Newton Mthethwa
Mining, whether open cast or underground, requires adequate and appropriate wireless communication tools to ensure safety, security and operational productivity of the mine.
Mission critical wireless communication platforms have become inevitable within the mining sector, supported by active steps taken by the South African Department of Mineral Resources (DMR) to ensure a safer working environment for mining employees. Mines not complying to required safety and security regulations, which includes safe and secure communication systems, may face prolonged closure and in a worst scenario the risk of losing its operating license.
Since mining sites are often in geographically remote areas with very little infrastructure, choosing and installing a suitable wireless communication system should be one of the first decisions to be considered. The value of such an approach is that having an operational communication system in a remote area during the initial site and mine establishment will ensure onsite safety and security and provide management and operational communication support during this critical phase in the life of the mine.
In addressing the requirements for a safe and secure communication system the question arises “How do you choose the right communication system and tools for your mission critical requirements and operations?
The critical issues to consider when choosing a system should be guided by user requirements, spectrum, coverage, funding, implementation, business case, resources as well as procurement, explains Johan Hoolsema, MD for Expert System Solutions.
In addition, the international move from analog to digital communication has been adopted by South Africa with ICASA setting new guidelines for the conversion to digital communication systems. This brings another factor into play e.g. the conversion from existing operational analog systems to digital systems within the conversion guidelines provided by ICASA. These trends applies to Africa as a continent. It is important to stay in line with the international developments to ensure that manufacturers supply state-of-the-art communications equipment and solutions that is backed by maintenance and supply security. The operational risk of operating obsolete systems without proper maintenance and support can put mining safety, security and operations at risk.
The migration from analog to digital, has seen the birth of Digital Trunking Radio Systems such as the Terrestrial Trunking Radio (TETRA) and Digital Mobile Radio (DMR), offering a number of benefits over the traditional communication tools (analog).
DMR is a digital radio standard specified for professional mobile radio (PMR) users developed by the European Telecommunications Standards Institute (ETSI). In addition, it as an affordable digital communications platform that delivers a range of workforce efficiencies and operational benefits for mission critical users compared to traditional tools.
The standard is designed to operate within the existing 12.5 kHz channel spacing used in licensed land mobile frequency bands globally and to meet future regulatory requirements for 6.25 KHz channel equivalence.
The DMR protocol covers unlicensed (Tier 1), licensed conventional (Tier 2) and licensed trunked (Tier 3) models of operation, although in practice commercial application is today focused on the Tier 2 and 3 licenses categories.
The DMR standards has many benefits both in comparison to legacy analog systems and to other digital approaches, for instance the DMR systems enable: Double of capacity in existing licensed channels; backwards spectrum compatibility with legacy systems; efficient use of infrastructure equipment; longer battery life and greater power efficiency; ease to use creation of data applications; system flexibility through simultaneous use of TDMA channels; advanced control features; superior audio performance as well as security of supply through a fully open, well established, widely backed standard.
In comparison to analog legacy DMR as a digital communication offers more benefits, however when comparing an apple with an apple, the technology still lags behind. If you compare the basic technical specifications of the two digital technologies, that is, DMR and TETRA the difference between the two technologies is more prominent.
Terrestrial Trunking Radio (TETRA)
TETRA is the industry’s leading de-facto standard for critical communications. TETRA’s open standard (interoperability) means that network operators and end users are free to choose from the many manufacturers and suppliers of: TETRA infrastructure and radios for solution to meet their precise needs. The unrivalled TETRA interoperability Certification Process (IOP), managed by the TCCA, gives TETRA users complete confidence that certified interoperable TETRA equipment will work seamlessly in multi-vendor systems.
TETRA’S Key features
TETRA’s value adds on, makes the system capable of dealing with the everyday operational tasks and maintenance of the site, sometimes in extremely hazardous conditions. The TETRA’s standards include the following features:
Cellular radio network architecture (like cell phone GSM); Frequency efficient (2 x better than conventional radio or GSM); digital 4 slot TDMA (6.25 kHz equivalent) —- no audio noise like in analog; 25kHz radio bandwidth: full duplex capabilities; Voice and data service simultaneously; Automatic call hand-over between cells; Fast call set-up network-wide; and Scalable with high-level security options (Authentication, Encryption), makes it one of the must have in order to guarantee safety as well as productivity.
TETRA provides excellent voice quality vocoder, elimination of background noise- TETRA’s voice capabilities are second to none. With instant connection and excellent voice clarity. In addition, TETRA delivers integrated voice and data services over an IP network. TETRA Enhanced Data Services (TEDS) is the wideband solution delivering higher speed data transfers for richer applications interworking within the secure TETRA communications environment. It also offers Status messages and short data service (SDS) which can be organised and stored.
TETRA also has the options for Trunked Mode Operation (TMO) and Direct Mode Operation (DMO). Trunked Mode shows TETRA’s capability to prioritise one-to-many group communication one-to-one calls. Trunked Mode pulls together users into groups. Thus allowing users to be linked into priority groups for faster communication in emergencies and operational tasks. Centralised control makes it possible to prioritise certain groups, and therefore providing efficient method of sharing a single infrastructure by different virtual private groups.
DMO is the ability to communicate between terminals outside the coverage of a radio network, which is an essential element in emergency situations if users find themselves outside the range of network. Coverage can be increased via a DMO repeater, and can be connected to Trunked Mode via a DMO gateway.
Open cast mining environments can be very challenging making priority and pre-emptive calls a key feature, hence a priority call is treated by the network as being more important than a standard call, and is given instant access to a voice channel, enabling situations such as man-down or alerts to override a standard call. Additionally, a pre-emptive priority call is a service that ranks calls based on their criticality, the highest priority being the emergency call, states Johan Hoolsema.
One of the interesting features of DMR and TETRA is being a GPS compatible technology. If an incident happens as TETRA devices are equipped with GPS receiver and antenna to receive and decode data from GPS satellites and establish the geographic location of the device, the control room will know exactly where the incidence is taking place and be able to dispatch help from the closest emergency personnel. The GPS location data can be transmitted during emergencies and used to track missing and potentially endangered personnel, further elaborates Johan Hoolsema.
TETRA however is a much better carrier of high volume GPS and other data messages such as telemetry/telecontrol date transmission. TETRA provides another important safety feature that is archiving all the data messages (e.g. GPS, telemetry / telecontrol etc.) that can be used for incident and accident management investigations.
In comparison to analog legacy both DMR and TETRA as digital communication tools offer more benefits, however when comparing an apple with an apple, DMR still lags behind. For instance if you compare the basic technical specifications of the two digital technologies, that is, DMR and TETRA the difference between the two technologies is more prominent.
DMR and TETRA are narrow bandwidth technologies with excellent coverage distance but not suitable for HD video streaming. Technologies like Wi-Fi and LTE provide broad band mobile data services, but with short distances. Most TETRA suppliers already stated integration with LTE to give both broadband and narrow band mission critical voice and data communications.
In conclusion, DMR systems are in general used for low density with high demand of coverage. TETRA is general used for high density mission critical communication requirement with high level of redundancy such as mining, police, airports, municipalities.
