In the midst of a disaster, whether natural or man-made, communication between emergency services and utilities is essential. Commercial communication techniques cannot be relied on as they are costly, inefficient, and vulnerable in a disaster. The City of Cape Town has equipped itself with a digital radio system across the entire city – allowing for easy communication and fast response in the event of a disaster.
Public cellular networks come under considerable strain at a time of emergency, or even during a significant incident such as a traffic jam on a busy highway. This is why dedicated mission critical communications networks remain essential. While many public safety officers and other critical personnel utilise public mobile communications systems during their normal working day, at critical times these networks cannot offer the resilience, speed, coverage and special features that are essential for emergency response staff to do their work properly.
With the implementation of a terrestrial trunked radio (TETRA) system across Cape Town, the city aims to improve its reaction and response time as well as its efficiency. The digital radio trunking infrastructure was commissioned in 2000 after the six municipalities in and around Cape Town merged into one municipality. The system replaced the inadequate analogue radio systems used by the previous municipalities (see Fig. 1). Analogue radio systems are known to be problematic over long distances or in instances where there is a high signal-to-noise ratio – making its use in the mountainous and large Cape Metropolitan Area (CMA) difficult. The TETRA radio system is currently fully operational with over 11 000 uses from the city’s safety, security and utility services, and a further 2500 users from surrounding municipalities.
Fig. 1: New TETRA radio tower at Wemmershoek Dam (Motorola).
Crucial to the successful operation of a system is the reliability of its individual components. Tied to this is maintainability. The TETRA system undergoes constant maintenance including the upkeep of hardware, software, and personnel, as well as network management. Upgrades take place every five to seven years, and the most recent upgrade in June 2015 saw the system change to the new Motorola Dimetra IP 8.2 TETRA system. After a $681-million global investment into research and development last year, Motorola is working to provide a system which is more resilient. This means having a system which can still operate in a variety of circumstances – during high traffic, over long distances, and when one or more element of the system fails or falters. Each component the TETRA radio system has been tested and analysed in terms of its likelihood of failing, as well as the consequences of failing. This has led to the incorporation of built-in redundancy to all key elements, meaning that operations can be maintained despite
multiple equipment failures (a reality in the event of a large-scale disaster).
Another factor contributing to the resilience of the TETRA system is the core network architecture. The Dimetra IP 8.2 system uses distributed IP architecture. Traditional circuit switched networks used a centralised/hierarchical architecture which presents many potential failure points. In a packet switched IP network, voice and data can take various routes through the network to reach a destination, giving the system the ability to compensate for component breakdown (see Fig. 2). The system has various one fallback features. If the radio terminals are disconnected from the master switching office (MSO) they will revert to local area service. The radios will automatically connect to the closest remote site and communicate with each other via this site. However, as both MSOs have a geographically redundant system, both MSO sites would have to fail in order to revert to local area service. If the local areas service fails or the radio moves out of the coverage area of the system, the radios will get an alert that they cannot communicate. At this point, the user then has to switch to direct mode operation (DMO), enabling direct terminal-to-terminal style communication (see Fig. 3).
Fig. 2: Design comparison between the traditional hierarchical circuit based approach and the distributed packet-based approach (Motorola).
Fig. 3: Trunked TETRA vs. DMO (TETRA Forum).
The new system aims to keep communication across devices secure and private, using encryption to keep out listeners with police radio scanners. Real-time GPS also means that the command centre can monitor users, and send support to a precise location in the event of an emergency. Individual radios can also be stunned if reported stolen, meaning that all output audio from the radio is muted. However, the stunned radio can still receive input audio, allowing for the command centre to listen in on the events at that location. The radio’s GPS is also still active in the event of stunning, making it easy to recover the device if lost/stolen.
The new system upgrade comes with many improvements, one of which is that it allows for any radio terminal to be configured to any user through their unique configuration code. The radio transmission range has also improved from its previous range of 34 km to a new range of 54 km – making its use in helicopters more realistic.
The instant group communication allowed by the push-to-talk makes for easy communication in a disaster. However, to have this activated at all times would be unnecessary and may be problematic for individual departments. For this reason, users are separated into various user groups. In the event of a disaster or serious emergency, the communication pathways are opened between all users. If there are too many users simultaneously, there is a second control channel which helps with the amount of traffic.
Individual radio terminals are all equipped with cameras, and can send and receive text, video and images to and from the MSO. Motorola has also manufactured the MTP8550Ex radio for use in potentially combustible situations involving oil and gas (see Fig. 4). These radios are specifically designed to be useable while wearing thick protective gloves. All radios on the TETRA system include Emergency Notification or Emergency Shut-down when an incident occurs, and the Man-Down feature can be set to send a notification to the controller if the user falls or is inactive. GPS notifications are sent from the handheld or mobile terminals to the controller so that the nearest worker or vehicle can be sent to the incident, and geo-fencing can be used to provide automatic alerts when selected areas are entered. Devices also feature embedded secure Bluetooth which enables connectivity with accessories and collaborative devices.
Fig. 4: The MTP8500Ex radio terminal for use in hazardous situations (Motorola).
With all the features of the TETRA radio system, there is a need for a command station in place to manage events and all the data that they bring. Motorola offers a command and control solution implementation platform called MotoCLOC (city live online control). This system comprises three modules/screens which work together – a 2D or 3D mapping which monitors resources such as vehicles, sensors, alarms etc., an incident management platform, and a live video feed displaying various mobile and fixed feeds simultaneously (see Figs. 5 and 6). This system works in conjunction with various outside data sources such as emergency reports, CCTV cameras throughout the city, alarm systems, radio feeds from emergency services, and even Twitter feeds from Cape Town residents. Using real-time digital footprints throughout the city, the online control system keeps track of events and can even prompt the user on the best way to react. The system has the capacity to keep track of events and distinguish patterns so that preventative measures can be put in place before disaster occurs. The incident management platform also allows for the TETRA radio users to log information into the platform remotely so that an up-to-date record is kept of response and actions of the emergency team.
Fig. 5: MotoCLOC control room view (Motorola).
Fig. 6: Event management system (Motorola).
The MotoCLOC geographic information system (GIS) and mapping module seen in Fig. 7 supports 3D mapping and analysis based on Esri ARC GIS server 9.3, and displays types and severities of events or incidents by assigning icons. It also features a critical event pop-up notification which automatically configures with the incident management platform. Remote control cameras and other ad hoc resources can also be managed from the map. The map also links to an in-vehicle mapping application for response teams.
Fig 7: 3D mapping module screen (Motorola).
The aim of MotoCLOC in conjunction with a TETRA system is to take the layers of undefined data made available every day, and turn it into actionable intelligence. Using data which is spread around the city, the system can pick up suspicious behaviour, track suspects, and inform officers of actions to take. By providing structure to the data, intelligent links can be made which can limit the effects of a disaster. This data-driven public safety system could enable the City of Cape Town to take one step closer to becoming a smart city.
Contact Francois Stoffberg, Motorola Solutions South Africa, Tel 021 946-9914, f.stoffberg@motorolasolutions.com
The post Digital integrated radio system for disaster management appeared first on EE Publishers.