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To familiarize students with the equipment and the types of networks available to for the specific needs of emergency responders, from local links of institutional emergency response services to the international networks used by providers of international humanitarian organizations. This third module also reviews these telecommunications tools in respect to their appropriateness under the conditions in various countries and the limitations of each system. In addition, the role of telecommunication satellites in private and public networks will be considered
Today's public networks offer numerous services, but they are mostly commercial venues. In order to be sustainable on longer term, even public networks built as part of development projects need to work on the basis of cost recovery. This limits their deployment to areas with an adequate density of potential subscribers, and even areas with a high vulnerability to hazards may therefore have only very limited coverage. The public access to a network implies the inevitable risk of overload in case of any unusual event.
These two factors, together with the specific need of some emergency response services, create the need for networks with limited capacity, excluding public access. The need for specialized capabilities of telecommunication links exists not only among emergency services and disaster responders, but also among users such as private enterprises in commerce and industry and, not to forget, the military.
In an emergency situation, private networks serving other than emergency purposes should not be overlooked as potential resources when it comes to using what is available. We shall in the following consider the type of telecommunications networks needed to cover the specific needs of emergency services and disaster relief providers. We shall then also look at possibilities to apply the capabilities of some other, non-public networks in emergency telecommunications.
The requirements of rapid deployment and of operation in unpredictable locations make wireless communications the means of choice. They are best grouped in respect to their range. The communication modes are often those already considered when reviewing public networks in module 2, and some special technical aspects will be covered in module 4.
Short-range radio networks are mostly operating in the VHF ("Very High Frequency") and UHF ("Ultra High Frequency") part of the radio frequency spectrum. The range achievable on this part of the frequency spectrum is similar to what we are familiar with from FM broadcast and TV stations, typically line-of-sight, and depending on the topography of the terrain. Mobility of equipment is most important in networks covering the site of an event and its immediate surroundings; transmitters and receivers should therefore be small and light. Users of such equipment are mostly individual relief workers, people who need reliable and user-friendly tools requiring only a minimum of training and not hindering them in the performance of their tasks.
The most common type of equipment is the so-called "transceiver", a combination of a transmitter and a receiver in one package. The hand-held "walky-talky" in the size of a mobile phone is most often seen in the hands of those working on the site of an emergency. Similar equipment in the size of a car radio is usually installed in vehicles operating within an affected area. Portable, hand-held transceivers are powered from own small batteries, mobile transceivers from the battery of the car they are installed in. The antenna of a portable unit is commonly attached directly to it, while that of a mobile unit is usually mounted on the outside, preferably the roof, of the vehicle. [illustration 3.1] [illustration 3.2]
VHF and UHF equipment and networks most commonly use what is called the "simplex" mode of operation. At any time, a station can only receive or transmit. [illustration 3.3] The operational consequences of the use of simplex links rather than "duplex" connections [illustration 3.4], such as common on the public telephone network, will be considered in module 4 of this course.
The limited power available from the small batteries of a portable transceiver and the very limited efficiency of its often very short antenna limit the range to the dimension of a few kilometres in most terrain or environment. Line-of-sight links, such as between the top of hills or high buildings, increase their range, which can under good conditions reach tens or even hundreds of kilometres. Mobile stations have more power available, and, together with their usually more efficient antennas, this allows them to cover a somewhat larger range.
The same type of equipment used in vehicles can also serve as a base station in a fixed location, such as an on-site operation center. Such installations can use highly efficient antennas, mounted as high as possible on masts or buildings, and might even have access to more power than a mobile station would usually have at its disposal. Such a fixed station can therefore serve as the base- or control-station of an emergency network.
Substantive improvements to the range covered by a VHF or UHF network can be achieved through the use of repeater stations. A Repeater station consists of a receiver, receiving the signal from a portable, mobile or base station, and and a transmitter, re-transmitting this signal. To make this possible, the repeater station has to listen on one frequency or channel, and has to transmit on a second, different, frequency or channel. The station using the repeater has to do the same, but in reverse order. A repeater station, receiving and transmitting at the same time, also needs either separate antennas for receiving and transmitting, or one antenna with a very effective filter, a so-called duplexer. In addition to receiver and transmitter, it needs a control unit, which switches the transmitter on whenever a signal is received, and which might have additional features such as an automatic identification, telling the users what repeater station they are operating on. [illustration 3.5] [illustration 3.6]
Depending on the number of users, a VHF or UHF network can be rather complex and busy. Strict discipline is therefore mandatory. Guidelines for operation in such a voice network will be given in an annex to module 4 of this course.
The VHF and UHF networks described above are mostly used for voice communications, but with the necessary additional equipment they can also carry data. A combination of both communication modes is possible, and allows additional features such as selective calls to individual stations, or the transmission of automatic position reports.
Medium range communication, typically beyond the range of a VHF network with or without repeater stations, are possible on frequencies in the HF spectrum, also known as the shortwave bands. As shortwave broadcast listeners know, the propagation of radio waves in this part of the spectrum follows different rules, and the conditions change, depending on the time of the day and on several other factors. The waves travel in two different ways: direct, following the surface of the earth, and via reflections in the upper layers of the atmosphere. The dimension of an effective antenna depends on the frequencies or wavelengths in use. The wavelength of VHF and UHF used for the networks described above is between 30 cm and 3 meters, that of the HF or shortwave bands between 10 and 100 metres. HF antennas are consequently much larger than VHF or UHF antennas. Their installation as well as the set-up of the radio station itself needs the expertise of a technician, and the efficient use of HF links requires some basic training. Shortwave links are more affected by interference from a multitude of sources, and voice might be somewhat more difficult to understand than on VHF and UHF links. Fixed stations therefore often use trained operators, which can ensure the best use of the equipment.
HF stations are mostly transceivers, like those described above, but their volume and weight is normally higher. Their use is therefore restricted to fixed or mobile stations. They are however capable to cover wide areas without the use of repeater stations. The modes of communication on medium range HF networks are voice and data, again with the option to combine both modes just like on VHF and UHF. [illustration 3.7]
Long-range communications are another capability of the HF or shortwave bands. Over the long distances covered by international or intercontinental links, the propagation conditions become even more important and efficient antennas are indispensable. Data modes are the predominant type of operation; they allow error free connections even under critical conditions. The skill of the operators is a key factor in long-range networks.
Such shortwave links will always remain a mainstay of emergency telecommunications over long distances. A great advantage of shortwave networks is, that they do not depend on any infrastructure other than the equipment under direct control of the users. The initial investment to set up a private network is usually much higher than that necessary for access to a public network, but the cost for its use is normally much lower. A service provider operating a public network needs to recover the initial infrastructure investment as well as the cost for network maintenance and operation, and will do so by charging recurrent fees depending on the duration of calls or the quantity of data carried.
Own, private networks are in many cases not only the most appropriate solution when emergency responders and providers of disaster relief have special telecommunication needs, but they can on the long range also be the most economic solution. User groups other than those involved in emergency operations use non-public networks, and in many cases these telecommunication facilities can also assist in covering emergency telecommunication needs.
Radio communication is the only form of telecommunication available to ships at sea. The maritime radio service has its own structures and rules. Beyond its task as the means of contact between ships and dedicated coast stations, the latter usually provide links into public telecommunication networks, thus providing ships with the possibility of communicating with subscribers of the public telephone and data networks.
The communication modes in the maritime service are voice and data. Telex used to be very common, but e-mail is increasingly replacing this form of written messages. The maritime service uses internationally defined fixed channels within the bands allocated to this service in both the VHF and the shortwave range. These bands are separate from those allocated to the fixed and mobile land services; communication between stations of different services is not normally permitted and often not technically possible.
If communication with stations of the maritime service becomes necessary in an emergency situation, such operation is permitted under the general rule permitting the use of all available telecommunications links for emergency traffic. In such a situation, a land-based station will try to contact a shore station of the maritime service; such stations keep a permanent radio-watch on specified, published frequencies and can assist in forwarding an emergency message through their own or a public network.
Logistics operations might require communication with vessels transporting relief goods. The modalities for direct contact with such a ship should, if at all possible, be arranged with the ship's owner in advance. If such traffic is intended and needs to take place on channels allocated to the maritime service, and only an operator familiar with maritime telecommunication procedures should try establish such a contact.
More details on the maritime service are available in the ITU Handbook on Emergency Communications, part 2, Chapter 4.2.
Most of what has been said above in respect to the maritime radio service applies to the aeronautical service as well. This service too uses internationally defined frequencies or channels within the VHF, UHF and HF bands allocated to it.
If logistics operations, such as in case of an airdrop of relief goods in a remote location, require direct communications with an aircraft, such communication must be arranged in advance. The VHF equipment used on aircraft is not compatible with that used in land based networks. Consequently, it is necessary to equip either a land-based station with a transceiver for the aeronautical service (a so called air-band radio) or to equip the aircraft with a radio of the land mobile service. The latter solution is more difficult to implement, as the plane would also have to be equipped with an additional antenna. To operate within the aeronautical service requires knowledge that only an appropriately trained operator has. Due to the high importance of this service for the safety of air traffic, any such operation has to be planned with utmost care.
More details on the aeronautical service are available in the ITU Handbook on Emergency Communications, part 2, Chapter 4.3.
A particularly valuable tool for emergency telecommunications is the Amateur Radio Service. It offers a global network of radio stations, working without any infrastructure beyond the equipment used by the individual operators. Many stations are particularly disaster-resistant thanks to independent power sources. Most important is, however, that the skilled volunteers operating these stations know best how to establish communication links even under the most adverse conditions and with very limited means.
In the same way as the maritime and aeronautical services, the amateur radio service is a recognized telecommunication service. To obtain an amateur radio license, the operator has to pass an exam, administered or recognized by the respective government authorities. Beyond the technical and operational qualifications required for the exam, amateur radio operators or "hams", as they are often called, continuously upgrade their knowledge and are offered specialized courses in emergency telecommunications. In many countries, the national amateur radio associations have established permanent co-operation with emergency service providers and disaster relief organizations and hams regularly participate in training courses and emergency response exercises. The international Amateur Radio Union, the organization of all national amateur radio societies, has a co-operation agreement with the United Nations and participates in the work of the International Telecommunication Union (ITU) on emergency telecommunications.
International regulations do not generally allow the handling of third-party messages by stations of the amateur radio service. Some administrations allow the handling of messages with strictly non-commercial content, and given the strictly non-profit character of the service, all such activity must be free of charge in any case. Recognizing the importance of the amateur radio service in emergency telecommunications, the ITU World Radiocommunication Conference (Geneva, 2003) has just recently modified the respective regulations. The national authorities regulating the amateur radio service in each country are now encouraged, to allow third party traffic in emergency and disaster situations as well as during related training activities
Emergency telecommunications have a long tradition and are an important part of the activities of the amateur radio service [example 3.8]. Today, like throughout the past 100 years of history of radio communication, hams are often at the forefront of technological developments and, most of all, they are "radiomen" and -women in the true sense of the word. The use of radio communication equipment is part of our daily lives, but when the user-friendly facilities like mobile phones are not available, the skills of the radio amateurs an invaluable asset.
It is for this reason that many hams are not only involved in volunteer services providing emergency and disaster response, but are found in senior positions as emergency telecommunication managers in numerous organizations. Local clubs and national associations of the amateur operators should be contacted whenever emergency telecommunication preparedness plans are being developed.
More information on the amateur radio service can be found in the ITU Handbook on Emergency Telecommunications, Part 2, Chapter 5, and at <www.iaru.org>
Such services include networks operated by institutional providers of emergency services such as police, fire brigades, and ambulance services. They use mostly VHF and UHF networks, often with repeater stations, and always with a range corresponding to their usual operating area. In wider areas with very low population density, they might also use HF systems for their needs. HF networks might in such areas also serve for educational and other purposes and may well be the only available communication links in emergency situations.
The use of radio communications for personal or professional purposes is authorized in various forms by the authorities in different countries. Licenses are issued in some cases only to persons or enterprises having a specific need for such use (construction companies, courier services, pizza delivery services and so on) and in others to anyone upon a simple request (citizens band, personal mobile radios). Equipment used must in all cases be type-approved and power is strictly limited in order to protect other users from interference.
To know, what non-public, land based communications networks exist in a given area, must be part of any emergency telecommunication preparedness plan.
Radio services for other than communication purposes include navigation services. The user of the service is in most cases only receiving signals and does not need to transmit. One well-known radio navigation aid is the Global Positioning System (GPS). A hand-held or mobile GPS receiver allows the user, to determine his or her accurate location. Such information can then be forwarded through a telecommunication network, thereby allowing a base station to quickly determine the position of mobile or portable stations of its network. This forwarding can even be automatic, a capability which is available on different systems.
A relatively new development is the "wireless" network with very short range, usually less than 100 meters, typically used to provide links among personal computers and laptops as well as for connections between these and wider networks, including the Internet. Such networks are operating on frequency bands specifically allocated to this type of data communication and the user does not normally need to obtain a radio license.
Their use in emergency telecommunications is mostly limited to connections inside an on-site operation center, providing access to the actual telecommunication links between such a temporary establishment and the "outside world". A Wireless Local Area Network or "wireless LAN" can greatly facilitate cooperation between the partners in relief operations and allows the sharing of telecommunication links by giving a number of users access to a single outside connection.
Links via satellites are part of many of the networks of public and private telecommunication services. A link to a satellite is normally a "line-of-sight" link, and frequencies in the UHF range and even higher are therefore perfectly suitable even for intercontinental communication. The condition is, of course, that the satellite can "see" both terrestrial stations involved, in emergency telecommunications typically one at the disaster site and one in another country or even another continent.
For public services, satellite links are nothing else than very efficient replacements for connection to mobile phones or data terminals, or for long-distance cables of national and international networks. In private networks, two or more stations are connected with each other via a satellite.
The area on the earth's surface that the antennas of a satellite can cover, determines the range of a satellite. This area is called the satellite's "footprint" and can extend over the whole surface "visible" from the satellite or regions of particular importance for the network the satellite serves. Two fundamentally different types of satellite are most often used for telecommunications:
Geo-stationary satellites are positioned in an orbit above the equator and rotate at a speed corresponding to the rotation of the earth. This position can be maintained only at a specific distance from the earth. All satellites of this type are lined up around the globe like pearls on a string. They appear to be stationary, allowing the use of highly directive and therefore very efficient antennas, without the need to continuously adjust the antenna position. The use of high performance antennas is necessary, as the long distance to geostationary satellites can be bridged only by strong signals. [illustration 3.8]
The "satellite dish" or parabolic antenna used for TV reception is typical for the fixed, high performance antennas used with geostationary satellites. Bigger parabolic antennas are used to not only receive, but also transmit and receive higher volumes of data to and from telecommunication satellites. The closer the ground station or user is located to the equator, the steeper is the vertical angle or elevation of the antenna. On the equator, the antenna will almost "lay on its back". A geostationary satellite cannot cover the polar areas. [illustration 3.9]
Non-geostationary satellites can be positioned in a multitude of orbits. Lower orbits require higher speeds, and such satellite will consequently circle the globe many times per day. The much lower orbits do however allow the use of less efficient antennas and very low power, making it possible to use even hand-held phones without high performance antennas. Non-geostationary satellite orbits are usually designed in a way, that the whole globe is covered, including the Polar Regions. [illustration 3.10] [illustration 3.11]
The owner or operator of a telecommunication satellite is usually a commercial enterprise. The operator often leases capacity or bandwidth on the satellite to one or more service providers, who in turn sell their services to the user. In public networks, these users are mostly the providers of public network services; for private network, the actual users rent bandwidth for their specific needs.
Keeping these basic facts in mind, we shall now look at some of the typical satellite networks used in emergency telecommunications. More details on the systems mentioned in the following are available at their respective web sites
Inmarsat was the first provider of mobile satellite telecommunication services. Initially focusing on the needs of the maritime service, they quickly also became very popular with other users requiring communication with remote and isolated locations.
Different types or "standards" of Inmarsat equipment allow the transmission of voice and data. Inmarsat ground stations provide connection into all types of public networks. Inmarsat uses geo-stationary satellites, positioned over the Atlantic, Pacific and Indian Ocean, thus covering the whole globe - with exception of the Polar Regions.
In emergency operations, Inmarsat terminals are most suitable for temporary fixed installations, because their directive antennas must be pointed towards the satellite. For mobile applications on vessels or vehicles while in motion, complex systems are needed to continuously correct the antenna position. Using only 4 satellites, each of them covering roughly a quarter of the world and the capability to provide a large number of simultaneous links, the Inmarsat network is somewhat less overload-prone than terrestrial public networks.
Thuraya is a geo-stationary system with coverage of only part of the globe. Its satellites use high power and very large, high performance antennas, allowing communication with low-power hand-held phones not much bigger than normal mobile phones. To a limited extent, Thuraya phones also allow data communication when connected to a laptop computer or other peripheral equipment. The antennas on the phones are bigger than on a terrestrial mobile phone, but need not be aimed accurately. For the user, the Thuraya phone is simply a mobile phone with global coverage. Whenever it is used within the range of a terrestrial cellular GSM network, it will connect to this network rather than establishing contact with the satellite. This is particularly useful, when the user is indoors; different from mobile phones, satellite phones cannot normally operate inside buildings.
Iridium and Globalstar are typical non-geostationary systems. In both cases, numerous satellites circle the earth, each spot on its surface being within the range of at least one satellite at any given time. The coverage of Iridium is truly global, as calls are forwarded from the satellite in contact with the subscriber via other satellites until one is reached that has contact with the ground station. In the Globalstar system, a satellite needs to have contact with the subscriber and with a ground station at the same time, and that the limited number of ground-stations limits the coverage of the system. Like the Thuraya phones, Iridium and Globalstar equipment automatically connects through a terrestrial mobile telephone network, wherever such a service is available.
Non-geostationary systems are somewhat more overload-prone than geostationary systems, because each satellite covers only a relatively small area and can handle less simultaneous communications than the large-area geostationary satellites. A sudden increase of demand in the area covered by one satellite can therefore saturate its capacity more easily. In emergency telecommunications, all above systems have their applications. Additional systems are in use in some parts of the world, and satellite telecommunication technology is developing very rapidly.
In Private Networks, satellite links can replace terrestrial long distance radio communication. After the type of antennas used, they are called VSAT, "Very Small Aperture Terminal" systems. The user leases channels on a satellite, operated by a commercial telecommunication satellite operator. The network is therefore no longer fully under the control of the user, but it remains a private network, as it does not provide a public service. The terminals and all related equipment on both ends of a VSAT link are provided by the user.
VSAT links are useful when larger bandwidth than that of shortwave radio links is required. A VSAT network provides voice and data channels; the cost for such a link is much higher than that for a shortwave radio link. A VSAT link can however, if its terminals are linked to the appropriate peripheral equipment, carry broadband services such as needed for full Internet access. In emergency telecommunications, VSAT systems are not commonly used during the initial phase of rapid response, but they are very valuable tools in operations of longer duration. Typical users are international organizations but VSAT systems also have many commercial applications in trade and industry.
Installing a VSAT network needs in any case the expertise of a specialist.
For details about VSAT see www.gvf.org/index.cfm
Co-operation is the key to success in emergency response. Like all social interaction, co-operation in an emergency situation depends on the goodwill of the partners. In order to make a wanted co-operation work, partners need to communicate; telecommunications help them to do so, they cannot, however, replace the initial will to work together and to accept co-ordination.
For emergency telecommunication, the ideal solution would be full inter-operability. Technical reasons do not always allow this. Interfaces offer the next best solution; connection points between different networks can forward information that needs to be exchanged between the users of separate, technically or operationally incompatible networks.
Co-ordination mechanisms need to be in place for both of the above solutions. Like all co-operation, co-ordination requires the will to work together, the will to share information and resources. Emergency telecommunication preparedness plans need to include the modalities and mechanisms of interfacing or, wherever possible, and at least try to achieve inter-operability.
Among VHF, UHF and HF radio networks, inter-operability depends mostly on two factors, communication modes and communication frequencies. Stations equipped for voice communication on VHF or UHF use frequency modulation, a mode which ensures good sound quality, high resistance against interference, and user friendly operation of the equipment. They all operate within the frequency ranges or bands internationally allocated to the land mobile service, and inter-operability it therefore primarily a matter of common frequencies or channels. Even a repeater station can be shared among different groups of users, if they all agree on the operational procedures. The practical limits are set by the size of such a network; as only one station can transmit at the same time, the network may easily become congested.
In a local network, the solution to this operational problem is the establishment of network plans attributing channels to separate networks for the communication among individual groups of users, in addition to a common network, allowing information exchange between such user groups This allows the use of the same equipment but the efficiency of such a combined network requires discipline and the strict compliance of all users with established procedures.
In medium- or long-range networks, the solution can be similar. Technical aspects however are making its implementation more complex, and specialist advice will be required to ensure technical as well as operational inter-operability. International networks include stations subject to different national regulations, which may restrict their ability to conform to a concept of shared frequencies. We shall have to consider this issue in more detail when looking at regulatory matters in module 5 of this course.
Interfaces are indispensable when communication among users of different communication modes is to be established. A VHF station can in no case communicate with an HF station, and the same applies to the exchange of information between a station operating in voice mode and one using a data mode. A telephone cannot "talk" to a fax machine, and an FM broadcast receiver can not hear shortwave broadcast programs.
Most interfaces need be operated manually. They require the intervention of an operator, who receives the information from one network and re-transmits it in another format and mode on another network. In some cases, automatic interfaces are possible; one example for this is the "phone patch", by which a fixed station is able to establish a connection between a mobile station and a subscriber of the public telephone network. In some cases, even networks using different modes can communicate automatically, examples are phone calls made from a computer with Internet connection to subscribers of the public telephone network (the mode is known as "voice over IP", IP standing for "Internet Protocol") or the transmission of fax messages from and to Internet connected terminals.
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