Mining Telephone / Mine Phone

This article considers how VoIP Mining Telephone / Mine Phone Systems can be used to improve underground communications and safety. It will also look at critical issues to consider when installing an effective underground mining communications system.

A challange for the Mining industry

The success of any mining operation depends on effective underground communications. From preventing business critical disruptions to ensuring life safety of mining workers, an effective communications tool is one of the most important installations in a sub-surfance mining environment.

Focus on health and safety

Safety has long been a controversial issue in the mining business. While mining today is substantially safer than it was in the previous decades, mining accidents are still relatively frequent and are often very high profile, such as the Quecreek Mine Rescue saving 9 trapped Pennsylvania (USA) coal miners in 2002. The constant threat of both technology failure and mining accidents remains a significant concern for many miners throughout the world, including Indonesia, South Africa, Chile, Brazil, Peru, Russia, China, Mongolia, USA, Canada and Australia.

Accidents can easily happen in sub-surface mines, both in terms of failures in construction as well as un-intended exposure to harmful gases, oxygen starvation, heat and dust. An example of a challenging environment, is the TauTona mine in South Africa, which began operation in 1962. By 2008, the mine reached some 3.9 km underground, making it the deepest mine in the world, employing some 5,600 miners. Air conditioning equipment is used to reduce the heat from 55 centigrades down to a bit more bearable 28 centigrades, but even so, the mine remains an extremely dangerous place to work and an average of five miners die in accidents each year. In the 2008 financial year, four employees were killed at the TauTona mine.

The Answer

The installation of a mining telephone / mine phone system inside sub-surface mines is seen as critical in order to improve underground communications, deal with ongoing maintenance and to summon help in cases of emergency.

Norphonic has a history of delivering Heavy Duty VoIP telephones into some of the world’s most challenging areas, ensuring essential voice communications when it is most needed. In the remaining part this article we shall look at some of the issues that needs to be addressed when selecting an effective telephone solution in your underground mining application.

A Typical Underground Mining Communications System

The below figure shows a typical Heavy Duty VoIP Telephone installation within a sub-surface mining environment. Telephones can either be connected in a circle formation to provide a redundant network or in a line to connect directly to a PBX. The distance between telephones can differ greatly in various environments, but it is usually recommended that organisations do not extend beyond 150 meters between telephones for safety reasons.

The above schematic

shows a mine shaft going down into the underground mine. Such mining shafts can sometimes be 12 stories deep and reach 3-4 kilometers below the surface. There are usually many horisontal "arms" shooting off the main mining shaft. These horisontal tunnels can be many kilometers long.

In the above schematic there are 3 underground communication systems installed: a robust VoIP telephone system; a signaling system; and a leaky feeder system. There are a number of reasons why a mining company may need several communications solutions installed. First, local governments often legally require mining companies to have at least two different communication systems in case of a critical system failure. Secondly, there are practical / operational reasons why a company may opt to have more than one communication system installed.

In the example schematic drawing above, Robust VoIP Telephones (marked in RED) are installed at regular intervals on the fiber optic network running along the mining tunnels. This allows miners to communicate with each other or with the central control room at surface level. These VoIP telephones are also installed in the Refuge Bays (marked in YELLOW). Refuge Bays are specifically constructed underground evacuation rooms stocked with drinks, foods and medical supplies for miners in case of emergency evacuation. A signalling system is also installed close to the mining shaft (marked in BLUE), allowing miners to call for the elevators (lift) and robust VoIP telephones are installed next to the signaling system devices to allow clear communication with the elevator operator at surface. In the example, a leaky feeder communications system is also installed (marked in GREEN) which consists of a coaxial cable which emits and receives radio waves. The cable is leaky in that it has gaps or slots in its outer conductor to allow signal to leak into or out of the cable along its entire length.

VoIP vs. Analogue Mining Telephones / Shaft phones?

There are a lot of analogue phones installed in mines today, fitting in with the traditional land line service which many mining companies still use. However, analogue technology is both cumbersome and costly to maintain and are therefore rapidly being replaced with modern VoIP telephone technology.

VoIP telephones (VoIP is an acronym for “Voice over Internet Protocol”) allows users to make telephone calls using their existing data networks rather than from the traditional analogue land line service. These calls can be made from one computer to another or to landlines as well. There are a number of important reasons why most organisations now are converting their system into a VoIP telephone systems. This includes both economical and practical safety reasons.

First, since the VoIP telephone uses IP fiber networks to carry voice communications, it has additional software features which makes such a system very attractive in terms of underground mining applications in particular. For example, all Norphonic Heavy Duty VoIP telephones comes with a self monitoring and fault check function as standard. This is a highly useful feature, as it allows central control room staff to automatically know if the telephones is working at any given time. The control room can also get information about the telephone components, if the telephone hook is left in an on/off position etc. This is obviously an important safety feature in many underground applications as, by comparison, there is no way of knowing if a comparable analogue telephone will work until you actually try to use it.

Second, with Norphonic robust VoIP mining telephones, the control room staff can use the Remote Management Feature to upload software updates from a central location, switch the telephone on/off, or control other telephone components remotely, thereby slashing the maintenance costs usually encountered with comparable analogue systems.

Third, since a VoIP telephone can use the existing LAN / IP data networks to carry voice, it offers much lower installation and operating costs than traditional analogue telephones. There are no hard-increments to worry about and you do not need to send down and electrician to install IP technology.

Fourth, and finally, IP is the future of all industrial comms. All modern system today runs on IP technology (ventilation fans, fire detection, surveillance cameras, access control, gas detection etc) and it is only natural to use that same network for telecoms. Not to mention saved calling cost by using your existing data network for telecom purposes.

The Norphonic VoIP Mining Communications System

The Norphonic Heavy Duty VoIP Mining Telephone is a robust, weather resistant telephone built to withstand extreme temperatures, humid and dirty environments. It is perfectly suited to underground mining areas with an overall weather resistance to IP65. The unit is manufactured in a durable aluminium casing, resistant to rust, condensation and corrosion. The hookswitch has no moving parts, making the telephone ideal for use in mining environments exposed to high levels of dust or grime. It comes complete with a 80 dB ringer as standard and an optional visual Flashing Light Beacon, ideal for use in noisy areas where a ring may not easily be heard.

A key feature is the Quality of Service (QoS) functionality, which enables optimal priorisati on of network traffic and impeccable transfer of voice a nd data. The telephone can be maintained and upgraded from a remote location, thereby slashing maintenance costs associated with conventional telephone systems. A Self Monitoring and Fault Check function is also included, ensureing maximum up-time and further saving maintenance costs.

The Norphonic Heavy Duty VoIP Mining Telephone solution is typically connected to an IP based Public Branch Exchange (PBX) on a fiber / Ethernet network as shown in the example below:

Ethernet Networks are Ideal for Underground Communications

Modern and efficient mining facilities utilise improved control methods and increased mechanisation to achieve optimum productivity. Ethernet / Fiber optic networks have a proven track record within underground areas to monitor, analyse and control both equipment and facilities, increasing both safety and production efficiency.

Fiber Optic / Ethernet networks are today used to manage, control and interconnect a wide range of technology in underground mining environments, including:

• VoIP Telephone systems
• Conveyor Belt, and Ventilation Control systems
• SCADA systems
• Interlocks, and Access Control systems
• Fire Detection systems
• Remote Video Monitoring systems

Considering a Wireless / WiFi VoIP Mining Telephone Solution?

Although the Norphonic VoIP mining telephones are typically interconnected to the Ethernet network using fiber cables, Norphonic IP telephones can also be connected to an external WiFi tranceiver / antenna in order to transmit and receive signals, thereby providing a Wireless solution for mining areas. See the example schematic below.

The flexibility of the Norphonic VoIP Mining Telephones therefore means that it could be used on a fixed fiber cable layout or in a wireless VoIP environment. There are no particular barriers to installing Wireless / WiFi solutions, but the network designer should be aware of potential voice quality pit-falls and plan for these.  Some key things to be aware of in terms of voice quality when designing your network layout:

Latency - delay from data is transmitted until it is received. Noticable in conversations if latency goes above 100ms.
Jitter - variances in latency between packets. High jitter means large variance in packet latency and degrades speech quality.
Out of order datapackets - degrades speech quality, is often caused by jitter

IP Telephony through Leaky Feeder ("Line-of-Sight" / IP - TCP Solution)

Though Norphonic is most frequently connected via fiber cable to the Ehternet Network, it can also be interconnected using a Leaky Feeder system. As mentioned earlier, a leaky feeder underground communications system consists of a coaxial cable which emits and receives radio waves.

In cases where the end user wants to use this for VoIP communications, the Norphonic telephones can be connected to a "two-way" leaky feeder system via an external smart amplifier to provide high speed TCP / IP data transfer. These external amplifiers are inserted at regular intervals, typically every 350 to 500 meters, to boost the signal. Such Leaky Feeder Amplifier systems make use of industry standard modem technology to provide wired and wireless Ethernet applications such as computer networking, IP cameras and Norphonic VoIP Telephones in underground hotspots.

However, it is important to be aware that these Leaky Feeder systems are limited because of the high frequency they use. Leaky Feeder transmissions cannot pass through solid rock, which limits the system to "line-of-sight" applications only. This is particularly important to be aware of when installing telephones in underground refuge rooms where the doors may also limit the signal. Additionally, it is important to keep in mind that the Leaky Feeder system have to be able to send and receive signals (two way leekys feeder / transceiver) as the VoIP telephone need to send and receive data (voice).

Another limitation of Leaky Feeder solutions is the noise level in these networks. Because the signal is amplified and picked up at other points, there is easy for other machines and equipment to cause inference with the signal. This means that, the miner can be very difficult to hear due to inherent network noise caused by LOS (line of sight) and other signal amplification limitations. For this reason, it is usually recommended that mining organisations install an ethernet fiber calbe network even if they already have a leaky feeder network installed. This is both for redundancy reasons but also for emergency communications needs, inside emergency rooms where leaky feeder systems can not operate due to line of sight limitations.

What to look for in a VoIP Mining Telephone?

There are many issues that needs to be addressed prior to commissioning an IP mining telephone, such as evaluating the installation environment, functionality and temperature ranges. Below are some key pointers to look at when choosing your underground communication system:

• Can the system work with your existing systems and infrastructure? The key thing to look for in this regard, is to examine if the telephone is built on Open Standard SIP technology. Norphonic Heavy Duty VoIP systems are built on Open Standard SIP technology, and tested to be compatible with all major PBX and network systems (Alcatel, Cisco, Asterisk, Broadsoft etc).
• Is the system future proof? Can the system be upgraded or changed in the future without having to change all the telephones and the entire network? All Norphonic Heavy Duty telephones can be changed with other systems without loss or differentiation to the level of service.
• Is the telephone dust and water proof? Underground mines are some of the most challenging areas in the world, exposed to extreme levels of dust and water. The highest level of dust protection is essential. The ingress IP rating to IP65 is therefore recommended in all mining applications. See definition of Ingress Protection in the below Glossary for further information.
• Is the telephone condensation proof? –This can otherwise lead to severe problems in operation as water can easily form inside the unit, affecting performance.
• Does the hookswitch contain moving parts? All Norphonic Heavy Duty VoIP telephones do not contain moving parts, and can therefore operate in extreme areas where dust or exposure to grime is a challenge for traditional telephone systems.
• Can the system work in extreme temperatures? Underground mines can be notoriously hot and/or cold, so a wide operating temperature functionality is recommended, from –20 up to +55 celcius degrees.
• Does the telephone incorporate VSQ - Voice Sound Quality? This is a standard feature in all Norphonic telephone systems, ensuring loud and clear sound, even in noisy ambiance areas.
• Does the VoIP telephone incorporate a QoS – Quality of Service functionality? This feature, found in all Norphonic telephones, guarantees a certain level of performance in a data flow, ensuring impeccable delivery of voice communications in an IP Network.
• Is the telephone colored in such a way that it is easily identified by users? The Norphonic Heavy Duty VoIP comes in a bright yellow color as standard. Colours can also be customised depending on the user needs and order volumes.
• Is the system easy to install and to maintain? Norphonic Heavy Duty VoIP telephones are easy to install and have in-built status monitoring and fault check functions. This means that the status of the telephones can be monitored from a remote location, saving you considerable maintenance  costs.
• Is the telephone CE approved? CE marking means that the product is certified to meet EU consumer safety, health or environmental requirements. End users should be aware that some telephones use the intentionally confusing term ”CE” for ”China Export”, and the only way consumers can check this is to closely examine the CE mark/ logo as the two logos are very similar.

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