Tait and Digital Mobile Radio (DMR): An overview

Trevor Laughton, Chief Technology Officer at Tait Radio Communications, will be discussing digital standards such as P25 and Tetra at this year's IWCE in Las Vegas between 1.00 and 2.30 on 19 March 2009. Here he writes of the Tait strategy for DMR and gives prospective digital buyers some food for thought.

Tait and DMR

Tait has always pursued open standards and open interfaces to the benefit of those interested in securing value and flexibility from their radio solution. For us, this has not just been the commercially sensible thing to do, for utility co-operatives, municipal transport providers and public safety agencies where taxpayers' money was at stake, this was the ethical thing to do.

We were a major contributor to the establishment of the MPT 1327 standard back in the 1990s and have hundreds of customers who are now asking "how do we move from MPT to DMR?"

The strength of DMR is that it is an open standard with agreed and published standards for conventional and trunked radio operation. With Tait and other manufacturers offering this technology, buyers can avoid being locked into a proprietary solution.

Because trunked DMR is intended to replace MPT 1327 trunking systems and Tait has so many MPT 1327 customers, we are committing to DMR rather than the lower featured and currently incompatible dPMR standard. This is not just because we want to ensure our own customers' migration is smooth, but because Tait believes the DMR standard has many advantages over the 6.25 kHz FDMA offerings.

To predict the future, try to understand the past

As a replacement for MPT 1327, gauging the possible success of the DMR Tier III (trunked) standard requires us to look at what made MPT 1327 so very successful around the world.  That trunking standard was open: which lead to competition, value and innovation. It has also proven to be very scalable - from one site to 960 – and can meet the territory coverage needs of the largest organisations. It handles both voice and data, and manufacturers like Tait continue to innovate in this area. Perhaps this explains the standard's success and the fact that, for many organisations around the world, MPT 1327 will remain a solid option for many years to come. By the way, the digital processing within MPT 1327 equipment, and the ability to migrate into a trunked DMR solution, blurs the boundary between what is meant by the terms analogue and digital standards.

Some manufacturers would like to wave a wand across the world and neatly and quickly magic away analogue systems. Industry history shows us that the world implements new radio technology in a more "patchy" way. There are two lessons for buyers from this messy evolution model. First don't be drawn into the "the analogue is dead" hype: to paraphrase Mark Twain, "rumours of its death have been greatly exaggerated." Second, ongoing innovation, backwards compatibility and smooth migrations will continue to be the names of the game.

There are several business gains of going digital including spectrum efficiency, digital audio clarity and data integration. But there are many ways to "skin the digital cat." At IWCE 2009, I'll be talking about rival standards in the digital domain.

Here are THREE current considerations when thinking about DMR

1. Incompatibility built-in!

Although there's only one letter difference in the acronym, the reality is that the equipment using the various 6.25 kHz FDMA* standards will not be interoperable with DMR equipment which uses TDMA+. Only one letter difference in the acronym, but a world of difference in everything from power consumption to the amount of infrastructure and equipment needed to guarantee coverage. With such uncertainty hanging over the evolving technology, caution will be the name of the game.

American newspaperman H.L. Mencken said: "for every complex problem, there is an answer that is clear, simple and wrong." The relevance to today's DMR choices will be the importance to take a clear-eyed view, make a rounded assessment based on a combination of complex factors in play.

2. Act in haste: repent at leisure

The industry is in flux and complex radio installations are not like Blu-Ray players; there's no kudos for being leading edge when it could be the edge of a cliff. With technology maturing, it's usually better to let the dust settle - the price can fall, the technology and its reliability and interoperability can become more proven. Sometimes I think DMR could stand for Don't Migrate Rapidly!

But what if you can't wait and need to start planning now because of the FCC-mandated narrow-banding change to a 12.5 kHz environment by 2013?  Well, first just check you are affected by the mandate: for example 800 and 900 MHz bands are not impacted. Second, don't rule out MPT 1327 which delivers 12.5 kHz today (as well as proven value and features) with a smooth route to 6.25 kHz equivalency into the future.

If your legacy systems simply must be replaced in the next 12-18 months, then what to do? Well, before considering which of today's digital PRODUCT will be the best choice, it might be prudent to consider which PARTNER will work with you to minimise the business disruption of any "forklift" wholesale change. No product is an island. It's all very well having a DMR product, but if you can't configure, install, migrate from your old system and test your new system seamlessly then the implementation will be far from smooth.

3. Open interfaces, open standards and an open philosophy

Open interfaces allow customisation, so a solution can be adapted to an organisation's very specific need thus becoming the right fit. The Tait way of delivering trunked DMR will follow this "ethos of openness."  And it's not just the openness of the DMR interface which will enable this.  Our P25 products and the latest TM8000 mobiles were engineered with flexibility in mind, for example, providing enough space for options boards and comprehensive developer kits to support those devising a modification. By providing these features and designing based on this open philosophy, Tait radios became a favourite with system integrators and experts in the field who were external to Tait, but who could adapt the product and embed it into their own solution.

Some manufacturers might be content with a One Size Fits All DMR radio. The Tait way will be to offer a set of DMR products that can be adapted, modified and adjusted so it can become the right fit. As well as being customisable, to earn the blue circle on the front, Tait DMR products will be reliable. This reliability comes from customer-lead design, rigorous testing, design / manufacturing excellence and over 4,000 man-years of Tait-accumulated RF engineering expertise.

There's a saying that "wisdom is the reward for a lifetime of listening." Well, Tait has been listening to customers for 40 years and we can help guide you through the choppy waters ahead. The listening is sure to continue over the next 40 years and we look forward to talking to you about your DMR needs.

*Frequency Division Multiple Access  +Time Division Multiple Access

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