Launceston radio enthusiasts, and perhaps a few crooks, knew what it meant - the switch to digital was on.

They were right.

On Monday, police in the Launceston area switched to a secure digital radio network as part of an "indefinite trial".

The digital switch will be rolled out next in Hobart before going statewide if "teething problems" to do with sound quality can be overcome.

Police have spent some $29 million on upgrading its Trunk Mobile Radio Network since 2008.

The network offers both analogue and digital transmission but, until Monday, the digital capability had been only been used by police during special operations.

This was mainly due to coverage issues.

Acting Inspector of Radio Dispatch Services, Natasha Leaman, said the move to digital meant communications were more secure because third parties could not listen in on conversations via a scanner.

Unlike analogue transmissions, digital communication can be encrypted.

Acting Inspector Leaman said there had been no discernible coverage issues since Monday but sound quality was a teething problem.

Officers have been advised to switch back to analogue transmissions, which can be monitored with a $400 scanner, if they encounter coverage issues.

In May Auditor-General Mike Blake recommended police and other emergency services switch to a secure and confidential radio network.

His report advocated the use of secure radio to prevent criminal misuse of information to mislead or evade

the police and discourage the media and the public from attending emergency locations.

pbillings@examiner.com.au