Atmospheric conditions increase risk of Freeview reception trouble
High pressure will provide the perfect conditions for disruption to Freeview this week, especially in western areas.
Atmospheric conditions will allow TV and radio signals to travel further than normal, causing increased interference. The worst affected areas include Wales, SW and NW England. For a brief time, reception issues could temporarily spread to cover areas further east, before the high pressure gives way at the end of the week.
Viewers are advised not to retune their Freeview TV or box, as this will not restore channels.
Reception impact can be worst during morning and evening hours, as the phenomenon known as tropospheric propagation reaches its peak and TV and radio signals are reflected, scattered or refracted in the tropospheric layer of the atmosphere.
Such atmospheric conditions under high pressure systems are normal, but in most areas the main Freeview channels have been allocated frequencies that are least prone to incoming interference. However smaller channels, as well as some HD services are more prone to drop outs.
Constrained by the laws of physics and a high demand for frequencies, there's little broadcasters can do to mitigate reception issues due to atmospheric conditions, and some viewers may occasionally lose services as a result.
However, viewers who frequently suffer Freeview outages are advised to have their aerial installation checked, and to see if there are better options for TV reception - in recent years, additional relays have gone live in some locations, which may provide a more stable signal. And following recent frequency changes, some viewers may need a different type of aerial to receive Freeview reliably.
In the analogue TV era, such interference manifest itself in horizontal lines appearing on TV images, which would get progressively worse, even resulting in another area's TV service replacing the original service in the worst conditions. On digital, signals tend to pixellate and break-up. Retuning may result in the channel list filling up with weak signals from neighbouring regions and countries, which then disappear when the conditions change.
Annoying for regular TV viewers, but the foundation of a hobby for Distance Reception enthusiasts who, with the aid of sophisticated receiving equipment, search and log incoming TV and radio signals from distant places, with some receiving terrestrial TV services from right across Europe under ideal conditions.
FM and DAB radio reception can also be impacted under the same conditions, with signals fading or breaking up.
Broadband, cable and satellite services provide an alternative option for reliable reception.