achieved by carrying out a signal strength check whilst viewing a programme as the transmitter channel number is usually given along with the signal strength indications, try this whilst viewing the BBC, Rowridge being Ch24 / Hannington Ch45 / Midhurst Ch55.
It would also be of assistance if you could provide the model number of your Samsung TV, as Samsung in common with LG's etc do not use the same menu system across their ranges.
Angie: Just to clarify on that said, I am looking at it from the point of view that should it be found out that others are also experiencing similar problems to yourself, then it would be somewhat pointless in paying out for another aerial installer to visit your property for the purpose of checking your aerial system out, but though on the other hand if it transpires that no-one else seems to have any complaints about their reception then your difficulties "might" simply be caused by your TV having auto-tuned onto a station whose signal is prone to being received in a somewhat erratic fashion at your location, this being the reason for the signal level / transmitter number tests.
Of course, needless to say that should the latter be found NOT to apply then it certainly is time to seek the assistance of an aerial installer, although before actually doing so I would try and vet (by asking around) whoever you might be thinking on contacting bearing in mind that you were previously told that your aerial was OK.
By the way, if you find anyone who does not have any complaint with their reception, then have a quick glance up at their roof to check on the direction that their aerial is facing.
Hi, hope you can advise on my problem.
Three years ago we decided to upgrade the aerial system to our home. We only had an aerial pole mounted and feeding our main living room TV. This had been installed about four year previously.
We asked for a signal in each of our three upstairs bedrooms and left the guys to it. After completion we were shown the TV in each bedroom working fine with a good picture on screen.
However within a month or so we found picture quality very erratic and unreliable. Sometimes no signal being received at all on at least one set. Checking out in the loft we found that from a second aerial added to our roof pole a single coaxial cable led to three co-axial cables. All taped together with insulating tape and with a cable leading down to each bedroom.
Would installing a booster in the loft improve the signal and give us three televisions we can rely on once again. And if so can you recommend a good booster. Thank you.