Underground Communications and Tracking: Frequently Asked Questions
With so much focus on our products and their use in emergencies we would refer you to the Frequently Asked Questions below for simple clarification on how two of our key technologies actually operate and are used, being the PED System and TRACKER Tagging System.
1. TRACKING
What does a tracking system do?
The Tracker Tagging system provides the ability to monitor, in real time, the location of personnel, vehicles and equipment underground in a mine.
What does the underground tracking system consist of?
The system consists of:
- Readers or Beacons: These are Digital Access Points that detect an WiFi based RFID Tag, worn by a miner or installed on a vehicle, as they pass by an Access Point (AP).
- RFID Tag: These are active RFID Tags that transmit their unique ID and status data on the Wi-Fi 2.4 GHz signal band. These signals are received by the Reader Access Points. MST's Tags come in two main versions, one version powered with their own battery pack that can be attached to a vehicle or carriedby a person; whilst the other version is designed to fit within certain miners' cap lamps, ensuring it is always with the miner.
- MineDash - the System Software: MineDash is the operator interface software that displays where all the tagged miners and vehicles are underground. It is displayed in graphical format on a mine map and as a table sorted by names, dates, etc. MineDash also has a range of search, alarm and report generation functions. The software requires access to a database server, such as SQL, where the raw tag data is received and stored.
What is required to operate and connect the TRACKER system together?
The TRACKER system Readers are actually Underground Digital Access Points, and are connected by Optic Fibre. Wireless Mesh is also used where installation of cabling may be difficult, e.g. in a working section or along a longwall face.
Do I know the exact location of someone wearing a Tag?
The location is known within zones. That is, the Tag location is not determined down to the exact foot, but is known within a zone between two Access Points (Readers). RSSI and ToA can refine the location accuracy, but our long experience using RSSI & ToA underground shows that it is not as reliable as it is in open air, surface installations. Underground we find such things as mutli-pathing, reflections, even day to day changes in dust and humidity levels, affect RSSI and ToA calculations. In summary, the spacing of the Readers determines the size of the detection with RSSI used for improving resolution where required.
What sort of RFID Tags are available?
Active RFID Tags are supplied as individual devices with their own internal battery pack that worn on a miner's belt or mounted on a vehicle or other equipment. The Tags can also be supplied as a part of an integrated unit in the ICCL Cap Lamp Battery or the Koehler Li-16 battery pack.
How long do the Tag batteries last?
This depends on the transmit rate of the Tag. Our experience shows that a relatively high transmit rate is reqired to ensure accurate and reliable reads underground, especially with peope travelling in vehicles. Though the batteries have the potential for 3 to 5 years life, we set the trasnmit rate higher to ensure reliablity and hence the stand alone Tag battery lasts approx 10-12 months before the battery require replacing. When the battery capacity drops below a preset level, this is indicated on the Tag itself, as well as on the surface tracking software, giving at least 4-6 weeks notice to change the battery pack out.
Is there any limit to the number of Tags or Beacons I can use?
No, there are no limits to the number of Tags or Beacons you can use. The number of Tags is guided by the size of the workforce, the number of vehicles, and number of visitors that may be underground. The number of underground Wireless Access Points is really just limited to the resolution required and the practicality to install and maintain the whole system. Note that some mines do install additional Access Points to provide seamless signal coverage when the underground tracking infrastructure is also used as the two-way communication backbone for VoIP telephone handsets.
What else can the system do?
As mentioned in the last point, the same digital network we install for the tracking system can also be used for underground two-way communications by using VoIP Telephones. Our Mine-Phone is simply another Wi-Fi device (client) that operates by using the digital network, in affect a mobile phone for underground. Other applications and devices used with our underground ImPact Digital Network include:
- PDA's
- IP Video Cameras
- Vehicle diagnostic and laod data upload (via VIP module).
- Lap Tops, where permitted.
- Basically, any 802.11 b/g enabled device.
Is the system MSHA approved?
Yes the Tags are MSHA approved devices.
The Access Points and VoIP MIne-Phone are currently being assessed by MSHA.
2. Through-the-Earth Signaling
What does "Through-the-Earth" Signaling mean?
The use of ultra low frequency signals means the signals can travel through several thousand feet of rock strata. Hence an antenna can be located on the surface only at a mine site, and provide signal coverage to all parts of the underground mine.
If the terrain makes a surface antenna impractical to install, then the antenna can be installed underground. But because the signal travels through rock, the antenna does not need to run into all parts of the mine to achieve mine wide signal coverage, thus minimizing the risk of damage during an incident.
Can other communication systems provide redundancy to ensure they keep working in an emergency?
No, not reliably. More than one or two alternate pathways for leaky feeder or optic fibre cable, or alternate routes for wireless mesh systems, are simply not available in an underground mine. Plus the power cables to each of these devices is vulnerable, and battery back up may not be available or of sufficient duration in an extended rescue scenario. Hence these cable based systems (either data or power cables) can be easily disrupted.
Leaky feeder radio, wired and wireless mesh systems are excellent day to day communication systems but should not be the only communication solution to be relied upon in an emergency. This is because these other systems are based on significant amounts of hardware underground that can, and would, be damaged in any major incident.
Hence the effort we at MST have invested in Through-the-Earth (TTE) technology over the last 20 years. TTE signaling is the only communication technology that can ensure a high level of availability in all circumstances underground, as we have seen with over 170 installations around the world since 1991. MST feels our though the earth mine communication systems complement our other radio and digital mine communication technologies to provide an optimum overall communication solution for a mine's day to day operations, as well as address their emergency communication preparedness.
What is PED?
PED is an emergency warning system that uses ultra low frequency signals to transit information directly through rock strata (through-the-earth signaling). Text messages are sent to special PED Pager receiver attached to an underground miner's cap light.
Where is PED Used?
It is used in over 170 mines (both coal and hard rock mines) in Australia, China, USA, Canada, Africa and Sweden.
Can a miner underground respond to messages?
PED is a one-way pager, a miner underground cannot send a message back. The inherent reliability of a well maintained PED System will ensure a message is received, but currently there is no through the earth (TTE) return signal available for underground communications.
However, MST are currently finalizing the development of our TTE technololgy to provide two-way capability. This will provide a communication link for the miner underground back to the surface without the need for any cables or mesh networks (both of which are very vulnerable to disruption in any major event underground).
So can one way paging make a difference in an emergency?
Yes, without doubt the ability of PED has made an enormous difference to some miners working underground at the time of an incident (e.g. Willow Creek Mine Fire in 1998). The ability to just advise them to evacuate or perhaps to hit the roof with a rock bolt because seismic sensors are installed and listening can, and have, literally made the difference between life & death. We are confident that our Two-Way TTE System will offer even greater safety benefits when it is released.
How else can PED be used?
The ability to send a message to a person, wherever they are underground, means that PED is a very useful day to day communication system that complements your other underground communication devices (such as phones and radios).
PED used as a communication tool is very effective for managing and directing maintenance personnel, electricians, mechanics (fitters) and organising mine consumables immediately to where they are needed
PED can also be used to turn pumps, fans and other equipment ON/OFF in a mine using the ControlPED units. These units use the same transmission system as the PED communications receivers. What maintenance does the system require? PED is a relatively simple system to install and maintain. But like all electronic or communication systems some level of maintenance is required to ensure it operates efficiently.
Considerations for installation?
A surface antenna only requires access to the area to install the PED antenna cable.
Underground antennas need to be installed in fresh (intake) air due to the power in the cable (approx. 150 volts at 5 amps). Also, care must be taken when installing cables near old phones lines etc to limit the possibility of any interference.
Is PED reliable?
Yes, history of use shows PED is extremely reliable, as long as the simple maintenance referred to above is undertaken.
GENERAL QUESTIONS
Who is MINE SITE TECHNOLOGIES?
MINE SITE TECHNOLOGIES (MST) is the global leader in mining communications, particularly underground mine communications.
Privately owned it has been established for 20 years, MST has a highly innovative product range to suit the special needs for communications in the mining industry. Continually improved products enhance the safety and productivity for both local and global customers. MST is an organization with an ongoing commitment to innovation, safety and productivity and has a strong focus on providing overall solutions and customer satisfaction.
What are the key technologies of MINE SITE TECHNOLOGIES?
- ImPact - takes a mine's WLAN seamlessly underground, enabling a single communication infrastructure to provide a range of high data applications such as tracking, video, VoIP, remote vehicle diagnostics, and control.
- VDV Leaky Feeder - 2-way voice and data VHF radio, reliable and easy to maintain.
- PED - ultra-low frequency paging and emergency warning system. PED is the primary evacuation warning system in many mines.
- BlastPED - remote blast initiation system that uses radio signals, rather than hard wire networks, for safer blasting.
- TRACKER - is oen of the more important applications that operates using our ImPact digital network. TRACKER allows the underground location of miners and equipment to be monitored coninuously, and in real-time .
- ICCL - Integrated Communications Cap Lamp, only 1/3 of the weight of existing units but can include a range of communication and safety devices such as PED and/or Tagging and/or Radio.
- Wireless Mesh via Rajant BreadCrumbs for open pit and underground mobile applications.
What clients does MINE SITE TECHNOLOGIES work with?
Our clients include: Xstrata, BHP Billiton, Centennial Coal, Rio Tinto, Peabody, Datong Coal, Newmont Gold, Barrick, Newcrest, Anglo Coal, Ningxia Coal, Consol Energy, Homestake Gold, Inco, Pittston, Energy West, Stillwater Mining, Hebi Mining and others.
How can I download the manuals?
The product manuals are reserved for operators using our equipment.
You may still download all our information brochures for our products and systems:
- PED
- ImPact
- VDV
- Tracker
- ICCL
How can I get in contact with MINE SITE TECHNOLOGIES if I have more specific questions? Just send us an email to mst@minesite.com.au we will come back to you as soon as possible.