Over 400 000 MOTOTRBO units have already been sold worldwide. However, as more competitor offerings come onto the digital radio market, consumers will be hard pressed to choose the solution that's best for their requirements. To do this, they need to consider the real differences between the technologies on offer. Here we explain why Motorola has chosen to back the DMR standard and why MOTOTRBO customers around the world can rest assured that they've made the right choice.

Digital Mobile Radio (DMR) is an open digital standard that was developed by the European Telecommunications Standards Institute (ETSI). It delivers improved range, higher data rates, more efficient use of the frequency spectrum and longer battery life than analogue, making it ideally suited for industrial and business-critical markets.

Since their introduction in 2007, DMR radios are now in use in over 100 countries around the world and are estimated to have gained over 80 percent digital market share of business and professional users in the EMEA region. This has added impetus to the creation of a DMR Association dedicated to promoting and driving interoperability, innovation and worldwide adoption of the DMR standard. The benefit for end users will be a wider choice, increased functionality and more competitive costs.

So, why have companies like Motorola, who is a founding member of the DMR Association, put their money behind DMR instead of alternative systems? Because DMR is based on Time Division Multiple Access (TDMA) technology. TDMA enables the full 12.5kHz channel width to be retained but it divides the channel into two alternating time slots, doubling capacity and enabling voice and data transmissions to occur simultaneously. The channel as a whole maintains the same profile as an analogue 12.5kHz signal, allowing users to receive all the benefits of digital while retaining their existing licences. TDMA also supports interoperability between analogue and digital radios within the same spectrum - which is important for a smooth and gradual migration - and it is more resilient to interference.

The alternative approach to increasing capacity is called Frequency Division Multiple Access (FDMA) and it is used for the likes of NXDN and dPMR competitor systems. With FDMA, separate  6.25kHz channels are used. The potential problem with this is that many countries don't allow two 6.25kHz channels to operate in an existing 12.5kHz licence or do not licence individual 6.25kHz channels. In addition, operating two adjacent channels at one site can cause interference. For this reason, users will generally need to obtain a new licence in another area of the spectrum to increase capacity with an FDMA digital system.

DMR TDMA also requires less equipment than FDMA solutions because it provides two communication channels with one repeater, one antenna and a simple duplexer. FDMA requires a dedicated repeater for each channel as well as costly combining equipment to allow multiple frequencies to share a single base-station antenna, as can be seen below.

And finally, TDMA radios use up to 34% less battery capacity than FDMA models, making them more power efficient and giving DMR users the benefit of longer battery life as well as a leaner and greener radio network.

The advantages of migrating from one channel to two channels using DMR are thus clear. It is a widely supported, open standard that's economical, power efficient and doesn't require any extra space or additional maintenance.