Topics:
| 4.1 | Who do you want to talk to? |
| 4.2 | Licences |
| 4.2.1 | Applying for a licence |
| 4.2.2 | Licence Fee |
| 4.2.3 | Frequency choice |
| 4.2.4 | Limitations |
| 4.2.5 | Import Licence |
| 4.3 | What type of radio communications? |
| 4.3.1 | Citizen Band |
| 4.3.2 | VHF |
| 4.3.3 | Amateur Radio |
When it is decided that your group needs some form of communication and could benefit from a radio communication network you should consider what this implies in some detail. Before you get down to choosing a transceiver from the glossy brochures there are some general aspects to be considered. What are the facilities you would like and what facilities you can actually afford to buy, licence, operate and maintain? What form of radio communication between which places will the Government of the country permit? You may plan several different systems on paper before you arrive at the one which is acceptable in all its aspects. Keep all your various plans because you could find that after going through various planning and costing stages and through government departments etc. you need to go back to an earlier plan!
The first stage of your planning should be to take a good look at the present method of communication between your locations and to make an assessment of their needs. Look at how long it takes to get urgent and routine information passed on, how much it costs, how far away from good roads each location is and from towns that might possibly have a telephone link or from other groups with a radio link. Then decide which locations have the highest priority for a radio link. You will probably give priority to the most isolated and distant places but there may be others which could be usefully linked by radio even though they are more accessible.
You may think that a place with a good road link does not need a radio even though it has no telephone, that in an emergency a journey by vehicle could be made. However where the costs of running a vehicle are high, where there can be risks of fuel shortages and the availability of vehicles are often in doubt, then a radio link may prove invaluable in an emergency situation as well as cost effective in routine matters. You must think carefully about the advantages and possible disadvantages. For instance, while radio messages will certainly speed up your communications, it is possible that they can also put understaffed headquarters under a lot more pressure as outlying stations may come to expect instant responses to their demands. You do not want the introduction of a radio link to become "more nuisance than it's worth!"
You should decide which location is to be your Headquarters (HQ) station and most likely use this station to control the operation of the radio network. At this stage you should plan for locations to be able to speak directly with each other rather than have messages relayed by intermediate stations as this can be a source of introducing errors into messages. There is a party game where one person whispers a message to the next person and so on until it is relayed round the room to the last person. Invariably the message quoted at the end differs considerably from the original one. This demonstrates the hazards of relaying messages by speech. From Table 4.1. emerges the number of transceivers required, the distances that each station has to communicate over and the cost of the present method of communications.
Table 4.1.Existing methods and cost of communications.
Making a list similar to this for all your stations should help you decide which places really need a radio. When you have reached this decision then draw a geographical map to scale showing the locations of the proposed radio stations with respect to the HQ station. Join together with a straight line the stations which are to speak directly to each other. Write beside each line the number of kilometres it represents, see the example in Fig.4.1. Let this be your basic plan for the future network.
Licences for radio communication equipment are usually obtained through the national post and telecommunications office of the country concerned. e.g. in Zaire - Office National des Postes et Telecommunication du Zaire (ONPTZ). Whilst these deal with the technical aspects, approval may also be needed from the state security. So you should have a licence before you use your radio or you may be in trouble!
4.2.1. Applying for a licence
Attempt to discover all the information you can about licensing conditions before you purchase your radio. You may be able to get information from the authorities or from other groups who are already licensed to operate. There may be a central body which is experienced in applying for licences and may handle the applications for you. In Zaire such a body is L'Eglise de Christ du Zaire (ECZ) which is recognised by the Government as representing the Protestant Churches. Obtaining licences can sometimes take a long time and you may have to fill in many forms and supply technical specifications and circuit diagrams of the radios you intend to use together with maps and plans of your network for each proposed station. You should obtain the technical specifications and circuit diagrams from the manufacturer of the radio you hope to use but you should not purchase or import your radios until you have the licences for them, sometimes the condition of importing them is that you must have the licence first. Also it is possible that the authorities might not give you the required permission or might impose limitations on the sort of radios you can use.
Some countries may wish to study a complete technical specification of the particular type of radio in order to give "type approval" before it is imported and used there. Sometimes "type approval" may have been given previously to another group using that particular radio so this is one stage where you may experience little delay. If "type approval" is a necessary stage in your particular country, enquire which types of radio have already been approved in this way as it could be helpful for you to chose one that has been approved. Do ask people who are already licensed for advise on all the things you can, e.g. you might learn, perhaps, that it is better to apply for more licences than you need because it is the practice of the authorities to only grant five out of ten applications.
One question which appears on application forms is often "What is the distance to the nearest public telephone?" It is reasonable that if the national telephone service has provided a telephone system, both private and public, that works then it should be used where possible. The operative words being "that works". The national telephone networks of several countries in East Africa are being extended into the rural areas, some telephones being linked by VHF radio not by telephone wires. One mission with 55 licensed radio stations in its network had the licences of 20 stations withdrawn as telephones became available as an alternative means of communication. Before spending a large sum of money on a radio telephone network it would be as well to enquire if there are plans to extend the national network to any of your areas. The plans and timetable of any proposed extension of the national system should be looked at through the eyes of experience of that particular country. To some authorities success is the provision of marvellous plans and this is an end in itself. The fact that these plans may never be implemented for years or decades is of no consequence.
4.2.2. Licence Fee
The annual licence fee for a transmitting station varies greatly from country to country. In 1987 the licence fees in some African countries varied from the equivalent of £25 to £75 per station. It is an offence to operate a transmitter without a current licence therefore it must be renewed annualy.
4.2.3. Frequency choice
When applying for your radio licence you can mention the time of day you want to speak over the radio link, the distances to be covered and suggest a suitable frequency. You may then be allocated a frequency of the order you require. Alternatively you may be given a frequency and have to schedule your operating times on it for satisfactory ionospheric propagation. See the information on propagation in Chapter 1.
4.2.4. Limitations
You may wish to use a synthesised transceiver capable of operating at any frequency from 2 to 30 MHz. However the ability to transmit on all these frequencies may not be acceptable to the licensing authorities. You may only be permitted to use a transceiver containing the frequencies for which you have been licensed. Your plan may be for a network with twenty stations with whom you wish the HQ station to communicate direct as suggested in 4.1. Such an arrangement may not be agreed by the licensing authority. For instance they could suggest that your twenty stations be divided into four groups of five stations. Each group having a principal station with whom the other four communicated and only these four principal stations permitted to communicate directly with HQ. The reason for this might well be that they do not want too many high-powered stations and they could limit the power of the subsidiary stations in each group to, perhaps, only 25 or 40 watts depending on the local situation.
4.2.5.Import Licence
At the same time as you apply for the licence to operate the radios you should also enquire if a licence is needed to import them. Enquire about customs charges and if any exoneration from duty is available to churches or aid agencies. If the radios are being purchased by a mission or aid agency in another country as a gift to your organisation you may need papers giving proof of this. It is important to make sure that you have all necessary documentation with the equipment when it arrives or it could be stuck in a customs store while you obtain what you need. In such a situation there is always a danger of loss or damage as well as the risk of being charged large sums of money for storage.
There are many different types of radio communication ranging from local Citizen Band (CB) to the men who talked to earth from the moon! Within each type there are many methods of transferring information, for example by the spoken word, morse code, teletype, picture and data transmissions. Methods of radio communication normally used by groups who have no access to a telephone are CB, VHF (Very High Frequency) and HF. The subject of CB and VHF are covered briefly but the main concern of this book is with HF radios.
4.3.1. CB
The use of CB radio is authorised by the Governments of many countries. There are no international regulations for standardising the service,though the majority of countries allocate frequencies in the range 26.96 to 27.41 MHz. One country allocates 49 MHz and a further two allocate frequencies between 476 and 479 MHz. The U.K. has made an allocation just above 900 MHz as well as 27.6 to 29.9 MHz. Typical values of maximum transmitter power allowed is 5 watts of FM and AM and 12 watts of SSB, though some countries limit the power to 0.1 watt. The result is that legal CB is meant to be for local use, typically up to 8 kms range. But if one or both stations are on high ground then longer ranges are possible. Also if the transmitter power is increased to 40 or 100 watts or if beam aerials are used ranges up to 30 kms. may be achieved.
The types of modulation used in CB sets can be AM, FM and SSB. Some sets are capable of producing all three types of modulation and have a selector switch. Other sets are only for one type e.g. AM. A FM transmission cannot be understood on a AM receiver or a SSB transmission on a FM receiver. Therefore you should ensure that any CB radios you obtain all have the same modulation system.
For a few years, each time the sunspot number is around its maximum, CB can be used for long distance contacts between countries and continents. Such contacts are often not within the terms of the CB licence. CB radios are readily available and often at low cost so depending on your distance requirements CB may be an economic solution. It is a useful solution for communication within a mission or other establishment e.g. a hospital complex, where the buildings are spread over a wide area and where an internal telephone system would be impossible to install and maintain owing to its high cost and to the possible theft of overhead lines as has happened in some cases. CB has proved to be very useful within towns and cities which have no satisfactory telephone system. For it to provide a good service some form of co-ordination is necessary. In one African city a mission group took the lead and produced a list, updated twice a year, of some eighty CB users. This gave the channel on which each one listened and their individual call-sign. The CB transceivers were left switched on all day, with the squelch control set to prevent noise from the loudspeaker until a signal was received. So by using the correct channel and callsign one could call a required station as easily as using a telephone. Most CB sets have forty channels, others may have eighty.
4.3.2. VHF
VHF can be a reliable form of communication as it is not dependent upon the fluctuations of the ionosphere but its range is limited. For networks using 25 watt transmitters ranges up to 80 kms. may be achieved. However the range is very dependent upon the topography of the area. A rough guide is that if there is a "line of sight" between the two VHF aerials then communication is possible. Range can be extended beyond the horizon and round intervening hills by unattended automatic VHF relay stations. These can be located on a hill or high building and can greatly increase the area served by VHF transceivers. This is because there can be line of sight from each station to the elevated repeater even though stations are not visible to each other. Therefore it may be possible for all stations within a 80 kms. radius of the repeater to communicate with each other. VHF systems often operate in the 70 and 150 MHz region. The operational requirements for a VHF radio network should be specified with the help of a radio engineer who would then produce a plan and a list of appropriate equipment to satisfy your needs.
4.3.3. Amateur Radio
The facilities provided by the amateur radio service should not be confused with CB or privately licensed networks. Amateur frequencies are allocated on an international basis and range from 1.8 MHz to 10,000 MHz and enables global communication including the use of satellites. All types of communication are possible including normal speech, television, teletype and computer talking to computer. However as the name suggests the facilities are intended for the amateur enthusiast and not for commercial organisations. The restrictions on what communication can be performed by amateur radio varies from country to country. Most countries expect the amateur to pass certain examinations before a licence is issued and some will only permit the licence holder himself to speak on the radio. Others will allow anyone to speak under the supervision of the licence holder. Also others e.g. USA, will allow the amateur to connect his amateur friend from another country into the telephone system via the radio so enabling him to speak to non-amateurs. Unfortunately in UK for example this is never permitted. Amateurs are also expected to co-operate with the International Red Cross and Government departments during disaster and relief operations. The facilities of the amateur service are many and varied and are also continually increasing therefore you should enquire if the amateur service is relevant to your situation and if so encourage some of your personnel to obtain an amateur licence. Many expatriates use amateur radio for a daily or weekly talk with their friends in their home country. However it should be noted that some countries put many restrictions on amateurs, others make it difficult to obtain licences while a few ban amateur radio completely.