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Digital


channel – as the main digital opportunity, es- pecially when DMR Tier III (trunked) equip- ment eventually reaches the market. “Tier III could, if it is very successful, sweep away all the MPT 1327”, he said. “Certainly, Tier III DMR is the leap that is needed.... At the moment, the DMR being sold is tending to be a con- ventional [PMR] replacement.” And he com- mented that DMR was proving very successful in this respect, having already sold one million terminals.


More alternatives But Mr Taylor went on: “We shouldn’t forget NXDN. NXDN is a collaboration of Kenwood and Icom. It’s 6¼ kHz FDMA, just as dPMR is. It’s the same codec, it’s the same modulation but it’s incompatible. “It’s one of these ‘publicly available specifi ca-


tions’ – they say people can write in and get the specifi cation. So we shouldn’t forget it, be- cause there is a signifi cant market out there that could be buying it. In terms of Ofcom, I think it’s something they need to consider, because it’s another 6¼ kHz technology.” Adrian Grilli, managing director of JRC Ltd,


added some further digital possibilities. “T ere’s Tetrapol out there still, although I don’t think that’s still a serious contender”, he said. “T ere’s [APCO] P25 in some parts of the world and now Detracom [France] are promoting what they call e-DMR, which is a three-channel ver- sion of DMR.” But he warned: “Apart from the fact that


there are these multiple standards, it’s actually causing immense confusion and lack of inter- operability. If you’ve got an FM push-to-talk analogue radio, it’s not only cheap but it’s inter- operable with loads of stuff ! “All these new suppliers coming in with their


diff erent fl avours of digital are actually confus- ing the market and making people reticent, because they are just seeing a proliferation of digital technologies, all incompatible.”


The wrong technology Showing a chart illustrating the application are- as of the main digital contenders (right), David Taylor pointed out the large overlaps between them. While acknowledging that these were benefi cial for customers because they created competition, he agreed with Adrian Grilli that they could also lead to confusion. ”I think also it means that an awful lot of peo-


ple succumb to supply a pressure and probably get the wrong technology”, he went on. “T e one that is quoted is the North Sydney Hospital. Is Tetra really the right solution for a single-site hospital? It could well be that DMR could do it and be a lot more spectrum-effi cient.” Looking at motives for making the change to a digital system, Mr Taylor suggested that data


LAND mobile October 2011


applications were attractive but were probably not suffi cient on their own. “T e functionality is usually not a real reason to switch unless you have reached the end of life of your system”, he said. “People are going to be looking at capital cost of ownership, and if they can see that it’s going to be more expensive than analogue, why go there?” In the US, the regulator is mandating the


transition to digital. But in the UK, Ofcom is sticking to its ‘technology-neutral’ stance, while retaining the option of using the pricing mechanism as a means of accelerating the digital changeover. However, Mr Taylor commented: ”I’m not sure the licence fee plays a big part when somebody is buying a new system... I’m not sure it necessarily is a big enough carrot.”


Narrowband, broadband T e big saviour, he suggested, would be migra- tion to DMR within users’ existing 12½ kHz channels – supplemented, perhaps, by creating a dedicated block of spectrum for the 6¼ kHz technologies so that they would not simply half-fi ll a great many 12½ kHz channels.


However, he warned PMR users of trouble-


some interference problems ahead if they stayed too long with their analogue systems when oth- ers around them had moved to digital. Digital PMR radios did not show the courtesy of wait- ing for analogue traffi c to fi nish before fi ring up on their channel. “With analogue radios, if there’s a 12½ kHz


DMR radio within range, it’s just going to come in as white noise, if it’s strong enough”, he pointed out. “So I can see all sorts of interfer- ence if you are trying to coexist – like two taxi companies sharing a channel. At the moment you can use CTCSS. But in a mixed analogue- digital world, I can see great hassle. “Perhaps Ofcom would have to be proactive


in that situation and re-allocate licences and move people around, and possibly insist that people actually do move to digital.” Mr Taylor’s fi nal point was a question about


PMR users. “Are they going to want mobile broadband for their business? T ey may well want to access databases, they may want video; certainly the emergency services are very keen on mobile broadband.... Now, is that going


Beyond technology: the implementation F


our digital PMR technologies are on offer in the UK (Tetra, DMR, dPMR and NXDN),


all of them providing 6¼ kHz-equivalent spectrum effi ciency and thus doubling the potential capacity of today’s PMR bands. “The key, really, is for dealers to work with


their users, and I think it’s very important that they look beyond technology”, advises David Taylor, of Analysys Mason. “At one of the Tetra conferences, people were saying, ‘Which is better?’ And I was say-


ing, ‘Well, hang on a second, it’s not which is better, it’s which solution gives you what you want’. “If you are the fi re service and you want


duplicated links to your sites and you want resilient control, a DMR solution might not have that infrastructure in it – whereas the Tetra infrastructure probably has. “So don’t necessarily look at the technol-


ogy. You can look beyond the technology at how people are implementing it.”


A choice of digital technologies: European standards for mobile radio and how they match the various segments of the market (diagram: David Taylor, Analysys Mason)


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