deployment “Tis overlapping coverage ensures a resilience of service.
Anywhere in the country, users are covered by more than one base station. In Dublin, you’d probably be covered by three or four.” Tese overlaps also add immunity to any local service
interruptions.
Shared service Today, some 15000 Gardaí (police officers) are live on the NDRS – but joining them on the shared network are a variety of government and public organizations and groups, including other bodies which have a role in safety and security.
Skyward-facing GPS antennas mounted on this TETRA Ireland equipment cabin provide an accurate timing signal for synchronizing the digital network equipment
out in TETRA Ireland’s bulky loose-leaf catalogue. “Te agencies can select the choice of manufacturers terminals and accessories, and we will then provision them on the network”, he explains. “Tis ensures that the users’ bespoke needs are addressed at every stage and their experience is unique to their planned usage.”
Go-live support Te voice quality of the TETRA radios was a clear improvement for users, and police switch-over to the new network was handled smoothly. “We spent a lot of time on the migration”, Mr Kelly says. “We also offered go-live support at every station and prison. “Te Dublin region go-live involved a few thousand officers
migrating in just two days. We had to be sure that this last stage of the experience would be a good one. We knew that was the first touch-point with the network. With TETRA, it’s very important to get that right.”
Network quality Te high network quality did not come cheaply, but Mr Kelly believes that a superior coverage specification is better value in the long run than having to add sites later – for example, when improved in-building coverage is required. For the tender specification, enhanced in- building coverage was a basic requirement. “Two thousand buildings were chosen throughout the
country to give enhanced in-building coverage”, he says. “So, throughout the country, hospitals and important state buildings are included in the NDRS coverage. Large building coverage features a 15dB uplift and, in small buildings, 5dB. “Te number of sites provides excellent overlapping
coverage. For example, about 46 sites cover Dublin, providing excellent in-building coverage.
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TETRA Ireland’s triple antenna design: all three are used for receiving, and just one of them for transmitting. “Obviously you can put a lot more power out from the base station because you are connected to the
electricity mains, than you can from a handportable”, explains RF expert John Reilly. “A handportable is at a major disadvantage. So what you do is to balance
things up. First off, at the base stations you spend a bit more money on designing the receivers to make them to be able to hear slightly better than the ones in the handportable. The next step, then, is you put up three
antennas instead of one. So you are listening three times instead of once.... and they are perfectly balanced with 25 watts at one end and one watt at the other. All the rest of the engineering goes into making that balance”
TE TRA TODAY Issue 3 May 2011
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