4G and 5G Interference with Freeview: Symptoms and Fixes

4G and 5G mobile networks broadcast in the 800 MHz and 700 MHz bands, directly above the frequencies Freeview uses, so a nearby mast can cause pixellation, blocking or lost channels — usually on some multiplexes but not others. The fix is a filter: the Restore TV scheme (formerly at800) supplies free filters to affected homes, and an installer can fit an LTE filter before any amplifier. A booster is not the answer and often makes it worse.

Here’s why it happens, how to recognise it, and how to fix it properly.

Why mobile signals ended up next to TV signals

UK television broadcasts on UHF (Ultra High Frequency) spectrum. Before 2013, television occupied everything from 470 MHz up to about 862 MHz. Since then, two slices of the top end have been sold off to mobile networks:

Band	Cleared from TV	Now used for	TV retunes required
800 MHz	2013	4G (LTE)	2012–13
700 MHz	Completed August 2020	5G and 4G	2017–2020

Today’s Freeview band ends at 694 MHz (UHF channel 48). Mobile signals now sit immediately above it, with only a thin guard band between them. Older aerials, amplifiers and TV tuners were designed to receive the whole of the old band — so they happily pull in mobile signals too, and a strong 4G or 5G transmission can swamp the wanted TV signal.

Two distinct things go wrong:

Direct interference. Your TV tuner receives the mobile signal alongside the TV multiplex (MUX — a bundle of channels sharing one broadcast frequency) and can’t separate them cleanly, especially on MUXes near the top of the band.
Amplifier overload. If you have a masthead or distribution amplifier (a powered signal booster, usually in the loft), a strong mobile signal can drive it into overload. An overloaded amplifier distorts everything passing through it — so reception breaks up on all channels, not just the ones near the mobile band.

Symptoms: what 4G/5G interference looks like

Pixellation, picture freezing or “blocking” (the picture breaking into squares), often intermittent rather than constant.
Some MUXes affected, others fine — you might lose the channels on one or two MUXes while BBC One carries on perfectly. Interference is frequency-dependent, so it rarely takes out everything unless an amplifier is overloading.
Worse at certain times of day — mobile mast traffic varies, so interference can come and go with network load.
Started suddenly — classically after a new mast goes live nearby, or after a network switches on 700 MHz 5G in your area. If your reception was fine for years and broke without a storm or any physical change, a new mobile transmission is a prime suspect.
Worse the closer you are to a mast — homes within a few hundred metres of a mast, especially with line-of-sight from the aerial to it, are most affected.

These symptoms overlap with other faults — water in the cable, a shifted aerial, a failing amplifier — so don’t assume. Our guide to why your Freeview signal disappeared covers the full differential. The tell for mobile interference is the pattern: sudden onset, some MUXes only, no visible damage.

The free option first: Restore TV (formerly at800)

When the 800 MHz band was cleared for 4G in 2013, the mobile operators funded a mitigation body called at800 to deal with the TV interference their new networks caused. Its successor scheme, Restore TV, performs the same role for the 700 MHz/5G rollout: if a new mobile mast disrupts your Freeview reception, the scheme supplies a free filter, and in harder cases can arrange further help.

Before you spend anything, check whether Restore TV covers your situation — a free, operator-funded filter posted to your door is the right first move if a mast has recently gone live near you. It’s a simple in-line device you connect between the aerial wall socket and the TV.

The limitation: a plug-in filter at the TV end can’t fix amplifier overload, because the overload happens upstream in the loft or on the mast, before the filter. That needs the filter moved to the right place in the system — which is where an installer comes in.

LTE filters: what they do and where they go

An LTE filter (LTE stands for Long Term Evolution, the technical name for 4G; the same filters block 5G in the 700 MHz band) is a low-pass filter — a passive device that lets everything below a cut-off frequency through and blocks everything above it. A modern “5G-ready” filter passes UHF channels 21–48 (up to 694 MHz) and rejects the mobile bands above.

Placement is the whole game. The filter must sit before the first amplifier in the signal chain:

No amplifier? A filter at the TV end, or better still where the aerial cable first enters the house, is fine.
Masthead amplifier (fitted on the mast below the aerial)? The filter needs to go between the aerial and the amplifier input. Many modern masthead amplifiers have the filtering built in — older ones don’t.
Loft or distribution amplifier feeding several rooms? Filter on the amplifier’s input. Fitting filters at each TV does nothing if the amplifier upstream is already overloaded.

If your system was installed after about 2021, there’s a fair chance the aerial and any amplifier are already 5G-filtered — reputable installers have fitted filtered kit as standard since the 700 MHz clearance completed in 2020. Systems older than that are a lottery.

When a grouped aerial helps

Aerials come in frequency groups — designed to receive only a slice of the UHF band — or as widebands, which receive the lot. A wideband aerial from the pre-clearance era is, by design, an efficient collector of what is now mobile spectrum. If you live close to a mast, replacing an old wideband with a grouped aerial matched to your transmitter (most main transmitters now fit within group A, B or K) rejects mobile frequencies at the aerial itself, before they enter the system at all. Our guide to UK aerial groups explains how to find your transmitter’s group.

This is worth doing when a filter alone isn’t enough — typically very close to masts — or when the aerial is due for replacement anyway. It’s not the first resort: a £10 filter usually beats a new aerial.

What not to do: add a booster

The instinct when a picture breaks up is to add amplification. With mobile interference this is precisely backwards — the problem isn’t that the TV signal is too weak, it’s that an unwanted signal is too strong. An unfiltered booster amplifies the mobile signal along with the TV signal and pushes the system closer to overload. If you already have a booster and interference symptoms, try removing it (or fitting a filter ahead of it) before anything else. Our booster vs amplifier guide covers when amplification genuinely helps and when it hurts.

While you’re checking the system, check the cable too: old or degraded coax with poor screening lets interference in along its whole length, filter or no filter. See our coax cable guide for what decent cable looks like.

Confirming it properly: the signal meter

You can gather good evidence yourself — your TV’s signal screen will often show one MUX with poor quality despite reasonable strength, which is the interference signature (our signal strength guide explains how to read it). But confirming 4G/5G interference definitively needs a spectrum analyser — a professional meter that displays the whole band, showing the TV MUXes and any mobile carriers sitting above them, and revealing whether an amplifier is overloading. An installer with a proper meter can diagnose this in minutes on the roof or in the loft, rather than guessing with trial-and-error filter placement.

Typical costs if the free Restore TV route doesn’t apply: a quality LTE filter is £5–£15 supply-only; a call-out to diagnose and fit filtering in the right place is usually well under the £150–£250 cost of a full aerial installation, unless the aerial itself needs replacing with a grouped model.

If you’ve tried a filter and the picture still breaks up — or you’d rather have someone with a spectrum analyser find the actual cause first time — send us your postcode and symptoms via our contact page. We route enquiries to local installers who cover your area and can diagnose interference, fit filtering in the right place, or repair the aerial system if the fault turns out to be something else.