As the Garda finally moves closer to upgrading to a Tetra digital radio network, Karlin Lillington finds out how the system is working in Helsinki

For the gardaí, it was a routine call-out that went very wrong.

Several youths in Cork were seen interfering with a car late one August night a few weeks ago. When the gardaí went to question a group of suspects a short distance from scene of the incident, they were assaulted, bitten and kicked.

When one garda radioed for help, the 30-year-old analogue radio network failed, with dispatchers left unable to hear the officers as they tried to make contact.

One garda was eventually able to ring for help on his mobile phone, but due to the delay in back-up help arriving, five officers ended up in hospital for treatment. The next day, the Garda Representative Association (GRA) angrily demanded why a far more secure and reliable digital radio system that would prevent such mishaps still remained unbuilt, even though it was promised since 2000.

GRA spokesman Mick Corcoran said: "This analogue radio system has given us unbelievable trouble. It has nearly resulted in members being killed on different occasions." Its vulnerability has also resulted in serious risk to the public.

Last year Minister for Justice Michael McDowell was asked in the Dáil when the long-promised digital radio system would arrive, after a TD explained how a constituent was burnt out of his house after drug dealers listening in on the Garda analogue network heard his address being given as the source of a complaint about their suspicious activity.

What the Garda want and have been promised - and what many other countries already have - is a Tetra (terrestrial trunked radio) digital system, a radio network that is clear, secure, adaptable and - the vendors say - "futureproof".

Built to a standard developed in Europe, a Tetra system, one of a variety of digital radio systems, is also expensive. The estimated price tag of the long-promised system for the Garda - called the National Digital Radio Service (NDRS) - is at least €100 million. If, as some of the shortlist of bidders for installing the system would propose, it is extended into an emergency service network for all services - fire, ambulance, police - costs could run much higher.

The networks are already in use in Ireland. Dublin gardaí have had a pilot network in place since 2001, built by Airbus parent company Eads; the Police Service of Northern Ireland has a Tetra system; and there are numerous private networks.

A Tetra network will be in place for the Beijing Olympics and several European countries, including Finland, Belgium, and the Netherlands have national emergency networks. Germany just signed contracts to build what will be the largest Tetra system in the EU.

The Finns are serious Tetra enthusiasts, with the world's largest national Tetra authority network, Virve. It coordinates security, police, fire, ambulance, social services, maritime rescue and some volunteer organisations through 15 regional emergency centres. The system, built by Eads, is owned by a state-owned company set up to operate the security networks used by government agencies.

The centres currently respond to some four million emergency calls every year, with a single emergency response centre (ERC) operator handling close to 10,000 calls a year. This is all Tetra-based, as are all the networks each of the rescue and emergency services use.

In Finland, police would be unlikely to find themselves in the situation endured by the five Cork gardaí last month. As Jari Juvonen, a police officer and system engineer with the ERC in Pori, northwest of Helsinki, explains, the handsets can be located precisely by a global positioning system (GPS). They all have an emergency button that, if pressed, makes the call the highest priority, while another button allows the handset user to turn the handset into a microphone, enabling the dispatcher to hear what is going on even if the user cannot speak.

If, during a scuffle, a handset is stolen, a dispatcher can simply disable the radio. Communication channels are secure and numerous channels with numerous participants can be set up quickly, enabling police services to talk directly with ambulance and fire brigades, for example.

While users of the system and the Finnish government are proud of their network - which serves a population not much larger than the Republic's at 5.2 million people but over a much larger territory - getting the system in place was a slow and somewhat painful process.

It took the guts of 20 years for the Finnish government to commit to a Tetra system after a long-running trial was set up in 1996, says Jukka Aaltonen, director of the ERC in Pori. Five years later, the Finnish parliament passed an act to authorise a nationwide system, but this required compressing the existing 58 regional response centres into just 15, and - harder still - convincing all the different services to share a system rather than each having a discrete network.

Now, he says, it is more economical to run the centres. The various authorities and services work closely together, often setting up direct links to talk over their Tetra system rather than going through a central dispatcher.

"During this process, we found that we can cooperate, we have to cooperate, and why didn't we do this 50 years ago," he says.

Some of the ERCs, including the one at Pori, are built underground - the cautious legacy of Finland's close proximity to major nuclear power Russia. Visiting the centre requires descending several staircases and passing through triple steel doors complete with an airlock and radiation shower.

But then, it is in a rather stylish underground bunker of Scandinavian wood and steel, where operators oversee their three computer screens from comfortable orthopedic chairs. Of course, the centre has its own sauna, a gym and kitchen for workers. All systems have backups, including generators to run the centre for two weeks if electricity goes down. It's an impressive if slightly disconcerting set-up in its mix of Cold War precaution and Finnish home comforts.

With final bids for an Irish system submitted by six consortia in early August, the Garda is moving slowly towards getting, if not centres complete with saunas, a Tetra radio system. And at least one of those bids - from BT Ireland, Eads and Siemens - is pushing for a more comprehensive nationwide emergency network, with one eye on the Department of the Environment's upcoming framework proposals for a national emergency management system.

Insiders say getting such a scheme will take major political will.

That hasn't been much in evidence during the slow saga of the proposed Garda Tetra system, but with background threats of global terrorism, the potential for a nuclear incident at Sellafield, and fears of a global flu epidemic, maybe Dáil resolve will have stiffened.

Analogue versus Tetra radio systems

Analogue radio, when used for communication, is a radio signal directly broadcast over the airwaves in the same way that radio programmes are, using a slice of specially-allocated radio spectrum.

Because radio waves are subject to interference and degradation of signals, connections can drop, the line can be too full of noise to hear a person speaking, and channels are not easily secured from eavesdroppers because encryption is difficult to use on analogue lines. Stolen or lost radios cannot be disabled.

Digital radio works by sampling the radio wave, converting it into numbers (digits) and transmitting the signal in this digital form.

While minor noise can interfere slightly with a transmission, lines are very clear. Conversations are maintained over varied terrain and long distances by passing the signal between base stations.

Conversations can be sent through numerous secure, encrypted channels. These channels can be set to allow one-to-one conversations or controlled sets of participants. Lost or stolen handsets can be disabled by dispatchers. The entire system can be monitored on computer screens by dispatchers.