Local wireless communication specialist Multisource is aiming to advance two-way radio communications with its introduction of digital private mobile radio (dPMR) Mode 3 to South Africa.
The company’s launch of dPMR Mode 3 took place at St George Hotel in Rietvleidam, Gauteng, recently, where users of two-way radio systems, including members of the military, were given an overview of how the system works, the advantages of the new standard over existing standards, and the improved and increased functionality of products that operate on the dPMR standard.
The dPMR standard covers 3 modes: Mode 1 – peer to peer; Mode 2 – via centralised repeaters; and Mode 3 – via managed repeaters (trunking). The emphasis with dPMR is on a fully functional radio system that can seamlessly integrate with IP networks, and is capable of offering customisable application software tailored to any business communication needs.
Interoperability is key
According to Richard Smuts-Steyn, CEO of Multisource, there is a great need among South African government institutions for communication platforms that can be integrated. “For users of two-way radio, planning a future migration path to new technology platforms can be bewildering,” he stated. “Interoperability, as well as the integration of analog and digital, is required, and the choice of radio standard is a difficult one.”
“Many state institutions collaborate at different times, for example on border patrols, and it is vital that whatever platform is chosen in the future can be integrated with existing infrastructure and offer interoperability. Each radio system needs to be able to talk to the other – dPMR offers this advantage,” he said.
The global trend for digital migration is based on the simple fundamental requirement for more channels. The radio spectrum is a limited resource and demand for channels exceeds supply, resulting in interference and an insufficient number of channels, especially in big cities.
Since the beginning of PMR radio, there has been a constant juggling act between available spectrum and channel size. As filter and modulation technology has advanced, the channel size has progressively reduced from 100 kHz to 50, then 25, then to the current size of 12,5 kHz we have known for the past 20 or so years.
“In light of the current policy of spectrum pricing, it became clear that a new advance was needed to make the most efficient and economical use of this scarce resource,” Smuts-Steyn said.
Up to now 6,25 kHz was not possible with analog technology, but research by Japanese wireless communications manufacturer ICOM, together with Kenwood and the UK-based Fylde Micro, has proven that 6,25 kHz could be achieved using a new digital protocol. These corporations then undertook to develop this technology.
National and international coverage available
dPMR Mode 3 solutions offer wide area multisite, multichannel trunked repeaters capable of national and international coverage if required. dPMR radio equipment can also be easily integrated into existing IT networks with both text messaging and voice calls using the voice and data functionality of dPMR. Solutions already exist for PC-based remote control of dPMR base stations to give completely configurable dispatcher functionality.
dPMR Mode 3 also offers users the possibility to operate efficiently in ‘direct mode’ separately from the network or beyond the coverage area of the network for special purposes such as on-scene activities.
Why change?
One of the oldest trunking radio standards is Tetra, which provides four timeslots in a 25 kHz channel. However, the coverage penetration of Tetra is poor compared to 12,5 kHz analog FM and dPMR, and this standard requires a specially allocated spectrum to avoid interference.
Tetra has traditionally found favour in government and private systems where wide-area coverage is not required but performance, particularly under duress, has been disappointing and costs have escalated.
APCO-25 or P25 (phase 1) equipment is outperformed by dPMR, which has a better signal bit error rate performance than P25 phase one. dPMR technology also offers improved audio quality compared to P25 audio. Using the AMBE+2 vocoder makes this possible.
DMR is to some extent vying with dPMR to become the digital radio standard of the moment. There are, however, a number of advantages dPMR has over DMR, according to Smuts-Steyn.
dPMR uses one repeater per channel, while DMR uses two. Therefore, in the event of repeater failure, both channels are lost. On the other hand in the case of interference on a dPMR channel, only one channel is affected.
dPMR also allows for the deployment of an odd number of channels, meaning no timeslots are wasted. Technical difficulties are experienced when using DMR in terms of the near-far effect. Importantly, dPMR radio equipment is also cheaper to manufacture than DMR equipment.
dPMR offers scaled migration
The dPMR system allows users to scale migration to a digital system at their own pace and needs, while running their existing system. If the radio users increase in the future, or require expanded communication coverage is required, the dPMR conventional system can be upgraded to a multi-site system, or grow into a Mode 3 trunking system while using the same subscribers, hosting up to 1024 site networks and in turn up to 500 000 subscribers. This provides investment protection for the communication system.
ICOM’s comprehensive range of IDAS products has found favour across the globe, with the largest single user being the US Department of Defense together with the US Marine Corps. This low-cost, low-maintenance equipment is built to withstand the most extreme industrial conditions.
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