PMRExpo “
Console with a migration plan W
hen the customer chooses a digital technology – be it TETRA,
Nexedge, MotoTrbo, DMR, Tier 3, dPMR – we believe that the best way of doing
that is to use a console, an operator position, to minimize the risk of migrating to digital”, said John Whitcomb, seated at a large touch-screen control panel on the Zetron stand. By linking the old radio
system with the new via a console, he explained, a client could migrate even one radio at a time to digital, if he wished, while still maintaining communication between all his radios through the system – and keeping his options open for the future. Setting up a ‘patch’ on the screen, he picked up a TETRA radio and pressed the PTT, and a fraction of a second later his voice issued from a nearby DMR handportable. “They may choose to do one group of
Bridging the worlds of analogue and digital, John Whitcomb of Zetron shows off the capabilities of the versatile DCS5020 communications control terminal
radios fi rst, or one talkgroup or one radio site or one radio channel”, he went on. “That way they mitigate any risk in terms of understanding different technologies and also, more importantly, cost. So, each year as they have different budget, they can gradually migrate to digital until
“What we’re demonstrating today is our ability to incorporate many different technologies”, said John Whitcomb, “– the idea being, of course, that migration to digital is going to happen slowly and the installed base is predominantly analogue”
they have fi nal obsolescence with their analogue equipment.” On the screen were touch-panels
representing access to radio systems of various technologies, analogue as well as digital, and telephone lines. At PMRExpo, one single operator position was on show, but Zetron can supply much larger systems: for example, British Airways has a system at London Heathrow Airport with 97 operator positions.
IP-based TETRA: fl exible and dependable O
n the Rohde & Schwarz stand was the latest evolution of the company’s Accessnet-T TETRA infrastructure,
which has now become wholly IP-based. “Accessnet-T was already IP-based internally
since the very beginning”, explained product manager Markus Oltmanns. “But we are now also using IP backbone networks in a complete IP-based environment. “We can use existing IP-based connection
lines that the customer already has. We can adapt to these networks and connect our network elements such as base stations and switching units and also gateways to the existing IP network.”
Distributed intelligence As an alternative to the traditional central switching arrangement, Accessnet-T IP supports distributed switching intelligence within the network. T is takes advantage of the self-healing capability of IP networks, which enables traffi c to be re-routed around an equipment or line failure. “Let’s say, if more than one connection line
fails, you can already maintain sub-networks that are still alive until every connection line
Issue 2 February - April 2011 TE TRA TODAY
breaks – and then the single base station will go into fallback mode”, continued Mr Oltmanns. “T is is already known to TETRA, specifi ed in the standard. And as soon as the connection lines are available again, all the connections are set up.... All the base stations and switching synchronize each other automatically, with a very low amount of traffi c on the IP network.” In addition, an IP architecture provides
design fl exibility. “You can have a gateway at one base station, and let’s say a PABX gateway at another base station and an application gateway at another base station”, Mr Oltmanns said. “So you can freely distribute all gateways and interfaces within the network as you need it.” In addition, he added, the IP network
Markus Oltmanns introduces Rohde & Schwarz’s Accessnet-T IP technology for TETRA networks: “As far as I know, it’s unique to the market that we provided this distributed switching infrastructure”, he said
can very easily be resized to match changing communications needs. “You can do a rapid redeployment of the network so you can take more base stations into the network, you can take base stations out of the network. T ere is great fl exibility and means of scalability. “You can start with a very small network
when you have a small industry, and when your business grows the TETRA system will grow with your business.”
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