Guide · TV & satellite
4G and 5G interference on Freeview
If your Freeview picture breaks up at certain times of day, and a new phone mast has gone up nearby, mobile interference is a likely cause. It's usually simple to fix with the right filter in the right place.
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Why mobile signals affect TV
Freeview and mobile networks share the same part of the radio spectrum. Over the last decade, frequencies that used to carry TV have been cleared for mobile use: first the 800 MHz band for 4G, then the 700 MHz band, cleared in 2020, for mobile including 5G. TV channels were moved lower to make room. The result is that mobile signals now sit right next to the frequencies your aerial is picking up.
Most of the time that causes no problems. But close to a mobile mast, the mobile signal can be much stronger than the TV signal. An aerial without a filter picks it up, and an amplifier boosts it along with the TV signal, which can overload the amplifier or the TV's tuner. The result is pixelation or loss of picture.
The signs of mobile interference
- It comes and goes. Mobile traffic changes through the day, so the picture often breaks up at busy times and recovers late at night.
- Some channels suffer more than others. Channels on frequencies nearest the mobile bands are usually hit hardest.
- It started recently. Often after a new mast went up, or an existing one was upgraded.
- The signal screen looks odd. Strength may look fine while quality drops.
- Your amplifier is involved. Systems with masthead or distribution amplifiers are more vulnerable.
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How it's fixed
A filter in the right place
A filter blocks the mobile frequencies while letting TV signals through. Where it goes matters. If you have an amplifier, the filter needs to go before it, so the amplifier never sees the mobile signal. If you don't, it can go at the TV or at the point where the cable enters the house.
Choosing the right filter
Older filters were designed for 4G at 800 MHz and don't block the 700 MHz band now used for mobile. If you fitted a filter years ago and the problem has come back, it may need replacing with one that covers both.
An aerial with built-in filtering
When an aerial needs replacing anyway, we fit models with filtering built in, so the mobile signal never enters the system.
Setting the amplifier correctly
An amplifier turned up too high makes interference worse and can overload TVs on its own. We set amplifiers to the level the system needs, not flat out.
What isn't mobile interference
Not every intermittent fault is caused by a phone mast. Water in a cable, a loose connector or a failing amplifier can also come and go, especially with the weather. That's why we measure before fitting anything: there's no point adding a filter to a system with a failed cable. Our guide to why your TV picture pixelates covers the other common causes.
Where it's most common in East Anglia
Interference is most likely in towns where homes are close to mobile masts and some distance from the TV transmitter, so the mobile signal is strong relative to the TV signal. Busy town centres, homes near main roads and railway lines with new masts, and anywhere with an amplified communal system in a block of flats are the usual suspects.
How we test
We measure the TV signal at the aerial and at each socket, look for the tell-tale signs of mobile signals on the meter, and check whether an amplifier is being overloaded. Then we fit the right filter in the right place, or an aerial with filtering built in, and check every channel before we leave.
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FAQ
Common questions
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Call 0800 151 2978How do I know if it's 4G or 5G interference?
Typical signs are break-up that comes and goes, often worse at busy times of day, affecting some channels more than others, starting after a new mobile mast appears nearby. A meter test confirms it.
Will a new aerial fix mobile interference?
Sometimes, if the new aerial has a built-in filter. Often a filter on the existing system is enough. It depends on where the interference gets in.
Do I need a filter if I have no amplifier?
Possibly. Interference can affect the TV's tuner directly. But homes with amplifiers are more often affected, because the amplifier boosts the mobile signal along with the TV signal.
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