at sea
VHF in a number of circumstances, both operationally and in trials. And while there will ‘always’ be a need for maritime VHF – “Tat’s a given”, he said – if a user needs or wants to add TETRA to its communications capabilities, gateways are available to enable both to interoperate. But with radio there is usually a need for frequency
licensing. “TETRA systems at sea very often replace traditional IP DECT systems in order to provide ordinary telephone calls internally, as well as ship-to-shore”, said Svein Damre, vice president of the radio systems supplier Zenitel Norway. “Frequencies for international use are not yet defined and approved for TETRA systems, thus leaving the responsibility for any interference with other systems to the individual ships’ captains. “TETRA systems, however, provide more reliable operation
and make coverage within metal ‘constructions’ on ships easier to obtain. User terminals are available in a very wide range including mobile, handheld and ATEX terminals with and without interface for headsets and key switches for PTT operation. Zenitel has developed its own PTT switch for ATEX radios fitting with a Peltor headset. “As for infrastructure”, he continued, “the TETRA
infrastructure to be used on ships needs to operate on 24V/48V and must be robust in situations where voltage drops and power failures may occur. Further, the size of the systems supplied must be designed for rack mounting with limited space available. Systems must also be humidity and vibration resistant.” Zenitel makes specific references in its literature to the
fact that “TETRA does not have a universal radio spectrum for marine usage. Each installation will require a case by case approval for frequency licensing. It is the ship owner’s responsibility for obtaining the frequency license from the port authority”.
Coastal missions A view of current use of TETRA in coastal applications around the world is provided by two of Motorola’s TETRA team, Raúl Carpio and Bjørn Rasmussen. Some countries in Scandinavia are already using TETRA
for the police inshore and the coastguard, said Raúl Carpio, business solutions manager. “In the UK”, he went on, “county police forces with stretches of coast to monitor have marine units and marine inspection units, which intercept and inspect incoming vessels such as cargo ships and ocean-going yachts. “Because of the hazardous materials they may find, e.g.
explosives, they purchase and use a small number of ATEX – intrinsically safe – terminals. Tese will only be used on the occasions when they are inspecting such vessels, so they will not be in everyday use.” For those users who require dedicated ‘onboard’ equipment
in waters such as the North Sea, equipment from Motorola Solutions and Zenitel’s VINGToR product family can provide onboard communications within a vessel, interoperating between DECT, VHF and TETRA.
Oil and gas Bjørn Rasmussen, Motorola’s sales manager for Nordic subscribers, added: “We see a clear tendency now, especially on new oil rigs and for ship-to-shore communications, that
Issue 5 2011 TE TRA TODAY
A typical VINGToR marine TETRA installation consists of a base station with one
or more carriers, an outdoor antenna and an indoor coverage system using a combination of antennas, splitters and coaxial cabling. The VINGToR TETRA solution supports a wide set of two-way calling and telephony service integration. The TETRA server connects to the AlphaCom Marine exchange over the data network (SIP trunk) for telephony services. Through the exchange, handheld TETRA radios can call telephones, intercom or external telephones, and initiate public address broadcast
they are going for TETRA due to many features which surpass the previous analogue systems. “Tere was a major event at the end of October in Stavanger
in Norway where users in the oil and gas industry stated they are going to change their older systems to TETRA, replacing analogue ATEX radios and also using repeaters for range. “In the past year they have ramped up their pace of upgrade
to TETRA so they can use it for telephony and security, connecting several oil rigs to the same system in a cluster. But what they are able to do is install a lot of the TETRA-related equipment on the shore side – the switches and servers – without having to install much on the oil rigs. All they need at sea is the base station to connect several rigs over an area of several square kilometres. “For emergencies, or just daily use so they can maintain
day-to-day standard communications between rigs, TETRA handles everything. Te exact ranges being achieved depend on how the base stations are deployed. But the oil field network will have its network plan and part of the equipment used will include repeaters to expand coverage.”
At sea, at speed Meanwhile, in the Nordic area and also in Middle Eastern countries, emergency forces which have converted to TETRA for land operations, including police and fire departments, are more and more equipping their lifeboats and ribs with the technology. In this way, inshore crews can keep in touch with their land-based command and control centres. “Tis is a challenge because
normally when you are racing at high speed on sea to a rescue or interception, there is a huge amount of wind that would normally make voice comms very difficult”, Rasmussen continued. “Motorola has been doing some trials with microphones and headsets
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Repeaters are part of the network planner’s tool-kit for extending networks beyond their normal range. Seen below is the channel-selective CSR438 repeater from Axell Wireless, which adds secure radio coverage to any TETRA network. Its wireless interface permits the operator to configure RF parameters remotely and to monitor alarms
(illustration: Zenitel)
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