Freeview Help: Interference

Weak signal strength is the most common cause of TV picture break-up. Your Freeview receiver just can’t get enough signal to hold a decent picture.

Most Freeview set-top boxes and TV sets have an on-screen signal strength meter. This can be useful in working out how good your incoming TV signal is. You may have measurements for both Quality and Strength – the measurement for ‘Quality’ is very important – if this is high, then you’re likely to get good pictures even if the ‘Strength’ is much lower.

If your signal is weak, check your Freeview coverage. If you’re in a good Freeview coverage area, then a weak signal could point to an aerial issue.

You should find the on-screen signal strength meter somewhere in one of the menus. Check your receiver’s manual for details.

It’s also worth re-scanning your Freeview channel list a couple of times too.

Are your neighbours affected by interference?

• Yes: In that case, it could be an issue with your local transmitter, the weather, signal in your area, or local interference
• No: This would indicate a possible problem with your aerial or cabling

Sorting out your aerial cabling can make a serious difference to your reception. Just replacing your flylead from the aerial socket on your wall to the Freeview receiver could make a significant difference.

Use a high-quality screened co-ax aerial cable with gold-plated co-ax connectors (such as those from Maplin), don’t run your aerial cable anywhere near your mains cables, and don’t use longer cables than you actually need.

Another option to try (although it didn’t work for us), is to wind your aerial flylead through a ‘ferrite ring‘. These are designed to reduce electromagnetic and RF ‘pickup’ and reduce the interference before it gets into your receiver. These are available for a few pounds from Maplin Electronics.

For more help on tips for improving your TV aerial cabling, see our TV cabling advice.

Make sure your aerial isn’t damaged, misaligned, or not up to the job. For best results, you need a good quality rooftop aerial, pointing directly at the appropriate digital transmitter.

For aerial advice, see our TV aerial advice section.

In some cases, a booster / signal amplifier can improve your reception and reduce interference, most commonly if you’re feeding lots of TVs and recorders around the house.

Note that in cases of low signal, boosters are less effective as they amplify noise as well as signal.

See our boosters and splitters page for more.

If you’re splitting aerial cables so that you can get TV in other rooms, consider a mains-powered booster with multiple outputs. This can help to overcome signal loss in the cables.

It’s also worth trying a basic connection (i.e. removing feeds to other room or other equipment) to see if it is the extra cabling or connectors that are causing interference.

This is another major annoyance – a common example being picture breakup when a light is switched on, the washing machine is running, the heating thermostat clicks on, a car or bus drives past or there’s other electrical activity in the area.

Freeview can be prone to electrical interference, and here are a few hints to help you cure this:

• Keep your aerial leads and connectors as far away as possible from electrical mains leads as possible.
• Make sure you’re using good quality leads to connect from your aerial to your receiver, and from your set-top box to your TV or video. For a new extra pounds, a good quality aerial flylead cable with a gold-plated connector from Maplin Electronics may help.
• If you’ve got lots of aerial joins, connectors or unshielded aerial adapters, these can make a weak link in your setup. Make as few joins as possible, and keep joins away from all mains cables.
• If these don’t work, a good quality external roof aerial with good quality unbroken TV aerial cable straight to your set top box should be the answer.
• Interference problems from things such as lawnmowers, thermostats, arc welders or faulty gas-filled lamps can be hard to cure, and often the answer is to repair or switch off the source of interference.
  In some cases, it may help to replace all coaxial cable with modern "double-screened" type, make sure any connectors, splitters and wall-plate sockets are screened and, occasionally, a ferrite filter might help.

The advice in the "Radio Interference" section may also be of help.

If your TV picture is breaking up at random, it could be that the TV is getting interference from a neighbouring transmitter.

If you live close to a taxi firm, radio ham, CB user or police station, your TV set may be incapable of handling the unwanted "RF" (radio signals) from their transmitter.

In many cases, filtering of the unwanted RF signals will solve the problem, and this can be done using an RF filter (pictured here).

If possible, look for what’s called a "UHF Band Pass Filter" or a "High Pass Filter", which will let TV signals through, but restrict signals from other frequencies. Maplin stock a TVI ‘High Pass’ RF filter designed for the job.

Some of the other tips in this section can help to screen out RF as well as electrical interference.

Bad weather can have an effect on your reception – strong winds blowing your aerial will affect your signal, as will heavy rain (specially in weak signal areas).

Good, sunny weather can have an effect on your reception if you’re in a weak signal area, due to high pressure atmospherics.

Equipment such as video recorders and some set-top boxes ‘re-broadcast’ their signal via a TV aerial cable. This is known as ‘modulating’, and it allows TV sets that don’t have a SCART socket to view the output of video recorders and set-top boxes.

If you’re seeing interference to channels, this could be being caused by something in your setup clashing with other channels. See our advice on "RF channels".