Standby for no signal: TV/Radio atmospheric interference risk returns

A strong area of high pressure will provide the potential for more TV and radio interference this week.

As clear skies over the British Isles give way to fog and low cloud trapped under the high pressure, the resulting temperature inversions could again cause reception problems, with the return of tropospheric ducting in the atmosphere, just three weeks after the last main incident.

The UK is expected to experience the highest air pressure for decades at the beginning of the week.

On TV, viewers with Freeview and YouView are affected, while FM and DAB radios could also have reception trouble.

Satellite and cable networks are not affected by this type of interference.

During temperature inversions in the troposphere (shown in the picture above) - a mirror-like wall for TV and radio signals is created. Any signals that would normally fade into space are instead reflected back down and over the curve of the earth, beyond their normal range. As a result, they interfere with local signals, resulting in pixelation and no signal messages on TV sets. As the interference affects transmitters using the same frequencies in different regions or countries, the effect is called 'co-channel interference'.

Viewers are advised not to retune - reception will restore itself when conditions change.

In a statement, Freeview said:
If you have an internet-connected Freeview Play TV or one that has the players available to view, you will still be able to watch live and on-demand content from the likes of BBC iPlayer, ITV Hub or All 4.

Viewers that frequently encounter reception issues are advised to contact their local aerial specialist - particularly in some coastal areas new alternative transmitters less liable to interference may be available, for others free-to-air satellite may provide an alternative option.

What's bad for regular viewers and listeners is good for radio enthusiasts who will be monitoring the airwaves for distant stations: during the last major atmospheric disturbance at the end of December, many enthusiasts reported receiving French radio on FM and DAB across Southern and Central England.

Updated 17:12 19/01/2020.