Why Does My Freeview TV Signal Break Up & Pixelate

July 24, 2017
by
Tom Smart

Why Does My Freeview Signal Keep Breaking Up And Pixelate?

 

Your sitting at home, you put your feet up whack your favourite TV programme on only for it to be blighted with pixilation. Although digital TV has dramatically improved our TV experience and expectations. When it goes wrong it goes completely wrong and becomes something completely unwatchable something we refer in the trade as the “Cliff Effect” – unlike the old analogue signals which would degrade gracefully, becoming grainy and snowy before they would disappear altogether.

 

This is going to be a difficult one to say for certain what may or may not causing your Freeview TV reception to break and pixelate or cause complete loss of signal altogether as the problems with digital TV reception will always manifest themselves in the same way. What it will do is give you an idea as to what the most likely reasons which could be causing your TV signal to fail.

 

Without any further ado let’s begin and shed some light as to why you have poor TV reception.

 

But one last thing, if you just cannot receive certain channels, such as Dave, Viva, many of the +1’s it’s possible that the TV transmitter that you are receiving your TV signals from may not actually broadcast the channels. There are a series of relay transmitters across the county which receive a signal from a main transmitter and re-transmit the signal on a different frequency to an area which for whatever reason such as large buildings and the general landscape may not be able to receive the original signal. We call these transmitters ‘Relay’ transmitters and the vast majority only broadcast what is known as Freeview Light or Freeview Lite which is about half the channels. To find out more about Freeview Light please read an old blog of ours.

 

https://www.smartaerials.co.uk/blog/what-is-freeview-lite-light

 

Reasons Your Freeview Reception Is Poor

 

Digital TV is literally in its simplest explanation a series on and off commands represented as 0 and 1 on a carrier wave. This simple phenomenon in a variety of ways can supply us with all the information we need for some 150 services including digital TV and radio including HD which we can now receive through Freeview.

 

Any problem with the data stream. Literally 0’s being mixed up as 1’s and vice versa when they become too frequent will cause the TV signal to pixelate. You will always have some errors within the signal and there is also some built in error correction which should iron these out and also meaning there is no such thing as a perfect signal.

 

Not Enough Signal Strength

 

Sounds obvious, right? Well that’s because it’s self-explanatory. It’s what the software in your TV or set top box says when there is any sort of problem. When a signal is too weak the TV will struggle to make sense of the of the data stream. The TV signal at the receiving end for Freeview should be a strength of at least 50dB, no less than 45dB.

 

You should try to find what is causing the signal to be weak and improve it using all passive techniques possible first. This may include replacing cables, aligning or replacing TV aerials, replacing fly leads and wall plates for high quality versions. Otherwise the installation of an amplifier at the aerial end should help. Please be aware that amplifiers are only intended to overcome the signals occurred as a result of cable lengths and splitters. Although it would help amplification should be used to try and create signal where it isn’t already coming off the aerial.

 

For more information on how to install a masthead amplifier at the aerial end where there is no power socket, please read our blog on how to install a masthead amplifier.

 

https://www.smartaerials.co.uk/blog/how-to-install-a-masthead-amplifier-and-power-supply-unit

 

Too Much Signal

 

No one ever believes this one when you tell them. So, mean to say that the reason my TV reception has been breaking up is because I actually have too much signal! Yes, this is a genuine problem.

 

TV’s and TV equipment all have a maximum threshold of signal which they can handle. Although in blocks of flats where TV aerial and satellite signals are ‘launched’ they can often handle signals of up to 120dB which is the same as 1V. In a domestic environment, the receiving signal at the receiving end should not be above 80dB, ideally no more than about 77dB.

 

Fortunately, this is lovely problem to solve so much easier than working in a weak signal area. Firstly, you should aim to remove any unnecessary amplification first as this could be what is causing the signal to over-load. Distribution amplifiers could be replaced with passive splitters. Where the signal is still too strong you would need to install an attenuator or a couple of attenuators. These come in different levels of attenuations depending on how much you want to drop the signal down. 3dB, 6dB, 10dB, 12dB as well as adjustable versions are common.

 

Before you decide that your reception issues are because you have too much signal you may just want to check a transmitter map to see how close you are to the transmitter. If you are with a few miles chances are you are going to have loads of signal.

 

Interference

 

With our wireless modern lives, there is so much going on with radio waves and other stuff going on Freeview reception is subject many forms of interference. I have broken this section into the most common types that are likely to affect your TV reception. This is somewhere satellite has a distinct advantage over terrestrial TV signals as it is much less likely to be effected by such issues. This does not mean it is impossible however and when your TV aerial has been installed correctly you should expect to not suffer from TV interference.

 

4G Interference

 

Thanks to the advancements in mobile internet technology more and more demands for frequency bandwidth. Thanks to this and because the fact that digital TV needs less bandwidth space than the older analogue transmissions part of the UHF band which was used for TV was sold off to the mobile broadband service operators.

 

It can cause problems with Freeview when there is a 4G mast nearby and the interfering 4G signal gets above a certain strength and overload the TV equipment. Obviously old aerial equipment was designed to pick up and receive these frequencies so they can actually make this problem worse.

 

This problem can usually easily be solved with a 4G filter. This needs to be installed before any amplification or distribution equipment so where you have multiple Freeview TV points so a trip up to the loft or roof may be necessary. New aerials and amplifiers are actually designed to filter out 4G signals so with a new aerial and amplifier you are much less likely to suffer from 4G interference. Do beware however than when installing a new amplifier that it does not filter out some of your services too. Some amplifiers will only pass up to channel 57 nowadays which presents the obvious problem when there are transmitters that use channels 58, 59, and 60 like the White hawk TV transmitter in Brighton and the Dover TV transmitter.

 

Interference from Neighbouring Transmitters

 

It is possible that in your quest for a full Freeview service and not being content with your local Freeview Lite service that you have aligned your area to a weak out of area transmitter possibly with an amplifier. Your local transmitter may be so strong that it itself may be overloading your TV equipment.

Efforts should be made to remove local TV transmitters that you’re not using from the signal that you deliver to the TV. This is usually solved with the installation of a bandpass filter or otherwise notch filters could be used.

 

Impulse Noise / RF Interference

 

All electrical equipment emits some form of electro-magnetic field which could cause your TV signal to pixelate. The majority of electrical equipment installed comes with a suppressor to limit this, but this doesn’t mean it will be effective or actually working for that matter.

 

I can recall a situation only a few years ago when I had installed a brand-new aerial which was working fine only for the customer to call me and say it wasn’t working. I went back to find it timed exactly as the when the tree surgeons across the road were powering their chain saws. They finished and everything was fine again.

 

I had another issue where I had installed a new aerial only to get a call with problems. After I had finished the installation the client had put their wireless router next to the TV. I found this to be the problem and moving it only a couple of feet away solved the problem.

 

You may yourself remember when a mobile phone going off has caused the TV picture to play up or when someone has started the ignition on their car.

 

To limit this effect, you should always install aerials with an integrated balun or a log periodic design, double screened coaxial cables and screened wall plates and splitters. Filters sometimes can be effective at combating this too.

 

Co-Channel Interference

 

Often just called “Co-channel” in the trade. This is when an interfering signal comes in on the exact same frequency that you want to use from your TV transmitter. It literally knocks it out. If you were to take signal strength readings they would come back fine, the C/N or MER readings wouldn’t look good at all however.

 

Co-channel Interference usually comes from a neighbouring transmitter and can rear it’s ugly head in periods of high pressure when signals travel further. In the South East we can actually get Co-channel interference on the coastal transmitters from abroad places like France, Germany and Belgium in high pressure.

 

We also have a problem where a transmitter on the South Cliff Tower on Eastbourne seafront knocks out half of the stations from the Hastings transmitter.

Co-Channel Interference can be a pain as it can’t be filtered out because to do so would mean that you would filter out the TV signal that you want to keep. The only real solution is to try and re-align your TV aerial to another TV transmitter.

 

Other Communications / Tetra Interference

 

Aside from interference from 4G and neighbouring TV transmitters there are others sources which cause loss of TV reception. Interference from Tetra a communication which operates in and around 395Mhz and is used by the emergency services. This has become very rare these days however as the vast majority of equipment comes with a built in Tetra filter and the emergency services are actually not using these frequencies so much as they used to.

 

Communication links has cause problems. If you are near a train station or an airport for example there is a chance that the communication links could interfere with the TV signal.

 

Again, all of the above should be easily fixed with the installation of an appropriate filter.

 

5g Interference

 

At the time of writing this is not yet happened. But like 4G much of the UHF reserved for Freeview is being sold off for more mobile internet services. We are likely to see repeat of what 4G has done to TV reception. The vast majority of homes will not be effected but it is worth noting that TV equipment that will are fitting today will likely do nothing to protect against 5G interference on Freeview Channels 50 and above are going.

 

This does present the obvious problem that large amounts of TV transmitters will be moving their transmitting frequencies. Meaning people will need to retune their TV equipment, something itself which can cause problems and I will be telling more about in this blog.

 

Faulty Equipment

 

There is a chance that it is just the equipment you have at your home that is causing the interruption to your Freeview service. This is far more common than anything external to your property such as interference or problems with your TV transmitter.

 

Faulty/ Waterlogged Cables

 

This is very common, as it is widespread to have your TV aerial cables installed on the outside of your property over time these could break down and fail. You should make every effort to secure the cable as best as possible including where it may run down the roof tiles as if it is allowed to move it is likely that it will chafe and cause a break in the cable.

 

Also, the sun over time will leak out the plasticiser in the cable it brittle and eventually over time fail apart. Believe it or not black cables will actually last longer than white cables because of the effect the sun will have on this colour. So, it’s better when installing cables outside that you use a black cable instead of a white cable.

 

It is very common in both of the above instances that once the PVC has broken on the cable that when it rains the rain water actually enters the cable and remains in the cable. Worst case scenario is that the water will use the cable like a slide and slide down it all the way and enter your TV equipment.

 

You be amazed at how much water can actually be held within a cable. I have personally on more than one occasion cut a cable and for a period of time it ran like a tap, usually brown rusty water that you don’t want leaking over your carpet. If you have water in your cable you need to replace it right away as it could damage your TV equipment.

 

Another common issue is a faulty fly lead connecting between your TV wall plate or between your TV/ AV equipment. You should always discard the factory fly-lead that often comes with your TV equipment and have a good one made up with double screened coaxial cable ideally with all copper conductors.

 

Faulty Amplifiers / Distribution Equipment

 

A faulty amplifier is a very common cause of poor TV reception. The signal goes in fine and comes out awful. It’s a simple fix usually – replace the amplifier. A faulty amplifier or power supply unit used to be really easily in the analogue days as often you would get a black rolling bar known as a “Humm-bar” across your TV picture. There is no such opportunity with digital TV signals.

 

Passive equipment can become faulty as well. This is usually some form or physical damage which could cause passive splitters to become faulty. Another common reason that cause this is the constant disconnecting and connected of cables such as in wall plates which can break and ruin the TV signal.

 

Faulty TV / AV Equipment

 

Although your TV may be giving you a “No or weak signal” message it is possible that the signal is absolutely fine and it is just the TV or AV equipment which is faulty. This is actually very common. I have personally taken a TV out of a box to set up for a customer only to find it is faulty.

 

There are still people who repair TV’s but sadly as the cost of TV’s has fallen and fallen often it makes more sense to just replace the thing and receive a new warranty foe the new TV.

 

There could also be a connection issue where the aerial signal has been looped between some AV equipment such as a Sky box, DVD recorder or Freeview+ recorder before it reaches the TV. There is a potential that one of these pieces of equipment is ruing your Freeview signal.

 

Faulty Aerial / Faulty Antenna

 

Obviously if you can see the aerial lying on your roof that is the problem. If it looks fine it usually is. The majority of problems around a broken aerial are usually because water has been allowed to enter the dipole. Some aerials are more prone to this than others but often the water has just forced its way in or the aerial has been installed incorrectly.

 

Another potential thing that could break your TV aerial is a nearby electrical storm or lightning strike. The aerial itself may look fine but the inside may be completely fried.

 

Trees

 

Another very common problem, trees are an aerial and satellite installer’s worst enemy. One day they are fine but as they move, grow and leaf during the different seasons they can cause problems.

 

The odd tree is fine but as the trees become more and more dense the will cause more and more of a problem for Freeview TV reception.

 

Your aerial should be cunningly installed to avoid the trees as much as possible. Usually this would mean getting your TV aerial moved to the roof or high up on a wall but on occasion I have found actually lowering the TV aerial to miss the branches and leaves – I would never assume this however as it is not common and a signal test should always be performed beforehand.

 

Transmitter Problem / Poor Signal Area

 

Sometimes you may do everything right. Install an antenna with a balun, use double screened coaxial cable and wall plates, install your aerial high up on a chimney stack with a filter to remove any unwanted signals or interference and a working TV and you still get problems. There is a chance that there is a problem with the transmitter.

 

Transmitter problems are not as common as some people think, they usually occur when the transmitter is under some form on maintenance but they do sometimes happen.

 

You may just be in area where you can’t get Freeview, again this itself isn’t very common. Because Freeview is broadcast from a land based transmitter the land itself, buildings and trees can get in the way. If this situation you should either satellite TV and opt for Sky or if you do not want to pay a monthly subscription Freesat which itself is very similar to Freeview but not exactly the same.

 

TV not tuned correctly

 

Some people often look at me in disbelief when I go to the manual tuning settings instead of the auto-tune. I going to save you a full reason because I have written a whole separate blog on this subject which you can read here.

 

https://www.smartaerials.co.uk/blog/why-should-you-manual-tune-your-tv

 

Essentially when you run an auto scan you TV may see signals from neighbouring transmitters and want to store them instead in place of the good TV signals that you want to use. These signals themselves may not work properly and cause the TV the pixelate.

 

Where this is the case, the best option would be to try and filter out the unwanted TV signals. Another thing you could do is to fit an attenuator whilst you tune the TV and remove when the auto scan has completed. With the right sized attenuator, you would weaken all the signals but should weaken the signals you do not want so they are no longer recognising the unwanted TV signals and still recognising the signals you do want. This is a challenge in itself so you may want to be purchase am adjustable attenuator to right the right balance or get your aerial installer to supply you one. Should only cost you a few quid extra as well.

 

There you have it, by far our longest blog to date. There are of course many more ways that your Freeview reception can be disrupted but this blog would have gone on forever. I’m not sure anyone would have made it to the end.

Of course, as always, please do LEAVE A COMMENT if you have any questions you would like me to answer. Until then bye for now.

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