Emergency Services / Government
NSW GRN Network (Trunked coverage extension into Sydney’s Harbour Tunnel, specifically required for Sydney’s Ambulance and Fire Brigade departments)
Smartbridge® Talk Group Extender system
Sydney Harbour tunnel, which is located in close vicinity of the Sydney Harbour Bridge. It is about 3 Km’s long.
The moment a vehicle enters the tunnel, GRN radio contact is lost. A vehicle travelling at a speed of (say) 60 km/hour, takes approximately 3 minutes to get through the tunnel, and a 3 minute loss of radio contact is a major problem to the NSW Ambulance and NSW Fire Brigade communication systems. Accidents in the Tunnel can (and do) happen, and obviously, continuous coverage throughout the Tunnel is essential for any Emergency vehicles attending to the Emergency situation.
A 3-channel Smartbridge® system was chosen to provide a perfect and cost effective answer to the coverage requirements. Two channels are allocated to the NSW Fire Brigade, the third channel links the NSW Ambulance Talk Group to any of its vehicles in the Tunnel. Physically, the system is distributed, that is, the GRN Radio/Smartbridge® combinations are installed in/on the North East Pylon of the Bridge to provide a link to the nearest GRN Site, connecting via 600 Ohm land line links to the 3 Conventional Repeaters located in the "Radio Re-Broadcast Room" inside the Tunnel. The Repeater RF signals are distributed throughout the Tunnel using "leaky feeder" radiating cable.
Emergency vehicles entering the Tunnel switch their radio from their GRN Talk Group to the Conventional radio channel of the required Smartbridge® system, and continuous coverage is guaranteed. The coverage is practically speaking "seamless" too, as GRN radios have the ability to switch instantly from a "Talk Group" to a "conventional" channel, by a simple "flick of the switch". (In contrast, many, if not most MPT1327 radios require a full re-initialisation cycle before they will switch to or from a Conventional channel. This can take from several to many seconds, which in this particular case would be a very objectionable situation).
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Turning a Single Site MPT1327 system Into a Full Area Wide Network
General Communications, Newcastle, NSW, Australia
Newcastle and Hunter Valley, NSW, Australia
Originally started with a humble Tait T1810 Single Site MPT1327 system, General Communications was soon looking for a cost effective solution to network coverage extension.
Cell Extender® proved to be the answer to Gencom’s requirements, also, as there is basically no limit to the number of Cell Extender® s that can operate from the one and the same Donor site. The Gencom network currently deploys some 8 Cell Extender® sites of the 1+2 type, which have expanded the original Single Site system into an Area Wide system, covering large areas, including a two-hop Cell Extender® link that stretches all the way into Sydney (a distance of well over 100 KM’s).
Gencom's Managing Director, Martin Mcleod, says that the feedback from clients using the system has been very positive. The network was started up in the last quarter of 2001, and the last Cell Extender was installed only recently.
"Currently, the system services hundreds of users, and we are finding a real niche in the marketplace," Mr Mcleod said.
Click here for more information about trunking repeater technology.
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