THE garda's new €100m communications system will play havoc with television reception around the country.

Garda stations are preparing for hundreds of complaints from householders over severe disruption to their TV services.

The new digital mobile radio service, Tetra, is being rolled out nationwide for use by the garda and emergency services. It is vastly superior to the existing garda radio system and is encrypted, ensuring criminals cannot use scanners to monitor police communications.

The communications regulator Comreg said it had already prepared an information leaflet, which is being distributed to garda stations nationwide, for householders whose TV reception is affected.

"People who live in close proximity to a garda station or another facility where a Tetra base station is installed may experience degraded terrestrial television reception if they have an unfiltered wideband masthead amplifier installed with their television aerial," said Comreg. "Cable and satellite systems that are not directly connected to a terrestrial television reception system will not be affected."

The 'masthead amplifier' is used throughout the country to receive TV stations from abroad, particularly along the border and on the east coast. It is also used when householders want to split the TV signal so they can watch programmes on different TV sets around the house.

"The degradation of reception experienced when a masthead amplifier is installed occurs when unwanted nearby signals from outside the television band enter the masthead amplifier causing it to overload and operate incorrectly," said Comreg.

Perplexed homeowners who have watched their TV screens go fuzzy since the rollout of the Tetra system have two options. They can remove the masthead amplifier, but weaker signals from stations outside the Republic would no longer be received. Alternatively, they can add another filter which will cut out unwanted signals from Tetra, mobile phones and private mobile radios.

"Television reception systems have traditionally been installed in such a way that they only account for conditions that are present at the time of installation," said Comreg. "This means that a filter would not have been installed unless a signal that could overload an amplifier was present at the time of installation. However, now that spectrum in Ireland is being used more as technology advances, it is good engineering practice to install filters in all new installations.

"It is important to note that within the Republic of Ireland, no protection is afforded to television services originating from another jurisdiction," Comreg added.